Optic disc cupping and prematurity. Large cups as a possible low birth weight sequel.

In a previous ophthalmic study of ex-prematures around the age of 10 years it was accidentally found that cupping of the optic disc was significantly more pronounced in children of a low birth weight (less than 2000 g) than in full-term controls (Fledelius 1976). This was true for cup size (cup/disc diameter ratio) as well as depth (as indicated by a visible cribriform plate). The present analyses make up an extension of the above study, with additional calculations based on some of its data. Within the ex-prematures (n = 268) the cup size did not seem to be related to birth weight, sex, or visual acuity. Eyes with myopia of prematurity were not especially 'loaded' with large cups. For the whole sample (including the 187 full-term control there was a weak association between cup size and refraction (and axial eye length). Larger cups occurred relatively more often in myopic eyes. Possible mechanisms behind early changes in disc are discussed (astroglial hypothesis--distension of disc--loss of retinal nerve fibers). It is felt that this new observation--large disc cupping as a possible low birth weight sequel--has to be substantiated by further clinical evidence, as statistical type 1 error (mass significance) cannot be ruled out.