GP Lens Case Grand Rounds Troubleshooting Guide – 42

Post-Penetrating Keratoplasty – Herpes Simplex Keratitis: Robert Maynard, OD

Background

This 64-year-old physician presented in August 2000. He had a corneal transplant OD which was the result of herpes simplex keratitis.

Test Procedures, Fitting/Refitting, Design & Ordering

Manifest Refraction:

OD: +3.25 -0.75 x 064 >20/400 (Count Fingers at 8″)

Keratometry:

OD: 45.25 @ 138; 50.50 @ 048

Slit Lamp Evaluation:

There was corneal edema and scarring from 7:00-8:00 in front of the pupil. The iris was badly damaged with an offset pupil. The scarring and edema were on an “island” of tissue. At the time of this first visit, two Surgilenses (reverse geometry from Con-Cise) were used for an initial trial fit.

Initial Fit:

Lens Parameters:

Lens TypeBCR(mm)Power(D)OAD/OZD(mm)Cap Size (mm)SCR/W(mm)PCR/W(mm)

OD Rev Geom 8.04 +4.00 10.3/7.7 7.7 7.50/.6 10.80/.5

Visual Acuity:

OD: 20/25-1

Slit Lamp Evaluation:

OD: The right lens moved well and decentered nasally to the limbus. With fluorescein, there was apical clearance with slight inferior edge clearance.

One Week Follow-Up Visit:

Over-Refraction/Visual Acuity: Plano 20/25-3

Slit Lamp Evaluation:

OD: The right lens decentered nasally and locked on over the nasal limbus exhibiting no movement with the blink (Figure 1). With fluorescein, there were isolated areas of pooling superior, nasal and inferior and dimple veiling observed
between 11:00-1:00. Upon lens removal there was an adherence ring observed (Figure 2).


Figure 1


Figure 2

Two Week Follow-Up Visit:

Manifest Refraction:

OD: +3.00 -0.50 x 165

Over-Refraction/Visual Acuity:

OD: +0.25 -1.25 x 065 20/25-1

Slit Lamp Examination:

OD: The lens appeared to still be adherent. However, there was no signs of abrasion or edema and some tear exchange is present. Clearance is present, both superior/temporal and inferior/nasal.

The over-refraction was placed into spectacles to provide optimum vision for the right eye.

Follow-Up Care/Final Outcome

Final Fit:

A larger diameter and flatter base curve radius lens was ordered in a hyper Dk material. The final lens parameters were:

Lens Parameters:

Power(D)BCR(mm)OAD/OZD(mm)Cap Size(mm)Material

OD: +4.00 8.13 10.80/8.60 8.60 Boston XO

Visual Acuity (with Lens):

OD: 20/25-2

Corneal Topography:

Slit Lamp Examination:

OD: The lens decenters slightly nasally with slight movement with the blink and mild apical clearance. There is a small area of inferior bearing but no staining in this area.

Overall, he has been very satisfied with his vision and comfort achieved with the final lens.

Discussion/Alternative Management Options

This case demonstrates the importance of using reverse geometry designs in irregular cornea patients. Although the topography map did not exhibit a clear paracentral/midperipheral steepening pattern and reverse geometry lenses have their greatest indications in post-refractive surgery and corneal reshaping cases, this case does show how they can be successful in post-penetrating keratoplasty patients.

Large diameter lenses (i.e., Intra-Limbal from Lens Dynamics and other similar designs) are often indicated in these cases due to their ability to center, to optimize initial comfort and to overlap the graft. In this case a 10.80mm lens was found to provide the best fitting relationship. It is also important to emphasize the fact that an ideal alignment fitting relationship is very difficult to achieve in these cases; therefore, there may be some decentration, regional bearing and/or excessive clearance. The risk-to-benefit must be considered, especially as it pertains to the patient’s quality of life.

This case also shows the importance of in-office modification. A simple edge or surface polish or — as in this case — reblending or flattening of the peripheral curve radii can result in an improvement in comfort, fitting relationship, or both. Likewise, the use of a hyper Dk lens material such as the Boston XO (Bausch & Lomb) is indicated as well to optimize corneal integrity and minimize the potential for edema in the newly transplanted cornea.

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