CASE STUDY I - Dr. Barr

Patient KC History

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

Patient Ks and Rx

• 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 7.9 BCR, 8.2 OAD, 7.3 OZD, 10/.45 SCR, -1.75 PMMA, blended VA 20/20 -
     OS 7.9 BCR, 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

1st 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 typically 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 II - Dr. Barr

Patient MW History

• 36-year-old female with history of wearing only piggy-back lens fit
• Wears CIBASOFT 8.4, -8.00, -7.00
• Polycon 9.0 OAD, +0.50 OD
• 9.5 OAD, plano OS
• "Because that's what the Dr. did, and it's a hassle"

Patient Ks and Rx

• K Readings
     OD 52/53 @ 165 distorted
     OS 53/53 @ 165 distorted
• See maps
• Spectacle Rx
     OD -10.00 -0.75 x 030 20/40
     OS -10.50 -1.00 x 050 20/50

Subjective Symptoms

• History of abrasions with PMMA and RGP lenses
• Asthenopia with computer use
• Irritation after 7-8 hours wear

Slit Lamp Findings

• Central SPK OU
• Vogt's Striae OU

Trial Dx Lens Fitting

• CLEK Trial Set = 8.6 OAD, 6.5 OZD, 8.5 SCR, 11.5/0.2mm PCR
• OD 6.4, 6.5, 6.7, 6.5 light touch with excess edge lift
• OS 6.3, 6.5, 6.6, 6.4 light touch with excess edge lift

Lenses Ordered

• 6.50 BCR, 6.50 OZD, 8.6 OAD, 7.5 SCR/0.4, 9.0 TCR, 10.5 PCR/0.2, -8.75 0.12 CT
• 6.40 BCR, 6.50 OZD, 8.6 OAD, 7.5 SCR/0.4, 9.0 TCR, 10.5 PCR/0.2, -10 0.12 CT
• 60DK

Follow Up

• VA OD 20/25 variable, OS 20/25+, WT 14 hrs
• PR OD plano to -0.50 variable, OS +0.50
• OD apical touch, good edge lift, centers or drops
• OS minimal apical touch, good EL, centers
• Less SPK
• Change OD to 6.45, -7.75 to balance with OS ... good result, no central SPK, mild 3/9

Assessment

• Flat or Steep or Minimal Touch -- Which is best?
• Best is what gives patient best vision, comfort, WT, and minimal tissue change

Summary

• Goal 1: Apical touch or minimal apical touch with minimal bearing on apex and minimal mid-peripheral bearing if vision and comfort and WT and tissue change are adequate
• Goal 2: Increase apical touch progressively until best patient satisfaction is achieved
• Goal 3: Flat high riding large lens that stays in eye

Options

• Aspheric posterior surface
• Off center optic zone
• Toric SCR/PCR
• Back (bi) toric
• Piggy-back options
• (Semi)Scleral
• Surgeries - PTK, Intacs, PK