Second, it is strongly recommended that newer objective tests be used routinely. In practical terms, high-resolution, spectral-domain optical coherence tomography (SD-OCT) is widely available in many retina specialty practices and some general ophthalmology offices and appears to be more sensitive than fields. (Older time-domain OCT units do not have sufficient resolution for screening.) SD-OCT is an imaging technique that creates an optical cross-section of the retina and visualizes early damage from the drug as thinning in the parafoveal region (see Figure 3). The multifocal electroretinogram (mfERG) tests electrical function of the retina topographically across the macula; in essence, it is an objective visual field (see Figure 4). It is highly sensitive like the SD-OCT but not so readily available. Fundus autofluorescence is also objective but still is under evaluation for sensitivity.
Bottom Line
It is not adequate just to send patients off to the local optometrist or ophthalmologist for screening for HCQ toxicity unless that eye specialist is aware of the new AAO guidelines and has the means to obtain (where possible) an SD-OCT or mfERG test.2 Also, a baseline retinal exam is advised within the first year after a patient starts the drug to assess any underlying maculopathy. This is critical because underlying maculopathy can confuse later assessment of toxicity and become a relative contraindication to using the drug.
HCQ retinopathy is, sadly, very much alive and well. Much of the responsibility for informing patients and initiating screening falls on rheumatologists because they are usually the primary doctor initiating use of the drug. The patient is at risk—and the physician is at risk medicolegally—if adequate screening is not performed. Although the AAO recommendations represent guidelines, they are often recognized as a standard of care. The key points to remember are the following:
- Don’t overdose—400 mg/day is too much for short individuals, using ideal weight.
- Obtain a baseline eye exam, and start annual screening after five years.
- Be aware that longer use increases the risk.
- Be aware that effective screening now should include at least one objective test (such as SD-OCT). Do not rely on observation of the retina for screening, and be wary of visual field testing unless done by a practitioner attuned to look for early and subtle changes.
Dr. Marmor is professor of ophthalmology at Stanford University School of Medicine in Stanford, Calif.
References
- Wolfe F, Marmor MF. Rates and predictors of hydroxychloroquine retinal toxicity in patients with rheumatoid arthritis and systemic lupus erythematosus. Arthritis Care Res. 2010;62:775-784.
- Marmor MF, Kellner U, Lai TYY, Lyons JS, Mieler WF; American Academy of Ophthalmology. Revised recommendations on screening for chloroquine and hydroxychloroquine retinopathy: Ophthalmology. 2011;118:415-422.
