Visual Field Test Catches Some HCQ Retinopathy Missed by OCT

Jenni Laidman

February 05, 2014

Physicians may miss some cases of hydroxychloroquine (HCQ) retinopathy if they skip visual field tests in favor of objective measurements alone, according to results from a study published online January 17 in Ophthalmology.

Michael F. Marmor, MD, professor of ophthalmology, Byers Eye Institute, Stanford School of Medicine, Palo Alto, California, and Ronald B. Melles, MD, from the Department of Ophthalmology, Kaiser Permanente Northern California, Redwood City Medical Center, examined the charts and clinical data of more than 2000 patients at risk for HCQ retinopathy because of a cumulative HCQ exposure of more than 1000 g. Among these patients, 150 showed clear evidence of toxicity.

The researchers compared findings made by using visual fields with those made by using spectral-domain optical coherence tomography (SD-OCT). The study found that SD-OCT failed to identify parafoveal ring scotomas in 11 of the 150 patients. None of these 11 patients had a history of other macular disease or other potential causes of the bull's-eye pattern. In contrast, all cases with clear parafoveal damage on SD-OCT showed signs of parafoveal field visual loss.

"This should encourage the inclusion of visual fields as a key screening tool, even when SD-OCT (a more specific and objective test) also is performed. The combination of visual fields and SD-OCT gives both sensitivity and specificity while avoiding unnecessary stoppage of the drug," the authors write.

Dr. Marmor toldMedscape Medical News that he and Dr. Melles decided to conduct the study when they began to notice patients with classic visual field loss among those with normal OCTs while conducting other research on HCQ. "We both started to notice patients who surprised us by having classic visual field loss even though the OCTs seemed basically normal. Yet the visual fields were clearly abnormal."

The current study reports only cases with conclusive visual field evidence of toxicity, Dr. Marmor said. The results support the American Academy of Ophthalmology recommendations to screen for HCQ with both visual fields and objective measures, Dr. Marmor said.

Abdhish R. Bhavsar, MD, clinical spokesperson for the American Academy of Ophthalmology, told Medscape Medical News that the study confirms the necessity of multimodality screening for HCQ toxicity. "That's a good concept. If you only do one test, you may miss something. This research provides a reminder that one test is not a good idea, and it's not recommended."

One additional lesson from the study is the fact that the 10-2 visual field with white target was effective in finding toxicity, Dr. Bhavsar said. A weakness of the study is that it is not a prospective, randomized trial, he noted. Dr. Bhavsar, who was not involved in the current study, is a retina specialist and surgeon at the Retina Center in Minneapolis, Minnesota.

It is important for physicians to tread carefully when it comes to making recommendations about the use of HCQ, Dr. Marmor told Medscape Medical News. "I do want to emphasize that [HCQ] is a very good drug, and it's relatively nontoxic systemically, and particularly for lupus, it reduces the frequency of attack," he said. "You want to be sure you've got a couple of pieces of evidence that there really is toxicity before you stop the drug. We can't prevent toxicity. We don't have any way of knowing who is going to become toxic and when, but we try to stop the toxicity disease at a very early stage, before there is a risk for losing central vision."

The authors and Dr. Bhavsar have disclosed no relevant financial relationships.

Ophthalmology. Published online January 17, 2014. Abstract

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