CASE STUDY I - Dr. Barr

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 kcone 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) larger diameter      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 cone design

After you have the design right:
     • What material would you order?
     • What lens care system would you Rx?

 
CASE STUDY II - Dr. McMahon

History: 28-year-old white female with a history of mild keratoconus OS and very early asymptomatic keratoconus OD. The patient has a long history of soft lens wear but complained of poor vision OS with these. She was fitted a year ago with a spherical GP lens in the left eye. Despite several parameter changes she tolerated the lens only 2-3 hours per day. A recent piggy-back trial also failed to provide more than 3 hours of wearing time OS. She returned to discuss her remaining options.

Medical history: Seasonal allergies requiring topical antihistamines during active periods.

Ocular history: keratoconus OS>OD, dry eyes

External exam: Shirmer basal secretion testing 2mm wetting at 1 minute OU (with anesthesia).

Topography: See below.

Refraction: OD -4.75 SPH 20/20 and OS -5.50 + .75 X 15 20/30-2

Slit lamp exam: OD normal exam, OS inferior Fleischer ring, mild inferior paracentral thinning.

Options: 1) Macro lens, 2) Intralimbal design, 3) Softperm

A Dyna Intralimbal lens from Lens Dynamics was tried.
Trial parameters: OS 7.85/ -2.50/ 11.2 OAD/ 9.0 OZ. Standard peripheral curves, material Boston XO.

This lens centered with a slight superior bias. Minimal but acceptable edge lift. There was bearing at the cone apex. Best corrected VA was only 20/30, however.

The lens was ordered and dispensed. Lens tolerance was better, but wearing time was only 6-8 hours and the patient complained of blurred VA OS.

A lens with a steeper base curve was ordered.
New parameters: OS 7.62/ -3.75/ 11.2 OAD/ 9.0 OZ, standard peripheral curves, material Boston XO.

Results: To be determined.

 
CASE STUDY III - 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
     • 20/30 OU
     • "Because that's what the doctor did, and it's a hassle."

K readings:
     OD 52/53@165 distorted
     OS 53/53@25 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

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

Follow-up:
     • VA OD 20/25 variable, OS 20/25+, WT 14 hours
     • OR 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, -8.75. Good result, no central SPK, mild 3/9 stain.

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
     • Other KC Special Designs
     • Off center optic zone
     • Toric SCR/PCR
     • Back (bi) toric
     • Piggy-back options
     • (Semi) Scleral
     • Surgeries: PTK, Intacs, PK

 
CASE STUDY IV - Dr. McMahon

History: 57-year-old white male with a history of keratoconus OU and a PK OD 22 years ago. The patient called and came in complaining of irritation and a "film" over his right eye for one day. He discontinued lens wear for the right eye when the symptoms started.

Visual acuities: VA OD 20/400 without correction, OS 20/40-3 with a GP lens. Spectacle correction showed no improvement in VA OD. Over correction OS was plano with no improvement in VA.

Slit lamp exam: The right cornea was significant for a thick hazy graft. Superficial vessels were noted superiorly extending to the graft margin. The host cornea was thick and hazy inferotemporally as well. The left cornea was remarkable for central thinning, a large well demarcated Fleischer ring, and a linear 3 mm vertical stromal scar extending from Bowman's layer posterior to Descemet's membrane. The anterior chambers were deep and quiet, and the crystalline lenses were clear.

IOP: 20 mmHg OD by pneumotonometry

Pachymetry: .993 OD

Assessment: Graft rejection OD

Plan: Pred forte 1% OD q 2h while awake. Return in one week.

One week later the right looked unchanged. Despite the thick hazy graft two issues seemed atypical of a graft rejection: 1) despite pancorneal edema no KP were found (unusual but not unheard of), and 2) host corneal edema.

A) Dx changed to Host corneal hydrops temporally with secondary extravasation of fluid into the graft. Cornea specialist opinion was sought and dx was concordant with my diagnosis.

P) Continue Pred forte for one week at q 2h, then taper and follow.

Over the next three months the graft slowly thinned to a reading of .663 and cleared. The host cornea temporally remained edematous. IOP was 22 mm HG.

A month later the patient returned with a stable graft and a tinned inferior temporal host. He requested a return to contact lens wear. Topography of the right cornea (see below) demonstrated an oblate with-the-rule map (horizontal green bowtie) and significantly steep periphery approximately the graft-host margin.

Refraction: OD -9.00 + 2.25 X 85 giving 20/50, and OS -17.75 SPH giving 20/80-2.

What options do we have? I see a few: 1) fit with a conventional spherical back surface GP; 2) due to the relatively flat center and steep periphery try a reverse geometry design; 3) Macro lens; and 4) Intralimbal lens.

I would not normally go to a toric design here with this cylinder level, and a soft lens would most likely not work with the geometry you see.

I opted to try a straightforward spherical GP design first.

Parameters trialed: 7.58 (44.50 D)/-7.00/ 9.5 OAD/ 8.1 OZ

This lens demonstrated mildly erratic movement and excessive edge lift. The central fluorescein pattern showed focal central pooling with mid-peripheral bearing.

Next lens tried: 7.40 (45.50 D)/ -7.00/ 9.5 OAD/ 8.1 OZ

This lens positioned centrally to superocentrally. Movement was regular and not excessive. The central pattern looked similar to the prior lens but larger in area and the edge lift was reduced.

Overrefraction: -1.00 sphere 20/20.

This lens was ordered and dispensed and is being worn 16 hours per day successfully to this day.