Quantitative fundus autofluorescence associated with a diseased Bruch membrane in pseudoxanthoma elasticum

Abstract

Purpose : To quantify lipofuscin-associated fundus autofluorescence in patients with a diseased Bruch membrane due to pseudoxanthoma elasticum (PXE).

Methods : For this prospective, monocenter, cross-sectional case-control study 49 patients with PXE (mean age 46 years, range 18-62) and 108 healthy controls (mean age 40 years, range 18-64) were investigated. All subjects underwent quantitative fundus autofluorescence (qAF) imaging with a modified scanning laser ophthalmoscope equipped with an internal fluorescent reference (modified Spectralis HRA-OCT, Heidelberg Engineering) to account for variations of laser power and detector sensititvity. The mean qAF values of a circular ring centered to the fovea (qAF₈) were measured and compared between groups.

Results : Overall, patients with PXE showed reduced qAF₈ values compared to controls (difference from controls -23%, 95% confidence interval (CI) -29 to -16%, p<0.001). The reduction was most pronounced in the subgroup between 40-60 years (-36%, 95% CI -42 to -30%, p<0.001) and was negatively correlated with the extent of Bruch membrane calcification (r=-0.51, 95% CI -0.69 to -0.26), measured as the eccentricity of the most central border of peau d’orange. Of the 13 cases below 40 years of age, 12 (92%) showed qAF₈ values within normal limits. Topographically, patients with PXE showed relatively higher values in temporal and relatively lower values in nasal segments. The phenotype of patients with reduced qAF values was characterized by pattern-dystrophy-like changes (70%; 21 of 29) and reticular pseudodrusen (60%; 18 of 29).

Conclusions : Reduced qAF₈ values are a characteristic finding in patients with PXE. The association with pathology of Bruch membrane expands the pathophysiologic understanding of PXE and of multifactorial diseases with pathology of Bruch’s membrane, such as age-related macular degeneration.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.