To the Editor.
—The recent article by McCarey and colleagues1 was most thought provoking and clearly demonstrated the state of the art. However, the authors' conclusion that the polysulfone implant produces a greater refractive change on account of its high refractive index is not wholly justified. The lidofilcon-B implants (refractive index, 1.3686) used by the authors had an average power in air of +10.00 diopters (D), the polymethylmethacrylate implants (refractive index, 1.49) had an average power in air of +26.25 D, and the polysulfone implants (refractive index, 1.63) had an average power in air of +36.75 D. Taking the authors' raw data and plotting a graph of implant power in air against corresponding change in ocular power found by retinoscopy, we find a remarkable linear relationship (Figure). Application of linear regression yields the following value: y = 5.53 − 0.53x; correlation coefficient = −0.9685; y indicates change in ocular power,
Patel S. On Predicting Ocular Power Changes in Refractive Keratoplasty. Arch Ophthalmol. 1987;105(8):1017. doi:10.1001/archopht.1987.01060080015003