Predicting refractive alterations with hydrogel keratophakia.

Hydrogel lenticules are being used as intracorneal lens (ICL) implants for refractive keratoplasty. The experimental surgical success can be evaluated through an understanding of their effect on the optical system of the cornea. An algorithm that utilizes elementary optics can be used to calculate the total corneal power produced through intracorneal lens implantation via either pocket or microkeratome dissection. Two groups of animal experiments involving ICL implantation using both pocket and microkeratome dissections were performed on Rhesus monkeys. The predicted effects of the surgical techniques were compared with the measured effects obtained via streak retinoscopy. The mean difference and standard deviation of the measured minus the predicted values for the pocket dissection group is -0.59 +/- 1.52 D, N = 7. The respective difference for the microkeratome group is -0.19 +/- 1.07 D, N = 4. These small differences illustrate the accuracy of the algorithm in predicting the effects of refractive keratoplasty with hydrogel intracorneal lenses.