Purpose:
To investigate the diagnostic capability of various structural and functional imaging modalities in X-linked retinitis pigmentosa (XLRP) carriers.
Methods:
Eleven carriers of XLRP (21 eyes) from 7 families and 3 female non-carriers (6 eyes) from the same families were examined. Subjects were imaged with color fundus photography, and had red free (RF), infrared (IR), fundus autofluorescence (AF) and spectral domain optical coherence tomography (SD-OCT) imaging with the Spectralis SLO-OCT (Heidelberg Eng.). Fundus images were aligned using software written in Matlab (MathWorks, Inc.). Horizontal and vertical line scans across the central 30º region were acquired in all subjects. Peripheral SD-OCT scans extending to an eccentricity of 27.5º from the fovea were acquired in 5 carriers and 2 non-carriers. Visual fields were obtained using the Humphrey Field Analyzer (24-2 SITA standard; Zeiss, Inc) and the MP-1 microperimeter (10-2 pattern; Nidek, Inc). Full field scotopic and photopic ERGs were performed in 9 carriers.
Results:
For the XLRP carrier group, the tapetal reflex was observed with all imaging modalities in 15 of 21 eyes and had the same retinal location on color fundus, RF and IR imaging but a different location on AF. In 18 of 21 eyes, the reflex had greatest visibility in RF images. The reflex was poorly visible in 4 eyes on color fundus photography and in 3 eyes on IR imaging. In 5 eyes, the reflex was visible with all imaging modalities except for AF, which least frequently showed the reflex. SD-OCT imaging appeared normal within the central 30º region, with the exception of 1 patient who showed loss of the inner segment ellipsoid (ISe) band (aka IS/OS junction). All peripheral SD-OCTs demonstrated breakdown of the ISe band. Visual fields exhibited patchy loss in 9 patients but were normal in 2. On full field ERG, 3 patients had normal rod and cone responses and 6 had abnormal rod and/or cone responses. Non-carriers showed no abnormal findings.
Conclusions:
Red free imaging, in which the tapetal reflex is most evident, and peripheral OCT scans, where loss of the ISe is observed, should be added to a multimodal imaging approach in the diagnosis of XLRP carriers.
Keywords: retinal degenerations: hereditary • imaging/image analysis: clinical • retina