Near-Infrared Autofluorescence in Choroideremia: Anatomic and Functional Correlations

Abstract

To investigate near-infrared fundus autofluorescence (NIR-AF) characteristics in patients with choroideremia and to correlate these with anatomic and functional parameters. Retrospective, observational case series. In this multicenter study, 43 consecutive choroideremia patients (79 eyes) underwent multimodal retinal imaging, including near-infrared fundus autofluorescence (NIR-AF), blue autofluorescence (B-AF), optical coherence tomography (OCT), fundus photography, and functional testing including fundus-controlled microperimetry. All eyes could be categorized into 3 groups based on patterns of NIR-AF over the island of surviving retinal pigment epithelium: Group 1 (preserved NIR-AF centrally), Group 2 (only disrupted NIR-AF), or Group 3 (absence of NIR-AF). Group 1 eyes showed areas of NIR-AF that matched the areas of B-AF islands (R2= 0.94, slope 0.84 ± 0.04) while Group 2 eyes showed significantly smaller areas of NIR-AF compared with B-AF (R2= 0.08; slope 0.02 ± 0.01). The 3 groups differed significantly in terms of residual B-AF island size (P < .0001), length of foveal ellipsoid zone (P= .03), foveal thickness (P=.04), and foveal sensitivity (P= .01). Visual acuity (P= .07) and central retinal thickness (P= .06) did not differ statistically. The length of the ellipsoid zone line was similar to the horizontal diameter of NIR-AF in Group 1 (R2= 0.97, slope 0.96 ± 0.04), while Group 2 eyes showedbroader ellipsoid zone than NIR-AF (R2= 0.60, slope 0.19 ± 0.03). Choroideremia patients can be stratified into 3 groups based on NIR-AF imaging, which showed morphologic and functional changes correlating with different stages of retinal pigment epithelium degeneration. NIR-AF could be a marker for disease staging in choroideremia, and could be used for patient selection or as an outcome parameter in interventional trials.