contact lens case reports
RGPs for Post-Herpes Simplex Keratitis
BY PATRICK J. CAROLINE, FAAO,
FCLSA, & MARK P. ANDRÉ, FAAO, FCLSA
Herpes simplex virus (HSV) is one of the more common ocular disorders that often requires RGP lenses to correct induced scarring and irregular astigmatism. HSV remains the most common infectious cause of corneal blindness in the United States with up to 500,000 cases diagnosed annually.
S.C. is a 47-year-old female who presented with a central corneal scar OS from an HSV infection five years ago. Her best corrected spectacle Rx was OD 2.50 1.25 x 170 and OS +2.25 1.00 x 170, with acuities of 20/15 and 20/50, respectively.
Slit lamp examination OS revealed a central corneal scar slightly below the corneal midline and some mild corneal neovascularization (Figure 1). Topographic mapping OD revealed normal, with-the-rule corneal astigmatism with Ks of 42.75 @ 180 / 44.25 @ 90. The map of the left eye illustrates the irregular astigmatism resulting from the infection. Typical of a post-HSV infection was the marked corneal flattening (the central blue/green area) over the site of the scar. A "melting" or loss of stromal tissue secondary to the viral infection flattens the cornea and ultimately causes a dramatic hyperopic shift. Keratometric readings OS were 40.00 @ 164 / 43.50 @ 75 (Figure 2). The virus' inactive status for the past year prompted us to consider RGP correction of the irregular astigmatism and induced anisometropia.
|Figure 1. Photokeratoscopy OS illustrating the central irregular corneal astigmatism post HSV.||Figure 2. Corneal mapping OU. Note the central corneal flattening over the site of the infection.|
Fitting RGPs Post-HSV
We determined the temporal corneal curvature 4.0mm from center (41.00D). This is the approximate area on which a 9.5mm diameter lens with an 8.2mm OZ will land on the cornea.
Figure 3. Fluorescein view of the optimum fitting RGP lens.
We placed a diagnostic lens of 41.00/3.00/9.5 on the eye. An over-refraction of +5.00D resulted in a VA of 20/25. We ordered RGPs for both eyes. The patient reported good lens comfort with a wearing time of 14 hours a day OU. The fluorescein pattern of the left lens revealed good centration with slight pooling over the central scar and greater peripheral lens clearance over the steepest area at 12 o'clock (Figure 3). The patient was treated with oral acyclovir prophylacticly and thoroughly instructed on signs and symptoms associated with HSV recurrence.
Patrick Caroline is an associate professor of optometry at Pacific University and an assistant professor of ophthalmology at the Oregon Health Sciences University.
Mark André is director of contact lens services at the Oregon Health Sciences University.