[Optic nerve head analysis using the confocal scanning laser ophthalmoscope (CSLO) of big cups versus normal cups]

To comparatively evaluate the optic nerve head (ONH) using the confocal scanning laser ophthalmoscope (CSLO) in normal eye subjects (NE) versus big cup (BC) patients.

A total of 83 NEs (43 subjects) and 44 BC eyes (22 patients) were evaluated in this prospective study. The ONH was imaged using the CSLO (HRT-II; Heidelberg Engineering, Heidelberg, Germany). Disc area, cup area, rim area, rim volume (horizontal integrated rim volume), cup/disc ratio, and cup volume were evaluated. Additionally, cup depth and retinal nerve fiber layer thickness (RNFL th) and csa (RNFL csa) of the ONH were also measured. These ONH parameters were compared between normal subjects and eyes with a big cup. We used the t test for statistical analysis.

The mean age was 46 and 44 years in the NE and BC groups, with a sex ratio of 1.26 and 0.69 (p=0.381), respectively. There was a significant difference in disc area (2.07+/-0.38, 2.73+/-0.45, p<0.01), cup area (0.52+/-0.8, 1.26+/-0.3, p<0.01), cup volume (0.14+/-0.14, 0.44+/-0.16, p<0.01), cup/disc ratio (0.24+/-0.1, 0.69+/-0.1, 0.46+/-0.06, p<0.01), Me cup disc (0.24+/-0.1, 0.37+/-0.1, p<0.01), rim volume (0.44+/-0.1, 0.34+/-0.09, p<0.01), rim area (1.56+/-0.27, 1.45+/-0.27, p=0.345), RNFL th (0.28+/-0.05, 0.23+/-0.05, p<0.001) and CSM-0.19+/-0.14,-0.08+/-0.06, p<0.001), RNFL csa (1.43+/-0.25, 1.37+/-0.29, p=0.849) in normal vs big cup eyes, respectively.

There is correlation between the cup and disc areas. Parameters evaluating the retinal nerve fiber were comparable in the two groups, except the RNFL thickness, which was lower in the BC group. This may be explained by the larger surface of the optic disc in this group.

HRT parameters might be part of the criteria favoring the physiologic character of big cups.