E5 SAMPLE Special Applications of Contact Lenses Lecture contributors Robert Terry Lewis Williams Others Lecture editor Bezalel Schendowich IACLE executive editor Lewis Williams IACLE reviewers ID: 799503
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Slide1
Special Applications of Contact LensesE5
SAMPLE
Slide2Special Applications of Contact Lenses
Lecture contributors*
Robert Terry, Lewis Williams, Others***
Lecture editor**Bezalel SchendowichIACLE executive editor**Lewis WilliamsIACLE reviewers**Nilesh Thite, Lewis WilliamsLecture updated2015-Apr-14Lecture content rechecked2015-Apr-28* Original author(s) of lecture(s)**2014/2015 Editors and reviewers
*** Ma Meredith REYES, Christopher SNYDER, David PYE, Prashant GARG, Les DONOVAN, Des FONN (Editor-in-Chief)
Slide3CIBA Vision
Bausch & Lomb
Allergan
AMOOcular SciencesWesley JessenMeniconPilkington Barnes-HindParagonAspect Vision CareSynergEyes
Slide4SAMPLE ONLYThe following slides are an excerpt
from the revised
IACLE Contact Lens Course lecture
Special Applications of Contact LensesE5
Slide5Post-Corneal Surgery CL Fitting
Slide6GP CLs are the modality of choice for post-RK fittingusually corneal shape is irregularTrial fitting essential
fluorescein
pattern assessment
Try simple CL designs first:spherical aspherical Consider toric if necessaryOrthokeratology designs (reverse geometry) may prove usefulSpecialized designs for RKPost-Corneal Surgery CL FittingPost-Corneal Surgery CL FittingRK CL Selection
Slide7Based on an analysis of corneal topography:pre-surgical keratometry
corneal topography
Based on the amount of myopia
Large CL Total Diameter (TD)Post-Corneal Surgery CL FittingCL Fitting
Slide8Adequate peripheral clearanceNo bubbles inferiorly Good tear exchange
Large optical zone extending to the corneal periphery
Larger than normal axial edge clearance
Post-Corneal Surgery CL FittingCL Fitting: Desirable Features
Slide9Expect to see:Central fluorescein
pooling
Lens
decentrationBubbles beneath CLPost-Corneal Surgery CL FittingCL Fitting Assessment
Slide10Fluctuating VisionDiurnal variation
Trial a flatter fitting
↑ CL centre thickness
Flare & Glare↑ BOZD↑ lens total diameter (TD)Trial an aspheric design Post-Corneal Surgery CL FittingSolving CL Fitting Problems
Slide11Post RK Fitting: CL is decentered: superiorly & nasally
Post-Corneal Surgery CL Fitting
Slide12↑ BOZDModify peripheral curvesTrial an aspheric design
Add prism ballast for high-riding CLs
Consider a reverse geometry design
Post-Corneal Surgery CL FittingSolving Decentration Problems - Superior
Slide13↓ CL masslenticulation
↓ CL total diameter (TD)
Use lower specific gravity (SG) material
Incorporate a minus lenticular designLarge BOZD with flat peripheral curvesConsider a reverse geometry designPost-Corneal Surgery CL FittingSolving Decentration Problems - Inferior
Slide14Excessivechange to an aspheric designInadequate
flatten/widen peripheral curves
Post-Corneal Surgery CL Fitting
Peripheral Clearance
Slide15Significant corneal stainingRecurrent corneal erosions (RCE)Infection
Vascularization
Post-Corneal Surgery CL Fitting
Post-Fitting Complications
Slide16Transverse incisions used in an attempt to correct induced astigmatism
Post-Corneal Surgery CL Fitting
Slide17InfectionEpithelial in-growthRecurrent corneal erosions (RCEs)
Corneal
oedema
Globe ruptureStellate iron lines (epithelial Fe deposits)Post-Corneal Surgery CL FittingRK Post-Operative Complications
Slide18Over-correctionUnder-correction↑ astigmatism
↓
best-corrected VA
Diurnal ↕ in visionMyopic or hyperopic shift↓ contrast sensitivity↓ tolerance of glarePost-Corneal Surgery CL FittingRK-Induced Optical Problems
Slide19Argon-fluorine excimer LASER (Ar
-F)
Emission wavelength of 193 nm
High photon energy breaks molecular bonds→ precise tissue removalMinimal thermal damage to adjacent tissuePost-Corneal Surgery CL FittingPhoto-Refractive Keratectomy (PRK)
Slide20Persistent stromal scarring
early or late onset
Optical degradation:
loss of BCVAhalos, contrast sensitivityDecreased corneal sensitivityRisk of infectionSteroid complicationsPost-Corneal Surgery CL FittingPRK Complications
Slide21Laser ASsisted
I
n situ
KeratomileusisPalikaris, 1990For high myopiaCorneal flap cut with microkeratomeLASER reshaping of the exposed stroma to effect desired changeFlap is replacedUsually, suturing not requiredBowman’s Layer preservedPost-Corneal Surgery CL FittingLASER-Assisted in situ Keratomileusis (LASIK)
Slide22Poor microkeratome cutsurgeon’s (in)experienceloss of suction
too deep ® corneal perforation
Flap complication
no hinge formed (detached flap)too thintoo thickwrinkling Post-Corneal Surgery CL FittingLASIK Complications 1
Slide23Epithelial in-growthDeposits in the flapDecentered ablation → monocular diplopia
Photophobia
Glare, halos
Dry eyeSubconjunctival haemorrhagesPtosisEquipment problems during surgeryPost-Corneal Surgery CL FittingLASIK Complications 2
Slide24Refractive problems
over or under correction
induced irregular astigmatism
decentered ablationregressionCorneal ectasiainsufficient stromal bed thicknessCorneal inflammation/infectionFlap striae Diffuse lamellar keratitis Post-Corneal Surgery CL FittingLASIK Complications 3GP corneal CLs on LASIK patients
Slide25Post-Corneal Surgery CL Fitting
Failed LASIK: Post-Surgical Corneal Topography
(Secondary Ectasia)
Slide26Post-Corneal Surgery CL Fitting
Failed LASIK: Post-Surgical Corneal Topography
(Secondary Ectasia)
Slide27Post-Corneal Surgery CL Fitting
Intra-Stromal Corneal Ring Implants
Barraquer
(1949) was first to discussintacs developed during 1990sintacs approved by FDA 2004Other intra-stromal products introduced subsequentlyintacs SKFerrara RingKeraringCornealring
Slide28A ‘mechanical’ correction device made from PMMA4 D myopia limit before spherical aberration becomes a problem
9 - 10 mm diameter
Range of thickness
0.2 - 0.45 mmthickness dictates refractive effectInserted in peripheral stromatwo thirds corneal depthinsertion is not a simple procedureFull circle, split-ring shape (one piece) or two ‘(’ segmentsPost-Corneal Surgery CL FittingIntra-Stromal Corneal Ring Implants
Slide29Post-Corneal Surgery CL Fitting
Intra-Stromal Corneal Ring Implants
Insertion channel @ 68% of corneal thickness
Slide30Patients with collagen, vascular, autoimmune, or immunodeficiency diseasePregnancy or breastfeedingKeratoconus
Recurrent corneal erosions (RCEs)
Corneal dystrophy
Users of:isotretinoin (Accutane)amiodarone (Cordarone)sumatriptan (Imitrex)Post-Corneal Surgery CL FittingIntra-Stromal Corneal Ring Implants: Contra-Indications
Slide31Exclusively available to IACLE membersTo access the complete lecture go to the member login at:
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Slide32THANK YOUwww.iacle.org