Abstract
Purpose :
Most studies on the effectiveness of hydroxychloroquine (HCQ) retinopathy screening methods have examined data before or long after patients developed toxicity. Few studies have investigated the sensitivity of screening modalities at the point of conversion. We have analyzed a series of patients with frequent examinations leading up to diagnosis of clinical retinopathy, to compare the sensitivity of OCT measurement techniques in detecting retinal damage and to look for warning signs that precede conversion.
Methods :
This is a retrospective analysis of 6 patients followed for HCQ usage who were eventually diagnosed with retinopathy using visual fields, conventional high-density OCT B-scans (singular cross-sections averaged over 100 repetitions, using CIRRUSTM, Carl Zeiss Meditec Inc.) and fundus autofluorescence images (FAF). Using additionally collected 6x6mm OCT cubes, we retrospectively made macular thickness measurements, custom tomographic maps indicating ellipsoid-zone (EZ) band integrity, and custom retinal Minimum Intensity (MI) maps.
Results :
Patients were followed pre-diagnosis for 3.5-9 years with at least 3 examinations. Cross-sectional and topographic OCT analysis of EZ integrity provided equivalent information about EZ loss in overlapping locations. However, topography showed broad areas of suspicious change in the parafovea of 3 cases and the perifovea of one Asian patient. ETDRS thickness maps showed steady thinning in these same regions over several years before clinical retinopathy was diagnosed. MI maps showed bright rings that expanded over several years in 2 eyes, consistent with thickness change and topography, but were vague or unreliable in other eyes. FAF and visual fields were inconsistent in showing damage.
Conclusions :
Conversion to HCQ toxicity is definitively recognized when the EZ line becomes compromised in a characteristic pattern. Our retrospective observations show that gradual thinning of para- or perifoveal regions begins much earlier, along with broad but indistinct changes in topographic maps of EZ loss and sometimes similar extensive bright regions in MI maps. However, these early and chronic changes have no clear endpoint, so it is difficult to determine when toxicity becomes clinically relevant. The use of multiple measurement techniques may help to provide enough evidence of retinopathy to justify drug cessation.
This is a 2020 ARVO Annual Meeting abstract.