Bull's Eye Maculopathy in Near-Infrared Reflectance as An Early Sign of Hydroxychloroquine Toxicity

Hydroxychloroquine (HCQ) ocular toxicity is rare but severe, and progression can occur even after termination of therapy. Case reports have suggested that a bull's eye maculopathy detected by near-infrared reflectance (NIR) may indicate early HCQ toxicity. This retrospective cross-sectional study evaluated patients treated with HCQ who underwent routine screening with optical coherence tomography (OCT), fundus autofluorescence (FAF) and 10-2 perimetry. NIR images captured alongside OCT were subsequently graded independently by 2 masked graders for the presence of bull's eye maculopathy, and the result was compared to the outcome of the screening. A total of 123 participants (246 eyes) were included, and 101 (90%) were female. The patients' mean age was 55.2 ± 13.8 years. The mean time of HCQ usage was 84.0 ± 72.3 months, and the mean weekly dose was 2327 ± 650 mg. Two eyes showed toxicity in all 3 routine screening exams, with one patient suspending HCQ. The prevalence of bull´s eye lesions in NIR was 13% (33 eyes) with substantial intergrader agreement, a 71.3% specificity and 88.0% negative predictive value for HCQ toxicity. We suggest that NIR changes may be a sign of early HCQ toxicity. The detection of NIR bull´s eye lesions may warrant an increased screening frequency.

Topographical Relationship Between Acute Macular Neuroretinopathy and Choroidal Watershed Zone or Patchy Choroidal Filling

PURPOSE

To study the topographical relationship between acute macular neuroretinopathy (AMN) lesions and the choroidal watershed zone (CWZ) or patchy choroidal filling (PCF) using multimodal imaging.

METHODS

Lesions in patients diagnosed with AMN were clinically examined using multimodal imaging, including fundus photography, near-infrared reflectance imaging, spectral-domain optical coherence tomography (OCT), fluorescein angiography, indocyanine green angiography, OCT angiography, and microperimetry. The topographical relationship between AMN and the CWZ or PCF was evaluated.

RESULTS

Seven eyes of six patients were included in the study. The mean age of the patients was 35.8 ± 11.7 years. The AMN lesions were collocated with the CWZ in five eyes and the PCF in one eye. Among these eyes, three had complete patterns, and three had partial patterns. Only one eye showed no topographical relationship between AMN and the CWZ or PCF.

CONCLUSION

The colocation of AMN and CWZ/PCF suggests that the AMN lesions were within an area with a dual-watershed zone: the watershed zone between the retinal deep capillary plexus and choriocapillaris, and the choroidal watershed zone or patchy choroidal filling. This retinal area was highly vulnerable to hypoperfusion. Our results suggest a novel pathophysiological mechanism for AMN.

Multispectral cross-polarization reflectance measurements suggest high contrast of demineralization on tooth surfaces at wavelengths beyond 1300 nm due to reduced light scattering in sound enamel

The enamel scattering coefficient decreases markedly with increasing wavelength from the visible to the near-infrared (NIR). However, beyond 1300 nm, the scattering coefficient is difficult to measure, and it is not known whether light scattering continues to decrease significantly at longer wavelengths. It is hypothesized that water absorption is a major contributor to the contrast between sound and demineralized enamel beyond 1300 nm since deeply penetrating photons in sound enamel are likely absorbed by water. Reflectance images of demineralization on tooth surfaces were acquired at wavelengths near 1450, 1860, 1880, and 1950 nm. The magnitude of water absorption is similar at 1450 and 1880 nm but varies markedly between 1860, 1880, and 1950 nm. Multispectral comparisons of lesion contrast provide insight into the mechanism responsible for higher contrast at longer NIR wavelengths. The highest contrast was at 1950 nm; however, the markedly higher contrast at 1880 compared to 1450 nm and similar contrast between 1860 and 1880 nm suggests that the enamel scattering coefficient continues to decrease beyond 1300 nm, and that reduced light scattering in sound enamel is most responsible for the higher lesion contrast at longer NIR wavelengths. This has important implications for the choice of wavelengths for caries detection and diagnostic devices, including the performance of optical coherence tomography beyond 1300 nm.