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Contact Lens Final Study Guide _Alana_

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Contact Lens Final Study Guide _Alana_ Powered By Docstoc
					CORNEA + CONTACT LENS FINAL

 ADAPTATION TO GPs

INTRODUCTION

    -   ADAPTATION contains and O2-component and a fit-component
    -   PRIOR: adaptation used to be driven by lack of O2
    -   CURRENT: adaptation now driven by edge comfort and mechanics of lens

RESEARH STUDIES
STUDY                  SET-UP                                         FINDINGS
Mandell, Harris        - Fit one eye of 4 unadapted patients w/       - 3-4% corneal swelling in contralateral eye due to reflex
(1969)                   PMMA lens                                      tearing from interaction of GP edge w/ cornea
                       - Measured corneal swelling of contralateral   - Reflex tearing lowers tear tonicity and results in K-edema
                         eye
Mandell, Polse, Fatt   - Fit PMMA bilaterally to 4 unadapted          - A-adaptors: maximum K-swelling of 5% (swelling due to reflex
(1970)                   patients                                       tearing); K-swelling decreased to 2% after day 1 (swelling due to
                       - Measured maximum corneal swelling &            lack of O2); fully adapted by day 9
                         adaptation                                   - B-adaptors: maximum K-swelling of 7%; K-swelling decreased to
                                                                        4% after day1; fully adapted by day 17
                                                                      - Maximum K-swelling occurred after 3 hours of wear
                                                                            o Basis of CL f/u  instruct patient to wear CL 2-4hrs prior to
                                                                              visit bc want to see CL at worst
Mandell, Polse, Fatt   - Fit 1 A-adaptor w/ AC PMMA                   - Maximum K-swelling of 9-10% 2 hrs after fitting
(1971)                                                                - Adaptation is related to fit
                                                                            o Steep fit (AC) will keep tears from sufficiently getting under
                                                                              lens  lack of fresh O2 to cornea
Brungardt, Potter      - 101 eyes of 53 patients fitted w/ PMMA       - Km steepened during 1st 5 days
(1971)                                                                      o Due to swelling (reflex tearing, lack of O2)
                                                                      - K-molding occurred
                                                                            o Distortion no longer seen from lack of O2
                                                                            o Distortion due to fit of lens + lens bearing on cornea
                                                                                 Lens fit/bearing will reshape cornea  can mold away
                                                                                  some toricity + make cornea more spherical
                                                                                 Molding can cause spectacle blur
                                                                      - Adaptation complete by 30 days
                                                                      - 75% were good adapters (A-adapters)
Portz, Brungardt       - Fitted unadapted patients w/ PMMA, CAB       - Faster adaptation with higher Dk material
                         (Dk 5), and SA (Dk 10)
Bennet (1997)          - 40 unadapted subjects received anesthetic    - Anesthetic group rated overall GP comfort/satisfaction
                       - 40 unadapted subjects received placebo         higher
                                                                      - PROS of anesthetics
                                                                           o Better initial experience
                                                                           o Fewer dropouts
                                                                      - CONS of anesthetics
                                                                           o Must adapt to the edge w/o anesthetic eventually
                                                                               Anesthetic wears off
                                                                           o Anesthetic softens the cornea  greater risk of abrasion
                                                                               Cannot feel if anything caught under lens
                                                                           o Cannot put anesthetic in rewetting drops



GP TIPS

    -   Fitting
            o Stay calm + exude confidence
            o Give patient something to do (distracts patient from feeling of the edge)
            o Instruct patient to look down (decreases blinking)
            o Instruct patient to blow nose (decreases tearing)
            o Use anesthetics
  -   Dispensing
         o Break in the CL gradually
                Avoid looking down and have patient look around to get used to sensation of the edge
                  interaction w/ eyelid
         o Exude confidence
                Be positive & encourage/reinforce patient
         o Discuss a wearing schedule
                Build up wear time over first week
                       2-3 hours the first day + build up an hour each day
                       Work around patient’s schedule (after school, after work, take breaks)
                Apply one hour after awakening and remove one hour before bedtime
                       Allows eye to rejuvenate btwn sleeping lack of O2 and CL lack of O2
  -   Follow-up
         o Assess if patient is happy with their vision and the comfort
                Look at the patient, talk with the patient, how do THEY feel about their contacts
         o Assess corneal physiology
                Corneal edema (O2 issues more prevalent in EW, low Dk materials)
                Corneal staining (mechanical issues more prevalent than lack of O2 issues)
         o Assess patient compliance
                Wear time
                Care system (show me your routine)
                Follow-up care

O2 DEPRIVATION ISSUES

  -   Edema/distortion indicators
         o Edema & lack of O2 issues not as prevalent anymore due to high Dk materials
         o Mechanical issues and fit are now the main source of discomfort/poor adaptation
                Indicator        A-adaptor               B-adaptor
                SLE              ≤ 1+ edema/staining     ≥ 2+ edema/staining
                Manifest VA      ≤ 3 letters worse       > 3 letters worse
                K-distortion     None                    Distortion
                Km               ≤ 0.50D steeper         > 0.50D steeper
                Management       Increase wear time OK   Fit problem + decrease wear time
  -   Central corneal clouding: hazy/clouding from localized edema/swelling due to lack of O2
          o Seen with: low Dk material or AC fit (poor tear exchange)
  -   Striae: vertical stretch marks found deep in stroma from swelling/edema due to acute lack of O2
          o Seen with: diabetics, k’conus, low Dk toric SCL, EW low Dk toric SCL (not as common with RGPs)
          o May appear like a corneal nerve but does NOT go out to limbus and does NOT bifurcate
  -   Microcysts: small fluid vacuoles found anteriorly in cornea (sub-epithelium) from long-term O2 deprivation
          o Seen with: EW low Dk lenses
          o Found w/ retro-illumination

NORMAL/ABNORMAL ADAPTATION

NORMAL                                                               ABNORMAL
o Better materials = lower incidence of adaptation problems          o Sudden pain (FB sensation)
o Tearing (should see progress while patient still in your chair)    o Persistent halos
o Minor irritation (tickling, awareness of lens)                     o Severe redness or irritation
o Intermittent blurry vision (due to tearing/lens wetting)           o Spectacle blur > 1 hour
o Light, wind, dust sensitivity                                      o Increasing eye discharge
o Mild redness                                                       o Lens adherence
o 1+ degree                                                          o 4+ degree
LONG TERM WEAR EFFECTS

  -   Lower incidence of long term issues due to better materials
  -   Keratometry: steeper/flatter K, distorted mires (results when lens doesn’t center/contour corneal well)
  -   Subjective refraction: spectacle blur (results when lens doesn’t center/contour corneal well)
  -   Biomicroscopy: corneal staining (glimpse into how lens fits/mis-fits and what changes need to be made),
      polymegathism/polymorphism
  -   K-topography: corneal warpage, corneal exhaustion

DEPRIVATION

  -   Reasons for deprivation of CL
         o Refit (deprivation not necessary)
         o Compromised cornea
         o Refractive surgery
  -   Refit
         o Combining the FP, OR, and better material will stabilize the CL and cornea very quickly
                 No need to deprive patient of their CL to refit  many patients do not have specs & many
                   patients will experience spectacle blur/distortions
         o Base curve: k’metry or FP
                 Re-fit by FP with goal of AA
                 K-values can change 2-3D (not as reliable)
         o CLP: SR or OR
                 Re-fit by OR (SAM/FAP)
                 SR can be all over the place
         o Material: Dk
                 Re-fit in a better Dk material
  -   Refractive surgery
         o Deprivation time: time out of CL is not the issue
                 Every surgeon has own CL deprivation times prior to corneal surgery
                 Times are not based on anything (arbitrary)
                 No formula for deprivation time  each individual is different
                         One individual’s deprivation time might not be enough for another individual
         o Corneal stability: stability of cornea is more important prior to refractive surgery
                 Repeatable SR
                 Good SR VA
                 Repeatable K’s
                 No K-distortion
                 Stable topography indicies: not as sensitive as SR and K-values/distortion
                 Good tear film: dry eye needs to be treated before surgery
                 No cone present: k’conus more noticeable and harder to manage after refractive surgery

 COMPLICATIONS OF GP LENS WEAR

GP LENSES GENERALLY HEALTHIER THAN SCL

  -   Smaller OAD = less corneal coverage + greater tear exchange
  -   Complications = fewer + less severe
  -   Properly fitted GP lenses provide:
         o Good comfort
                     Important to patient
                     Scleral lenses more comfortable than smaller OAD lenses that have more lid interaction
          o   Good vision
                     Precise OR
                     Correct astigmatism when needed
          o   Sufficient wearing time
          o   Good corneal health + good tear film
   -   Good corneal health depends on:
          o Well designed/fitted lens
                  No excessive edge lift (err on side of max PC bc minimal PC creates poor movement & poor tear exchange)
                         Minimal PC offers good centration and good comfort
                  High Dk material (no less than 60)
                  Good wetting material (clean and soak before dispensing)
          o Central/stable lens position (slightly superior OK)
          o Adequate lens movement
          o Sufficient tear exchange (adequate edge clearance = adequate tear exchange)
   -   GP lens complications arise when 1+ factors are not met
          o Complication defined by FDA as losing 2+ lines of vision
          o Corneal staining (due to misfit of lens)
          o Corneal distortion/irregularities (due to lens position/fit)
          o Corneal problems  dellen, VLK, PCD, dimple veil, hypoxia
          o Decreased VAs
          o Decreased WT (due to dryness)
          o Decreased lens comfort (due to EW, poor lens design, fit, edge interaction)
          o Increased lens awareness (due to dryness or poor lens design)

PERIPHERAL CORNEAL DESICCATION: 3-9 staining

   -   What: localized area of dryness
   -   Location: position of staining dependent on lens-cornea relationship
          o 3-9 o’clock: lens centered (nasal/temporal dryness)
          o 4-8 o’clock: lens riding high (lower dryness)
          o 2-10 o’clock: lens riding low (upper dryness)
   -   Symptoms: none
   -   Biomicroscopy signs
          o Staining shows areas of SPK at 3 & 9 o’clock regions
          o Use yellow filter in conjunction w/ slit lamp to observe subtle staining
   -   Severity
          o Mild: small areas of non-coalescing superficial punctate staining
          o Severe: coalescing areas of SPK with heavy/deep fluorescein staining
   -   Reasons for concern
          o Sign of dryness (3-9 staining depends on wetness, NOT oxygen)
          o Avenue for infection
          o Long-term PCD may lead to dellen formation
          o Scarring
   -   Causes
          o Minimal PC  minimal edge lift leads to poor lateral lens movement upon blink (lens too tight)
          o Maximal PC  excessive edge lift leads to areas of poor rewetting
                  Tear film disrupted leading to dryness + disruption of corneal epithelium
                  Lids being held away from lens leading to poor rewetting
          o Incomplete blink/lagophthalmos
          o Inferior GP lens position
   -   Management
          o Discontinue lens wear (moderate to severe)
          o Continue lens wear w/ ATs while waiting for new lens (mild to moderate)
                  Educate patient on ATs because they don’t have dry eye sx
          o Bandage SCL under existing RGP (chronic)
                  Provides more moisture  does NOT change fit/power
          o Antibiotic (severe)
          o Educate patient on awareness of complete blinks and increase blink frequency
          o Modify edge  decrease edge lift to increase lid apposition to peripheral cornea
                  Steepen BC
                  Steepen peripheral curves
                   Thinning edge profile (plus lenticularizing minus lenses >-5D)
   -   Edge-lift (holden study)
          o Setup
                   Q: is more edge lift better?
                          More edge lift = more tear exchange
                   Fit 16 pts with silicon acrylate GPs with 0.08mm edge lift
                   Increased edge lift by flattening secondary curve radius
          o Results
                   As edge lift increased, percentage of 3-9 staining increased
                   As edge lift decreased, percentage of 3-9 staining disappeared
          o Conclusions
                   3-9 staining is fit related, NOT material related
                   3-9 staining treated by decreasing edge lift via steepening 2ndry curve or thinning edge

DELLEN

   -   What: localized area of reversible thinning due to thinning of epithelium, bowman’s, and stroma
   -   Location: adjacent to an area of elevation (ex: GP lens edge, pinguecula)
   -   Symptoms: none
   -   Biomicroscopy signs
          o Kidney-bean shaped depression at limbus or adjacent to area of elevation
          o Fluorescein pooling in excavations
          o Minimal staining
          o Slit lamp beam bends as crosses over dellen
          o NO: infiltrates, AC reaction, cells/flare, hyperemia
   -   Reasons for concern
          o If untreated, vascularization & scarring can occur
          o If untreated, prone to infection
   -   Causes
          o Desiccation or dehydration of peripheral cornea seen w/ GP lens wearers
          o Severe PCD
          o Tear film instability + poor wetness
   -   Management
          o Eliminate the cause
                  Steepening GP peripheral curves for increased corneal apposition
                  Thinning edge profile of lens
                  Surgical removal of pingueculae
          o Copious lubrication
                  ATs in the AM (every ½ hour)
                  Viscous gels in the PM
          o Antibiotic

DIMPLE VEILING

   -   What: indentations of the cornea (no breaks in epithelium)
   -   Location: central or mid-peripheral
   -   Symptoms
          o None if peripheral
          o Visual blur if central involving visual axis
   -   Biomicroscopy signs
          o Needs NaFl to be seen
          o Dimple veils are circular, well-demarcated pools of fluorescein
          o Single or multiple
   -   Reasons for concern
          o Blurred vision if centrally located
          o Rarely progresses to other issues unless dimples become immobile
   -   Causes
          o Air bubbles trapped underneath lens
          o CO2 efflux from cornea due to area of lens clearance
   -   Management
          o Dimples will self-resolve if lens wear is discontinued
                 Time of discontinued lens wear depends on length of time dimples were present
          o Lens alterations
                 Flatten BC (if dimples central)
                 Decrease OZD (if dimples mid-peripheral)
                 Heavy blend on jxn btwn BC and PC’s allowing for better tear mvmt/exchange
   -   “Dimple veil” in silicone-hydrogels
          o What: mucin balls (spherical particles of mucous, lipids, proteins in post-lens tear film)
          o Caused by: flat fitting silicone-hydrogel lenses used for EW
          o Symptoms: none
          o Resemble: dimple veiling from GP lens wear

VLK: vascularized limbal keratitis

   -   What: rare inflammatory condition of cornea in which superficial & deep vascularization emanating from
       conjunctiva encircles the infiltrate and raised epithelial mass
   -   Location: conjunctiva/corneal limbus
   -   Symptoms: pain, redness
   -   Biomicroscopy signs
          o Invasive vascularization
          o SPK & epithelial chafing
          o Epithelial heaping (elevated limbal epithelial mass)
          o Acute hyperemia
          o Vascular leash
   -   Causes
          o Initially caused by desiccation or tear film disturbances associated with lens edge-lift
          o Chronic dryness/irritation from persistent 3-9 staining
   -   Reasons for concern
          o If untreated, elevated epithelium may erode (painful)
   -   Management
          o Eliminate cause by temporarily discontinuing lens wear
          o Stop inflammatory process
                  Rx ocular lubes and decongestants  constrict vessels + limit permeability of vessel
                  Rx topical steroid  treat infiltrate and regress vascularization
          o Refit GP lens for long-term mgmt
                  Smaller OAD
                  Flatter PCs to prevent chafing (CAUTION: flat PCs may disturb marginal tear meniscus)

HYPOXIA

   -   What: decreased availability of O2 resulting in an increase in CO2
   -   Prevalence: less common today due to higher Dk materials but found with EW + PMMA lenses
   -   Stromal edema
          o What: 8-10% swelling due to influx of water into stroma
          o Caused by: accumulation of lactic acid from increased anaerobic metabolism
          o Importance: amount of swelling inversely retated to amount of O2 in tears
   -   Microcysts
          o What: small 0.01 – 0.1mm transparent epithelial inclusion bodies found deep in epithelium
          o Caused by: chronic hypoxia (at least 2-3 months)
          o Importance: inclusions break and stain as they travel anteriorly through epithelium
                      Best seen w reverse illumination
  -   Striae/folds
          o What: fine white vertical lines
          o Caused by: corneal edema
                 5-6% corneal swelling = striae
                 10-12% corneal swelling = folds
          o Importance: seen more with low Dk EW SCL
  -   Management
          o Mild cases: decrease wear time
          o Moderate cases: refit w/ higher Dk material + decrease wear time
          o Severe cases: discontinue lens wear until neovascularization/chronic SPK regresses; refit lens

MECHANICAL COMPLICATIONS

  -   Foreign bodies
         o Reason for concern
                 Abrasions; epithelial staining
                 Tear pump or lens movement can dislodge FB
         o Symptoms: irritation
         o Biomicroscopy signs
                 FB tracks appear as thin linear streaks that stain w NaFl
                 FB tracks show movement of FB w lens mvmt & blink
         o Management (depends on severity of abrasion)
                 Prompt removal/irrigation of FB
                 Mild staining: discontinue lens wear for 24 hrs; rx ATs
                 Moderate staining: prophylactic antibiotic drops
  -   GPC: giant papillary conjunctivitis
         o What: mechanical insult caused by rigid lens edge + deposit formation
         o Biomicroscopy signs
                 Large bumps found on upper palpebral conjunctiva
                 Lid inflammation (due to deposits)
         o Management
                 Discontinue lens wear
                 Enzymatic cleaners to remove deposits
  -   Impression rings
         o What: marks left on cornea due to tight fitting GP lens (flat lens or steep PC)
         o Signs/symptoms
                 Corneal distortion
                 Spectacle blur
                 Mild-to-no staining
         o Treatment
                 Discontinue lens wear
                 Refit w/ steeper BC or flatter PC

TOXICITY

  -   Causes
         o Red tip cleaners
         o H2O2 care systems
         o Poor rinsing of lenses
  -   Signs
         o Diffuse SPK
         o Conjunctival injection
 DRY EYE (dr. kwan)

INTRODUCTION

  -   Definition
         o Dry eye is a multifactorial disease of the tears, eyelids, and ocular surface that results in symptoms of
             discomfort, visual disturbance, and tear film instability with potential damage to the ocular surface
         o Dry eye is accompanied by increased osmolarity of the tear film & inflammation of the ocular surface
  -   Symptoms
          o   Dry                                                     o    Itchy, scrathcy
          o   Uncomfortable                                           o    Foreign body sensation (distinguishes MGD from ADDE)
          o   Irritated                                               o    Gritty, sandy
          o   Tired                                                   o    Sore, painful
          o   Burn                                                    o    Sensitive to light
          o   Fluctuating/blurry vision                               o    Sticky
          o   Red                                                     o    Difficultly removing SCL
  -   Tear film
         o 3 thick (3000nm)
         o 3 dynamic, non-distinct layers
                 Lipid layer: 40-120nm thick; elastic; outermost layer; provides hydrophobic barrier
                 Aqueous layer: viscous; bulk of tears; promotes spreading of tear film and control of infectious agents
                 Mucin layer: innermost layer; produced by conjunctival goblet cells; enables tear film to adhere to epithelium
  -   Types of dry eye
         o 80%- Evaporative Dry Eye (EDE) = Meibomian Gland Dysfunction (MGD)
                 Inflammatory (blepharitis)
                 Non-inflammatory (obstructive or atrophic)
                 Intrinsic (meibomian oil def, disorders of lid aperture, low blink rate)
                 Extrinsic (vit-A def, topical drugs, CL wear, ocular surface disease)
         o 20%- Aqueous Deficiency Dry Eye (ADDE)
                 Sjogren’s (autoimmune)
                 Non-sjogren’s (lacrimal def, lacrimal gland duct obstruction, reflex block, systemic drugs)
         o Mixture: EDE + ADDE
         o Other
                 Ocular allergy
                 Epithelial basement membrane dystrophy
                 Recurrent corneal erosion

  -   Prevalence
         o 5-30% US population (different numbers due to different dry eye definitions)
                 17% globally | 30% in Asians
         o 44-75% of CL wearers
         o 40% of people have MGD (altered oil secretion)
  -   Risk factors
         o Age: older people
         o Gender: females > males
         o Systemic disease
                 Autoimmune diseases (arthritis, lupus, sjogren’s)
                 Diabetes (rate of corneal healing is impaired after epithelial damage)
         o Hormonal insufficiency:  testosterone =  dry eye (peri- and post-menopausal women)
         o Iatrogenic causes
                 Ocular surgery: LASIK, cataract surgery (corneal nerves cut  cant sense dryness, cant make tears)
                 CL wear (disrupts tear film and increases evaporation)(splits thin tear film into pre-tear lens and post-tear lens)
                 Medications: antihistamines, diuretics (only takes 4 days for TBUT to drop and staining to increase)
                 Computer use (blink rate decreases, fewer breaks)
                 Environmental stress: low humidity, dust, smog, AC vents, airplanes
                 Smoking
                 Alcohol, hydration level
  -   CL-related dryness
         o CL disrupts tear film and increases rate of evaporation
         o Underlying dry eye
         o CL-solution incompatibility
                Educate patient: not all solutions created equal
                           Not everyone can tell
                           Generic solutions known to cause greater area of staining
                           Educate on mechanical rubbing to loosen deposits
                           Ask about solution on f/u visit
                 Start with: MPS (puremoist, revitalens, biotrue)
                 Problem-solver: clear care (no-rub soln, loosens deposits well)
         o   CL-patient incompatibility (high Dk lens ≠ less dryness)
         o   Non-compliance  lens overwear, lens deposits

DRY EYE DIAGNOSIS

  -   PC/CL examination dry-eye evaluation
         o Biomicroscopy (lid margin eval)
         o TBUT
         o Schedule dry-eye workup if needed
  -   Comprehensive dry-eye evaluation billed to medical insurance
         o Billing codes: 99213 ($100) or 99212 ($55)
         o Diagnosis codes: 375.15 (tear film insufficiency) or 370.33 (KCS no specified as sjogren’s)
         o Get to know your rheumatologist + dermatologist (many arthritis/rosacea patients will have dry eye)
  -   Prior to comprehensive dry-eye evaluation
         o No CL wear for 2 days prior to appt (allows tears to restabilize and cornea/conj to heal)
         o Good night sleep night before exam
         o No eye drops day of exam
         o No eye-makeup day of exam (mascara/eyeliner can mask eyelid margins and can float into tears)
         o Bring list of all current meds and eye drops (OTC, vitamins, supplements, allergy, systemic, eye, ATs)
  -   SCCO comprehensive dry-eye evaluation
         o Least invasive to most invasive PRN
         o Case history
         o Schein or OSDI Questionnaire: provides sense of severity
         o BCVA
         o Topographer surface regularity index: >0.80 is irregular
                  Poor tear film will result in inaccurate topography
                  Oculus keratograph: topographer also allows NIBUT testing and measures tear meniscus
                    height on top of fitting GP lenses and diagnosing k’conus
         o Interferometry/tear film analysis: jagged/multi-colored is abnormal; smooth/white is normal
                  Interferometry is a judgement of tear film oily-ness
         o Tear osmolarity: >308mOsms/L is abnormal
                  Tear osmolarity measures salt/concentration of tears
                  TearLab: device samples small amount of tears; higher of 2 readings is used
                         Allows diagnosis of severity and monitoring effectiveness of treatment
                         Good specificity/sensitivity
         o Biomicroscopy: lid margin eval
                  Capped glands
                  Telangiectasia (tiny blood vessels seen in eyelid margin)
         o TBUT: ≤7sec is abnormal
         o Corneal staining w/ NaFl: amount of stain and location/pattern
                  Whole cornea stain  CL solution induced
                  Limbal area stain  CL removal, tight fit
                  Lower 1/3 stain  lagophthalmos, partial blinkter
                  3-9 stain  excessive GP edge lift
         o Conjunctival staining w/ lissamine green: coalesced or diffuse
                  Conjunctival staining often due to knife edge interaction
         o  Meibomian gland expression: thick/opaque is abnormal; clear is normal
                Gentle expression w/ q-tip for diagnosis
                Forceful expression w/ mastrota paddle for treatment
         o Meibomian gland dropout: n=24 is normal; more dropout seen nasally/temporally than central
                Meiboscopy: use transilluminator to evert lower lid and backlight MGs
                Meibography: assess if MGs are normal, shortened, or missing; calculate dropout %
         o Schirmer I test: <5mm in 5min is abnormal  designates aqueous deficiency
                Measures maximum ability to produce tears
                Done w/o anesthetic to provoke reflex tearing
                Distinguishes btwn aqueous deficiency and MGD
         o Phenol red thread test: <5mm in 15sec is abnormal  aqueous deficient
  -   Dr. Kwan’s minimal dry-eye workup
         o Careful case history
                What patient feels can be different than what optometrist sees
                Common patients with dry eye: fibromyalgia, sleep apnea, arthritis, rosacea
                Environmental conditions associated w dry eye: AC, cold mornings, wind, light sensitivity
         o Schein questionnaire
         o Biomicroscopy  eyelid/ocular surface evaluation
         o TBUT
         o Corneal staining w NaFl
         o Conjunctival staining w lissamine green
         o MG expression
         o Meiboscopy
         o LOTS of patient education

DRY EYE MANAGEMENT

  -   Customize treatment management to patient and treat according to etiology
      Meibomian gland dysfunction                                 Aqueous tear deficiency
      - Warm compresses and lid massage                           - ATs (systane ultra, optive)
      - Omega-3 FAs                                               - Omega-3 FAs
      - Doxycycline or minocycline                                - Restasis (cyclosporine A)
      - Oil-based ATs (systane balance, soothe XP)                - Lotemax
      - Azasite                                                   - Punctual plugs (temporary/permenant)

  -   Lines of defense
       1st line of defense       -   ATs + ointments
                                 -   Eyelid hygiene (warm compress/lid massage)
                                 -   Environmental modifications
       2nd line of defense       -   Oral medications (tetracyclines, omega-3s)
                                 -   Topical anti-inflammatory meds
                                 -   Consult PCP to modify systemic meds
       3rd line of defense       -   Punctual plugs
                                 -   Bandage soft or scleral contact lenses
                                 -   Moisture chamber glasses
       4th line of defense       -   Autologous serum (eye drops made from own blood plasma w growth factors to promote healing)
                                 -   Surgery (lid, tarsorrhaphy)

  -   Triad of treatment to ensure patient success: (1) ATs (2) short course of Lotemax (3) omega-3s
  -   More information on various treatments
         o Meibomian gland expression
                  Mastrota paddle used on palpebral conjunctiva side for forceful expression
                  Evacuates thick abnormal oil so fresh new oil can be produced
         o Artificial tears
                  Lubrication to soothe irritation and feeling of dryness
                  Types: oil, aqueous, gel, ointment
                        5 different Systanes (original, ultra, balance, gel, ointment)
                  Dr. Kwan’s favorite ATs: oasis tears (non-preserved); systane ultra (application + rewetting
                    drop for SCL and GPs); systane balance
o   Medication
       Anti-inflammatories (Lotemax, FML forte)
              Reduces inflammation
              Steroid drops  measure and monitor IOP
       Immuno-modulator (Cyclosporine or restasis)
              Increases tear production by helping lacrimal gland produce more normal tears
              Reduces inflammation
              Extends hours of comfortable CL wear
              PRO: subjective success;  success/compliance when coupled w other therapies
              CON: takes at least 3 months to see benefits; many adverse effects; doesn’t create
               drastic improvement in aqueous production (may increase TBUT from 1.21 to 3.24 but 3.24 is
                   still considered abnormal)
          Antibiotics
               Erythromycin ointment  used for severe bacterial blepharitis
               Azasite  azithromycin used for bacterial conjunctivitis; helps MGD
               Tetracyclines  doxycycline/minocycline used for MGD and rosacea
                      o Low doses used to prevent side effects
o   Omega-3 FAs
        Every person should have 650mg of EPA/DHA per day regardless of health status
        Benefits
               Both Omega-6 and Omega-3s are anti-inflammatory when ratio is < 4:1
                      o EPA/DHA in Omega-3s has anti-inflammatory effect
                      o Omega-6s become pro-inflammatory when ratio is > 4:1
                      o Typical N. American diet has a ratio of 15:1
               Omega-3s promote cardiovascular health as well
        Sources
               Dietary supplementation
               Diet (salmon, trout, sardines, oysters, tuna)
               Triple strength fish oil capsules (980mg EPA/DHA per capsule)
        Cautions
               High doses of Omega-3s can act as blood thinner
               Check labels  many say 1000-1200mg per capsule but only have 300mg of EPA/DHA
               Our body only has 10% conversion rate of -linolenic acid to EPA/DHA  skip flaxseed
                 oils and concentrate on fish and fish-oils
o   Moisture goggles
        Insulates the eye from external environment
        Creates a high humidity environment to stabilize the tears
o   Lid scrubs + compresses
        Promotes lid hygiene
        Loosens hard oil that may be blocking meibomian gland
o   Omega 7s
        Source: sea buckthorn oil
        Benefits
               Protects, hydrates, improves skin quality
               Comforts and lubricates internal mucous membranes
        Cons: minimal scientific evidence
o   Contact lens treatments
        Newer silicone hydrogel CLs w wettability coating
        GP lenses
        Scleral lenses: large OAD holds sterile saline on the eye all day and provides protection from
           external environment
          Bandage contact lens: steeper BC, temporary EW lens protects corneal surface from
           mechanical abrasion of eyelid to heal persistent epithelial defects
         o   Advanced treatments
                 Intense pulse light therapy: pulsing upper cheek area w/ light stimulates MGs & improves
                     secretion
                 Intraductal meibomian gland probing: probing MG with needle to loosen hard oil
                 
                 Lipiflow thermal pulsation system: in-office warm compress treatment that heats MGs from
                 
                 inside while pulsating and pushing oil out of glands
  -   Managing dry eye in CL wearers
        o Warm compress and lid massage daily in shower
        o ATs before applying CLs  makes ocular surface more wettable
        o Hypoallergenic and good-quality makeup
        o Rewetting drops during the day (systane ultra, blink, refresh optive, etc)
        o Reminders to blink and take breaks w/ extended near tasks
        o Omega-3s
        o Short-term doxy/minocycline

TAKE HOME MESSAGE

  -   Dry eye is the most common eye condition but most treatable by optometrists
  -   Treatment of dry eye can proactively prevent CL dropout & improve quality of life

 REFRACTIVE SURGERY (dr. tran)

INTRODUCTION

  -   LASIK does not take away money/patients from practice
         o OD gets 20% of LASIK price for co-management (~$800)
         o High myopes need annual DFE due to higher risk of retinal problems due to axial length
         o Patients still need plo sunglasses + readers
         o Patients still have vision insurance
  -   Co-management
         o Increases your liability  if something goes wrong, your name is attached to the case
         o Includes ~7 visits (pre-op and post-op visits) to monitor corneal health
  -   Goal of refractive surgery
         o Reduce need for glasses and CL (decrease dependency on eye wear)
                 Never guarantee that patient will not need another pair of glasses
         o High myopes benefit most from LASIK

REFRACTIVE PROCEDURES

  -   RK: RADIAL KERATOTOMY
         o History: Dr. Leendert developed concept of flattening cornea via incisions made on anterior surface
                Incisions = flatter cornea = less corneal power = patient less myopic
         o Procedure: series of radial incisions made on cornea (start w/ 8 incisions, adding 4 as needed)
         o Corrects for: low myopia (1.00-3.00D)
         o Problems
                Freehand procedure creates problems w consistency/predictability
                           Corneal depth? Straight incisions? Length of incisions?
                    Decrease corneal integrity over time due to irregular astigmatism
                           Vision great for 5yr and then patients deteriorate to high + rx
                Visual problems: over/under correction, irregular astigmatism, glare/halos from small OZD
                Limbal involvement: corneal neovascularization
  -   AK: ASTIGMATIC KERATOTOMY
         o Procedure: horiztonal/vertical cuts along meridian of astigmatism to flatten cornea in that meridian
                H cuts = ATR correction; V cuts = WTR correction
                Incisions “relax” corneal tissue to produce more spherical shape
         o Corrects for: astigmatism
         o Problems: same as RK
-   ASA/PRK: ADVANCED SURFACE ABALATION/PHOTOREFRCTIVE KERATECTOMY
      o Procedure: excimer laser removes 50 of corneal epithelium & sculpts exposed tissue
             Loosens/removes corneal epithelium/bowmans to expose corneal stroma
             Cornea reshaped to correct for patient’s prescription
             Bandage CL placed over open wound
      o Excimer laser: non-thermal laser beam of excited dimer molecules used in photoablation
             Plume-effect: beam releases molecules from tight binding creating cloud of free molecules
             Leaves clean/precise edges
      o Corrects for: low-moderate myopia (≤7.00D), astigmatism, hyperopia
             Beyond -7.00D depends on corneal thickness
             Results less predictable for hyperopia
      o Pros/cons
            PRO                                             CON
            - OK for thin corneas                          - Open wound leaves stroma exposed  bandage CL used
            - No flap complications                        - Delayed vision for 1-2wks as epithelium healed
            - Better long-term corneal integrity           - Discomfort for ~6mo
            - Predictable, precise                         - Risk of stromal haze
            - Good for pts w/ EBMD                         - High risk of infection/inflammation
            - Retreatment possible                         - Steroids for ~1mo (risk of high IOP; not good for glauc pts)
       o Mitomycin C
              Topical drug applied after laser treatment
              Reduces incidence of corneal scarring/hazing
              PRK renamed to ASA  regaining popularity
       o Post-surgery management
              Antibiotics QID to prevent infection
              NSAIDs QID to manage pain
              Daily follow up to monitor epithelium regrowth
              After epithelium completely reformed, remove bandage CL and begin steroid treatment to
                reduce risk of corneal scarring/hazing
-   LASEK: LASER ASSISTED IN-SITU EPITHELIAL KERATOMILEUSIS
       o Procedure
              20% alcohol solution loosens corneal epithelium so 50 flap can be lifted back
              Excimer laser sculpts cornea to correct the RE
              Epithelium is replaced over stromal bed
              Bandage CL applied over open wound
       o Epi-Lasik
              Blunt oscillating blade (epi-microkeratome) used to create corneal flap instead of alcohol
              Same procedure as LASEK
       o Corrects for: low-moderate myopia (≤9D), astigmatism, hyperopia
       o Pros/cons
            PRO                                            CON
            - Recovery shorter than PRK                   - Complications during flap formation
            - Patient comfort better than PRK             - Open wound leaves stroma exposed  bandage CL used
            - Predictable, precise                        - Epithelial flap sloughs off + replaced
            - Retreatment possible                            o Delayed vision as epithelium heals
            - Short-term medication (AB, steroids)            o Risk of stromal haze
                                                          - More discomfort than LASIK
                                                          - Recovery longer than LASIK

-   LASIK: LASER ASSISTED IN-SITU KERATOMILEUSIS
       o Procedure
              Microkeratome or IntraLase Femtosecond Laser used to create flap of corneal epithelium,
                bowman’s membrane, stroma (120-150 thick)
                    Flap preserves bowman’s layer
              Excimer laser ablates/reshapes corneal tissue to correct the RE
       o Corrects for: low-moderate myopia (≤9D), astigmatism, hyperopia
              Results less predictable for hyperopia
o   Pros/cons of LASIK
    PRO                                                         CON
    - Near-immediate vision                                    - Complications during flap formation
        o Functional w/in 24hrs; fully functional w/in 1wk     - Conventional LASIK can induce higher order aberrations
    - Bowman’s membrane preserved  no risk of scar                o Magnitude depends on amt of pre-op myopia
    - Fast recovery
    - Comfortable
    - Customized: imprints patient’s cornea
    - Predictable, precise
    - Re-treatment possible
    - Short-term meds (ABs, steroids)
o   Flap creation
        Microkeratome: blade
               Many moving parts  risk of mechanical breakdown + metal debris
               Less control over flap thickness/formation
                    o Size: limited to diameter of tool
                    o Thick: 160
                    o Variability in thickness across peripheral/central cornea & across different flaps
               Torsional effect
               Loss of suction can cause cornea to drop back down and create “buttonhole cut”
                    o Must let cornea heal and will typically not try LASIK again
        IntraLase Femtosecond Laser: bladeless
               Infrared light beam (2-3 in size) removes tissue via photodisruption
                    o Laser forms microscopic bubbles of CO2 and water vapor
                    o Thousands of interconnecting bubbles create separation btwn stromal layers at
                        very precise depth
                    o Similar appearance to “perforated paper”
               Flap
                    o Size: any size
                    o Thin: 110
                    o Precise flap thickness across peripheral/central cornea (minimal variability)
                    o Customized to patient’s corneal thickness
               Advantages/disadvantages
                      PRO                                                           CON
                      - Bladeless  no complications from blade                    - Cannot penetrate scars
                      - Consistent, repeatable, predictable, precise               - Opaque bubble layer  bubbles trapped
                           o Flap thickness + size precise                           and flap cant be cut
                           o Hinge location controlled                             - Elevated IOPs for longer duration
                      - Corneal surface + flap edge smoother
                      - Allows for thinner flaps for thinner corneas
                      - Fewer corneal nerves damaged
                      - Customized to patient
                      - Patterned edges  edge locks into base
                           o Less tension in suture
                           o Less alteration in K-topography
                           o Minimize amt of endothelial cells being exchanged
                           o Prevent epithelial cells from migrating into stroma
                      - Used in corneal transplant patients

o   LASIK add-ons
        Wavefront-guided or wavefront-optimized: custom LASIK to remove/prevent HOAs
        Active eye-tracking: high-speed computerized eye tracking to maintain the alignment of the
          laser with the position or movement of the eye
        Iris registration: accounts for cyclorotation of the eye
  -   CK: CONDUCTIVE KERATOPLASTY
         o Procedure
               Steepening of central cornea
               Controlled radio frequency energy shrinks small areas of corneal collagen in circular pattern
                 around peripheral cornea
         o Corrects for: low hyperopia (+0.75-3.00DS), presbyopia, astigmatism (≤0.75DC)
         o Pros/cons
              PRO                                            CON
              - Near immediate vision; immediate recovery   - Retreatment necessary (effects only last 3-5yrs)
              - Comfortable (mild FB sensation)             - Corneal scarring permanent
              - Predictable, retreatable                    - Small OZ in high Rx
              - Short term meds                             - Monocular procedure  temporary monovision
  -   INTACS: INTRACORNEAL RING SEGMENTS
         o Procedure
                 2 channels are made in peripheral cornea via IntraLase
                 PMMA segments inserted into channels in peripheral corneal stroma
         o Corrects for: low myopia, k’conus
                 Arc-shortening effect: rings apply pressure to peripheral cornea  central cornea flattens
                 Segments provide support and thickness to thin, weakened cornea
                 Procedure does NOT remove more corneal tissue
         o What patients should get INTACS
                 GP lens intolerant
                 Keratoconus
                 Pellucid marginal degeneration
                 Post-LASIK ectasia
         o Corneal health requirements
                 Clear central cornea
                 No scarring
                 Max K-value of 57D
                 No corneal neovascularization
         o INTACS does not
                 Halt or reverse progression of corneal thinning disease
                 Completely rid dependence on GP lenses or other visual correction
         o GOAL: improve CL fitting success
  -   CLE: CLEAR LENS EXTRACTION
         o Procedure: internal lens of eye is removed and a lens implant of a different power is implanted
         o Corrects for: hyperopia, high myopia, presbyopia, high rx’s
         o Recommended for: patients over 40 with high rx (near cataract age)
         o Not recommended for: younger patients bc younger patients will lose ability to accommodate
  -   ICL: IMPLANTIBLE COLLAMER LENS
         o Procedure: artificial lens implanted behind/in front of iris with natural lens remaining in place
                 Essentially, an internal contact lens
         o Corrects for: high amounts of myopia (>11D)
         o Recommended for: younger patients with high rx
         o Caution: touching natural lens during surgery will induce cataract & warrant removal of natural lens

ABERRATIONS

  -   Aberrations = errors of the entire eye (cornea, lens, shape, length, etc)
         o Lower order aberrations: sphere and cylinder refractive error
                Only treated via specs/CLs
         o Higher order aberrations: coma, spherical aberration, distortion, etc
  -   Zywave Wavefront Aberrometer
         o Narrow laser beam focused on retina to generate single, focused point source
         o Outcoming light rays bent by aberrations caused by refracting media (cornea, lens, vitreous)
         o Sensor detects how much outcoming rays deviate from original incoming rays
      -    Custom LASIK
              o Aberrometer uses wavefront analysis to measure aberrations unique to individual
              o Custom LASIK interfaces the aberrometer w/ the laser to eliminate higher order aberrations (HOAs)
              o Wavefront-guided: ablations treat refractive error and pre-op HOAs
              o Wavefront-optimized: ablations treat refractive error while preventing induction of post-op HOAs

LASIK/ASA POWER RANGES

      -    Correction HIGHLY dependent on corneal thickness  varies by individual
      -    LASIK/ASA
              o Myopes: < -11.00D sphere
              o Hyperopes: < +6.00D sphere
              o Astigmatism: < 6.00D cylinder power
              o Higher prescriptions can be managed via CLE, ICL, or a combination of treatments
      -    EXAMPLE: Patient with rx of -6.00DS OD, OS wishes to have LASIK. Patient’s CCT is 500 OD and 475 OS.
           If a stromal bed of 250 must be left, flap thickness is 125, and each diopter of correction requires ablation
           of 16, should this patient get LASIK?
               o    Correction of -6.00 requires ablation of 96
               o    OD: 500 – 125 flap – 96 correction = 279  LASIK OK
               o    OS: 475 – 125 flap – 96 correction = 254  TOO CLOSE FOR COMFORT
               o    Suggestion: LASIK OD, PRK OS

LASIK CANDIDATES

      -    Patients may or may not inquire about LASIK
              o Inquirers: discuss what patient wants to accomplish with LASIK; send for consultation
              o Non-inquirers: don’t be afraid to ask patient if they have thought about it or why they are not
                 interested in it
      -    LASIK candidates
              o Adults over 18
              o Stable refractions (<0.50D change over last year; <0.25D change over last month)
                      When findings are repeatable, patient is ready
              o Adults w/ active lifestyles (water sports, outdoor activities, etc)
              o Patients with kids (avoid broken glasses, waking up in middle of night)
              o Patients who cannot get around in an emergency w/o their correction
      -    Good LASIK candidates
              o Motivated patients with realistic expectations
              o Patients with much to gain (high rx’s)
              o Patients who understand there are surgical tolerances
              o Patients who desire good “functional” vision
              o CL intolerant patients
              o Patients who want less dependency on glasses/contacts
              o Not an engineer

LASIK CONTRAINDICATIONS
                    RELATIVE                                       ABSOLUTE                                PRACTICAL
-   Anxiety                                     -   Severe dry eyes                       - Age (too old v. too young)
-   Mild dry eyes                               -   Active disease (HSV, K’conus, PMD)    - Unrealistic expectations
-   Lid disease (blepharitis, meibomitis)       -   Thin corneas                          - Myopic presbyopes (will lose near vision w/
-   Irregular topography (wait for stability)   -   Extreme rx                              LASIK and be unhappy)
-   Systemic disease (diabetes, etc)            -   Unstable refraction                   - Low refractive errors (low benefit)
-   Previous corneal surgery                    -   Unstable topography                   - More to lose than gain
-   Amblyopia                                   -   Monocular patients                    - Anxious/nervous
                                                                                          - Pregnancy/nursing
If patient is managed for these items, they     Patients with these items should NEVER
can become a good candidate for LASIK           undergo LASIK  look into other options
PATIENT PREPARATION

  -   Discontinue CL wear prior to surgery
  -   ABs QID day before surgery (zymar, zymaxid, vigamox, moxeza)
  -   Bring driver
  -   Eat before arrival
  -   Plan on being at surgical site ~2hrs
  -   Dress warmly
  -   Sleep as much as possible after
  -   Do not return to work same day
  -   Return to surgical site for 1 day check-up

				
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