Abstract
Abstract: :
Purpose: Although drusen of the optic nerve head is generally considered a relatively benign condition, several reports document that visual field loss may occur in a substantial number of patients. These studies have described the visual field abnormalities and their apparent similarity with glaucomatous visual field defects; however, few reports have described their incidence. In this study, we aim to characterize the nature and incidence of visual field defects seen in association with optic nerve head drusen. Methods: A retorspective analysis was performed on data from 111 eyes of 62 patients with funduscopically and/or ultrasonographically proven drusen of the optic nerve head, followed in the Neuro-Ophthalmology service at the University of Saskatchewan. Our study excluded all cases known to have potentially confounding co-morbid ophthalmologic diagnoses. All patients underwent visual field assessment using Humphrey or Goldman perimetry, or both. Individual visual field defects were initially categorized as follows: generalized constriction, enlarged blind spot, and nerve-fiber bundle defects. The latter was then subdivided into arcuate and sectoral defects. If more than one pattern of field defect was observed in an individual field, these patterns were tabulated separately. Results: Sixty-six of 111 cases (60%) demonstrated visual field abnormalities. Eighty-nine percent of visual field defects were of the nerve-fiber bundle type, 5.5% were enlarged blind spots, and 5.5% were generalized constriction. The single most common defect was an inferonasal sectoral scotoma. Conclusion: Our study clearly suggests a preponderance of nerve-fiber bundle defects due to optic nerve head drusen. Specifically, these defects are located in the inferior and nasal visual field. Our findings are consistent with previous reports suggesting a predominance of inferonasal field nerve-fibre bundle defects and their apparent similarity with glaucomatous visual field abnormalities. However, our population demonstrated a lower incidence of enlarged blind spot than has been previously documented.
Keywords: 487 neuro-ophthalmology: optic nerve • 624 visual fields • 354 clinical (human) or epidemiologic studies: prevalence/incidence