Bruch's membrane calcification in pseudoxanthoma elasticum: Visualizing the visual consequences

Abstract

Pseudoxanthoma elasticum (PXE) is a rare genetic disease which leads to ectopic calcification in the skin, vasculature and in Bruch’s membrane of the eyes. Bruch’s membrane is a thin membrane between the choroid and the retina. Eventually, PXE patients often develop macular degeneration similar to late age-related macular degeneration but earlier in life. This leads to a high prevalence of visual impairment at a relatively young age, often due to subretinal neovascularization but sometimes due to macular atrophy as well. Up to now, it is hard to predict the visual prognosis. This thesis investigates the ophthalmological consequences of PXE. We found that there is an area in Bruch’s membrane that is predetermined for calcification. Also, we demonstrated that visual impairment is frequent: of all patients over 50 years, 37% is visually impaired and 15% is blind. We found that more severe Bruch’s membrane calcification increases the risk of vision loss and this can be predicted early in life. To measure the severity of Bruch’s membrane calcification we developed a reflectivity measure based on optical coherence tomography that is promising for both research purposes and clinical monitoring. In short, this thesis provides new insights into the visual consequences of PXE which aid in better predicting the visual prognosis.