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Br J Ophthalmol 2003;87:902-908 doi:10.1136/bjo.87.7.902
  • Clinical science
    • Extended reports

Detecting chloroquine retinopathy: electro-oculogram versus colour vision

  1. A S Neubauer,
  2. K Samari-Kermani,
  3. U Schaller,
  4. U Welge-Lüβen,
  5. G Rudolph,
  6. T Berninger
  1. Department of Ophthalmology, Ludwig-Maximilians-Universität, Munich, Germany
  1. Correspondence to: Aljoscha S Neubauer, MD, Department of Ophthalmology, Ludwig-Maximilians-Universität, Mathildenstrasse 8, 80336 Muenchen, Germany; aneubaue{at}ak-i.med.uni-muenchen.de
  • Accepted 10 November 20002

Abstract

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.

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