PCL Final

GP lens solutions

• clean & condition (multipurpose)

  • Boston Simplus

  • Unique pH

• soap & disinfectant separate

  • Optimum

  • Boston

• used for both GPs & SCls

  • Clear Care

SCl Solutions

• all multipurpose

• mechanically clean lenses before storage

  • OptiFree

  • RevitaLens

  • BioTrue

  • ReNu

• H2O2 formulas for SCls

  • Clear Care

  • Oxysept

Functions of Wetting & Soaking Solutions

• enhance lens surface wettability temporarily

• maintain lens in hydrated state

• disinfect the lens

• acts like a mechanical buffer b/n: lens, cornea, & lids

Bactericidal Preservatives

• H2O2 solutions only

  • Benzalkonium Chloride (BAK)

  • Chlorhexidine

  • Thimerosal

  • Benzyl Alcohol

  • Polyaminopropyl Biguanide (PAPB)

Bacteriostatic Preservatives

• Ethylenediamine Tetraacetate (EDTA)

  • removes proteins and minerals that can interfere with the cleaning process

Purpose of Preservatives

• provides necessary degree of disinfection in the environment in which they are used

• cause no toxic reaction

• compatible w/ lens material

• compatible w/ tear film

Most Common Preservatives

• Bactericidal

  • Benzalkonium Chloride (BAK)

  • Chlorhexidine

  • Thimerosal

  • Benzyl Alcohol

  • Polyaminopropyl Biguanide (PAPB)

• Bacteriostatic

  • Ethylenediamine Tetraacetate (EDTA)

Benzalkonium Chloride (BAK)

• quaternary ammonium compound

• often used at 0.004%

• often combined w/ EDTA (Ethylenediamine Tetraacetate) to enhance effectiveness

• toxic w/ hydrogel lenses

Chlorhexidine

• limited binding w/ GPs

• ineffective against:

  • yeast

  • fungi

  • serratia

• used in 10mL of 0.0005% in hydrogel lens disinfecting solutions

Thimerosal

• organic mercurial compound

• sensitivity in some hydrogel wearers

• slow acting

• rarely toxic w/ GP wearers

• should be used w/ other preservatives for optimal antimicrobial effectiveness (Chlorhexidine)

Ethylenediamine Tetraacetate (EDTA)

• not a true preservative

• chelating agent

• used in combination w/ other preservatives to enhance bacterial action against pseudomonas

Benzyl Alcohol

• originally a solvent for CL materials

• low molecular weight, bipolar, & water soluble

• negligible binding to GPs

• good antimicrobial activity

Polyaminopropyl Biguanide (PAPB)

• low sensitivity w/ hydrogel lens patients

• great antimicrobial activity

  • especially against serratia

• possible toxic reaction in rigid lens solution (misuse/ higher concentrations)

Wetting Agents

• Polyvinyl alcohol

• Methylcellulose

Polyvinyl Alcohol

• water soluble

• relatively non-viscous

• non-toxic to the ocular surface

• good spreading and wettability on the eye & lens surface

Methylcellulose

• may retard regeneration of corneal epithelium

• successful in more viscous GP solutions

Cleaning Agents

• nonabrasive surfactants

• abrasive surfactants

• surfactant soaking solutions

• enzymes

• laboratory cleaners

Non-Abrasive Surfactants

• contained in most GP cleaners

• remove contaminants

  • mucoproteins

  • lipids

  • debris

• digital pressure important to be effective

Abrasive Surfactants

• particulate materials

  • effective for mucoproteinaceous deposits

• more effective than non-abrasive

Problems w/ Abrasive Surfactants

• may cause lens scratches

• may induce minus lens power while reducing center thickness

• may be eliminated by using small - particle abrasive cleaner

Specialty Lens Requirements

• high corneal astigmatism

• residual astigmatism

• presbyopes

• irregular astigmatism

High Corneal Astigmatism

• CA >2.00D

• use of Back Surface toric GP lenses or Bi-Toric GP lenses

  • induced cylinder

• use of Aspheric GP lenses

  • for ATR astigmatism

Residual Astigmatism

• Front Surface Toric GP lenses

  • CA low with high RA

    • prism ballast

    • positive cylinder form (ground on front surface)

    • LARS

irregular astigmatism

• GP lenses (regular CLs wouldn’t correct) - astigmatism corrected by tear lens power

• keratoconus

• pellucid marginal degeneration (inferior margin)

• post graft (irregular surface → need GP fitting)

• post refractive Sx (LASIK induced ectasia)

Corneal Topography

• curvature of the entire cornea (from limbus to limbus)

• color coded map

  • helps educate patients on the shape of their cornea & ability to fit

• expensive

  • refer to large practices, hospitals, or institutions

Keratometer

• measures 4mm of the entire cornea

• only 8% of the cornea is measured

Placido’s Disk

• Reflected on topographer

• shows corneal irregularities

• mires more separated = Steeper cornea

• mires Closer = Flatter cornea

Irregular Astigmatism CL Fitting

• vision improves w/ RGP vs specs or SCLs

• most fitting is trial and error

Keratoconus

• #1 use of GPs

• progressive (7 - 20 years)

  • sooner presentation = worse prognosis/ faster progression

• asymmetric

  • one eye more advanced than other

• non - inflammatory

• self - limiting

• bilateral: 96% cases

Keratoconus Etiology

• not exactly known

• hereditary

• nutritional factors

• atopic factors: hay fever, asthma, eczema

  • 50% patients

  • itching

• contact lenses

  • rigid lenses due to mechanical pressure & hypoxia

Keratoconus Histological Changes

• thinning of corneal stroma

• breaks in Descement’s membrane

• iron deposits in corneal epithelium (Fleischer Ring)

Keratoconus Early Sxs & Clinical Signs (thorough Hx)

• monocular diplopia or ghost images

• patient may own several pairs of glasses (frequent Rx changes)

• asthenopic complaints: photophobia, halos

• gradual decrease of VA (1st clinical sign)

• “Scissor - like” motion in retinoscopy

  • may just be corneal astigmatism

Keratoconus Keratometry

• lack of parallelism in mires

• distorted mires

• almost impossible to overlap the (+) and (-) signs

• increase & shifting of corneal astigmatism to an oblique axis

Keratoconus Corneal Topography

• needed to diagnose keratoconus

• localize cone apex and localized steepening seen with color coded map

Keratoconus Slit Lamp

• essential for Keratoconus Dx

• clinical signs

  • Vogt’s striae: vertical lines in central cornea in descent’s (post. cornea)

  • Fleischer ring

  • scarring

Vogt’s Striae

• stretching of the posterior stroma or descement’s membrane

Fleischer ring

• in 50% keratoconus cases

• outlines base of the cone

• hemosiderin (brown iron pigment) deposits in the deep epithelium

Other SL findings

• corneal thinning

• increased visibility of nerve fibers at the cornero-scleral junction

• corneal hydrops (severe)

  • secondary to decrements rupture (aq. humor passes thru damaged stroma → edema → scarring)

• Munson’s sign (external finding)

Keratoconus Ophthalmoscopy

• circular/ oblong shadow against the red retinal reflex (confused w/ indefinite cataract)

  • inferior dark reflex

• Fundus details are difficult to observe

• use photo diagnosis to monitor size, shape, & location of the cone

Keratoconus DDx

• corneal warpage syndrome

• high riding RGP lens (steeper)

• Pellucid Marginal Degeneration

  • later in life

  • High Ks: 60D - 80D

• Keratoglobus

  • general corneal thinning

  • congenital

Corneal Warpage Syndrome

• due to long term CL wear w/ Hx of hypoxia or mechanical effects (PMMA)

• reversible if d/c CLs

• no slit lamp sign like keratoconus

• keratoconus like scissors motion

Keratoconus Classification : Shape & size

• nipple cone (MC, smallest)

  • 3-4mm, round in shape

  • inferior to inferonasal

• oval cone

  • 5-6mm, oval in shape

  • inferonasal to inferotemporal

• globus cone (similar to keratoglobus)

  • >6mm

  • inferotemporal

Stage 1 Keratoconus

• can be corrected w/ spectacle

• slight increase in refractive astigmatism

• mild scissor reflex in retinoscopy

• slight or no keratometric mire distortion

• difficult to diagnose

Stage 2 Keratoconus

• corneal distortion & irregular astigmatism

• increase in myopia & refractive astigmatism

• 1-4D of keratometric steepening

Stage 3 Keratoconus

• decrease BCVA w/ spectacles (oval shape)

• difficult to get accurate K readings

• increase in irregular astigmatism

• SLE: Vogt’s Striae, Fleischer’s Ring, Corneal Thinning

Stage 4 Keratoconus

• corneal steepening: >55D

• apical corneal scarring

• <

• Munson’s Sign

• Hydrops

Keratoconus Management

• spectacles or CLs

• GP lenses

• Hybrid lenses

• Scleral lenses: comfy patient sees well

  • O2 compromised

  • 0.35 to 0.4mm thick → Dk good but not 1st choice

  • Dk/t = 100/0.4 = 25 (minimum Dk/t to prevent hypoxia is 24)

• Specialty soft lenses

Presbyope CL Correction

• RGP and soft bifocal lens designs

  • multifocal (progressives)

  • disposable

  • aspheric

Presbyope CL fitting preliminary exam

• tear stability (decreases w/ age)

• pinguecula/ pterygiums MC in older eyes

• loss of endothelial cells (cornea more susceptible to edema)

• crystalline lens changes

• loss of eyelid tonicity (problems translating bifocals)

Presbyope CL fitting: Tests to Perform

• Hx:

  • goals & motivation

  • past medications

  • previous surgery (cosmetic lid surgery)

    • affects RGP bifocal positioning

  • visual & occupational requirements

    • lifestyles

    • employment

Presbyope CL fitting: Anatomic measurements

• palpebral aperture

  • patients w/ “low” lower lid will have trouble with translating bifocals

• pupil diameter

  • large pupils → ghosting of images

• tear quality (TBUT)

  • <5s contraindicates CL wear

• Tear quantity (Schemer, Phenol red test)

Presbyope CL Fitting: Refraction

• best candidate requires >1.00 of hyperopia or >1.25 of myopia

• low hype ropes expect better vision with bifocals bc specs not needed prior to presbyopia

• low myopes are difficult bc can see well at near w/o correction

• contraindicated in amblyopic

  • further compromises vision

  • modified MF: add more (+) to amblyopic eye for N, other for D

Presbyope CL Fitting: Patient Motivation

• be aware of levels of visual quality to be expected before the initial fitting

• education for correct amount of optimism & realism about bifocal CLs

Presbyope CL Fitting: Patient’s Expectation

• critical task at near may fail w/ bifocal CLs

• patient interest, qualified, positive, & optimistic is best

• may not experience same quality of vision

  • provide clear vision for minimum 85% of normal visual needs

• satisfied w/ specs & concern of visual compromise = not best

• 20/happy not 20/20

Presbyope CL Options: CL correction for D supplemented with reading specs

• best vision at D & N

• need to put and take off specs frequently

Presbyope CL Options: Monovision

• one eye for D, other for N

• for critical vision tasks: supplement vision correction

  • second distance CL or driving specs

Presbyope CL options: Bifocal CLs

• visual freedom

• binocularity

• higher cost

• possibility of lens change to fine tune the fit

Presbyope CL Fitting: Types of Bifocal CLs

• simultaneous vision

  • soft & rigid

• translating

  • rigid

simultaneous vision

• patient sees through D & N rx simultaneously

• aspheric

Back vs Front Aspheric CLs

• back aspheric

  • clear distance vision w/ limiting reading power

• front aspheric

  • clearer near vision compromising distance

  • most designs are front aspheric

Aspheric CLs

• pupil dependent

  • pupils constrict w/ near tasks

  • pupil dilates at distance; more of Dist RX covering pupil

• must be well centered

Aspheric CL Types

• Air Optix MF

• Proclear MF & Frequency 55/ Biofinity (Coopervision)

• Acuvue Oasys (Vistakon)

Air Optic MF (Alcon)

• progressive, aspheric, simultaneous vision SCL

• center - Near = Add Power

  • power concentrated on central portion of optical zone

• near portion compacted: ~4mm

• large peripheral distance zone

• 3 Add powers (Low: up to +1.25, Med: +1.50 to +2.00, Hi: +2.25 to +2.50

• smooth uninterrupted transition zone

• BC: 8.6 Dia: 14.2

• Optical Zone: 7.8mm (~3.8mm for Dist)

• Dist power ranges: +6.00 to -10.00

Air Optix MF Trial Lens Selection

• sphere-cylindrical refraction and near add

• trial: vertex correction, SE, add according to patient’s add

• Ex: -3.00 Add: +1.00

  • Trial: -3.00 Low Add

• Ex2: -4.50-0.75×090 Add: +2.00

  • vertex: -4.25-0.75×090; SE = -4.50

  • Trial: -4.50 Med Add

Air Optix MF lens evaluation

• allow to settle for 10-20min

• evaluate binocularity

  • subjective: ask patient

  • objective: binocular acuity

• near point eval.

Air Optix MF movement eval.

• Push - up test

  • flat fit adversely affects vision

Air Optix MF: Refine initial Rx

• loose lenses/ flipper bars

• check N & D w/ each lens change

• visual quality > visual acuity

• only refine distance

Air Optix MF Patient Management

• what to expect

  • ghosting of letters

  • night driving: light halos, star burst effect

• F/u 3-4days

Air Optix MF: Straight Binocular Correction

• preferable

• full D & N Rx fitted in both eyes

Air Optix MF: Modified Bifocal Correction

• adding (+) to distance power of non-dominant eyes (improves near)

• adding (-) to distance power of dominant eye (improves distance)

Air Optix MF: Enhance Monovision Correction

• fitting dominant eye w/ single vision CL & non-dominant eye w/ bifocal

  • improves distance

• fitting non-dominant eye w/ single vision CL for near, decreasing distance power of bifocal on dominant eye

  • improves near

Proclear/ Biofinity

• monthly progressive bifocal

• visibility tint

• two different lenses

  • D lens: dominant eye, center distance

  • N lens: non-dominant eye, center near

Proclear/ Biofinitiy Parameters

• BC: 8.7 Dia: 14.4mm

• Lens Powers: +4.00 to -6.00D

• 4 Add powers (+1.00, +1.50, +2.00, +2.50)

• cast molded

Proclear/ Biofinity preferred patients who are:

• single vision lens wearers needing an Add

• highly motivated SV patients wearing reading Rx inconsistently

• patients unsatisfied w/ other correction modalities

Proclear/ Biofinity preferred patient who do not:

• have dist Rx < ±1.00 and astigmatism >0.75

• satisfied w/ monovision or SV Cls w/ reading specs

• exhibits amblyopia or monocularly

Proclear/ Biofinity initial lens selection

• subjective refraction, add power

• determine eye dominancy

  • ± 2.00 in front of each eye (eye w/ worse VA = dominant)

• initial lens

  • vertex distance Rx

  • SE

• Add power

  • dependent on patient’s add correction

Proclear/ Biofinity initial lens selection Example

• spec Rx: OD +1.25-0.25×090 Add: +1.75 (OD dominant) OS +1.75-0.50×090 Add: +1.75

• initial lens

  • OD: +1.25 Add: +2.00 (D lens)

  • OS: +1.50 Add: +2.00 (N lens)

Proclear/ Biofintiy Refining Rx

• flippers, horopter influences pupil size

• add ± 0.25 for D & N to determine lens changes

3 common GP problems

• reduced vision

  • flexure

  • warpage

  • decentration

  • poor surface wettability

  • power change

• corneal desication

• refitting

GP problems: Reduced Vision - Flexure

• from bending force of upper lid during blinking

• induces toricity w/n the lens

• causes

  • steep fitting relationship

  • reduced center thickness (CT)

  • larger OZD

  • material flexibility

GP problems: Reduced Vision - Flexure Dx

• perform over keratometry

• toricity in measurement may be caused by flexure

GP problems: Reduced Vision - Flexure Management

• change lens parameters

  • flatten BCR: by minimum 0.50D

  • increase CT by 0.02mm per diopter of corneal astigmatism

• reduce OZD: minimum 0.3mm

• change materials

  • from higher to lower Dk

GP problems: Reduced Vision - Warpage

• permanently induces toricity w/n the lens

• differs from flexure

  • radioscope BCR measurement verifies toricity (flexure verifies as spherical)

  • warpage acquired over time, flexure evident immediately

• causes

  • excessive digital pressure during cleaning process

GP problems: Reduced Vision - Warpage Management

• minimized by

  • routinely verifying BCR in FU visits

  • educate pt to clean CL in palm

  • change to lower Dk material

• once warpage has occurred lens change is required

GP problems: Reduced Vision - Decentration

• results in numerous problems

  • corneal desiccation

  • corneal warpage

  • poor corneal alignment

  • reduced vision

  • poor tear exchange & lens adhesion

GP problems: Reduced Vision - Inferior Decentration

• lens too steep

• lens too heavy

• inadequate lens edge

• to minimize

  • flatter BCR for myopic patients

  • keep CT at a minimum w/o affecting lens flexure

  • use lenticular designs when indicated

  • consider lid attachment fit

GP problems: Reduced Vision - Superior Decentration

• slight is beneficial for vision & comfort

• excessive decentration → lens adherence

• to minimize

  • consider steeper BCR

  • use thinner edge designs

  • increase CT

GP problems: Reduced Vision - Lateral Decentration

• most frustrating

• may result from:

  • decentered corneal apex

  • ATR astigmatism

• management

  • use aspheric CL design (Boston Envision)

  • fit larger OAD

  • selecter steeper BCR

  • if all fail → soft toric lens

GP problems: Reduced Vision - Initial Poor Surface Wettability

• manufacturing problem

  • too much heat buildup

  • poor polishing

  • improper/ old diamond used for cutting

  • residual polish left on lens surface

• Dx

  • tear film breakup on the lens surface

GP problems: Reduced Vision - Initial Poor Surface Wettability Management

• presoak lens for 24hrs before dispensing

• use lab cleaner (Boston Lab Cleaner) or solvent to remove residual polish

  • recondition lens w/ wetting solution

• light polish of lens surface (rarely needed)

GP problems: Reduced Vision - Acquired Poor Surface Wettability

• mucoprotein film or haze over lens anterior surface

• w/n weeks or months of lens wear

• causes

  • poor tear quality

  • improper blinking

  • inadequate compliance

  • improper use of solutions

GP problems: Reduced Vision - Acquired Poor Surface Wettability Management

• daily use of surfactant or abrasive cleaners

• daily liquid enzymatic cleaner

• rewetting drops

• reeducate the patient on lens cleaning

• changing lens materials

GP problems: Reduced Vision - Power Change

• increase in minus power accompanied by decrease in CT

• cause

  • use of abrasive cleaner

  • forceful digital cleaning in circular manner

GP problems: Reduced Vision - Power Change Management

• use mild abrasive cleaner

• rubbing lens gently in the palm

GP problems: Corneal Desiccation

• 3 & 9 O’clock staining

  • drying or dehydration of peripheral cornea

  • occurs in >50% patients wearing GPs

  • severe cases occur w/ ulceration, NV, & scarring

GP problems: Corneal Desiccation from Lens material

• poor wettable materials

• management

  • use low Dk lens materials, FS/A

  • improve tear film over the lens surface

GP problems: Corneal Desiccation from Lens centration

• poorly centered lenses

• management

  • use lid attachment fit

  • superior lens to cornea fitting relationship

  • reduces interference w/ normal blinking

GP problems: Corneal Desiccation from Edge Clearance

• avoid excessively high edge lift

  • reduce peripheral tear volume

  • reduce gap in periphery b/n lens & cornea

  • reduces interaction b/n lens & cornea

    • not compromising normal blink rate

• use tricurve or tetracurve lens design

  • w/ peripheral edge width no larger than 0.3mm

  • w/ peripheral curve radius no flatter than 11.0mm

• use aspheric designs

  • better alignment of the lens

GP problems: Corneal Desiccation from Tear Film Stability

• minimum TBUT of 5s

• low to borderline TBUT (5-9s)

  • subjective symptoms of dryness

  • corneal desiccation by evaporation of peripheral tear pool

• management

  • use rewetting drops every hour

  • use highly wettable materials

GP problems: Corneal Desiccation - Vascularized Limbal Keratitis

• more acute complication of corneal desiccation

• most common in rigid extended wear lenses

• long term wearers of S/A lens material

  • w/ steep lens to cornea fitting relationship

  • peripheral seal off