Multifocal ERG in chloroquine retinopathy: regional variance of retinal dysfunction

Background: A study was carried out to evaluate the regional variance of re tinal dysfunction in chloroquine retinopathy. Methods: In three patients wi th different stages of chloroquine retinopathy, ophthalmologic evaluations including recording of full-field electroretinogram (ISCEV standard) and mu ltifocal electroretinogram were performed. Results: III one patient with mi ld chloroquine retinopathy the visual acuity, visual fields and full-field electroretinogram were normal, but retinal dysfunction was indicated by col or vision disturbances. The second patient had moderate chloroquine retinop athy with normal visual acuity, visual fields and dark-adapted full-field e lectroretinogram; light-adapted and flicker full-field electroretinogram re sponses were, however, borderline and color vision was abnormal. The third patient had severe chloroquine retinopathy with reduced visual acuity, visu al field and color vision defects, and a reduced full-field electroretinogr am. In the multifocal electroretinogram, recorded with 61 hexagons, amplitu des and implicit times were evaluated in rings surrounding the center. In a ll three patients severe dysfunction (either amplitudes or implicit times) was found in the parafoveal and perifoveal areas. In the fovea and towards the periphery the function was normal or only moderately reduced. Conclusio n: Chloroquine retinopathy of different severity presents with characterist ic alterations in the multifocal electroretinogram. Regional distribution o f cone dysfunction is in agreement with previously reported histologic find ings. The multifocal electroretinogram can detect retinal dysfunction in ch loroquine retinopathy even when the full-field electroretinogram is normal and retinal alterations are subtle.