The Eye and Eye Diseases

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					 The Eye and Eye Diseases.
STATS 19 SEM 2. 263057202.
          Talk 7.

            A.L. Yuille.
        Dept. Statistics.
Neural Prostheses.

• Forms of Neural Prostheses already used.
  (Simpler than last week). CNN story.
• Brain messages transmitted to nerve ends
  on pectoral muscles of the chest.
• Thoughts cause chest muscles to contract,
  activate prosthetic arm.
Mike May’s and Others
• Project Prakash (light). Pawan Sinha (MIT).
• Sinha studies how children’s brain adapt to years
    of blindness followed by sight.
•   Studies in India. Children have cataract surgery.
•   Sinha “Merely treating the eyes is not enough.
    No one knows if the visual modality will reclaim
    areas in the brain that it lost to other senses
    during blindness”.
•   Some patients commit suicide after recovered
Mike Mays and Others

• India has the world’s largest population of
  blind children. 100,000 children.
• 20% have Cataracts, which can be
• Poverty, inter-marriage to blind relatives,
Mike May and Others.

• Mondloch (McMaster).
• Children with cataracts in the left-eye, can
  recognize faces after surgery.
• Children with cataracts in the right-eye,
• But probably too late if surgery happens 2
  months after birth.
• Brain imaging (FMRI) show that neural areas in
    the brain devoted to vision can perform different
    functions for the blind.
•   Vision area – Touch area.
•   Increased activity in the Visual Cortex when
    blind subjects “read” by using Braille.
•   Areas of the Visual Cortex get activated when
    blind patients remember words and do other
    verbal memory tasks. (Normal subjects use
    language areas).
The Big Three Eye Diseases.

• Cataracts
• Glaucoma
• Age-Related Macular Degeneration.
The Eye
• Anatomy
The Eye
• Imaging and the Lens.
The Eye
• Photoreceptors: Rods
  and Cones.
The Eye
• Where things go wrong:
• (I) The Lens (focuses light).
• Lens structure can change. (Cell growth, protein
    changes). Cataracts.
•   (II) Eye contains fluids. The pressure of the fluid
    can get high (insufficient drainage). This affects
    nerve cells. Glaucoma.
•   (III) Retina failure. Age-Related Macular

• With age, the Lens enlarges and the
  protein structure changes (e.g. lens can
  go yellow). Most people over 65 have
  some cataracts.
• Symptoms: Poor distance vision, blurred
  vision, frequent prescription changes, poor
  night vision, glare, halo around lights,
  double vision.
• The Lens.
• Risk Factors:
• Age, Diabetes, Women/Men, Race,
 Developing countries near the Tropics,
 Hereditary, Smoking, Some Medications,
 Excessive sunlight.

• Second sight: vision appears to get better,
 but then gets far worse.

• Surgery is Effective. (These days).

• Glass is well-tolerated by the Eye (2nd
  World War).
• Remove parts of Lens (by Microsurgery).
• Implant plastic.
• Outpatient: go home the same day.

• Glaucoma “silent thief of vision”.
• Very difficult to detect. Accounts for 12%
  new blind cases in the US each year.
• Start by gradually losing peripheral vision.
  This causes irreversible damage.
• Regular Eye exams. Diagnose pressure in
  the eyes.
• Glaucoma is a collection of different eye
•   All raise the pressure of liquid inside the eye.
•   The Eye is basically hollow, like a balloon. It
    contains fluid that helps keep its shape.
•   New fluid comes in, old fluid is drained out.
•   But sometimes the drain gets blocked – raises
    fluid pressure, damages the optic nerve
    (irreversible). Glaucoma.
• Draining.
• Recall, the image is formed by the Rods and
    Cones on the retina.
•   These send nerve impulses to the brain via the
    Optic Nerve. The Optic Nerve starts at the Optic
•   High fluid pressure in the Eye damages the Optic
    Disk. Exact mechanism is unknown.
•   Peripheral vision is often lost before patients are
    aware of it.
• Optic Nerve.

• Treatment.
• Lower the fluid pressure.
• Eye drops, drugs, lasers, surgery.

• Risk factors: Age, Hereditary, Race
 (African Americans).
Age-Related Macular Degeneration.

• Least understood.
• Ageing of the outermost layer of the
• Progressive degenerate changes in the
  epithelium cells, photoreceptors (rods and
• Major cause of blindness in US, England,
Age-Related Macular Degeneration.

• Cells on retina.
Age-Related Macular Degeneration.

• Risk Factors.
• Women/Men, Heredity, Blue eyes –
 particularly Caucasians, smoking, high
 blood pressure, sunlight.

• Treatment is limited. Some forms respond
 to lasers, surgery,…
General Health Care.

• Diabetes – major cause of blindness
  among working people in US.
• Increases risk for Cataracts and Glaucoma.
  But also damages the retina directly.

• Main risk factor for Diabetes – high blood
General Health
• High-Blood Pressure (Hypertension). Damages
  the blood arteries in the retina.

• AIDS/HIV. Affects the immune system.
  Microorganisms CMV (Cytomegalovirus).

• CMV attacks the retina of about 30% people
  with AIDS. Destroys tissue, causes bleeding,
  retinal detachment.
Alan Scott and Botox

• Botox was developed by an Eye Surgeon –
  Alan Scott.
• It is used to relax eye muscles and allow
  eyes to track objects.
• He sold the idea to a company for
  development. Later, the company realized
  that Botox could be used for cosmetics.
Traditional Low-Vision Devices.

• Low tech.
• Hand-held magnifiers.
• Telescopes.

• Review of the Eye.
• Three Major Eye Diseases: Cataracts,
  Glaucoma, Age-Related Macular
• First two treatable, if Glaucoma detected
  early enough.
• Major advances in treatment.

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