Here are 3 options for very difficult post-graft cases when standard lenses are not working: 1. Try a scleral lens with a large optic zone to vault over the irregularity. This can improve comfort and vision. 2. Consider corneal collagen cross-linking (CXL) to strengthen the cornea followed by intracorneal ring segments (Intacs) to help regularize the shape. 3. As a last resort, a second corneal transplant may be needed to obtain an adequate surface for contact lens wear or improve vision. However, the success rate decreases with subsequent grafts. The key is finding the best option to improve vision and comfort while protecting the ocular surface long-term. A

3. Dr. Mohammad Amiri , OD
Department of Optometry ,Faculty of
Rehabilitation
Shahid Beheshti Medical Sceince University
Vision Care of Menicon
Keratoconus
And specialty contact lens fitting of irregular
corneas

4. Keratoconus
• Is a progressive disorder in which the cornea has irregular
shape
• Onset: around puberty
• Autosomal dominant
• Usually bilateral; but assymetrical
• Systemic association: e.g. Down syndrome; Turner syndrome;
Marfan syndrome
• Ocular association: e.g. retinitis pigmentosa; vernal
keratoconjunctivitis;

5. • According to
morphology can be
classified into
• Nipple cones: small size
5mm; steep curvature;
the apex of the cone is
central or infero-nasally

6. • Oval cones: 5-6mm size;
ellipsoid (oval) &
displaced
inferotemporally

7. • Globus cones: the
largest >6mm

8. • Presentation: visual impairment due to progressive myopia & astigmatism
(usually reported for one eye); changes in spectacle Rx; decrease tolerance
to contact lens wear;
• Signs: central or paracentral stromal thinning; apical protrusion; irregular
astigmatism; steepening of the cornea graded according to keratometry
readings (mild <48D, moderate 48-54D, severe >54D)
Early in the disease: oil droplet reflex on ophthalmoscopy; irregular scissor
reflex on retinoscopy; Vogt lines (i.e. deep vertical stromal striae) on slit-
lamp exam; irregular astigmatism on keratometry; abnormal corneal
topography

9. Vogt striae (i.e. line) in keratoconus

10. Munson sign in keratoconus
Late in the disease:
Munson sign (i.e.
bulging of the lower lid
on downgaze); visual
acuity worsens;
watering; oedema;
stromal scarring after
beaks healing;

11. Keratoconus
• What have the years taught us?

12. 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).

13. Keratoconus
• Non-Inflammatory Ectasia
• Stromal Thinning
• Disruption of Bowman’s
Membrane
• Corneal Ectasia
• Myopia
• Irregular Astigmatism
• Optical Correction
• Spectacles– early
• Contact Lenses– later

14. Keratoconus
• Demographics
• Estimates vary from 50 to 170
per 100,000
• Obscure Etiology
• Heredity
• Allergies, Eye Rubbing

15. Why Does the Cornea Bulge in
Keratoconus?
• Corneal tissue is
abnormal
• Too elastic?
• Abnormal cross-linking of
collagen?
• Loss of structural
integrity of Bowman’s
Layer?
• Keratocyte apoptosis
• Trauma (eye rubbing)
• Corneal tissue bulges
because it is too thin?

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

17. Causes of Keratoconus
• Heredity vs. Mechanical
• Cellular
• Tissue
• Genetic

18. 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.

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

20. 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?

21. 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.

22. Additional Information
Male to Female Ratio = 3:1
Approximately 20% result in PKP.
90% are diagnosed by optometrists.
Mean age of diagnosis is 22.88 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).

23. 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.

24. Possible Aggravating Factors
• UV exposure.
• Allergies.
• Vigorous eye rubbing.
• Poorly fitting contact lenses.
• Inflammation.

25. 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.

26. Nipple/Oval Cone
• Central Steepening
• Steepest form

27. Keratoglobus
• Wider – 75 to 90% of cornea.
• Not as steep.

28. Pellucid Marginal Degeneration
• Peripheral Thinning

29. Orbscan Analysis

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

34. 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.

35. 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

36. 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.

37. 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.

38. 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).

39. Fitting the Rose K2
• Too high – tighten edge lift
reduce OAD
steepen base curve
• Too low – increase edge lift
increase OAD
flatten base curve

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

41. Rose K2IC
• IC stands for irregular cornea
• Larger diameter
• Larger optic zone
• Aspheric for aberration control
• Reverse geometry design

42. • PMD
• Keratoglobus
• LASIK induced ectasia
• Corneal transplants

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

44. What is That?

46. Asymmetric Corneal Technology
• ACT.

47. ACT – Continued…

48. Fitting with ACT
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 3 (1.3mm steeper)
Grade 2 (1.0mm steeper)

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

50. Toric Peripheral Curves

51. 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.

52. 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.

53. 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

54. Rose K2 Post Graft

55. PKP Topography

56. 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.

57. 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.

58. Post Graft – Too Steep

59. Post Graft – Too Flat

60. Post Graft – Good Fit

61. Watch Vasculature

62. 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.

63. What Do You Do?