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Marc L. Braithwaite, OD Vision Care of Maine. Keratoconus  What have the years taught us?

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Presentation on theme: "Marc L. Braithwaite, OD Vision Care of Maine. Keratoconus  What have the years taught us?"— Presentation transcript:

1 Marc L. Braithwaite, OD Vision Care of Maine

2 Keratoconus  What have the years taught us?

3 Keratoconus 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).

4 Pathology of Keratoconus  Loss of Bowman’s Layer.  Stromal Thinning.  Apoptosis.  Increased Enzyme Activity.  Enlarged Prominent Corneal Nerves.

5 Causes of Keratoconus  Heredity vs. Mechanical  Cellular  Tissue  Genetic

6 Heredity 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?

7 Cellular 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.

8 Tissue Changes  Loss of Bowman’s layer.  Lamellar slippage.  Lack “anchoring” lamellar fibrils.  Apoptosis of the stroma causing anterior thinning.

9 Genetics  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.

10 Additional Information  Male to Female Ratio = 3:1  Approximately 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).

11 Progression 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.

12 Possible Aggravating Factors  UV exposure.  Allergies.  Vigorous eye rubbing.  Poorly fitting contact lenses.  Inflammation.

13 Types of Keratoconus  Nipple/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.

14 Nipple/Oval Cone  Central Steepening  Steepest form

15 Keratoglobus  Wider – 75 to 90% of cornea.  Not as steep.

16 Pellucid Marginal Degeneration  Peripheral Thinning

17 Orbscan Analysis

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21 How to Treat Keratoconus  Spectacles  Contacts Soft Standard Soft Custom RGP Standard RGP Custom Hybrid  Surgery Intacs Penetrating Keratoplasty  Riboflavin/UV treatment

22 When 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.

23 Which RGP Design?  Early Keratoconus Standard RGP KC RGP  Mid-stage Keratoconus KC RGP Custom KC RGP  Advanced Keratoconus Custom KC RGP Intra-limbal or Scleral RGP

24 My “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.

25 Nipple/Oval Cone Fitting  Most common form of KC.  Early stages - simple RGP or KC RGP  Later stages – KC RGP usually small and steep.  The steeper the cone, the smaller the lens diameter.

26 Rose K2  Rose K vs. Rose K2  72% of patients notice an increase in acuity with aspheric, aberration control.  Lens to be centered on the cone.  Reduce excessive movement (1 to 2mm).

27 Fitting the Rose K2  Too high – tighten edge lift reduce OAD steepen base curve  Too low – increase edge lift increase OAD flatten base curve

28 Fitting the Rose K2  Centrally fitting the lens on a nipple cone better insures optimal acuity and comfort.

29 Rose K2IC  IC stands for irregular cornea  Larger diameter  Larger optic zone  Aspheric for aberration control  Reverse geometry design

30  PMD  Keratoglobus  LASIK induced ectasia  Corneal transplants

31  Corneal Dystrophies  Traumatic Corneas with Scars  Post RK  Irregular Astigmatism or Corneal Warpage

32 What is That?

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34 Asymmetric Corneal Technology  ACT.

35 ACT – Continued…

36 Using ACT ( Asymmetric Corneal Technology) 3 standard grades available Option also to specify degree of tuck in 0.1 steps from 0.4 to 1.5mm Grade 1 ( 0.7mm steeper) Grade 2 (1.0mm steeper) Grade 3 (1.3mm steeper) Fitting with ACT

37 NO ACT WITH ACT ACT - Improved comfort, lens stability and vision Fitting with ACT

38 Toric Peripheral Curves

39 Fitting 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.

40 Penetrating 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.

41 Post 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. Spectacles RGP contact lenses. LASIK

42 Rose K2 Post Graft

43 PKP Topography

44 Rose 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.

45 K2PG Fitting Pearls  Don’t be intimidated!  Watch tear flow!  Also good lens for ectasia patients.  Stay with your fitting basics Fit base curves. Adjust diameter. Adjust peripheral curves. Use ACT or Toric PC if needed.

46 Post Graft – Too Steep

47 Post Graft – Too Flat

48 Post Graft – Good Fit

49 Watch Vasculature

50 The Difficult Ones  Nothing is comfortable.  Acuity isn’t improving..  Eyes are too dry. (Sjogren’s Syndrome)  Cornea is too irregular for any lens to fit properly or in a healthy manner.

51 What Do You Do?

52 Mini-Scleral Design - MSD  Large RGP  Vaults 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.

53 MSD - Advantages  Very Stable lens.  Fluid filled environment.  Improved comfort.  Good visual acuity.

54 Mini-Scleral Design

55 MSD – Fitting Pearls  Central Feather-touch.  Intra-limbal adjustment.  With or without fenestration or fenestrations.  Watch edge for tightening.

56 Practice Management Issues  Setting Fees.  Bill for services performed.  Insurances and fee collection.  Appropriate diagnostic and treatment equipment. Topography/corneal mapping. Pachymetry. Fitting sets.

57 Refractive Surgery Specific  Moderate – Large Diameter (10.5 mm Standard Diameter, 9.5 mm to 12.0 mm).  Reverse Geometry Transition.  Post Surgical Central BC.  Curves Paracentral Fitting Curves. Asymmetric Corneal Technology (ACT).

58 Thank You!


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