The optic nerve head in highly myopic eyes is distinctly different from normal optic disks. We performed magnification-corrected morphometry of photographs of 51 optic nerve heads in highly myopic eyes (myopic refraction of more than -8.00 diopters). Mean refraction was -15.49 +/- 5.76 diopters (range, -8.00 to 28.00 diopters), mean age 63.0 +/- 12.1 years (range, 27-87 years). The disks were significantly (P less than 0.000001; Wilcoxon-Mann-Whitney test) larger and more ovally configurated than 457 unselected normal optic nerve heads with a myopic refraction of less than -8.00 diopters. Refraction, size of the disk, and area of the parapapillary region with chorioretinal atrophy were significantly (P less than 0.00001) correlated with each other. The parapapillary vessel diameter was independent from the disk size. Highly myopic disks can be regarded as secondary acquired macrodisks, the size of which is correlated with refraction and possibly age. They should be differentiated from secondary, acquired macrodisks in congenital glaucoma and from primary macrodisks. As in normal eyes, the parapapillary vessel caliber can be used to estimate the optic disk size in relative and approximately absolute units.

Four hundred twenty-seven optic discs of 233 unselected patients suffering from chronic primary open-angle glaucoma were morphometrically evaluated and compared with the optic nerve heads of 253 unselected normal subjects. Only one randomly chosen eye per patient was taken into consideration. We found that glaucoma leads to a change in the characteristic configuration of the neuroretinal rim that in normal eyes is significantly (P less than 0.001) largest at the lower disc pole, smaller at the upper and nasal disc side, and smallest in the temporal disc region. Based on this information, significant (P less than 0.001) morphometric differences between "early" glaucomatous and normal discs are: (a) the neuroretinal rim area in the lower temporal disc sector is smaller than in the upper temporal disc sector; the smallest rim width is outside the horizontal temporal disc sector ("pathognomonic"); the quotient of horizontal to vertical c/d ratio is lowered; and (d) the lower temporal, upper temporal, and total rim area are decreased. No significant difference in overall optic disc size and form exists between normal and glaucomatous eyes. Smaller optic nerve heads are not more susceptible to glaucoma.

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The neuroretinal rim as equivalent of the retinal nerve fibers is the target in the evaluation of glaucomatous optic nerve heads. Its area was measured in absolute size units using photographs of 234 normal optic disks and correcting the photographic magnification according to Littmann’s method. High myopic eyes ( < -8.00 dptr) were excluded. The mean rim area was 2.09 ± 0.60 (0.80–3.80 mm²). It was significantly correlated (p < 0.00001) to the optic disk area. In optic disks without cupping, the neuroretinal rim area was identical with the disk area (r = 1.0, slope of the regression line = 1.0). In disks having cups with temporal flat slopes, the rim area increased by a factor of 0.71 with the disk size, in disks with circular steep cups, by a factor of 0.26. This interindividual variability and the correlations between rim and disk area might be clinically important for morphometry of glaucomatous optic nerve heads. There were no significant correlations between rim area and age, sex, refraction or axial length.