contact lens case reports
Soft Lens Orthokeratology
BY PATRICK J. CAROLINE, FAAO, & MARK P. ANDRÉ, FAAO
We've recently reported (Case Reports, June 2005 and May 2006) that orthokeratology-like changes may result from the inadvertent wearing of everted (inside-out) minus-powered silicone hydrogel lenses. Surprisingly, all of the patients in our reports noted excellent comfort when wearing their lenses inside-out.
Figure 1. Fluorescein patterns of our subject's everted –9.50D Night & Day lenses. Note the reverse geometry-like patterns OU.
Therefore, we wanted to determine whether it's possible to perform ortho-k on patients who have low myopia using everted, high-Dk silicone hydrogel contact lenses.
Figure 2. Corneal topography OD showing a corneal power change of –1.00D.
A patient elected to wear everted Night & Day (CIBA Vision) lenses overnight to perform soft lens ortho-k for his –1.00D OU correction. We informed him that this would be an off-label use of silicone hydrogel lenses. We then assessed baseline corneal topography measurements and fit him with everted Night & Day soft lenses, base curve 8.4mm, power –9.50D, diameter 13.8mm (Figure 1).
We examined the patient in the morning after his first night of wear. At that visit the patient reported excellent overnight comfort with the everted lenses. Corneal mapping showed –0.50D of corneal flattening that was well centered over his pupils.
Figure 3. Corneal topography OS showing a similar orthokeratology-like change.
We instructed him to continue the modality and return for follow up in one week. At that time he had an uncorrected visual acuity of 20/20 in both eyes and excellent overnight comfort with the lenses. Topography showed well centered treatment zones with a –1.00D correction in both eyes (Figures 2 and 3). The patient currently sleeps with the everted lenses every other night. He continues to report "perfect" visual acuity throughout his 48 hours of no lens wear.
Further Study Warranted
This patient experience shows us that ortho-k-like refractive and topographic changes can occur with overnight wear of everted, high-minus silicone hydrogel lenses.
It's clear that further work needs to take place to better understand the nature and extent of the corneal changes associated with these lenses. Our clinical experience indicates that in the future, some type of silicone hydrogel lens design might be used for possible overnight ortho-k, especially for individuals who have low myopia. CLS
Patrick Caroline is an associate professor of optometry at Pacific University. He is also a consultant to Paragon Vision Sciences and SynergEyes, Inc. Mark André is an associate professor of optometry at Pacific University. He is also a consultant for CooperVision and SynergEyes, Inc.