Major determinants of optic nerve head topographic characteristics in a normal Turkish population

To determine the factors affecting the topographic characteristics of the optic nerve head in a normal Turkish population.

A cross-sectional study was performed on the optic nerve head of the right eyes of 613 healthy subjects of both sexes aged 11-77 years using a confocal scanning laser ophthalmoscope. The study population was divided into three groups (<20 years, 20-50 years, and>50 years) to evaluate age-related changes in the optic nerve head topography. A total of 15 variables were determined. Statistical analysis was performed using Student's t-test, anova, Tukey HSD test, linear regression analysis and Pearson's correlation coefficient.

Four eyes were excluded from the study due to poor image quality. There were 307 female subjects and 302 male subjects. The mean age of the subjects was 42.1 +/- 15.1 years. The mean optic disc areas were 1.99 +/- 0.45 mm2 and 1.97 +/- 0.41 mm2 for male and female subjects, respectively. The disc area of the subjects ranged between 1.01 and 4.19 mm2. Disc area was found to be associated with all of the optic nerve head variables studied, and was also found to be significantly increased with advancing age (P < 0.05). The only variable that showed a sex-related difference was neuroretinal rim volume, which was found to be higher in female subjects in all cases.

Optic disc area was found to be the main determinant of the optic nerve head topography in a normal population. Optic disc area was found to be significantly increased with ageing in a normal population. These acquired changes to the optic disc could suggest stretching of the scleral ring, which may highlight the role of advancing age on the pathogenesis of glaucomatous optic neuropathy.