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—We are pleased that the results of the PERK Study regarding the factors affecting the outcome of radial keratotomy confirmed the findings of the UCLA clinical trial described by Dr Hoffer and colleagues in their preliminary report in 1981. A major difference is present, however. Hoffer and colleagues stated that age did not correlate with the change in refraction in their study. The PERK Study and other studies have demonstrated that older patients achieve a greater change in refraction after radial keratotomy than younger patients, the amount being approximately 0.50 diopters per decade on the average.We fully agree that the role of the corneal curvature in the outcome of radial keratotomy has not been properly defined yet, and further research is needed in this area.
Waring GO, Lynn MJ. The UCLA and PERK Studies-Reply. Arch Ophthalmol. 1987;105(5):610. doi:10.1001/archopht.1987.01060050028007