[A morphological study of neuroretinal rim for different types of optic disc in normal eyes and early glaucoma]

To investigate the morphological characteristics of neuroretinal rim in different types of the normal optic disc and early glaucoma.

The subjects were divided into four groups: (1) 41 eyes with physiologic small disc. (2) 40 eyes with physiologic large disc. (3) 42 eyes with normal size disc. (4) 45 eyes with early glaucoma. The optic disc area, neuroretinal rim area, cup area and a circuit (each 10( degrees ) neuroretinal rim widths were measured by using computerized imaging system. The curve of sequential neuroretinal rim widths was made from temporal to superior, nasal, and inferior.

(1) The morphological characteristic of the curve of sequential rim widths in normal eyes was that there were double humps in inferior and superior section, double valley in nasal and temporal section. (2) The loss of double humps of inferior and superior section was at the curve of sequential rim widths in early glaucoma. It was lower than nasal and higher than temporal section. (3) The inferior rim width of the physiologic large disc was the widest, while the superior rim width was the widest in the physiologic small disc, followed by the nasal and temporal section. (4) The correct discrimination ratio was 85.7% and 90.6% with rim area plus C/D and sequential neuroretinal rim widths (inferior 6:20 and superior 1:00 neuroretinal rim widths were the most effective) respectively in the multivariate discrimination.

The nasal neuroretinal rim width itself is regarded as the standard, and compare the superior and inferior with nasal neuroretinal rim width in estimating the morphological characteristics of neuroretinal rim. This way is very effective in discriminating physiologic large optic cup from the cup of early glaucoma.