Large optic discs in large eyes, small optic discs in small eyes

The optic disc area, varying interindividually by a factor of 1:7, is correlated with the count of the retinal ganglion cell axons and photoreceptors. This study evaluated whether the variations in the disc size are additionally correlated with those of the coronary diameters of the globe. Fifty-three normal human donor eyes with a mean age of 54.2 +/- 19.6 years were included in the study. After performing a 16-mm corneoscleral trephination, the globes were fixed and the horizontal and vertical diameters of the globes were measured. We cut the globes into meridional slices sticking together at the posterior fundus region. The areas of the whole retina and the optic disc were planimetrically evaluated on photographs with a millimeter scale aligned. We found that the horizontal and vertical diameters of the globe were correlated with the optic disc size and the retinal surface area. Eyes with long horizontal and vertical diameters had a larger optic disc and a larger retinal surface area than eyes with short diameters. The results suggest the combination of large optic discs in large eyes and of small optic discs in small eyes. Taking into account the relatively low correlation coefficients of 0.3 and 0.4, the study also suggests the existence of other not-evaluated factors influencing the occurrence of large optic discs. The results go along with the reported association between a large optic disc area and a large cornea size.(ABSTRACT TRUNCATED AT 250 WORDS)