MODEL FOR DENYING THE OPTICAL-PERFORMANCE OF THE MYOPIC EYE CORRECTEDWITH AN INTRACORNEAL RING

BACKGROUND: The intracorneal ring has been advanced as a mechanical de vice for the correction of myopia. The device may reduce refractive er ror, but the effect on the overall optical performance of the eye has been neglected. This paper addresses this issue by presenting mathemat ical models that will predict the effect of the intracorneal ring on r efractive error, corneal asphericity, and the spherical aberration of the eye. MATERIALS AND METHODS: Algorithms are derived for predicting the corneal apical radius, asphericity, and the change in myopia after inserting intracorneal rings of any thickness and diameter. RESULTS: The model predicts that the magnitude of myopia reduction is a functio n of both ring thickness and diameter. The large diameter (9 to 10 mm) , thin (0.1 to 0.2 mm) intracorneal ring is less likely to adversely a ffect corneal asphericity and therefore not significantly enhance the spherical aberration of the eye. CONCLUSIONS: An intracorneal ring can not correct more than 4.00 diopters (D) of myopia without significantl y increasing ocular spherical aberration, which, in turn, will comprom ise the final visual outcome.