Toxicidad de Plaquenil
Understanding Plaquenil Toxicity
This section explains what retinal toxicity is, why it occurs, and how common it can be in patients who use hydroxychloroquine for long periods.
Plaquenil toxicity is irreversible retinal damage that can continue to progress even after the drug is discontinued. Early detection is essential because the vision loss is irreversible. The drug accumulates in the pigment epithelium and photoreceptors, interfering with critical cellular processes. The initial damage is subtle and only detectable with modern imaging techniques. Studies indicate an approximate risk of 7.5% after five years of therapy and close to 20% after twenty years. The risk is much lower when the daily dose does not exceed 5 mg/kg of actual body weight.
Early detection and screening
Screening tests allow retinal changes to be discovered before symptoms appear, increasing the chances of preserving vision.
In the early stages, toxicity is usually asymptomatic, but later it can cause: SD-OCT shows retinal layer thinning and IS/OS junction alterations, very early markers of toxicity. FAF detects abnormal autofluorescence changes that indicate pigment epithelium dysfunction before damage is visible on clinical examination. The mfERG measures the electrical function of different areas of the retina and confirms deficits that are not yet apparent in other tests.
Risk factors
Several factors increase the likelihood of hydroxychloroquine damaging the retina. Understanding these factors helps personalize the follow-up plan.
Exceeding 5 mg/kg/day significantly increases the risk of toxicity. The danger increases with years of treatment and reaches significant levels after a decade of continuous use. Reduced renal elimination increases the systemic concentration of the drug and, therefore, the eye risk. Drugs such as tamoxifen can increase the toxic effect on the retina when used together with Plaquenil.
Monitoring and advice
Structured monitoring allows for the detection of toxicity in early stages and adjustment of therapy as needed.
Before starting treatment, a complete examination is performed, visual field 10-2 and at least one objective test such as OCT or FAF. If the dose is appropriate and there are no other risks, annual check-ups help identify changes before symptoms appear. Those receiving high doses, who have kidney dysfunction, or who take tamoxifen may need screening before the age of five and more frequent check-ups.
Treatment and dose management
The goal is to balance the control of systemic disease with the protection of vision.
If retinal damage is confirmed, the medical team evaluates discontinuing the drug or reducing the dose. Damage may continue to progress for some time after stopping the medication, highlighting the need for early detection. It is recommended to keep the dose below 5 mg/kg/day and adjust it according to actual weight and renal function. Monitoring the cumulative dose is as important as the daily dose.
Retinal examination process
During the consultation, several tests are performed which, combined, offer a complete view of retinal health.
The specialist examines the retina with high-resolution equipment and explains each result to the patient. The 10-2 protocol detects loss of sensitivity in central vision, often the first functional sign of toxicity. OCT reveals thinning and subtle structural alterations in the retinal layers. It highlights areas of abnormal autofluorescence that may indicate early pigment epithelium toxicity. It evaluates the electrical response of multiple retinal regions and complements the findings of other tests.
Patient education and ongoing follow-up
Understanding the risks and maintaining a regular check-up schedule are key steps to preserving vision.
When the patient is aware of the risks and the need for screening, they actively participate in protecting their eyesight. Detecting small changes, such as difficulty reading or seeing a blind spot, prompts quick assessments that can prevent permanent damage. The risk of toxicity persists over time, so an annual check-up is recommended starting five years after treatment, even if vision appears stable.
Connect with our retina specialist
Hydroxychloroquine remains a valuable medication, and with an appropriate screening program, it can be used safely. Our team is committed to early detection and personalized care to help you preserve your vision while receiving the treatment you need.
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