Rapid macular thinning an early sign of hydroxychloroquine retinopathy
28 May 2022
In patients on long-term hydroxychloroquine (HCQ) therapy, rapid macular thinning appears to alert a potential retinal damage related to HCQ treatment, a study has found.
The study used data from Kaiser Permanente Northern California and included 301 patients receiving long-term HCQ therapy. All of them had a minimum of four optical coherence tomography (OCT) studies, which included Early Treatment Diabetic Retinopathy Study (ETDRS) retinal thickness values over a minimum interval of 4 years.
Researchers created sequential retinal thickness plots to analyse the rate of change in macular thickness within ETDRS regions. They identified rapid macular thinning, compared patients with rapid thinning with those who had stable macular thickness, and compared patients with rapid thinning who had vs had no conventional OCT or 10-2 visual field signs of HCQ toxicity.
In 219 patients on long-term HCQ therapy and with stable macular thickness, retinal thinning averaged 0.62 microns per year. In comparison, 82 patients exhibited a period of relatively linear rapid thinning, with a mean loss of 3.75 microns per year.
Among patients with rapid thinning, 38 developed conventional OCT or 10-2 visual field signs of HCQ retinal toxicity. The cumulative retinal thinning in this group of patients was a mean of 25.1 microns as opposed to a mean of 15.7 microns among patients without conventional toxicity (p<0.01).
The findings underscore the importance of the role of sequential plots of inner and outer ETDRS ring macular thickness in providing objective evidence of an early structural change several years before conventional signs appear. This approach can warn patients and prescribing physicians of potential retinal damage.