Mesopic and Scotopic Light Sensitivity and Its Microstructural Correlates in Pseudoxanthoma Elasticum

Area of Science:

• Ophthalmology
• Retinal Imaging
• Genetics

Background:

• Pseudoxanthoma elasticum (PXE) is a genetic disorder affecting the Bruch membrane, leading to vision impairment.
• Interventional trials for PXE require understanding Bruch membrane alterations and their functional correlates.
• Current knowledge lacks detailed quantification of light sensitivity and its microstructural associations in PXE.

Purpose of the Study:

• To quantify mesopic and scotopic light sensitivity in patients with PXE.
• To identify microstructural correlates of light sensitivity associated with Bruch membrane disease in PXE.
• To assess the accuracy of predicting retinal function from microstructural data using machine learning.

Main Methods:

• Prospective, cross-sectional case-control study involving 22 patients with PXE and 40 controls.
• Mesopic and scotopic (2-color fundus-controlled perimetry) light sensitivity were measured.
• Multimodal retinal imaging (SD-OCT, OCT angiography) and machine learning were used for structure-function correlation.

Main Results:

• PXE patients exhibited significant losses in mesopic, dark-adapted cyan, and red light sensitivity, with a centrifugal pattern in non-neovascular cases.
• Retinal sensitivity could be accurately predicted from microstructural data (mean absolute errors < 5 dB).
• Machine learning identified associations between inner retinal thinning, pigment-epithelium-photoreceptor complex separation, and vision loss.

Conclusions:

• PXE is characterized by significant rod photoreceptor dysfunction, indicated by dark-adapted cyan sensitivity loss.
• Pathologic Bruch membrane changes in PXE appear to primarily impact rod function.
• Inner retinal abnormalities and pigment-epithelium-photoreceptor separation are correlated with overall visual dysfunction in PXE.