Preservation of nerve fiber layer by retinal vessels in glaucoma.

The authors evaluated the correlation between various parameters and the local preservation of the retinal nerve fiber layer in 156 glaucomatous eyes. A vessel-associated preservation of the nerve fiber layer was observed in 45 of the 156 glaucomatous eyes. The presence of "straight" retinal vessels (either arterioles or large venules) and "tortuous" retinal vessels (large or small venules) inside of the scleral ring was correlated with the local preservation of the nerve fiber layer (P less than 0.001 and P less than 0.05, respectively). A local elevation of the floor of the cup was also correlated with the preservation of the nerve fiber layer (P less than 0.01). However, no correlation existed between either the preservation of the nerve fiber layer and the type of glaucoma, sex or age of patient, tilting of the disc, cilioretinal vessel, vertical cup-to-disc ratio, refractive error, disc size, distance between the disc and foveola, or the index of ovalness of the disc. These results suggest that retinal vessels in the disc significantly influence the vulnerability of the nerve fibers to glaucomatous damage.