Nerve fiber layer assessment with scanning laser polarimetry in glaucoma patients and glaucoma suspects

PURPOSE. TO investigate whether scanning laser polarimeter can differentiat e glaucoma and suspected glaucoma patients from normals. METHODS. Polarimetric measurements were obtained using the nerve fiber anal yzer (NFA)-I from 80 eyes of patients with glaucoma with mostly moderate gl aucomatous optic nerve damage (37 eyes with primary open angle glaucoma, 21 with normal tension glaucoma, 17 with pseudoexfoliative glaucoma, 3 with a ngle closure glaucoma, and 2 with juvenile glaucoma), 53 eyes of patients s uspected of glaucoma based on disc appearance, and from age-matched healthy volunteers as control groups. Ratios (superior/nasal, inferior/nasal, supe rior/inferior) were used for assessing nerve fiber layer (NFL) thickness. S tudent's t-test and linear regression analysis were used for statistical an alysis. RESULTS. Both the glaucoma patients and glaucoma suspects had significantly lower NFL ratios (mean S/N 2.34 +/- 0.47, I/N 2.46 +/- 0.52, S/I 0.94 +/- 0.18) than the control groups (respectively 2.88 +/- 0.48, 2.88 +/- 0.48, 1 .00 +/- 0.13) (p < 0.05). There was an ample overlap between the patient gr oups and the normals. The superior and inferior NFL ratios in glaucoma pati ents gradually decreased as the mean defect in visual field increased (line ar regression analysis, p < 0.05). CONCLUSIONS. The NFL of glaucomatous eyes and eyes suspected of glaucoma ba sed on disc appearance was significantly less thick than normals, NFA-I det ects pathological abnormalities in some patients with glaucomatous optic ne rve damage and normal visual fields as measured by conventional achromatic computerized perimetry. NFA-I, however, is unable to distinguish these pati ents from normals, at least using these parameters, because of the consider able overlap.