Revised guidance for patients exposed to chloroquine, hydroxychloroquine

Based on new data, the authors have revised the Academy’s 2011 guidelines to make screening recommendations more concise and practical.

Ophthalmologists play a vital role in educating both patients and prescribing physicians about the risk of toxicity associated with exposure to hydroxychloroquine (HCQ) and chloroquine (CQ) drugs. Because the damage from these drugs is irreversible, knowledge of proper dosages and familiarity with the signs of early stage retinopathy are critical for preventing central vision loss. 

Summary of dosing guidelines

• The new recommended daily dose of HCQ is less than 5 mg/kg of real weight, which has been shown to correlate better with risk than ideal weight. There is no similar demographic data for CQ, but older literature suggests less than 2.3 mg/kg real weight.
• At the recommended doses of HCQ, the risk of toxicity is less than 1% up to 5 years and less than 2% up to 10 years, but it increases sharply to almost 20% after 20 years.
• Major risk factors for toxicity include high doses, long duration, concomitant renal disease, or use of tamoxifen.

Summary of screening guidelines

• Baseline fundus exam should be performed to rule out any pre-existing maculopathy. Annual screening with automated visual fields and SD-OCT should commence after 5 years for patients on acceptable doses and without major risk factors.
  • Signs of damage on visual field testing: Central field abnormalities (most frequently in the inferotemporal region), corresponding superonasal field defects
  • Signs of damage on SD-OCT: Localized thinning of the photoreceptor layers in the parafoveal region
• Asian patients often show an extramacular pattern of damage, which should be taken into account during visual field testing and SD-OCT imaging.
• Due to inadequate sensitivity, the following tests are no longer recommended: fundus photography, time-domain optical coherence tomography, fluorescein angiography, full-field electroretinography, Amsler grid, color vision testing, and electro-oculography.

Once definitive signs of retinopathy are recognized, the decision to stop medication should be made in conjunction with the patient and the prescribing physician to ensure that medical risks, such as a potential flare of systemic lupus erythematosus (SLE), are managed.

The patient can be advised about the risk of further visual loss depending on the severity of the retinopathy. This risk is minimal if the retinopathy is detected early but significant if there is already a bull's-eye lesion and some reduction in central foveal thickness.