Assessment of retinal-neural function before neodymium:YAG laser capsulotomy

The aim of this study was to evaluate a clinical test of hyperacuity in the assessment of retinal-neural function in patients with posterior capsular opacification.

Neodymium (Nd):YAG laser capsulotomy was performed on 39 subjects (mean age, 76.72 years +/- 10.41 years). Measurements of refractive error, logMAR acuity, and displacement threshold hyperacuity (DTH) were made before and 3 weeks after Nd:YAG therapy. The DTH task involved measurement of the smallest detectable displacement of an object relative to two stationary references. In addition, an independent fundus examination was performed before and after therapy to determine the presence of retinal disease. By ophthalmoscopic examination, a blind protocol was adopted for the classification of subjects as normal or as having retinal disease.

Preoperative measures of logMAR visual acuity were of no value in distinguishing between patients with retinal disease and normals (P > 0.1) and were a poor indicator of postoperative logMAR acuity (r2 = 0.2). Preoperative DTH could be used to distinguish patients with retinal disease from normals (P < 0.005) and were found to be correlated with measures of postoperative logMAR acuity (r2 = 0.4). Preoperative DTH correlated well with postoperative DTH (r2 = 0.7), which is consistent with its resistance to optical image degradation.

The results of this study indicate that DTH is of value in the presurgical assessment of visual function in patients with media opacification if adequate fundus examination is not possible.