Redefining the Spectrum of Pentosan Polysulfate Retinopathy: Multimodal Imaging Findings from a Cross-Sectional Screening Study

Abstract

There is growing evidence of a direct association between pentosan polysulfate (PPS) therapy and the development of macular changes. Using standardized visual acuity (VA) testing and multimodal imaging, we investigated the impact of PPS therapy on vision and described an expanded spectrum of imaging findings among PPS users. Cross-sectional screening study. Thirty-nine patients who were current or recent users of PPS. The participants underwent a brief eye examination and answered a comprehensive medical and ophthalmic history questionnaire. Color fundus photography, fundus autofluorescence (FAF), and spectral-domain OCT (SD-OCT) were performed. The images were evaluated by expert graders at Wisconsin Reading Center. Abnormalities were categorized as definite toxicity (DT) if seen on both FAF and SD-OCT and as questionable toxicity (QT) if seen on either FAF or SD-OCT. ETDRS and Snellen VA, the dosage and duration of PPS exposure, and the prevalence of retinal toxicity on imaging. The mean ETDRS and Snellen VA of the study cohort were 85 letters and 20/22, respectively. The mean PPS daily dose was 282 mg (range, 88-400 mg), whereas the mean cumulative dose was 915 g (range, 19-3650 g) over a mean period of 8.8 years (range, 2 months-25 years). There was evidence of retinopathy in 41% of the eyes; DT was identified in 24 eyes (31%) and QT in 8 eyes (10%). Retinal pigment epithelium (RPE) abnormalities (thickening or thinning or both) were present in all eyes with DT. Retinal pigment epithelium atrophy was seen in 7 eyes (9%). In addition to well-established findings, the unique SD-OCT features of this cohort included interdigitation zone abnormalities and the presence of a flying saucer-type defect. Fundus autofluorescence abnormalities were seen in 24 eyes (30.8%), with 20 (66.7%) of these exhibiting abnormalities located outside the central subfield and extending beyond the arcades. Findings from the masked grading of multimodal imaging at a centralized reading center suggest a wider phenotypic spectrum of structural abnormalities among patients taking PPS. Macular changes selectively involve the RPE and outer retina, with a range of findings often seen beyond the arcades. The subtle and atypical findings in this cohort should prompt clinicians to consider lowering the threshold for diagnosing PPS retinopathy.