Neuroretinal rim area in early glaucoma.

Neuroretinal rim area (NRA) is the only clinical measurement that reflects the real amount of nerve fibers in optic disc. We measured the photographs of the optic disc in 132 eyes of 132 subjects in 6 groups: normal subjects with small cups, normal subjects with large cups, suspected glaucoma with small cups and those with large cups, primary open angle glaucoma (POAG), low tension glaucoma (LTG). The mean NRAs of POAG, LTG and suspected glaucoma with large cups were less than those of normal subjects with large cups. In normal subjects, a high correlation between cup area and disc area was found, while NRA correlated weakly with disc area. Both semiquantitative scores of diffuse and localized retinal nerve fiber layer defects were correlated significantly with NRA. We suggest that measurement of NRA and examination of retinal nerve fiber layer defect could improve the detection of acquired changes of optic disc in early glaucoma.