Purpose: To examine the refractive and keratometric response of corneal refractive therapy (CRT) contact lenses for hyperopia (CRT) after a single night of contact lens wear with the goal of reducing hyperopia by +3.50 D.
Method: Twenty participants were fitted with a CRT HDS 100 contact lens, in one eye only. The back optic zone radius of the CRT lens was designed to correct 3.50 D of hyperopia. The eyes were randomly selected. The Nikon Auto Refractor was used to measure refractive error. Corneal topography and simulated K readings were measured using the Humphrey Atlas topographer. The lens was subsequently worn overnight, and the lens was assessed the next morning on awakening.
Results: Refractive error changed by 1.50±0.71 D (mean ± SD, range 0.50-2.75 D) immediately after lens removal in the experimental eye. Similarly, there was a change in flat K readings of 0.58±0.62 D with a range of −0.25 to +1.87 D. These results were significantly different from the baseline measurements (P<0.0001).
Conclusions: The fitting of CRT HDS for hyperopia has a significant effect on corneal shape and refractive error. There was a moderate yet significant steepening of the cornea.
From the Centre for Contact Lens Research (L.S.), School of Optometry, University of Waterloo, Waterloo, Ontario, Canada; and CibaVision (F.L.), Atlanta, GA.
The authors have no conflicts of interest to disclose.
Supported by Paragon Vision Sciences, Mesa, AZ.
Address correspondence and reprint requests to Dr. Luigina Sorbara, O.D., M.Sc., School of Optometry, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1; e-mail: firstname.lastname@example.org
Accepted November 3, 2010.