COULD A CYCLOPLEGIC AGENT BE REPLACED BY A FOGGING OR A CORRECTIVE LENS IN THE BIOMETRIC MEASUREMENT OF THE CRYSTALLINE LENS

This study investigated whether a fogging or a corrective lens could b e used to replace a cycloplegic agent in the ultrasonic measurement of crystalline lens thickness in myopia. A group of 28 Hong Kong Chinese adults with myopia was recruited. The crystalline lens thickness of t he examined eye was measured by A-scan ultrasonography while the fixat ing eye was in one of three conditions: fog (+2.00 D fogging lens), fu ll corrective lens, or cycloplegia (50 minutes after instillation of 1 % cyclopentolate HCl). We found that the mean lens thickness was signi ficantly different between the three conditions in our myopic subjects . The mean crystalline lens thickness under fogging and corrective len s conditions was significantly greater than the cycloplegic condition by 0.09 mm and 0.11 mm, respectively. The 95% limits of agreement comp ared to cycloplegia (fogging: -0.32 to +0.14; corrective: -0.35 to +0. 13) showed marked intersubject variability, indicating that there is a risk of overestimating the lens thickness when substituting cyclopleg ia with either a fogging or a corrective lens. (C) 1998 The College of Optometrists. Published by Elsevier Science Ltd. All rights reserved.