Purpose:Comparison of the visual field defects between the two eyes in patients with bilateral glaucomatous optic neuropathy, in order to determine any similarities in the topographic pattern of the scotomas.
Patients and methods:We studied retrospectively the visual fields of 240 consecutive glaucoma patients obtained with the Humphrey Field Analyzer.Patients with generalized depression of light sensitivity, unilateral visual field loss or advanced (in both hemiefields) absolute scotomas in at least one eye were excluded. Sixty six patients showed reproducible bilateral scotomas of various stage of progression in one hemiefield only. In those selected cases topography and depth of scotomas were pairwise compared. The recorded initial maximum intraocular pressure (IOP) before therapy were correlated to the visual field findings.
Results:Fifty one (77%) pairs of visual fields showed an interocular symmetric distribution of the scotomas in the affected hemifield. In the eyes with lower IOPs (<23 mm Hg) the frequency of interocular symmetry was higher than in the eyes with higher IOPs (>24 mm Hg) (85% v. 72%). Conclusion: The frequent existence of symmetric bundle field defects between the two eyes in patients with mild to moderate glaucomatous optic neuropathy indicates the involvement of a probably “genetic-dependent” structural factor of the optic nerve in the mechanism of the damage, particularly in cases with normal-tension glaucoma. Nevertheless the considerable number of cases with asymmetric pattern of visual field loss reflects the contribution also of other factors in the pathogenesis of glaucomatous optic neuropathy.