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A.C. Pluenneke, P.H. Blomquist; Utility of Red Amsler Grid Screening in a Rheumatology Clinic . Invest. Ophthalmol. Vis. Sci. 2003;44(13):160.
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Purpose: to investigate the usefulness of routine screening with the red Amsler grid for detection of hydroxychloroquine (HCQ) retinal toxicity in a rheumatology clinic setting Methods: Red Amsler grid screening was performed as part of the evaluation for 170 consecutive patients with rheumatoid arthritis (RA) and/or systemic lupus erythematosus (SLE) at the Parkland Memorial Hospital outpatient rheumatology clinic regardless of history of current or past HCQ use. Patients with an abnormality in one or both eyes on red Amsler grid screening were referred to the Parkland ophthalmology clinic for further evaluation. This included slit-lamp and fundoscopic examinations, color vision testing with Ishihara plates, red and white Amsler grid testing, and a Humphrey 10-2 visual field examination. Results: 158 patients were women and 12 were men. Ages ranged from 22-83 years with an average age of 52 years. RA was the diagnosis in 132, SLE in 29, and both RA and SLE in 9 patients. 91 patients had a history of current or past HCQ exposure, and the remaining 79 patients without HCQ exposure comprised the control group. 19 patients identified scotomata on red Amsler grid testing. 11 of those had a history of HCQ exposure, while 8 patients did not. The difference in positive grids in HCQ users vs non-users was not statistically significant. Only 9 of the 19 patients identified bilateral defects that would be consistent with HCQ toxicity. There were an additional 8 patients who noted the entire grid to be blurry OU due to uncorrected presbyopia. 9 of the 19 patients with abnormal red Amsler grid screening followed up in the ophthalmology clinic. 10 patients were lost to follow-up despite multiple attempts to contact them and schedule appointments. Of the 9 patients who followed up, 8 had an otherwise normal ophthalmic examination including normal Humphrey 10-2 visual fields. The false positive rate for red Amsler screening is in the range of 42-95%. If the uncorrected presbyopic subjects are included as false positives, the false positive rate increases to 59-96%. The one patient with an abnormality on red Amsler grid that was confirmed on Humphrey 10-2 visual field testing (the one true positive) underwent extensive further testing including electrophysiology, flourescein angiography, and MRI, and it was determined that her visual field abnormality was not due to HCQ toxicity. Conclusions: The false positive rate of 42-96% is too high to make the red Amsler grid a reliable predictor of retinal toxicity. Therefore, although the red Amsler grid is a simple and inexpensive measure of central vision, it is not a useful tool in a rheumatology clinic setting.
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