Case Studies for the April 12 Online Symposium, "Fitting the Irregular Cornea" with Joe Barr, OD, MS

After reviewing this case study, please click here to visit the Online Symposium room on April 12, 9:00-10:30 pm Eastern.

Case Study 1

Patient History:

• 33-year-old homemaker, diagnosed with keratoconus at age 30
• After frequent Rx changes, glasses are not adequate

Spectacle Rx:

• OD -2.00 -4.00 x 030 20/50
• OS -2.25 -5.25 x 123 20/60

Corneal Measurements:

• OD 49.00/53.75 @ 110
• OS 48.25/54.00 @ 042
• Mires distorted OU

Ocular Measurements:

Based on what you know about this patient, choose a type of initial diagnostic lens.

a) Korb design
b) McGuire design
c) Rose K
d) ____________________

Based on this fluorescein pattern, what changes would you employ? a) smaller diameter b) steeper base curve c) flatter base curve d) different kone design

Based on this fluorescein pattern, what changes would you employ? a) larger diameter b) steeper base curve c) steeper peripheral curves d) different kone design

Based on this fluorescein pattern, what changes would you employ? a) larger optical zone b) steeper base curve c) steeper peripheral curves d) different kone design

After you have the right design:

• What material would you order?
• What lens care system would you Rx?

Case Study 2

Patient KC History:

• 7/77, age 26
• No previous CL wear
• Increasing astigmatism
• City planning engineer
• Previous spectacle Rx approx. +2.50 -2.00 X 90
• Pachometry 0.51mm OU

K Readings:

• OD 42.62/43.50 @ 122 distorted
• OS 43.00/43.50 @ 012 distorted

Spectacle Rx:

• OD -1.75 -1.50 x 010 20/25 +
• OS -0.75 -1.50 x 145 20/20 -

Subjective Symptoms:

• Sees three moons
• Ghost images
• Spectacles cause vomiting
• Some blur with spectacles

Signs:

• Irregular retinoscopy and ophthalmoscopy image
• Vogt's Striae OU
• Some apical staining prior to CL wear in swirl, whorl-like shape at apex of cornea

Assessment:

• Keratoconus
• Differential Dx versus CL irregularity (no lens wear in this case), Pellucid marginal degeneration (no peripheral corneal thinning in this case), Keratoglobus (only the paracentral cornea has ectasia in this case)

Contact Lens Fitting Hx:

• Initial lenses:
  OD 7.9BCR, 8.2 OAD, 7.3 OZD, 10/.45 SCR,
  -1.75 PMMA, blended VA 20/20 -
  OS 7.9BCR, 8.2 OAD, 7.3 OZD, 10/.45 SCR,
  -1.50 PMMA, blended VA 20/20 -
• Dimple veiling above apex, decreased OZ, blended more
• 1981 due to corneal swelling, switched to 9.5mm Polycon 7.90, -1.75, -1.50 OU VA 20/20 OU

First Time Dx and Fit:
Keratoconus Summary

• He still wears these lenses
• Putting a lens on the eye confirms the diagnosis when "three-point-touch" is observed
• Some keratoconics don't change much and some really do

Discussion:

• First time keratoconus does not need special designs
• I like a small steep/clearance or minimal touch fit but a large touch fit that doesn't hurt the cornea
• Fit is not the critical issue! The real issues are wearing time with acceptable comfort, best vision, and minimal tissue change

Case Study 3 — PK

How well is this fit?

Case Study 4 — RK

Figure 1. Patient VB OD (left), OS (right).

Figure 2. Videokeratography OU.

Figure 3. Lid attachment spherical GP lens on RK eye.

Figure 4. Reverse geometry lens on RK eye.