Visual deficits in alexia without agraphia

Abstract

Objectives: Most patients with alexia without agraphia (AWOA) have a right homonymous hemianopsia, but some have partial right homonymous field loss and a few have normal visual fields. This reported variability of visual deficits prompted the present study which more precisely delineates visual function in AWOA. Materials and methods: Nine patients with AWOA underwent neuro-ophthalmologic examination including Goldmann perimetry. Results: Three patients had complete right homonymous hemianopsia, two had complete right homonymous hemianopsia with additional binocular or monocular left field loss, two had right superior quadrantanopsia, and two had bilateral superior or inferior quadrantanopsia. Right superior quadrant vision was impaired in eight patients and no patient demonstrated an isolated right inferior quadrantanopsia or an isolated left homonymous field defect. No patient attained 20/20 visual acuity OU. Cerebrovascular disease was the most frequent etiology of AWOA (six patients), and eight patients had bihemispheric disease. Conclusions: This study demonstrates that bilateral visual field loss and decreased visual acuity occur in many cases of AWOA. The frequent presence of right superior quadrantic field defects implies a critical role in reading for the ventral outflow pathways of the dominant calcarine cortex. Although right hemianopsia and a lesion involving left occipital lobe and splenium remain the paradigm for AWOA, bilateral field loss, decreased visual acuity, and bihemispheric disease are common in AWOA and may adversely affect the integrity of neural reading mechanisms.