Visual fields in a chloroquine treatment

Abstract

Purpose: In this study, we describe contrast sensitivity losses in the visual field of a patient affected by chloroquine toxicity, measured with stimuli favoring different visual mechanisms. We have compared these results with those of other, usual clinical tests. Methods: The vision of a patient who underwent ten years of chloroquine treatment was analyzed by a battery of clinical tests: visual acuity (VA), Amsler’s grid, Farnsworth–Munsell 100-hue test, spectral domain optical coherence tomography, multifocal electroretinogram (ERG), white-on-white and red-on-white Humphrey perimetries, chromatic and achromatic contrast sensitivity perimetry tests, and fluorescein angiography. Measurements were taken just before the cessation of the treatment, and 6 months later. Results: The subjective visual perception of the patient was worse (in comparison with the rest of the visual field at the time of the first visit) in the center of the visual field, and was impaired on the second visit. Although standard automated perimetry (SAP) was practically normal and ERG results did not worsen with time, VA, Amsler’s grid, and visual fields with stimuli favoring the magnocellular and chromatic pathways signalled progressive loss of visual function. Conclusions: Standard tests such as SAP or ERG may not detect visual field losses or progression of existing visual losses in a case of chloroquine toxicity, whereas tests evaluating contrast sensitivity with stimuli favoring different visual mechanisms may be more sensitive.