Detecting chloroquine retinopathy: electro-oculogram versus colour vision

• Published in: British journal of ophthalmology Vol. 87; no. 7; pp. 902 - 908
• Main Authors: Neubauer, A S, Samari-Kermani, K, Schaller, U, Welge-Lüβen, U, Rudolph, G, Berninger, T
• Format: Journal Article
• Language: English
• Published: BMA House, Tavistock Square, London, WC1H 9JR BMJ Publishing Group Ltd 01-07-2003; BMJ; BMJ Publishing Group LTD; Copyright 2003 British Journal of Ophthalmology
• Subjects: Aging - physiology; antimalarial toxicity; Antirheumatic Agents - adverse effects; Associated diseases and complications; Biological and medical sciences; bull’s eye maculopathy; Chloroquine - adverse effects; Clinical Science - Extended Reports; Color Perception - physiology; computer colour vision test; Cornea - pathology; Diabetes. Impaired glucose tolerance; Drug toxicity and drugs side effects treatment; electro-oculogram; Electrooculography - methods; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Epidemiologic Methods; Female; Humans; Male; Medical sciences; Middle Aged; Ophthalmology; Pharmacology. Drug treatments; Retinal diseases; Retinal Diseases - chemically induced; Retinal Diseases - diagnosis; Retinal Diseases - physiopathology; screening; Toxicity: eye; Vision Tests - methods; United Kingdom; Human; Retinopathy; Treatment; Color vision; Toxicity; Chloroquine; Comparative study
• ISSN: 0007-1161; 1468-2079
• DOI: 10.1136/bjo.87.7.902

Aim: To investigate the relative sensitivity and specificity of two tests of retinal function (the electro-oculogram (EOG) and a computerised colour vision test) in screening for ocular toxicity caused by chloroquine and hydroxychloroquine. Methods: 93 patients with rheumatic diseases receiving long term chloroquine and hydroxychloroquine therapy were followed for an average of 2.6 years. Clinical examination, an EOG, and a quantitative test of colour vision were carried out every 6 months. Results: Mild fundus changes were observed in 38 patients. Four patients developed typical bull’s eye maculopathy, three of whom had received 250, 365, and 550 g total dose of chloroquine, and one 1500 g of hydroxychloroquine. Statistical analysis of all patients showed that for those with no fundus changes or stippled pigmentation a number showed elevation of tritan threshold, so that if macular stippling is a sign of mild retinopathy the test on tritan changes has a 64% sensitivity and 63% specificity for an upper threshold value of 7%. All four patients with bull’s eye lesions showed a marked disturbance of tritan colour vision, with a threshold of 14.8%, a sensitivity of 75%, and a specificity of 94%. For protan colour vision a threshold of 10% gives 75% sensitivity and 91% specificity. By contrast, neither an absolute nor a relative EOG reduction was a valid criterion for early or late chloroquine retinopathy. In advanced retinopathy an Arden coefficient (AQ) <180% yields 50% sensitivity and 54% specificity. When AQ <160% is the threshold, sensitivity does not increase but specificity rises to 82%. Occurrence of marked corneal deposits on clinical examination yields 50% sensitivity and 90% specificity in this situation. Conclusion: Screening for chloroquine retinopathy can be improved by using a sensitive colour test. Disturbance of the tritan axis appears to occur first. A normal test result on computerised colour testing virtually excludes any retinopathy by antimalarials. The EOG is of little diagnostic value.