Retinal and choroidal vascular features in patients with retinitis pigmentosa imaged by OCT based microangiography

To image vascular features of retinitis pigmentosa (RP) using optical coherence tomography angiography (OCTA).

Patients with RP were imaged by spectral domain optical coherence tomography based angiography (OCTA). The optical microangiography (OMAG) algorithm was applied to scanned datasets to generate 3D OCTA retinal angiograms, i.e., OMAG angiograms. Motion tracking was used to minimize artifacts due to eye movement, and large field of view OMAG angiograms were achieved through a montage scanning protocol. For better visualization, depth volumes were segmented to separate the superficial retinal layers from deep outer retinal layers. The choriocapillaris and other choroidal layers were also segmented. To investigate the changes in retinal architecture, the inner segment/outer segment (IS/OS) junction to RPE layer was segmented to generate en face structural images through averaging intensity projection. Color fundus images and/or Goldmann visual fields were available for comparison of the findings to OMAG images.

A total of 25 eyes (13 patients, seven women and six men) diagnosed with RP at various stages were enrolled in this study from October 2014 to January 2016 and imaged by OCTA. The resulting OMAG angiograms provided detailed visualization of retinal and choroidal vascular networks presented within the retina and choroid in a large field of view (FOV) (∼6.7 mm × 6.7 mm). All patients with a severity score greater than 3 showed abnormal microvasculature in both deep retinal and choroidal layers on OMAG images. Images of patients with a score of 4 indicating only peripheral abnormalities demonstrated relatively normal vasculature networks. Microvascular changes in the retinal and choroidal vasculature correlate with structural changes in the slab from IS/OS junction to RPE layer.

OCTA is useful in evaluating the microvascular changes in a large FOV encompassing the maculae of patients with RP. The large FOV of OMAG angiograms, enabled by the motion tracking, provides visualization of high definition and high resolution microvascular networks at varying stages of RP. Microvascular imaging may have significant utility in the diagnosis and monitoring of disease progression in RP patients.