Nerve fibre bundle defects and their perimetric correlation.

The importance of red-free fundus examination in revealing functional loss of the retinal nerve fibre layer is highlighted in some optic nerve diseases as corroborated by a good correlation observed between NFBDs and visual field defects. Red-free fundus examination could predict the site of a visual field defects, thus enabling the perimetrist to concentrate on that area and to detect field defects which were missed in a previous field examination. In cases of optic atrophy, the extent of nerve fibre layer loss correlated better with the functional loss in terms of visual acuity rather than the pallor of the disc, which was quite often misleading as an indicator of functional damage of the optic nerve. The technique of red-free fundus photography employed was fairly inexpensive and simple.