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OPTO 292 - Introduction to Optometry

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					Course:       Introduction to Optometry     -     OPTO 292


Credits:      2 (hours for theory) + 0 (practical hours) = 2


Tutor:        Dr Kelechi Ogbuehi



Course Outline

      A Brief History of Optometry
      What role does Optometry play in the protection and promotion of
       Visual Health?
      A sample of rules and regulations governing the practice of
       Optometry
      What is the course content of a standard Optometry course?
      An overview of what you need to know to deliver proper optometric
       services to your community


Recommended Texts and Research Sources

1.       www.dos.state.pa.us/bpoa/lib/bpoa/20/opto_board/act_130-
         optometry-k0803.pdf
2.       www.wisegeek.com
3.       http://www.ishim.net/ishimj/4/10.pdf.
4.       Clinical Ophthalmology by Jack Kanski. Butterworth-Heinemann




OPTO 292 -      Introduction to Optometry - 2 + 0 = 2                 1
LECTURE 1


An optometrist is a doctor of optometry (O.D.), rather than a medical doctor. The
optometrist is licensed to conduct eye exams, prescribe corrective contact lenses and
glasses, and diagnose and treat eye disease. He or she will work through various vision
therapies to treat abnormalities, and can prescribe drugs for the eyes. If surgery is
required, the patient is sent to an ophthalmologist (specialized M.D.).

Many people mistakenly believe that an ophthalmologist, as a medical doctor, is better to
see for routine eye exams than an optometrist. Though there is nothing wrong with seeing
an ophthalmologist, his or her expertise is in surgery, while the optometrist specializes in
the kind of care required for routine eye exams and non-invasive therapies and treatments
for eye disease. If a problem arises that can be treated with surgery or alternate therapies,
the ophthalmologist might be more likely to suggest surgery, while the optometrist will
likely exhaust other potential treatments first. Unless a problem exists that requires an
ophthalmologist, an optometrist will likely be a more cost-effective choice for routine eye
care. A pertinent point to stress at this juncture is that all ophthalmic surgeons (who
perform surgery on the eye) must be ophthalmologists but not all ophthalmologists are
ophthalmic surgeons.

In the United States, a person that has completed at least three years of higher education
at an accredited university or college is eligible to attend an accredited four-year school
in optometry. Therefore, like all other professional courses (e.g. Medicine, Dentistry and
Law) Optometry in the States is what is usually referred to as a second degree course.
The Optometry degree course is followed by state board examinations, both written and
clinical. The optometrist may then choose to complete an additional one-year residency
to specialize in any number of areas including family practice, ocular disease, paediatric
optometry and vision therapy.

A routine eye exam is generally recommended at least once yearly. If you are
experiencing problems with your vision such as blurriness, burning or stinging, dryness
or loss of visual acuity, it is wise to see an optometrist immediately.




OPTO 292 -        Introduction to Optometry - 2 + 0 = 2                                 2
An Overview of the History of Optometry

Learning history is more about learning from the past to guide us for the future, taking
pride in those that have come before us, and placing what we do in its proper context,
than it is about memorizing names and dates. So the list of names below is meant as a
spelling guide rather than a list of names to be memorized:

Aristophanes
Euclid
Claudius Ptolemy
Johannes Kepler
Sir Isaac Newton
Snell
Monoyer
Empedocles
Leucippus
Democritus
Aristotle
Alhazen
Thomas Young
George Biddell
Airy Goodrich
John McAllister, Sr.
Christoph Scheiner
Aguillon
William Porterfield
Johannes Purkinje
Charles Wheatstone
Hermann von Helmholtz
Roger Bacon
Rivalto
Benito Daza de Valdes
William Molyneux
Peter Brown
John McAllister, Jr.
James W. Queen
 Benjamin Pike
James Prentice
Charles Prentice
Thomas Hall Shastid
James Cook McAllister
William Young McAllister
John P. Davey
Irvin Borish
Virgil McCleary
Hermann Wells

OPTO 292 -        Introduction to Optometry - 2 + 0 = 2                               3
Hermann Briscoe
Henry W Hofstetter
Merrill Allen
Gordon G. Heath
These are names of some of the luminaries in who have contributed immeasurably to the
establishment and practice of Optometry as we know it today. Unfortunately, an
exhaustive rendition of each individual’s contribution to our profession is beyond the
scope of this course but the student is encouraged to pick names at random and research
their contributions to Optometry.

1. What are the origins of optometric science?

1a. Optics
There is evidence that lenses for decoration existed up to 5000 years ago.

The ancient Greek author Aristophanes wrote in 434 BC about a burning glass.

The Greek mathematician Euclid in about 280 BC wrote about light travelling in
straight lines and the equality of the angles of incidence and reflection. He also talked
about the concept of the visual cone which is the equivalent of our concept of visual
angle today.

Claudius Ptolemy in about 150 AD measured angles of incidence and reflection from
air to water but did not discover the exact mathematical relation.

Johannes Kepler (1571-1630) presented many of the concepts taught today in geometric
optics.

Sir Isaac Newton showed how white light could be split into component colors
(dispersion) and then recombined into white light.

Snell discovered the law of refraction in 1621. Snell died at 35 years of age, and his
contribution was not widely recognized until after his death.

Inventor of the term diopter - Monoyer, 1872.


1b. Image formation by the eye

Empedocles (c. 450 BC) - Extromission theory, visual ray.

Leucippus, Democritus (5th century BC) - Intromission theory, eidola.

Aristotle (4th century BC) - Mediumistic theory

Alhazen (965-c.1041 AD) - proved intromission

OPTO 292 -        Introduction to Optometry - 2 + 0 = 2                                  4
Johannes Kepler - First accurate description of image formation on the retina

Thomas Young (1773-1829) - First to measure astigmatism (1801)

George Biddell Airy - English astronomer credited with being the first to design and
wear a spherocylindrical lens to correct astigmatism .


1c. Sensory physiology

Christoph Scheiner (1611) - Described several observations about the eye, including
the size of images reflected from the cornea. His double aperture principle is used in
most present-day autorefractors.

The mathematician Aguillon published one of the first significant analyses of
binocular vision in 1613.

William Porterfield made an optometer in the mid 1700s and noted the existence of a
relationship between accommodation and convergence.

Thomas Young - Trichromatic theory of color vision and crystalline lens as source of
accommodation.

Johannes Purkinje, Czech physiologist, published books on sensory physiology in
1823 and 1826. His name is attached to many phenomena - Purkinje images,
Purkinje tree, etc.

Charles Wheatstone invented the mirror stereoscope and in 1838 used it to
experiment on binocular vision and stereopsis.

Hermann von Helmholtz (1821-1894), physiologist and physicist, wrote A Handbook of
Physiological Optics.

According to Hofstetter, the background sciences for early optometry were stronger than
for any other profession. Optometry has incorporated knowledge of optics, mathematics,
psychology, and other sciences. Optometry has developed its own literature in clinical
practice and vision science. Optometry has been the leader in investigations on clinical
lens application, non-strabismic binocular vision problems, contact lenses, low vision,
role of vision in learning, etc.



2. When were the first spectacles made?

The exact origin and inventor of spectacles are unknown.



OPTO 292 -       Introduction to Optometry - 2 + 0 = 2                                 5
Roger Bacon in the middle 13th century talked about placing a planoconvex lens on
text for magnification.

Spectacles probably originated in the late 13th century in Italy. In a manuscript from
1305 AD, a monk from Pisa named Rivalto wrote, “It is not yet 20 years since there
was discovered the art of making eyeglasses.”


3. When were the first optometry books published?

In 1623 Benito Daza de Valdes published a book which covered optics, ocular
anatomy, and the use and fitting of spectacles. He included a system of lens grades
for lens power, and he resented a table of lens grades according to age in
presbyopia. He suggested that minus lenses for myopia should not be so powerful
as to cause perceived reduction in image size. Daza de Valdes also included case
reports.

William Molyneux published an optometry book in Ireland in 1692. He suggested
using the weakest lens that solves the problem and he discussed the occasional nearpoint
problems of myopes when they get new glasses.


4. How is optometry different from medicine?


4a. legally

Legal cases in the first half of the 20th century ruled that optometry was separate from
medicine.


4b. origins

Their origins differ both in the sciences from which they developed and in the shift of
tradesmen into the professions.

Scientific origins: optometry – optical sciences, medicine – biological sciences
tradesmen who entered the respective professions: optometry – jewelers (they had
the tools to work on spectacles), medicine – barbers (they had the equipment with
which early surgeries could be done)


4c. Areas of primary expertise

Optometry:     optics, refraction, vision science, non-strabismic binocular vision and
               accommodative problems.

OPTO 292 -        Introduction to Optometry - 2 + 0 = 2                                  6
Medicine:      surgery, anatomy and physiology, pharmacology, disease


5. What were optometrists called before they were called optometrists?

First use of the term optometrists is thought to have been by Landolt in 1886 to
describe the fitting of glasses. The term became popular in the first two decades of
the 20th century. Before then optometrists were usually referred to as opticians.
In the 19th century there came to be a distinction between refracting opticians and
dispensing opticians. Refracting opticians became known as optometrists.


6. When was the American Optometric Association formed?

It was formed in 1898 as the American Association of Opticians. In 1910, the name
was changed to the American Optical Association. By this time, many of its members
called themselves optometrists. In 1919, the name was changed to the American
Optometric Association.


7. When did the existing US optometry schools start?

Private schools:

•Illinois College of Optometry traces it roots to 1872 (some of its predecessor
schools were Northern Illinois College of Ophthalmology and Otology, Needles
Institute, Northern Illinois College of Optometry, Monroe College of Optometry,
Chicago College of Optometry)

•New England College of Optometry traces its roots to 1894 as the Klein School of
Optics (NEWENCO was at one time known as Massachusetts College of Optometry)

•Southern California College of Optometry started in 1904 as the Los Angeles
Medical School of Ophthalmology and later known as the Los Angeles College of
Optometry

•Pennsylvania College of Optometry, 1919

•Southern College of Optometry, 1932


University schools:

•Ohio State University, 1914

•University of California Berkeley, 1923

OPTO 292 -         Introduction to Optometry - 2 + 0 = 2                               7
•Pacific University, 1945 (originally North Pacific College of Optometry, a private
school founded in 1921)

•Indiana University, 1951 (pre-optometry started in 1951; first professional optometry
class started in 1953)

•University of Houston, 1952

•University of Alabama Birmingham, 1969

•State University of New York, 1970

•Ferris State University (Michigan), 1974

•Northeastern State University (Oklahoma), 1979
•University of Missouri St. Louis, 1980

•Inter American University of Puerto Rico, 1981

•Nova Southeastern University (Florida), 1989




OPTO 292 -       Introduction to Optometry - 2 + 0 = 2                                8
LECTURE 2

8.       How did the use of the Doctor of Optometry (OD) degree develop?

Various doctor titles were awarded even before 1900. The Philadelphia Optical
College may have been the first give a doctor’s degree to optometry graduates when it
awarded the Doctor of Optics degree in 1889. Before about 1920, optometrist
generally resisted using the term doctor, but this attitude gradually changed through
the 1930s and 1940s.

In 1950, all ten of the optometry schools in existence at the time required five years of
study past high school.
The private schools all offered the OD degree. Ohio State,

University of California Berkeley and Indiana did not offer the OD degree until
It switched to a six year pre-optometry and optometry curriculum.

Indiana University graduated its first OD class in 1968 and Berkeley graduated its first
OD class in 1970.


9.       What were the original stimuli for optometry to start studying ocular disease,
         and when were the first optometry diagnostic and therapeutic
         pharmaceutical agent laws passed?

Original stimuli for optometry to move into the area of ocular disease:

        Interest of some optometrists

        Optometrists were distributed more evenly across the country and were the only
         eye/vision practitioner in many rural areas and small towns. Optometrists had to
         refer eye disease to either the local general practice physician or to an
         ophthalmologist that may have been many miles away. Optometrists had more
         knowledge of the eye and had better instruments to view the eye (e.g., slit lamp
         biomicroscope) than the local GPs (General Practitioners), so it was good for rural
         or small town patients to be treated for minor eye disease by the local optometrist
         than by the local GP.

        Criticism by ophthalmologists - ophthalmologists sometimes had public
         campaigns that optometrists were poorly trained in eye disease

         First DPA law – Rhode Island, 1971
         First TPA law – West Virginia, 1976



OPTO 292 -         Introduction to Optometry - 2 + 0 = 2                               9
10.    What were oculists and what lesson does the history of oculists and
       ophthalmologists provide for optometry today?

       Oculists were eye care physicians who did not have residency training in
       ophthalmology.

       Optometrists knew more about refraction and prescription of lenses.

       Ophthalmologists knew more about eye surgery and eye disease.

So as residency training in ophthalmology became more common, oculists were no
longer needed. Ophthalmologists were not greatly interested in refraction and eyestrain
until the late 19th century and early 20th century.

Thomas Hall Shastid quotation in Borish article, IJO, Fall, 2001, p. 24:

The MDs generally would not recognize even the existence of such a thing as
Eyestrain. If there was any worse quackery than this of the regular medical
profession, I do not know what it was. Hardly anything that now I can recall
served so much to weaken the standing and influence of physicians in any community
than this absurd, ridiculous, hard-headed, stubborn...opposition to the fitting of
glasses.

Along with the spec-peddlers that Shastid refers to, persons who provided people
in need with spectacles included respectable and professional optometrists, but in
the minds of many physicians, the optometrists were not much better than the spec-
peddlers.

As American ophthalmologists started realizing the importance of spectacles, they
learned the methods of refraction from optometrists - quotation on pages 136-137 of
Hirsch and Wick discusses how the McAllisters taught oculists how to do refractions
The emphasis on good refraction techniques by optometrists and the precedence of
optometrists in refraction has resulted in our pre-eminence in this area to the present
day.

Lesson for today: Every profession justifies its existence (in part) by being better at
something than any other profession (a niche). We need to maintain our strength in
the treatment of refractive problems and eyestrain.

11.    What are some major optometric organizations and when did they begin?
a.     American Optometric Association mentioned earlier

b.     American Academy of Optometry - organized in 1922, serves to promote
       professionalism and high standards of patient care and to disseminate information
       through its journal, Optometry and Vision Science (previously known as
       American Journal of Optometry and Archives of the American Academy of

OPTO 292 -        Introduction to Optometry - 2 + 0 = 2                                   10
     Optometry and then later as the American Journal of Optometry and
     Physiological Optics).


c.   Optometric Extension Program traces its roots to a plan developed by the
     Oklahoma Optometric Association in 1928 for membership education.

     It quickly became a nationwide organization. It developed a standardized system
     of testing with numbered tests that helped promote standardization of testing that
     was badly needed at the time.

     Today OEP emphasizes what is often referred to as behavioural optometry.

d.   College of Optometrists in Vision Development developed in the early 1970s
     This is an organization of optometrists who practice vision therapy.
     They offer a certification program. Optometrists who complete it are Fellows of
     the College of Optometrists in Vision Development (FCOVD).




OPTO 292 -     Introduction to Optometry - 2 + 0 = 2                              11
LECTURE 3
What is an optometrist? – General Definition

An optometrist is a doctor of optometry (O.D.), rather than a medical doctor. The
optometrist is licensed to conduct eye exams, prescribe corrective contact lenses and
glasses, and diagnose and treat eye disease. He or she will work through various vision
therapies to treat abnormalities, and can prescribe drugs for the eyes. If surgery is
required, the patient is sent to an ophthalmologist (M.D.).

Many people mistakenly believe that an ophthalmologist, as a medical doctor, is better to
see for routine eye exams than an optometrist. Though there is nothing wrong with seeing
an ophthalmologist, his or her expertise is in surgery, while the optometrist specializes in
the kind of care required for routine eye exams and non-invasive therapies and treatments
for eye disease. An ophthalmologist will normally have higher fees than an optometrist,
and might hand off much of the routine exam to an in-house optometrist anyway. If a
problem arises that can be treated with surgery or alternate therapies, the ophthalmologist
might be more likely to suggest surgery, while the optometrist will likely exhaust other
potential treatments first. Unless a problem exists that requires an ophthalmologist, an
optometrist will likely be a more cost-effective choice for routine eye care.

In the United States, a person that has completed at least three years of higher education
at an accredited university or college is eligible to attend an accredited four-year school
in optometry. This is followed by state board examinations, both written and clinical. The
optometrist may then choose to complete an additional one-year residency to specialize in
any number of areas including family practice, ocular disease, paediatric optometry and
vision therapy.



A Sample of Laws Governing the Practice of Optometry – Pennsylvania State, USA


Examination and diagnosis.

Any examination or diagnostic means or method compatible with optometric education
and professional competence. The term shall encompass the use of pharmaceutical agents
for diagnostic purposes classified as miotics, mydriatics, cycloplegics, topical
anaesthetics and dyes when applied topically to the eye, which pharmaceutical agents
shall be approved by the Secretary of Health as provided
in section 4.3 and, subject to the rules and regulations of the board, provided however
that with respect to optometrists licensed before March 1,
1974, only such optometrists who have satisfactorily completed a course
in pharmacology as it applies to optometry, with particular emphasis on
the topical application of diagnostic pharmaceutical agents to the eye,


OPTO 292 -        Introduction to Optometry - 2 + 0 = 2                               12
approved by the board shall be permitted to use diagnostic pharmaceutical agents
topically in the practice of optometry. (Def. amended Dec. 16,
2002, P.L.1950, No. 225)


Fitting of contact lenses

A procedure in which a prescribed contact lens is placed upon the eye of a patient and the
lens-cornea relationship is evaluated with the use of a biomicroscope or slit-lamp.


Optometrist.

Any person who, following formal and recognized training in the art and science of
optometry has received a doctor of optometry degree from an accredited institution and is
qualified to seek or has acquired a license to practice the profession of optometry.

An optometrist shall be identified either by “Doctor of optometry (OD) or “Dr.” followed
by “Optometrist.”


PRACTICE OF OPTOMETRY

The practice of optometry encompasses the following:

      The use of any and all means or methods for the examination,
       diagnosis and treatment of conditions of the human visual system and shall
       include the examination for, and adapting and fitting of, any and all kinds and
       types of lenses including contact lenses.

      The administration and prescription of legend and non-legend drugs as approved
       by the Secretary of Health as provided in section 4.3 for treatment of the eye, the
       eyelids, the lacrimal system and the conjunctiva and the removal of superficial
       foreign bodies from the ocular surface and adnexia so long as treatment of
       diseases or conditions of the visual system, other than glaucoma, as authorized
       under this paragraph shall not continue beyond six weeks from the initiation of
       treatment unless the prescribing optometrist documents consultation with a
       licensed physician. As used in this paragraph, the initiation of treatment may, but
       need not, include the prescription or administration of pharmaceutical agents for
       therapeutic purposes.

      The practice of Optometry shall not include:

           o Surgery: Including, but not limited to, laser surgery; the use of lasers for
             therapeutic purposes; and the use of injections in the treatment of ocular
             disease.

OPTO 292 -       Introduction to Optometry - 2 + 0 = 2                               13
            o the use of Schedule I and Schedule II controlled substances.

            o treatment of systemic disease.

            o the treatment of glaucoma, except that optometrists may use all topical
              pharmaceutical agents in the treatment of primary open angle glaucoma,
              exfoliation glaucoma and pigmentary glaucoma.

(Def. amended Dec. 16, 2002, P.L. 1950, No.225)



Treatment

This is defined as the use of any and all preventive and corrective means and methods for
aid to the human visual system and shall include but is not limited to the adapting and
fitting of any and all kinds and types of lenses and devices including contact lenses and
the provision of vision developmental and perceptual therapy or ocular exercise for aid to
or enhancement of visual functions.

(2 amended Oct. 30, 1996, P.L.721, No.130)



Section 4             General qualifications for licensure.

      A person holding a Doctor of Optometry degree from an accredited optometric
       educational institution in the United States or Canada, who furnishes the board
       with evidence that he is at least 21 years of age, has completed the educational
       requirements prescribed by the board and is of good moral character, is not
       addicted in the use of alcohol or narcotics or other habit-forming drugs and who
       pays the appropriate fee may apply to the board for examination for licensure.


      The board may establish further requirements to be met by optometric graduates
       from unaccredited schools or colleges of optometry before granting such
       graduates the right to take an examination.


      An applicant who knowingly makes a false statement of fact in an application for
       examination shall be deemed to have violated this act and shall be subject to the
       penalties set forth herein.




OPTO 292 -        Introduction to Optometry - 2 + 0 = 2                             14
        The board shall not issue a license to an applicant who has been convicted of a
         felony under the act of April 14, 1972 (P.L.233, No.64), known as “The
         Controlled Substance, Drug, Device and Cosmetic Act,” or of an offence under
         the laws of another jurisdiction which, if committed in this Commonwealth,
         would be a felony under “The Controlled Substance, Drug, Device and Cosmetic
         Act,” unless:

                1.      at least ten years have elapsed from the date of conviction.

                2.      the applicant satisfactorily demonstrates to the board that he has
                        made significant progress in personal rehabilitation since the
                        conviction such that licensure of the applicant should not be
                        expected to create a substantial risk of harm to the health and
                        safety of his patients or the public or a substantial risk of further
                        criminal violations.

                3.      the applicant otherwise satisfies the requirements of this act.




COURSE CONTENT OF A STANDARD OPTOMETRY PROGRAM

The course contents of two university programs will be selected here.



1.       SUNY (State University of New York) State College of Optometry

Overview

The professional program leading to the Doctor of Optometry (O.D.) is four years in
duration. During the first phase of the program, students learn the basic biological and
visual sciences that constitute the foundation of clinical practice, as well as the
fundamentals of ocular examination, treatment, and therapy. Rotations through various
clinics in the University Optometric Center begin in the second professional year and
continue into the third and fourth years. During one-half of the fourth year, interns rotate
through off-campus hospitals and other health care facilities as part of the External
Clinical Education Program.




OPTO 292 -           Introduction to Optometry - 2 + 0 = 2                                15
Curriculum

First Year

This year establishes the scientific foundation for optometric practice. The program
builds from the knowledge base acquired prior to professional school and sets the
foundation for advanced basic and clinical activities during the next few years and for
one's professional life.

During this year, students are introduced to the profession of optometry, the health care
system, as well as optometric theory and clinical practice. Students are presented with the
theory as well as the methods underlying optometric practice.

A total of 15 hours for the teaching of Ethics has been integrated within the curriculum
and takes place during all four years. Specific topics are included within several other
courses including Optometric Orientation, Public Health, Geriatrics, Clinical Care, and
Clinical Seminar.

Fall Quarter

Course Title               Dept* Course Lec Lab Clinic Credit
                                                       Hours
General Histology          B      1101.01 3.0     2.0 0.0      4.0
Biochemistry &             B      1102.01 5.0     0.4 0.0      5.2
Molecular Genetics
Geometrical & Physical     V      1202.01 4.0     1.0 0.0      4.5
Optics I
Optometry I                V      1401.00 3.0     3.0 0.0      4.5
Optometric Orientation     C      1303.00 2.0     0.0 0.0      2.0
& Professional Ethics
Introduction to Clinical   C      1500.01 1.0     0.0 1.0      1.3
Care I
Total                                       18.0 6.4 1.0       21.5




OPTO 292 -        Introduction to Optometry - 2 + 0 = 2                              16
Winter Quarter

Course Title            Dept* Course Lec Lab Clinic Credit
                                                    Hours
Gross Human Anatomy B         1103.00 2.0   2.0 0.0   3.0
I
Physiology &            B     1104.01 4.0   0.6 0.0   4.3
Biochemistry I
Neuroscience I          B     1106.02 2.0   1.0 0.0   2.5
Geometrical & Physical V      1203.02 4.0   1.0 0.0   4.5
Optics II
Optometry II            V     1402.00 3.0   3.0 0.0   4.5
Introduction to Clinical C    1501.01 1.0   0.0 1.0   1.3
Care II
Total                                 16.0 8.6 1.0    20.1




Spring Quarter

Course Title            Dept* Course Lec Lab Clinic Credit
                                                    Hours
Neuroscience II         B     1106.03 2.0   1.0 0.0   2.5
Gross Human Anatomy B         1107.00 2.0   2.0 0.0   3.0
II
Physiology &            B     1108.01 2.0   0.3 0.0   2.15
Biochemistry II
Ocular Anatomy &        B     2102.10 3.0   1.0 0.0   3.5
Physiology I
Visual Optics           V     1205.04 3.0   1.0 0.0   3.5
Geometrical & Physical V      1207.01 3.0   0.0 0.0   3.0
Optics III
Optometry III           V     1403.00 3.0   3.0 0.0   4.5
Patient Care I          C     2600.00 1.0   0.0 1.0   1.3
Total                                 19.0 8.3 1.0    23.45




OPTO 292 -        Introduction to Optometry - 2 + 0 = 2       17
Second Year

The knowledge acquired in the first professional year sets the foundation for the second
year. By the end of the second year, students will be able to perform a comprehensive eye
examination. Basic knowledge acquired during this year generally is intended to enhance
the primary care clinical skills of students.


Fall Quarter

Course Title             Dept* Course Lec Lab Clinic Credit
                                                     Hours
General Pathology &      B       2101.00 4.0    0.0 0.0      4.0
Immunology
Ocular Anatomy &         B       2103.00 3.5    1.0 0.0      4.0
Physiology II
General Pharmacology I B         2106.20 2.0    0.0 0.0      2.0
Monocular Sensory        V       2205.02 3.0    1.5 0.0      3.75
Processing
Oculomotor Systems       V       2209.01 3.0    2.0 0.0      4.0
Optometric Procedures I C        2301.20 1.0    3.0 0.0      2.5
Patient Care II          C       2601.00 0.0    0.0 1.5      0.5
Total                                     16.5 7.5 1.5       20.75




OPTO 292 -        Introduction to Optometry - 2 + 0 = 2                            18
Winter Quarter

Course Title              Dept* Course Lec Lab Clinic Credit
                                                      Hours
Ocular Biochemistry       B     2104.10 2.0 0.0 0.0   2.0
General Pharmacology II B       2106.30 3.0 0.0 0.0   3.0
Microbiology I: General B       2105.20 2.5 1.0 0.0   3.0
and Ocular
Binocular Vision          V     2211.30 4.0 1.0 0.0   4.5
Ophthalmic Optics &       V     2218.00 3.5 1.0 0.0   4.0
Dispensing I
Refractive & Binocular    V     2220.01 3.0 1.0 0.0   3.5
Case Analysis
Ocular Assessment &       C     2221.10 2.0 0.0 0.0   2.0
Diagnosis
Optometric Procedures II C      2302.20 1.0 3.0 0.0   2.5
Patient Care III          C     2603.00 0.0 0.0 1.5   0.5
Total                                  21   7.0 1.5   25.0




OPTO 292 -         Introduction to Optometry - 2 + 0 = 2       19
Spring Quarter

Course Title               Dept* Course Lec Lab Clinic Credit
                                                       Hours
Microbiology II: Survey    B       2107.00 2.0    0.0   0.0     2.0
of Infectious Diseases
Ocular Pharmacology        B       3101.10 2.5    0.0   0.0     2.5
Visual Perception          V       2212.10 3.0    1.0   0.0     3.5
Human & Visual             V       2215.00 2.5    0.0   0.0     2.5
Development
Cornea & Contact Lens I V          3107.10 2.0    3.0   0.0     3.5
Clinical Medicine &        C       2214.10 2.0    1.0   0.0     2.5
Systemic Disease I
Ophthalmic Optics &        C       3307.00 2.0    1.0   0.0     2.5
Dispensing II
Visual Fields              C       2222.00 1.5    2.0   0.0     2.5
Optometric Procedures      C       2312.20 1.0    3.0   0.0     2.5
III
Total                                       18.5 11.0 0.0       24.0
Third Year

The students not only continue to acquire new information but are called upon to
demonstrate acquired knowledge while interacting with patients in the College's clinics.
Students also become proficient in such optometric specialty care areas as vision therapy,
contact lenses, paediatrics, low vision, and ocular disease. While course work continues
throughout this year, the major thrust in the educational program is within the clinic. The
University Optometric Center, our clinical facility, has a nationally recognized clinical
faculty who provide excellence in clinical care and education.


Summer Quarter

Course Title          Dept* Course Lec Lab Clinic Credit Hours
Clinic Orientation    C        3500.10 3.1 0.9    0.0     3.5
Optometric Clinic I C          3412.00 0.0 0.0    9.0     3.0
Total                                  3.1 0.9    9.0     6.5




OPTO 292 -        Introduction to Optometry - 2 + 0 = 2                              20
Fall Quarter

Course Title            Dept* Course Lec Lab Clinic Credit
                                                    Hours
General Vision Therapy V      3203.10 3.0   3.0 0.0    4.5
Strabismus &            V     3206.00 4.0   0.0 0.0    4.0
Amblyopia
Cornea & Contact        V     3207.20 2.0   3.0 0.0    3.5
Lenses II
Geriatrics              C     3208.30 1.0   0.0 0.0    1.0
Clinical Medicine &     C     3216.00 2.5   0.0 0.0    2.5
Systemic Disease II
Anterior Segment        C     3302.20 3.5   0.0 0.0    3.5
Diseases
Epidemiology            C     3310.10 2.0   0.0 0.0    2.0
Optometric Clinic II    C     3413.10 0.0   0.0 9.0    3.0
Total                                 18.0 6.0 9.0     24.0

Winter Quarter

Course Title            Dept* Course Lec Lab Clinic Credit
                                                    Hours
Behavioral Vision &     V     3200.00 3.0   2.0 0.0    4.0
Learning
Cornea & Contact        C     3210.00 3.0   0.0 0.0    3.0
Lenses III
Health Care Economics   C     2313.20 1.5   0.0 0.0    1.5
& Payment
The Glaucomas           C     3301.30 2.5   0.0 0.0    2.5
Paediatric & Special    C     3309.10 1.5   0.0 0.0    1.5
Population Optometry
Posterior Segment       C     3313.00 3.0   0.0 0.0    3.0
Diseases
Optometric Clinic III   C     3414.10 0.0   0.0 12.0   4.0
Practice Development & C      3319.00 12.0 2.0 0.0     0.0
Administration I
Total                                 16.5 4.0 12.0    21.5


OPTO 292 -       Introduction to Optometry - 2 + 0 = 2        21
Spring Quarter

Course Title             Dept* Course Lec Lab Clinic Credit
                                                     Hours
Vision Rehabilitation    V     3209.10 1.5   0.5 0.0    1.75
Neuro-Opthalmic          C     3315.00 3.0   0.0 0.0    3.0
Disease
Health Care Policy       C     3221.10 2.0   0.0 0.0    2.0
Laser and Surgical       C     3400.00 2.0   1.0 0.0    2.5
Management Eye
Disease
Optometric Clinic IV     C     3415.00 0.0   0.0 15.0   5.0
Practice Development & C       4311.00 2.5   0.0 0.0    2.5
Administration II
Total                                  11.0 2.5 15.0    16.75




OPTO 292 -        Introduction to Optometry - 2 + 0 = 2         22
Fourth Year

It is during all four quarters of the last year that patient care skills are fine tuned in order
to graduate competent practitioners. The clinical rotations take place in a number of
carefully selected internal and external sites in order to allow students to experience a
greater variety of clinical environments. This includes a diversity of ocular and general
conditions of patients of all ages, and socioeconomic backgrounds.

Course Title              Course       Term         Hours      Credit Hours
Clinical Internship I     4101.00      Summer       40         13.3
Clinical Internship II    4102.00      Fall         40         13.3
Clinical Internship III 4103.00        Winter       40         13.3
Clinical Internship IV 4104.00         Spring       40         13.3
Community CPR             4300.30      Variable     10         1.0
Clinical Seminar I        4501.00      Variable     2          2.0
Clinical Seminar II       4502.00      Variable     2          2.0
Note: All courses offered in the fourth year are administered through
the Department of Clinical Sciences.



* B - Biological Sciences
V - Vision Sciences
C - Clinical Sciences




OPTO 292 -         Introduction to Optometry - 2 + 0 = 2                                   23
2.       Department of Optometry, University of Melbourne


First Year (Pre-Optometry Year)

        650-141 Biology of Cells and Organisms [WebRAFT link]
        650-142 Genetics and the Evolution of Life [WebRAFT link]
        610-141 Chemistry [WebRAFT link]
        610-142 Chemistry [WebRAFT link]
        655-111 Vision: How the Eye Sees The World [WebRAFT link]
        655-152 Optics: From Rainbows to Digital Imaging [Blackboard link]

plus one of:

        640-141 Physics A [WebRAFT link]
        640-161 Physics: Principles & Applications A [WebRAFT link]
        640-151 Physics for Biomedical Science A [WebRAFT link]
        640-121 Physics A (advanced) [WebRAFT link]

plus one of:

        640-142 Physics B [WebRAFT link]
        640-162 Physics: Principles & Applications B [WebRAFT link]
        640-152 Physics for Biomedical Science B [WebRAFT link]
        640-122 Physics B (advanced) [WebRAFT link]



Second Year

        655-201 Anatomy and Histology of the Eye [WebRAFT link]
        536-206 Physiology (Optometry)
        521-204 Biochemistry and the Eye [WebRAFT link]
        655-221 Human Visual Functions [WebRAFT link]
        531-202 Basic Principles of Pathology - Optometry [WebRAFT link]
        655-222 Visual Processing and Control [WebRAFT link]
        620-270 Applied Statistics
        655-210 Optical Design and Ophthalmic Metrology




OPTO 292 -        Introduction to Optometry - 2 + 0 = 2                       24
Third Year

     655-321 Practical Problems in Vision [WebRAFT link]
     534-307 Pharmacology (Optometry)
     655-328 Visual Neuroscience
     655-330 Functional Disorders of Vision [WebRAFT link]
     655-341 Ocular Histopathology
     655-351 Ophthalmic Lenses and Optical Dispensing
     526-306 Microbiology and Immunology (Optometry)



Fourth Year

     655-461 Assessment of Ocular Disease
     655-441 Diagnosis of Ocular Disease I
     655-451 Contact Lenses
     655-430 Clinical Optometry Practice
     655-462 Therapeutic Management of Ocular Disease
     655-422 Occupational Optometry & Visual Standards
     655-442 Diagnosis of Ocular Disease II



Fifth Year

     655-510 General Optometry Practice
     655-520 Specialist Optometry Practice
     655-530 Ocular Disease Management
     655-540 Project Studies in Vision Sciences




OPTO 292 -      Introduction to Optometry - 2 + 0 = 2         25
LECTURE 4

The object of the next four lectures is to crudely divide the standard Optometry course
into tracts of study. Each tract will typically have two or more courses dealing with the
same or a closely related topic, studied in sequential steps in two to four semesters.

A handful of courses usually do not fall into any particular tract and do not have any
preceding or subsequent courses with which they have a significant relation. These
courses are listed under ‘Other Courses’.

My very crude attempt at dividing the Optometry courses into tracts of study follow
below:

      Anatomy and Physiology
      Visual Science
      Visual and Geometric Optics
      Ophthalmic Optics and Dispensing
      General and Ocular Disease
      Optometric Practice Management
      Binocular Vision and Orthoptics
      Pharmacology
      Contact lenses
      Clinical Methods in Optometry
      Specialty Population Optometric Practice
      Optometry Clinics
      Other Courses


In addition, some Colleges/Schools of Optometry require their students to select one or
more elective course which may include (but are not limited to) the following:

      Ocular Photography
      Directed Research – Independent clinical or lab research
      Directed Readings – Independent literature review
      Case studies in Ocular Disease

The next step in this lecture series to acquaint the student with one of the topics covered
in each of four selected course tracts:

      Visual and Geometric Optics
      Ocular Disease
      Binocular Vision and Orthoptics
      Other Courses



OPTO 292 -        Introduction to Optometry - 2 + 0 = 2                               26
Under Visual Optics, the main thrust of the study is ‘the eye as an optical system’.
Refractive components of the eye, refractive errors and optics of the eye based on
Gullstrand’s schematic and Gullstrand-Emsley Reduced eye models.

We will now discuss Refractive errors.


Spherical Ametropia


The Refractive Status of the Eye

Emmetropia

An unaccommodated eye which focuses the rays from a distant object (one at a
Distance from the eye’s principal point of 6 metres or greater) onto the retina is said to be
Emmetropic (normal). An eye which is not emmetropic is Ametropic.


Ametropia

An ametropic eye is said to have a refractive error, and such an error, because of its
refractive nature, can be corrected by optical aids (such as glasses and contacts).

The two main classifications of ametropia are:

i)     Spherical ametropia
ii)    Astigmatism.


Spherical Ametropia

In spherical ametropia, either the cornea is too powerful (myopia) or too weak
(hyperopia) in relation to a normal axial length of an eyeball. Otherwise, the axial length
is too short (hyperopia), or too long (myopia) with respect to a normal corneal curvature.

In short, in spherical ametropia, there is a mismatch between the corneal curvature (and
as a consequence, corneal power) and the axial length of the eyeball.




OPTO 292 -        Introduction to Optometry - 2 + 0 = 2                                  27
Myopia

As shown in figure 20, the image of a distant object comes to a focus in front of the retina
in an unaccommodated eye. This refractive state is called myopia.

Because the image of a myopic eye falls in front of the retina, for an object to be seen
clearly, that object must be moved to within 6 metres from the eye. The point to which
the object is moved, to form a clear image on the retina of the unaccommodated eye, is
called the far point (punctum remotum) of that eye.

The far point in myopia moves closer to the eye as the myopia increases.

Note that the far point of an emmetropic eye is at infinity* and, the far point of an eye is the furthest
point where an object can be placed in object space so that the image of that object is focused precisely
on the retina with accommodation completely relaxed.

By accommodation, the myopic eye can bring objects closer than the punctum remotum,
into a sharp focus. However, the uncorrected myope has a reduced range of clear vision
(i.e. the range from far point to near point) than the emmetrope.

Sometimes the rays from a distant object come to a focus behind the retina (in an
unaccommodated eye), so that an image of the object is not formed by the visual system.

This refractive condition is hypermetropia, a term vulgarly referred to as hyperopia.

In hyperopia, the axial length is too small for a normal corneal curvature or, the corneal
diameter is too large for a normal axial length of the eyeball. The uncorrected hyperope
has an increased range of clear vision over the emmetrope.

In the unaccommodated hyperopic eye, the far point is virtual because it is situated
behind the eye.

Since the rays from an object at infinity come to a focus behind the retina in the
unaccommodated hyperopic eye, depending on the accommodative amplitude of the
person (which is primarily dependent on age), and on the magnitude of the refractive
error, a hyperope can accommodate to compensate for his refractive error. As a result,
many young patients with large accommodative amplitudes hardly ever notice their
hypermetropia until later in life.

Axial and Refractive Ametropia

As has been mentioned, ametropia is due to a mismatch between the corneal power and
the axial length of an eye.

This mismatch, theoretically, is caused by a variation in corneal power with a normal
axial length, or a variation in axial length with a normal cornea power. In practice
OPTO 292 -          Introduction to Optometry - 2 + 0 = 2                                         28
Figure 4.1   Image formation by the emmetropic eye




Figure 4.2   Image formation by the myopic eye




OPTO 292 -     Introduction to Optometry - 2 + 0 = 2   29
Figure 4.3   Image formation by the hyperopic eye




Figure 4.4   Image formation by the astigmatic eye




OPTO 292 -     Introduction to Optometry - 2 + 0 = 2   30
OPTO 292 -   Introduction to Optometry - 2 + 0 = 2   31
however, especially in low degrees of ametropia, the distinction between axial and
refractive ametropia become blurred as both components are involved in determining the
refractive status in such eyes.


Important

How do spectacles/contact lenses correct Ametropia?

In myopia or hyperopia, an image located at the far point of the eye is focused on the retina without
accommodation.

What the minus lens which corrects myopia (or the plus lens which corrects hyperopia) actually does is
form an image of the distance object at the far point of the eye. It follows then, that the second
principal focus of the correcting lens must be coincident with the far point of the eye.

This image now becomes the object for the ametropic eye, which can then focus the image on the retina
without accommodation.



Vertex Distance

When spherical ametropia is corrected by spectacles, the only detail worthy of note is that
the second principal focus of the correcting lens must coincide with the far point of the
eye. When spherical ametropia is corrected with contact lenses though, the story is a
different one.

Since the contact lens is on the cornea, and the second principal focus of the lens must
coincide with the far point of the eye, it becomes obvious, that the contact lens power is
the same as the ocular refraction (K) of the eye.

Therefore there a change in power as a lens is moved from the spectacle plane to the
corneal plane. This power difference is negligible for powers of  5.00 D and less.




OPTO 292 -          Introduction to Optometry - 2 + 0 = 2                                        32
LECTURE 5

Overview of Binocular Vision

When a person with normal binocular vision looks at an object, both visual axes converge
such that they intersect at the object of regard.

When this object is at optical infinity (6 meters or greater), and the patient is emmetropic
or myopic, one or two types of vergence are responsible for the position of each eye.

      If the person is orthophoric (i.e. has no phoria), then only Tonic vergence is
       responsible for turning each eye to point at the target.

      Where a heterophoria is present, tonic vergence and fusional vergence are
       responsible for turning each eye to point at the target.


     Tonic vergence refers to the muscle tone of each of the six extraocular muscles.
     The tension in each muscle when it is completely relaxed helps to determine in
     which direction the eye will point when accommodation is completely at rest.


     It facilitates understanding to look at fusional vergence as a problem-solver. The
     problem here is a phoria. Fusional vergence is only used when there is a phoria,
     and just enough fusional vergence is used to correct that phoria.


     A phoria is therefore referred to as a “compensated (corrected) deviation”. If the
     phoria is so large that fusional vergence cannot correct it, the phoria is referred to
     as a “decompensated phoria”.


     When a phoria decompensates, and the emmetropic person looks at an object at
     optical infinity, only one visual axis is pointed at the target, the other visual axis
     points away from the target in a direction determined by the type of phoria the
     person is afflicted with.


     A decompensated phoria leads to a number of problems with binocularity.




OPTO 292 -        Introduction to Optometry - 2 + 0 = 2                                 33
     It is important to note that when fixating an object closer than 6 meters (20 feet):

      tonic vergence;
      fusional vergence (if there is a phoria);
      accommodative vergence (whenever we have accommodation, we have
       accommodative vergence);
      and proximal vergence (which is an increase in convergence which occurs
       because a person knows that the object he/she is looking at is close to him/her);

         all combine to determine the direction in which each eye will point.



Retinal Correspondence
When a person with normal binocular vision looks at an object, the image of that object
falls on both foveas. In this case both foveas receive information from the same object.
The foveas are then said to be related (conjugate or corresponding). This is Normal
Retinal Correspondence (NRC).

Abnormal retinal correspondence occurs when the images from the object above fall on
the fovea of one eye, and on an extrafoveal point of the other eye. It is important to note
that abnormal retinal correspondence only occurs when the old fovea to fovea
relationship is cancelled and replaced by a new fovea to extrafoveal point relationship. In
this case, the fovea of one eye is conjugate with the extra-foveal point of the other eye.

If we look at the schematic representation in fig 5b, we see that when the right fovea (FR)
and the left fovea (FL) are conjugate (in this diagram, with respect to the object point X),
the temporal side of the left retina is conjugate with the nasal side of the right retina (in
this example, with respect to the object point Z). Also, we see that the nasal left retina
corresponds with the temporal right retina (in this example, with respect to the object
point Y).


Panum's Area
Binocular vision as defined by Worth can be classified into three grades:

         Simultaneous Perception
         Fusion
         Stereoscopic Vision

Simultaneous Perception

This occurs in both binocular single visible (BSV) and binocular vision (BV) where the
images of the object of regard from both eyes are simultaneously perceived in the brain.

OPTO 292 -         Introduction to Optometry - 2 + 0 = 2                              34
Fusion

Combining both these perceived images into a single image is fusion. Fusion can be
sensory or motor.

Sensory fusion is the automatic ability to fuse the images from both eyes into a single
perceived image.

Motor fusion is the ability to maintain sensory fusion through a range of vergence (which
may be horizontal, vertical or cyclo).


Stereopsis

Fusion of these slightly different retinal images is the precursor to Stereopsis. Stereopsis
enables the perception of depth (3-D vision) and helps in the accurate judgment of
relative distance between two objects, and relative speed (or change of speed) of one
object with relation to another.

There are many cues to the perception of depth, but stereoscopic depth is the most
important.

Stereoscopic cues are caused almost exclusively by retinal disparities.

Retinal disparities are small positional displacements between otherwise well-matched
images.

In the visual system, because of the horizontal separation of the eyes, only horizontal
disparities convey depth information.

The concept of disparities is illustrated in figure 5a. Imagine looking outside your living
room through each of two windows which are located side by side. What you see through
the windows are almost identical, but the relative positions of the objects in the visual
scene are slightly displaced when looking through one window as compared to when
looking through the other one.

The horizontal shift in the objects’ positions is what happens in normal vision, and is the
result of the difference in horizontal positions of both eyes.




OPTO 292 -        Introduction to Optometry - 2 + 0 = 2                                35
Figure 5a    The same visual scene from two laterally displaced
             perspectives




OPTO 292 -     Introduction to Optometry - 2 + 0 = 2              36
Fusion and stereopsis only occur in binocular single vision.

The ability for the brain to fuse both retinal images is dependent on where the images of
an object of regard fall on both retinas.

We have already discussed the fact that, in normal retinal correspondence, when both
eyes look at an object, both visual axes intersect at the object of regard so the each image
falls exactly on the fovea of each eye.

Subsequently the brain is able to fuse these two images into one visual percept.


The question is: Can the brain fuse the images of both eyes if one image falls on the
fovea of, for example, the left eye, and the other image falls on an extrafoveal point of
the right eye?

The answer to the question above is YES, but only if the image on the right eye falls
within a circumscribed area known as Panum’s Fusional Area. If the image falls
outside of this area, then fusion is not possible. The first consequence of this is diplopia
which may or may not progress to cortical suppression.


Please note that any point on either retina (for example, a point X on the right retina)
has a relationship with a number of points within its Panum’s area on the opposite
retina. Such that, if the image of an object falls on X on the right retina, as long as that
same image falls on any point within X’s Panum’s area on the left retina, fusion will
occur and stereopsis will be present.

The fusion and stereopsis which occur in this case, are not as good as that which
occurs when there is normal retinal (point-to-point) correspondence.


To conclude: In abnormal retinal correspondence where the image of an object falls
on the fovea on one retina and on an extrafoveal point of the opposite eye, fusion and
stereopsis will occur only if the extrafoveal point lies with Panum’s area. If not, there
will be no fusion, no stereopsis and therefore there will be diplopia.


As we see in fig 5b, Y, X, and Z all lie on the same arc. We also know that each of those
points stimulate exactly conjugate points on the left and right retinae.

The term Horopter describes an arc, which contains all the objects that stimulate exactly
corresponding areas on the left and right retinae.




OPTO 292 -        Introduction to Optometry - 2 + 0 = 2                               37
Examining the schematic in fig 5b, Panum's space is a narrow area surrounding the
Horopter within which objects stimulate corresponding retinal areas, and thus give rise to,
binocular vision.

What then is the difference between the Horopter and Panum's space?

In fig. 5b we see that Y, X, and Z stimulate corresponding retinal points to result in
binocular single vision. The object point X, for example, stimulates the corresponding
retinal points FL and FR to result in binocular single vision.

An object that falls within Panum's space, but not on the Horopter, will also stimulate
binocular single vision but it does this by stimulating retinal points that do not have an
exact corresponding relationship.

In fig. 5c, the object O is located in Panum's space and stimulates FL and a point P on the
right retina. Even though FL should correspond with FR, it corresponds with P but still
results in binocular single vision. Therefore, there is actually no such thing as
corresponding points. Instead, a point, for example on the left retina, corresponds with a
well-defined area on the right retina. Therefore what exists in reality is a point-to-area
relationship rather than a point-to-point relationship.

Re-examining fig. 5c thus, FL does not correspond with FR but with any point, for
example, within the highlighted circle. This highlighted circle is referred to as Panum’s
area (or Panum's fusional area).


Theories of Sensory Fusion

As we have learned, the important features for sensory fusion are retinal correspondence,
retinal image disparity detection and neural summation.

Studies of higher mammals have shown that about 80% of the striate cortex cells can be
binocularly stimulated. For this to occur properly however, corresponding retinal areas
must be in proper alignment, if not the individual visual fields from both eyes (because
they are competing for the brain’s attention) mutually inhibit each other.

It is the proper binocular stimulation of these cortical cells that leads to unification of
both ocular images into a single binocular percept. The theory of binocular vision just
described is the theory of Binocular Neural Summation.

Another (older) theory (Retinal Rivalry or Alternation theory) asserts that no fusion of
both ocular images actually occurs. The argument was that the binocular field was
composed of a mosaic of monocularly perceived patches such that the visual input from
one eye at times dominates the perceived image, and at times is suppressed. This theory
left many features of binocular vision (such as contrast sensitivity enhancement)
unexplained and has since been found to be essentially incorrect.

OPTO 292 -        Introduction to Optometry - 2 + 0 = 2                                 38
             Figure 5b        The Horopter




OPTO 292 -     Introduction to Optometry - 2 + 0 = 2   39
Figure 5c    The Horopter, Panum’s Space and Fixation Disparity Angle




OPTO 292 -     Introduction to Optometry - 2 + 0 = 2            40
LECTURE 6

OCULAR DISEASE
The recognition and treatment or prompt referral of ocular disease cases has been one
of the hallmarks in the development of the profession of optometry. It is vital that the
student familiarizes himself with the numerous developmental, acquired and disease
disorders that affect the eye and its associated tissues.

For this brief introduction to ocular disease, we are going to discuss selected disorders
of the eyelids. Our discussions will be limited to:

       Disorders of the eyelashes
       Allergic lid disorders
       Lid Infections
       Chronic marginal blepharitis



Disorders of the Eyelashes

   1.   Trichiasis
   2.   Phthiriasis Palpebrarum
   3.   Madarosis
   4.   Poliosis

Trichiasis is a common acquired unilateral or bilateral condition in which the
eyelashes turn inward and irritate the eye. It may occur on its own but is more
commonly associated with an eyelid malpositioning such as is found with scarring of
the lid margin.


        Differential Diagnosis

              Pseudotrichiasis:       Trichiasis secondary to entropion.
              Metaplastic Lashes      New row of lashes which originate from
                                       meibomian gland orifices. Patients with Stevens-
                                       Johnson syndrome and chemical injury will have
                                       such lashes.
              Distichiasis            A partial or complete second row of lashes
                                       arising from or slightly behind the Meibomian
                                       gland orifices. These lashes are shorter and less
                                       pigmented than normal ones.

Treatment of Trichiasis is by epilation, cryotherapy, electrolysis, laser ablation or
surgery.




OPTO 292 -        Introduction to Optometry - 2 + 0 = 2                                 41
Fig. 6.1, 6.2 and 6.3 Severe corneal ulceration due to pseudo trichiasis;
Phthiriasis Palpebrarum; Poliosis of lashes and brows




OPTO 292 -      Introduction to Optometry - 2 + 0 = 2                       42
Phthiriasis Palpebrarum is an infestation of the eyelashes by the pubic crab louse
and its ova (nits). It usually affects children living in poor hygiene conditions and
results in chronic itching and irritation.

Treat by removing louse with forceps and delousing of entire family members,
clothing etc.


Madarosis is a decrease in the number of lashes and it can be caused by a variety of
factors ranging from chronic anterior lid margin disease and cryotherapy of lid
tumours, to psoriasis, myxoedema, systemic lupus erythematosus, syphilis and
trichotillomania (a psychiatric disorder of habitual hair removal).


Poliosis is a premature whitening of hair which may involve the lashes or brows.

       Ocular associations
           Chronic blepharitis
           Sympathetic Uveaitis

       Systemic associations

              Vogt-Konayagi-Harada syndrome
              Waardenburg syndrome


ALLERGIC LID DISORDERS

Acute Allergic Edema

May be caused by insect bites, angiodema or urticaria. It may also be caused by
certain drugs. It usually presents as unilateral or bilateral periorbital lid edema and
redness.

Treatment is usually by systemic antihistamines.

Contact Dermatitis

Usually caused by hypersensitivity to topical medication. May be unilateral or
bilateral.

Treatment is by cessation of the offending drug and the topical application of a mild
steroid such as 1% hydrocortisone.


Atopic Dermatitis (Eczema)

Very common and is usually associated with asthma and hay fever. It presents with
chronic irritation and itching with bilateral thickening and fissuring of upperlids.
Fig. 6.4, 6.5 and 6.6 Severe allergic eyelid edema; Contact Dermatitis; Severe


OPTO 292 -        Introduction to Optometry - 2 + 0 = 2                                   43
                 atopic dermatitis of upperlids




OPTO 292 -   Introduction to Optometry - 2 + 0 = 2   44
Treatment is with emollients such as oily cream to help hydrate skin. There is usually
secondary infection in which case antibiotic therapy may be required.


LID INFECTIONS

Herpes Zoster Ophthalmicus

Common unilateral condition that usually affects older patients. There is severe pain
(because of trigeminal nerve involvement), it affects one side of the face with
maculopapular rash (usually on the upper forehead) with crusting of facial skin and
periorbital edema (in severe cases).

Treatment is either by systemic anti-viral therapy 3X daily for 7 days or topical
antiviral therapy combined with a steroid-antibiotic combination (e.g fucidin H) until
the crust clear.


Herpes Simplex

Also a viral infection and also unilateral but this one is uncommon. Like herpes
zoster, it may be particularly severe in patients with depressed immune states.
Presents as crops of small vesicles which may or may not be associated with lid
edema.

Treatment is with topical antiviral creams.


Impetigo

This is an uncommon superficial skin infection with Staph aureus or β-haemolytic
streptococci and it occurs most frequently in children.

Treatment when localised is by topical antibiotics, when generalized, by systemic
antibiotics e.g. erythromycin.


Necrotizing Fasciitis

An extremely rare but serious cutaneous gangrene which occurs in the elderly or
debilitated patients following trauma. It presents with bilateral lid edema which may
progress rapidly to gangrene.

Treatment is by parenteral benzyl-penicillin and surgical debridement of necrotic
tissue.




OPTO 292 -        Introduction to Optometry - 2 + 0 = 2                             45
Fig. 6.7, 6.8 and 6.9 Herpes Zoster Ophthalmicus; Crusting of skin in impetigo;
                      Scales at lash base in staphylococcal blepharitis




OPTO 292 -      Introduction to Optometry - 2 + 0 = 2                        46
CHRONIC MARGINAL BLEPHARITIS

This condition is very common, usually bilateral and almost always symmetrical. It
may be anterior, posterior or mixed (both anterior and posterior).

The pathogenesis of anterior blepharitis is unclear but it involves both a
staphylococcus infection seborrhoea. Posterior blepharitis is associated with
meibomian gland dysfunction (ocular rosacea) which may or may not be associated
with acne rosacea of the face.

Because of the juxtaposition of the lid margin and the cornea and conjunctiva,
blepharitis may cause secondary changes in the conjunctiva and cornea.

Presentation of blepharitis is burning, redness and grittiness with mild photophobia.
There is also redness and crusting of the lid margins and these symptoms tend to be
worse in the morning.

In anterior blepharitis, it is usually easy to differentiate between staph. Blepharitis and
seborrhoeic blepharitis. In staph. blepharitis, what one sees is hard crusts at the lash
bases whereas in seborrhoeic blepharitis the lashes are more obviously greasy and
stuck together. Sometimes both types combine with combined symptoms, in addition
to follicles located at the anterior lid margin.


Posterior blepharitis may occur in isolation or with anterior blepharitis. The two main
causes of posterior blepharitis are meibomian gland dysfunction with seborrhoea and
meibomianitis. In meibomian seborrhoea there is little or no inflammation, just large
amounts of oil produced by the meibomian gland. This oil can be expressed by mild
pressure on the tarsus. In more severe cases, on examination of the lower lid, foam is
seen on the lashes of the inner canthus.

In meibomianitis, there is inflammation around the meibomian gland orifices and in
more advanced cases, there is cystic formation. Inflammation here occurs due to
blockage of the meibomian gland orifices.

Treatment ocular hygiene procedures of the lid margin and lashes and systemic
tetracylines administered for 6-12 weeks. Warm compresses also help to melt
solidified sebum. Mechanical expression of the glands may help to reduce the amount
of irritating lipids within the glands.


Note   With all cases of ocular disorders that require systemic treatment, the patient
       must be referred.




OPTO 292 -        Introduction to Optometry - 2 + 0 = 2                                 47
Fig. 6.10, 6.11 and 6.12 Greasy lashes in seborrhoeic bleph.; Oil capping of
                         meibomian gland orifices in post bleph.; Foam on lower
                         lid in post bleph. (meibomian seborrhoea).




OPTO 292 -      Introduction to Optometry - 2 + 0 = 2                        48
Fig. 6.13.   Blocked meibomian gland orifices and scarring of the posterior lid
             margin in longstanding posterior blepharitis




OPTO 292 -     Introduction to Optometry - 2 + 0 = 2                         49
LECTURE 7
In this last lecture, we will cover some topics in optics.



LENS ABERRATIONS

The aberrations that will be discussed here are termed Seidel aberrations (or
Third order aberrations) after Ludwig Von Seidel who first described them
in the 1850s.


      Spherical aberration

       Here, rays close to the principal axis of the lens system come to a
       focus behind rays in the periphery. This is because lenses tend to
       have more power in their peripheral curvatures than centrally.

       In optical instruments, this aberration is eliminated by the use
       aspheric lenses. In the human eye spherical aberration is reduced by


       (i)     A moderately small pupil which restricts the rays to the
               paraxial ones
       (ii)    The cornea is flatter peripherally than centrally
       (iii)   The lens has a higher refractive index in the nucleus than in
               the cortex.
       (iv)    Finally Stiles-Crawford effect causes a reduction in the
               image quality of peripheral (off-centre) objects.




               Schematic depiction of the principle of Spherical
Aberration




OPTO 292 -        Introduction to Optometry - 2 + 0 = 2                         50
       Coma

        Coma is spherical aberration produced by an off-axis (peripheral)
        object, when we a looking directly at some other object.

        Under normal viewing conditions coma is effectively eliminated by
        the pupil size.




       Radial Astigmatism

        Like coma, it affects only off-axis objects. Such objects are focused
        as astigmatic images.


       Curvature of Field

        Let us consider the following diagram.




             O                        L
                                                       I   S


Where O        =        object
               L        =        Lens
               I        =        Image

S       =      Screen

Lens systems tend to form curved images of flat objects. This is because
spherical aberration causes the peripheral rays of the objects to be focused in
front of the central rays. As a result, the central rays from an object are
focused on the screen and the peripheral rays are focused in front of the
screen.

Curvature of field is nullified in the human eye by:

    1. The size of the normal pupil
    2. The curvature of the retina



OPTO 292 -         Introduction to Optometry - 2 + 0 = 2                          51
        Distortion

         Distortion is the only Seidel aberration that does not result in any
         loss of clarity. It results because any straight part of an object is
         imaged as straight only if the rays from that part pass through the
         lens system at, or very close to, its optical axis. All other rays result
         in curved images.


MAGNIFICATION

A magnification of 3X means that the image is three times as big as the
object. If an instrument produces relative size magnification of 3X and a
relative distance magnification of 4X, its total magnification is 12X.

1.       Lateral, Linear, or Transverse Magnification

      Lateral Magnification (LM) =                        Image size/Object size
= l1/l = L/L1

         Where l1 and l represent image distance and object distance ( both
         in meters) respectively.

         Where L1 and L represent image vergence and object vergence
         ( both in diopters if l1 and l are in meters) respectively.


2.       Axial Magnification

         Axial Magnification = (LM)2


3.       Angular Magnification

         This is the magnification produced in an optical instrument (usually
         telescopes) by increasing the angular subtense of the object at the
         eye. This term is specifically applied when the size and distance of
         the object remain unchanged.

         Consider an observer looking at an aeroplane flying many thousands
         of feet above sea level. From the ground the airplane looks like a dot.
         When you look at that same airplane with a telescope, it becomes
         huge all of a sudden.

         The magnification of the airplane is not because the airplane was
         brought closer to the observer, nor because its size was increased.
         The only property that was altered was the angle subtended by the
         plane at the nodal point of the observer’s eye.




OPTO 292 -          Introduction to Optometry - 2 + 0 = 2                            52
       Angular Magnification = I1/I0 (Magnified image size / original
       image size).


       Spectacle Magnification

       This is the ratio between the size of the retinal image in an ametropic
       eye before and after correction.


       Relative Distance Magnification

       This is the magnification produced when the distance of the object
       from the eye is reduced. A microscope produces some angular
       magnification but its relative distance magnification is far greater.


MAGNIFIERS AND TELESCOPES

       The Simple Magnifier

       The object is viewed at the first principal focus of a plus lens. To
       calculate the magnification, we compare the angular size of this
       image with that seen by the unaided eye at 25 cm from the eye, the
       least distance of distinct vision.




            x     1
                                                                             2


                                                                         25
cm


                       f


With the magnifier, angular subtense,                1 = x / f

With the unaided eye, angular subtense,              2 = x / 25 cm      =     x
/ 0.25 m


Magnification = 1 / 2 = (x / f) / (x / 0.25)      = 0.25 / f       =
      0.25P = P / 4.




OPTO 292 -       Introduction to Optometry - 2 + 0 = 2                             53
The refractive power of the human eye is about +60 D. Therefore, the
magnification of the direct ophthalmoscope is about 60 / 4 = 15 X.



       The Astronomical Telescope

       Two positive lenses are used and the image is inverted. To right the
       image, an inverting prism is added.

       Magnification          =       Pe / P 0



                                                       F10

                                                       Fe




               Objective (P0) - +ve              Eyepiece (Pe) - +ve




       The Galileal Telescope

       The objective is a positive lens while the eyepiece is negative. The
image is erect.


       Magnification          =       Pe / Po




                       Objective (P0) - +ve              Eyepiece (Pe) - -ve




OPTO 292 -        Introduction to Optometry - 2 + 0 = 2                        54
The Surgical Loupe

A loupe is a telescope that has been modified for viewing objects at near and
is useful for improving near VA for the low vision patient.

A high power loupe (magnification greater than 6X) is an astronomical
telescope with inverting prisms. A low power loupe (magnification less than
6X) is a Galilean telescope.

In order to be used as a loupe, the telescope is fitted with an ADD lens.

The ADD and the objective are combined in one lens and the object must be
located at the first principal focus of the ADD. The effect of the ADD
therefore is to make light from the object parallel before going through the
telescope. The ADD acts as a simple magnifier.


Magnification of loupe                =       Mag. of ADD x Mag. of
Telescope
                                      =       (ADD/4) x (Pe/Po).




OPTO 292 -        Introduction to Optometry - 2 + 0 = 2                         55

				
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