Optic nerve disc in unilateral myopia in children

Purpose:
the evaluation of biomorphometric parameters of optic nerve head of the eyes in myopic anisometropia, to state if glaucoma similar changes described in adults were present.

Material and methods:
17 children, 14 girls and 3 boys at the age from 7-18 years, mean 12,6 years with unilateral myopia of mean value 8,6 D. The parameters of optic nerve disc: total contour area (TCA), cup/disc ratio (C/D), neuroretinal rim area (Rim), volume of neuroretinal rim (Vol. A), cup volume (Vol. B), maximum slope (MSL) and average slope angle (ASL) were examined using laser scanning ophthalmoscope in the TopSS system of Laser Diagnostic Technologies Inc. The I group consists of myopic eyes, in the II group there were emmetropic eyes of the same children.

Results:
refraction in the I group ranged from -4,5 to -12D, mean -8,6D, in the II group from 0 to +1,0D, mean 0,07D. The mean axial length of eyeballs was 25,57 SD 1,9 mm in the I and 22,47 SD 1,09 mm in II group – the difference was significant. There was not statistically significant difference between TCA in the I (mean 1,19 SD 0,75 mm2) and II group (mean 2,13 SD 0,49 mm2). Mean C/D ratio and cup volume were significantly smaller in myopic (C/D 0,23 SD 0,16 Vol. B -0,06 SD 0,05) than in emmetropic eyes (C/D 0,33 SD 0,11mm3, Vol. B -0,18 SD 0,14 mm3).

Conclusions:
Optic nerve disc images in myopic and glaucomatous eyes in children are different. Smaller optic disc cup in myopic than in emmetropic eyes can show, that children myopic eyeballs enlarged without nerve fibers atrophy