Hydroxychloroquine, often known by its brand name Plaquenil, is a medication widely prescribed for various autoimmune conditions, such as rheumatoid arthritis and systemic lupus erythematosus. It also treats malaria. While generally effective, it carries potential side effects. Among these, damage to the eyes, specifically the retina, is a rare but significant concern.
What is Hydroxychloroquine Retinopathy
Hydroxychloroquine retinopathy refers to damage in the retina, the light-sensitive tissue at the back of the eye. This damage primarily affects the macula, the central part of the retina responsible for sharp, detailed central vision and color perception. The precise mechanism of toxicity is not fully understood, but it is believed that hydroxychloroquine can accumulate in the retinal pigment epithelium (RPE), a layer of cells supporting the photoreceptors. This accumulation may interfere with the RPE’s metabolic functions, leading to photoreceptor cell degeneration.
The development of hydroxychloroquine retinopathy is linked to cumulative dose and daily dosage relative to body weight. While risk is low in the initial five years of treatment (under 1%), it can increase with prolonged use, potentially reaching nearly 20% after 20 years of continuous therapy. The condition begins with subtle changes in the outer retina or photoreceptor layer, often before noticeable symptoms appear. If undetected and medication continues, damage can advance, leading to widespread retinal atrophy and irreversible vision loss.
Screening and Monitoring for Eye Damage
Detecting eye damage from hydroxychloroquine relies on consistent and specialized ophthalmological screenings. A baseline eye examination is recommended within the first year of starting the medication to establish a reference point and check for any pre-existing retinal conditions. For most patients without additional risk factors and on appropriate doses, annual screening can begin after five years of hydroxychloroquine use. However, if risk factors are present (e.g., higher daily doses, kidney disease, or concomitant use of tamoxifen), annual monitoring should start from therapy initiation.
Several specialized tests are used during these screenings to identify early signs of retinopathy. Spectral-domain optical coherence tomography (SD-OCT) provides detailed cross-sectional images of the retina, allowing detection of subtle thinning or disruption of retinal layers. Automated visual field testing assesses central and paracentral vision to identify areas of diminished sensitivity or blind spots. Fundus autofluorescence (FAF) imaging can reveal changes in the RPE that may indicate early damage. These tests are designed to catch changes before a patient experiences noticeable vision problems, which is important for preserving vision.
The Reversibility of Eye Damage
Once hydroxychloroquine retinopathy is established, retinal damage is not reversible. Even if the medication is stopped immediately upon diagnosis, cellular damage can continue to progress, potentially leading to further visual decline. This continued deterioration is thought to occur because the drug binds to melanin in the RPE and remains in ocular tissues for an extended time, causing ongoing metabolic injury to retinal cells even after systemic drug cessation.
While retinal damage is permanent, early, subtle changes (sometimes called pre-retinopathy) may stabilize or slightly improve if the drug is discontinued promptly. This stabilization does not mean a full recovery of damaged retinal cells. The severity of damage at detection and duration of drug use are significant factors influencing prognosis. Cases identified at later stages, especially those with the classic “bull’s-eye maculopathy” appearance, are associated with severe and irreversible vision loss. Early detection through regular screening offers the best chance to preserve vision by limiting the extent of structural and functional deficits.
Minimizing Risk and Ongoing Care
Minimizing the risk of hydroxychloroquine retinopathy involves careful dosing and consistent adherence to screening protocols. The American Academy of Ophthalmology recommends a maximum daily dosage of 5.0 mg/kg of body weight, as exceeding this threshold increases toxicity risk. Physicians should calculate dosages based on the patient’s body weight to avoid overdosing, especially for individuals of shorter stature or those who are overweight.
If retinopathy is diagnosed, the medication should be discontinued immediately in consultation with the prescribing physician. This decision balances ophthalmic risks against the patient’s underlying autoimmune condition. Collaborative care between the prescribing physician (often a rheumatologist or dermatologist) and the ophthalmologist is important. The ophthalmologist communicates findings, and the prescribing doctor discusses alternative therapies and implications of stopping hydroxychloroquine with the patient. For patients who have experienced vision changes due to retinopathy, ongoing care focuses on managing remaining vision and providing support, as there is currently no treatment to reverse the damage.