I read with interest the article by Nucci et al1 on the correlation between the diffusion tensor imaging of the optic nerve with morphological indices obtained by other instruments used in diagnosis of glaucoma. The authors have mentioned one of the criteria used to diagnose glaucoma as, ‘asymmetrical vertical cup to disc ratio exceeding 0.5’. This is unusual, as most of the textbooks use asymmetrical cupping of 0.2 or more as diagnostic criteria for glaucoma. Moreover, vertical cup disc ratio of 0.5 or more is another criterion for diagnosis of glaucoma.

The authors have mentioned that the 24-2 SITA standard programme was used for visual field testing. The first criterion for diagnosis of …