To investigate the correlation between optic disc size and retinal nerve fiber layer (RNFL) thickness in healthy subjects and patients with normal tension glaucoma (NTG).

Optical coherence tomography was performed on 50 eyes of 50 healthy subjects and on 50 eyes of 50 NTG patients.

The optic disc size showed a significant correlation with the RNFL thickness in healthy subjects and in patients with NTG. Significant correlations were observed between the optic disc size and the ratio of superior-to-total RNFL thickness (r=-0.283, p =0.049) and the ratio of nasal to total RNFL thickness (r=0.403, p =0.004) in healthy subjects. In patients with NTG, significant correlations were observed between the optic disc size and the ratio of superior to total RNFL thickness (r=-0.314, p =0.029) and the ratio of inferior to total RNFL thickness (r=-0.302, p =0.034).

RNFL thickness increased significantly with an increase in optic disc size in both healthy subjects and NTG patients. The correlation between optic disc size and the ratios of each quadrant to the total RNFL thickness showed a different pattern between healthy subjects and NTG patients.