Asymmetrical cupping of the optic disc was found in 5.6% of normal individuals, in 30% of a group with ocular hypertension without field defect, and in 36% of those with established chronic open-angle glaucoma and field loss. Disc asymmetry was also instrumental in leading to the diagnosis of subacute angle-closure glaucoma and of chronic vascular insufficiency of the optic nerve. The search for disc asymmetry is an essential part of glaucoma screening.
Fishman RS. Optic Disc AsymmetryA Sign of Ocular Hypertension. Arch Ophthalmol. 1970;84(5):590-594. doi:10.1001/archopht.1970.00990040592006