Presentation on theme: "Keratoconus And specialty contact lens fitting of irregular corneas"— Presentation transcript:
1Keratoconus And specialty contact lens fitting of irregular corneas Marc L. Braithwaite, ODVision Care of MaineKeratoconus And specialty contact lens fitting of irregular corneasThank Elliott and Lee.Introduction
2KeratoconusWhat have the years taught us?Lawrence Gallomp
3Keratoconus Characteristics Non-inflammatory.Central or para-central corneal thinning.Corneal steepening or protrusion.Increased astigmatism and possibly myopia.Loss of best spectacle corrected visual acuity.Corneal striae and scarring.Corneal hydrops (inflammatory).
4Pathology of Keratoconus Loss of Bowman’s Layer.Stromal Thinning.Apoptosis.Increased Enzyme Activity.Enlarged Prominent Corneal Nerves.1- Epithelial cells seem to be in direct contact with stroma.2- In central and/or inferior cones, stroma can be less than ½ that of normal stroma. Epithelium 2-3 cell layers thick.3- Programmed cell death. Greater apoptosis in the anterior stroma. Repetative injury to epithelium stimulating greater apoptosis.4- Decreased presence of enzyme inhibitors.
5Causes of Keratoconus Heredity vs. Mechanical Cellular Tissue Genetic 2 doctors out of 250 still felt that KC was caused by eye rubbing. KC patients may indeed rub their eyes more than most, but maybe there is something about KC that makes them feel like they
6Heredity vs. Mechanical Does eye rubbing cause Keratoconus?2 out of 250 doctors feel that rubbing is a cause.KC patients do rub their eyes more often than those without KC.What is it that makes KC patients rub their eyes?
7Cellular Changes Keratoconus cells are hypersensative. Increased enzyme activity, lack of enzyme inhibitors.Matrix substrate instability in response to environmental stress factors.mtDNA damage and exaggerated oxidative response causing cellular damage.
8Tissue Changes Loss of Bowman’s layer. Lamellar slippage. Lack “anchoring” lamellar fibrils.Apoptosis of the stroma causing anterior thinning.
9Genetics Autosomal dominant w/variable penetrance. SOD1, an antioxidant enzyme, is abnormal in some KC corneas.No single gene responsible.10 different chromosomes have been associated with KC.Most likely multiple genes involved.
10Additional Information Male to Female Ratio = 3:1Approximately 20% result in PKP.90% are diagnosed by optometrists.Mean age of diagnosis is years.Visual outcome with RGP is better than PKP.More prevalent in certain ethnic groups (4x higher in Asians from Indian sub-continent regions than White Europeans).
11Progression and Prognosis Age is a big factor.The younger the diagnosis, the poorer the prognosis.Less likely to progress to the point of a transplant if diagnosed in the 30’s.20% of Keratoconus patients result in corneal transplants.35 to 45% of all transplants are due to Keratoconus.
13Types of KeratoconusNipple/Oval cone - central or mildly para-central localized thinning and steepening.Keratoglobus - Large generalized thinning and steepening.PMD (pellucid marginal degeneration) – peripheral thinning and steepening.Keratoconus Fruste – Less progressive and less manipulative.
22When to Intervene? Best Spectacle/Soft CL Acuity 20/30 or better? Good tolerance of acuity.Corneal health is not compromised.“If it aint broke, don’t fix it.”Best Spectacle/Soft CL Acuity worse than 20/30?Specialized contact lenses.My opinion, use RGP lenses.
23Which RGP Design? Early Keratoconus Mid-stage Keratoconus Standard RGPKC RGPMid-stage KeratoconusCustom KC RGPAdvanced KeratoconusIntra-limbal or Scleral RGP
24My “GO TO” Lens – Rose K Developed by Dr. Paul Rose. Designed to fit the irregular cornea.“Very forgiving lens”Multiple designs to fit all shapes of corneas and corneal conditions.Blanchard is very good to work with and has staff to assist with very difficult cases.
25Nipple/Oval Cone Fitting Most common form of KC.Early stages - simple RGP or KC RGPLater stages – KC RGP usually small and steep.The steeper the cone, the smaller the lens diameter.
26Rose K2Rose K vs. Rose K272% of patients notice an increase in acuity with aspheric, aberration control.Lens to be centered on the cone.Reduce excessive movement (1 to 2mm).
27Fitting the Rose K2 Too high – tighten edge lift reduce OAD steepen base curveToo low – increase edge liftincrease OADflatten base curveGenerally works for all types of RGP’s and corneas.
28Fitting the Rose K2 Centrally fitting the lens on a nipple cone better insuresoptimal acuity andcomfort.It is recommended that you fit the central base curve first and then make and adjustments to the diameter and edge.
29Rose K2IC IC stands for irregular cornea Larger diameter Larger optic zoneAspheric for aberration controlReverse geometry design
36Fitting with ACT Using ACT ( Asymmetric Corneal Technology) 3 standard grades availableOption also to specify degree of tuck in 0.1 steps from 0.4 to 1.5mmGrade 3 (1.3mm steeper)Grade 1 ( 0.7mm steeper)Grade 2 (1.0mm steeper)
37Fitting with ACT ACT - Improved comfort , lens stability and vision NO ACT WITH ACT
39Fitting Pearls Tendency to tighten after initial fitting. Light central touch will increase acuity.Avoid central staining.Movement is necessary but slight movement is usually sufficient.Pay attention to tear flow beneath lens.The steeper the lens, the smaller OAD and less movement.Don’t change too many parameters at once.
40Penetrating Keratoplasty When to refer? Acuity is 20/50 or worse.Patient intolerance to visual decrease.Scars within the visual axis.Multiple episodes of Hydrops.Contact lens intolerance.Unable to get adequate/healthy CL fit.Consider OD to OD referral.Give reasonable expectations.
41Post PKP Management How soon can you fit with lens? Why are the curvatures so strange?Do you have to wait for all sutures to be removed?Corrective options.SpectaclesRGP contact lenses.LASIK
44Rose K2 Post Graft Much more difficult to fit than KC. Patients are less tolerable to CL.Eyes are more dry.Ill-fitting contact lenses can lead to graft rejection.Lens design is crucial to success.
45K2PG Fitting Pearls Don’t be intimidated! Watch tear flow! Also good lens for ectasia patients.Stay with your fitting basicsFit base curves.Adjust diameter.Adjust peripheral curves.Use ACT or Toric PC if needed.
52Mini-Scleral Design - MSD Large RGPVaults the cornea, rests on the sclera.Creates a fluid filled environment.Can be used to treat any corneal condition.Can be used to treat other anterior segment conditions.
55MSD – Fitting Pearls Central Feather-touch. Intra-limbal adjustment. With or without fenestration or fenestrations.Watch edge for tightening.
56Practice Management Issues Setting Fees.Bill for services performed.Insurances and fee collection.Appropriate diagnostic and treatment equipment.Topography/corneal mapping.Pachymetry.Fitting sets.
57Refractive Surgery Specific Moderate – Large Diameter(10.5 mm Standard Diameter, 9.5 mm to 12.0 mm).Reverse Geometry Transition.Post Surgical Central BC.CurvesParacentral Fitting Curves.Asymmetric Corneal Technology (ACT).