ASSESSMENT OF RETINAL-NEURAL FUNCTION BEFORE NEODYMIUM-YAG LASER CAPSULOTOMY

Purpose. The aim of this study was to evaluate a clinical test of hype racuity in the assessment of retinal-neural function in patients with posterior capsular opacification. Methods. Neodymium (Nd):YAG laser ca psulotomy was performed on 39 subjects (mean age, 76.72 years +/- 10.4 1 years), Measurements of refractive error, logMAR acuity, and displac ement threshold hyperacuity (DTH) were made before and 3 weeks after N d:YAG therapy. The DTH task involved measurement of the smallest detec table displacement of an object relative to two stationary references. In addition, an independent fundus examination was performed before a nd after therapy to determine the presence of retinal disease. By opht halmoscopic examination, a blind protocol was adopted for the classifi cation of subjects as normal or as having retinal disease. Results. Pr eoperative measures of logMAR visual acuity were of no value in distin guishing between patients with retinal disease and normals (P > 0.1) a nd were a poor indicator of postoperative logMAR acuity (r(2) = 0.2). Preoperative DTH could be used to distinguish patients with retinal di sease from normals (P < 0.005) and were found to be correlated with me asures of postoperative logMAR acuity (r(2) = 0.4). Preoperative DTH c orrelated well with postoperative DTH (r(2) = 0.7), which is consisten t with its resistance to optical image degradation. Conclusion. The re sults of this study indicate that DTH is of value in the presurgical a ssessment of visual function in patients with media opacification if a dequate fundus examination is not possible.