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Pancorneal toric rigid gas-permeable contact lens for keratoconus improves vision
Eur J Ophthalmol. 2011;21(6):685-690.
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A novel pancorneal toric rigid gas-permeable contact lens significantly improved visual acuity and yielded discernable changes in corneal compression in patients with keratoconus, a study found.
"[A] hard contact lens may put pressure on the cone, leading to mechanical stress, chronic irritation and scarring of the cornea," the study authors said. "Changing to a pancorneal toric [rigid gas-permeable] contact lens may remove this pressure, as the toric shape of this contact lens allows the bearing towards the limbal area and may distribute pressure away from the cone to the rest of the cornea."
The retrospective study included 30 eyes with keratoconus that were fitted with a 12-mm contact lens with a toricity value of 0 to 1.2 between the end of the optical zone and the contact lens edge. Mean patient age was 48 years.
Corneal topography was assessed at the time of patient enrollment and after at least 2 months of contact lens wear to determine horizontal and vertical keratometry values and mean corneal eccentricity. Best corrected visual acuity was also evaluated. Mean follow-up was 22 months.
Study results showed changes in corneal compression in 23 eyes (77%). Mean best corrected visual acuity improved from 0.63 before contact lens wear to 0.70 after lens wear. Improvement in average BCVA was statistically significant (P = .007).
Data showed no appreciable changes in mean vertical and horizontal keratometry values or mean corneal eccentricity.
Further study is warranted, the authors said.
"It will be interesting to study patients prospectively to analyze whether these lenses will have any effect on the course of corneal thinning," they said.