[Effects of optic disc size on progression of visual field defects in normal-tension glaucoma]

To investigate the influence of optic disc area on the progression of visual field (VF) defects in normal-tension glaucoma (NTG). We evaluated the correlation between the right-left differences of the progression of VF defects and those of the intraocular pressure and the ocular anatomical factors.

Thirty two eyes of 16 NTG patients with a significant difference between the left and right optic disc area, were followed up for more than 5 years after diurnal variation analyzed with Heidelberg Retina Tomograph (HRT), and without myopic disc shape. The left and right eyes of the patients were allocated to two groups, a group with a relatively smaller eye disc and a group with relatively larger eye disc. They were studied regarding the probability of VF stability using the Kaplan-Meier life-table analysis. In addition, a comparison of clinical factors was evaluated between the two groups (Mann-Whitney U test).

The probability of VF stability at the 107-month follow-up was 60 +/- 13% (mean +/- SE)in patients with small disc area, and 25 +/- 11% in patients with large disc area. Optic disc area was found to have significant influence on the progression of VF defects (p = 0.022, log-rank test). In clinical factors, no statistically significant difference except disc area was found between the two groups.

These findings suggest that optic disc area is associated with the progression of VF defects in patients with NTG.