Standardized analyses of correction of astigmatism with the visian toric phakic implantable collamer lens

Abstract

Purpose: To demonstrate the methodology described by the American National Standards Institute (ANSI) Standard Subcommittee on Astigmatism Analysis reporting a standardized method of presenting astigmatism data by laser systems that reshape the cornea also applies to toric phakic intraocular lens (IOL) data.

Methods: The U.S. Food and Drug Administration trial of the Visian Toric Implantable Collamer Lens comprised 210 eyes of 124 study patients. The mean preoperative manifest refraction spherical equivalent for the study cohort was -9.36 +/- 2.66 diopters (D) (range: -19.50 to -2.38 D). The mean preoperative manifest refractive cylinder was 1.94 +/- 0.84 D (range: 1.00 to 4.00 D).

Results: Data were arrayed using the 11 tables and 4 figures suggested in the Subcommittee paper. Interpretation of the data from a toric phakic IOL study was similar to that of laser refractive procedures. The addition of a table of manifest refractive cylinder (in the spectacle plane) over time, which provides a direct clinical measure of clinical efficacy, is suggested. Mean postoperative manifest refractive cylinder was 0.51 +/- 0.48 D (range: 0 to 3.00 D) with 65.6% of eyes having < or = 0.50 D of refractive cylinder at 12 months. A table of observed stability of the toric phakic IOL orientation within the eye obtained by slit-lamp examination also is recommended, which is a useful table not applicable in laser refractive procedures.

Conclusions: The data presented demonstrate that the methodology developed by the ANSI Standard Subcommittee on Astigmatism Analysis, with some minor additions, accurately characterizes the efficacy of toric phakic IOLs in treating astigmatism.