Near-Infrared Autofluorescence in Choroideremia: Anatomic and Functional Correlations

PURPOSE: To investigate near-infrared fundus autofluorescence (NIR-AF) characteristics in patients with choroideremia and to correlate these with anatomic and functional parameters.

DESIGN: Retrospective, observational case series.

METHODS: 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.

RESULTS: 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 showed broader ellipsoid zone than NIR-AF (R2 = 0.60, slope 0.19 ± 0.03).

CONCLUSIONS: 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.