Phakometry and lens tilt and decentration using a custom-developed Purkinje imaging apparatus: validation and measurements

Abstract

We present a Purkinje imaging system for phakometry and measurement of tilt and decentration of crystalline and intraocular lenses (IOLs). Crystalline lens radii of curvature were estimated by using both a merit function and the equivalent mirror approaches. Tilts and decentrations were estimated by using Phillips’s linear analysis. We present a complete validation of the technique through exhaustive computer simulations and control experiments, and measurements in 17 normal eyes (mean age 26.67 ± 2.31) and nine postcataract surgery eyes (mean age 74 ± 2.3). Crystalline lens radii ranged from 12.7 to 8.81 mm and from −5.64 to −7.09 mm for anterior and posterior surfaces, respectively. Crystalline lens tilt ranged from 2.8 to −2.87 deg horizontally and from 2.58 to −1 deg vertically. Crystalline lens decentration ranged from 0.09 to 0.45 mm horizontally and from 0.09 to −0.22 mm vertically. IOL tilt ranged from 3.6 to −1.51 deg horizontally and from 5.97 to −1.85 deg vertically. IOL decentration ranged from 0.53 to −0.31 mm horizontally and from 0.13 to −0.96 mm vertically.