An objective method of diagnosing hydroxychloroquine maculopathy.

Area of Science:

• Ophthalmology
• Rheumatology
• Medical Imaging

Background:

• Hydroxychloroquine (HCQ) maculopathy is irreversible and necessitates regular monitoring for prevention.
• Current guidelines define toxicity based on abnormal screening tests; a quantitative interpretation method is presented.
• The study addresses the need for objective diagnostic criteria in managing HCQ toxicity.

Purpose of the Study:

• To develop and validate a quantitative method for interpreting screening tests for hydroxychloroquine (HCQ) maculopathy.
• To establish objective criteria for diagnosing HCQ toxicity based on visual field (VF) and optical coherence tomography (OCT) data.
• To aid in the early and accurate detection of HCQ maculopathy in patients undergoing long-term treatment.

Main Methods:

• Ocular coherence tomography (OCT) scans and 10-2 visual field (VF) tests were performed on 100 patients on HCQ and 70 controls.
• Linear regression determined cut-off points for VF and OCT in eight Early Treatment of Diabetic Retinopathy Study (ETDRS) macular sectors.
• Logistic regression calculated the probability of developing maculopathy, correlating outer nuclear layer (ONL) volume with toxicity.

Main Results:

• The study included 100 patients (mean age 59.9 years, 85% female) on HCQ for a mean of 6.3 years.
• Logistic regression revealed a strong negative correlation between outer nuclear layer (ONL) volume and the probability of HCQ toxicity.
• The Hosmer and Lemeshow test indicated high significance (P=1) for the model's goodness of fit.

Conclusions:

• Combining ONL volume reduction and VF retinal sensitivity reduction in ETDRS macular sectors offers an accurate, objective diagnosis of HCQ maculopathy.
• This quantitative approach supports optometrist-led or virtual services, reducing reliance on individual assessor experience.
• The findings facilitate timely intervention and primary prevention of HCQ-induced retinal damage.