Purpose
Retinitis pigmentosa (RP) is a heterogeneous group of hereditary retinal diseases that result in progressive loss of rod and cone photoreceptors. The ocular blood circulation has been shown to be altered in RP in many experimental and clinical studies. Optical coherence tomography (OCT) based microangiography (OMAG) was recently illustrated for the functional imaging of the microvascular network within the tissue beds. In this study we evaluated the retinal and choroidal microvascular architecture in RP patients using OMAG.
Methods
Eight patients (sixteen eyes) with Retinitis Pigmentosa underwent OMAG. OMAG was performed by Zeiss spectral domain OCT-angiography prototype using a 6 mm X 6 mm field of view around macular region. The resulting retinal image was segmented into two layers: the inner retinal layer from the ganglion cell layer to the inner plexiform layer, the deeper retinal layer from the inner nuclear layer to the external limiting membrane. The choroidal image was segmented into choriocapillaris and choroidal layers. The vascular distribution in each layer was depicted as an enface image.
Results
In all eyes with RP imaged by OMAG, abnormal microvasculature was detected in both the deeper retinal vasculature layer (from the inner nuclear layer to the external limiting membrane) and choroidal vasculature. A representative result from one patient (left eye) is provided in the figure attached. The OMAG results correlated very well with visual field testing and with reduced choroidal-retina thickness measured by Zeiss SD-OCT-angiography prototype in RP patients.
Conclusions
OMAG is a new imaging technique that can evaluate the microvascular network changes in the retina and choroid. OMAG imaging provided detailed, depth-resolved information about the microvasculature changes in Retinitis Pigmentosa patients. OMAG shows loss of normal vessel architecture in the choriocapillaris, choroid and deeper retinal vascular layer. These images corresponded well with published clinical and histological findings.