Characteristics of optic disc in healthy school children.

The ophthalmoscopic features of the optic discs were studied in a series of 411 non-selected school children representing four age groups from 7 to 15 years. The distribution of the cup disc diameter ratios (C/D) showed that in the majority of the eyes (58.8%) the ratio was 0.2--0.3, independently of the age group. The highest ratio recorded, 0.7, was found in two eyes of the series. An asymmetry of 0.2 or more in the C/D ratios of the eyes was found in 5.2% of the children studied. The correlation between C/D ratio and the age or refraction was not statistically significant although C/D ratio of 0.4 or more was significantly commoner in myopia of -2.0 D. or more than in the other eyes. A preponderance of large C/D ratio was also found in children with a birth weight of 2500 g or less but the difference from the distribution in the total series was not significant. Cilioretinal arteries were detected in 17.7% of the eyes and in 27.3% of the subjects studied. In 8.1% of the children the condition was bilateral. In children with a birth weight of 2500 g or less cilioretinal arteries were found in more than half of the cases.