Hydroxychloroquine (HCQ) is a medication widely used to treat various autoimmune conditions, including systemic lupus erythematosus, rheumatoid arthritis, and primary Sjögren's syndrome, as well as for malaria prevention [4, 5]. While generally considered safe and effective for long-term use, a potential serious side effect is hydroxychloroquine retinopathy (HCQR), a condition that can damage the retina and lead to irreversible vision loss if not detected early [1, 4].
The retina, the light-sensitive tissue at the back of the eye, typically remains clinically normal for many years while a patient is on HCQ. However, at an unpredictable point, signs of toxicity can develop [2]. To safeguard vision, updated guidelines from the American Academy of Ophthalmology emphasize the importance of regular eye screening and careful dosing to prevent and detect HCQR [1, 2].
Understanding Hydroxychloroquine Retinopathy Risk Factors
Several factors can increase a patient's risk of developing HCQR. Awareness of these risks is crucial for both patients and healthcare providers:
- Daily Dose: The most significant risk factor is the daily dose of HCQ relative to a patient's real body weight. Current recommendations advise a maximum daily dose of 5.0 mg/kg of real weight [1, 2]. For severely obese patients, the daily dose should be kept under 400 mg [2]. Using ideal weight for dosing is not recommended as it correlates less accurately with risk [1].
- Duration of Use: The risk of toxicity increases with the length of time a patient takes HCQ. At recommended doses, the risk is less than 1% for up to 5 years of use and less than 2% for up to 10 years. However, this risk rises significantly to almost 20% after 20 years of continuous use [1].
- Kidney Disease: Patients with concurrent renal disease have an increased risk of developing HCQR [2].
- Tamoxifen Use: Taking tamoxifen, a medication often used in breast cancer treatment, simultaneously with HCQ can also increase the risk of retinopathy [2].
- Older Age: Starting HCQ therapy at an older age is associated with a higher risk of toxicity [2].
When to Start Screening and How Often
Early and regular screening is vital for detecting HCQR before it causes noticeable vision changes. The American Academy of Ophthalmology provides clear recommendations for screening schedules:
- Baseline Examination: All patients should undergo a baseline eye examination shortly after starting HCQ therapy. This initial check establishes the health of the retina before any potential toxicity develops [1].
- Annual Screening: For most patients, annual screening should begin after 5 years of HCQ use [1].
- Earlier Screening for High-Risk Patients: If a patient has significant risk factors, such as a higher daily dose, concurrent renal disease, or tamoxifen use, annual screening should start sooner than 5 years [1, 2].
It's important to note that even after 20 years without developing toxicity, a patient still has about a 4% risk of developing HCQR in the subsequent year, underscoring the need for continued monitoring [1].
Advanced Tools for Early Detection
Modern ophthalmology offers advanced diagnostic tools that can detect subtle signs of HCQR even before a patient experiences any symptoms. This early detection is crucial for preventing severe vision loss [3]. The primary screening tools recommended include:
- Optical Coherence Tomography (OCT): OCT is a non-invasive imaging test that uses light waves to take cross-section pictures of the retina. It allows ophthalmologists to see the distinct layers of the retina and identify thinning or damage indicative of HCQR [2].
- Wide-Pattern Fundus Autofluorescence (FAF): FAF is another imaging technique that uses specific light wavelengths to highlight metabolic changes in the retinal pigment epithelium, which can be an early indicator of HCQR [2].
- Visual Field Testing: This test measures a patient's peripheral and central vision, helping to identify blind spots or areas of reduced sensitivity that might signal retinal damage. A 10-2 visual field test is often used for this purpose [1, 2].
The pattern of retinal damage can vary. Patients of European heritage often show a parafoveal pattern of toxicity (affecting the area near the center of vision), while East Asian patients may present with pericentral toxicity (affecting a wider area around the center). However, there are many exceptions, and screening examinations should look for both patterns [1, 2].
The Importance of Communication and Adherence
The effectiveness of HCQR prevention and early detection relies on strong communication between patients, their prescribing physicians, and ophthalmologists. Despite clear guidelines, adherence to screening protocols by prescribing physicians can sometimes be low [3].
Patients taking hydroxychloroquine should proactively discuss their medication dosage and eye health with both their rheumatologist or other prescribing doctor and their ophthalmologist. Early detection through advanced screening tests has led to a higher reported prevalence of HCQR and stricter guidelines for safe dosing, emphasizing the need for vigilance [3]. By adhering to recommended dosing and regular eye screenings, patients can continue to benefit from HCQ while minimizing the risk of vision-threatening retinopathy.
Sources
[1] Recommendations on Screening for Chloroquine and Hydroxychloroquine Retinopathy (2016 Revision). https://pubmed.ncbi.nlm.nih.gov/26992838/
[2] Special AAO Report: Recommendations on Screening for Hydroxychloroquine Retinopathy (2025 Revision). https://pubmed.ncbi.nlm.nih.gov/41232611/
[3] Rethinking the Hydroxychloroquine Dosing and Retinopathy Screening Guidelines. https://pubmed.ncbi.nlm.nih.gov/32610049/
[4] Hydroxychloroquine: A double‑edged sword (Review). https://pubmed.ncbi.nlm.nih.gov/39981928/
[5] Hydroxychloroquine in systemic lupus erythematosus and rheumatoid arthritis and its safety in pregnancy. https://pubmed.ncbi.nlm.nih.gov/21417950/