Refractive predictability of myopic hydrogel intracorneal lenses in nonhuman primate eyes

The refractive predictability of myopic hydrogel intracorneal lenses made of lidofilcon A was evaluated in 24 monkey eyes following a microkeratome dissection. All eyes were examined monthly for refractive alteration and clinical appearance during a follow-up period of 7 to 33 months. The refractive yield was measured by retinoscopy and found to be a function of the implant depth. The mean +/- SD percent of the desired correction achieved averaged 70% +/- 24% at a 36% to 60% depth (n = 8), 54% +/- 22% at a 61% to 79% depth (n = 7), and 12% +/- 14% in implants deeper than at a 79% depth (n = 9). For eyes with implants at a 36% to 60% depth, the predicted vs achieved refractive alteration yielded a correlation coefficient of .97 (88% within +/- 3 diopters of the correlation). The refractive outcome remained stable throughout 7 months of follow-up, whereas deeply placed lenses (greater than or equal to 80%) exhibited significant regression in power during this time.