Non-invasive optical coherence tomography angiography: A comparison with fluorescein and indocyanine green angiography in normal adult dogs and cats.

Abstract

PURPOSE: While the retinal vasculature can be assessed by simple funduscopy, a more detailed assessment can be performed by conventional angiography using dyes such as fluorescein or indocyanine green. The development of optical coherence tomography angiography (OCT-A) allows a non-invasive detailed examination of posterior segment vasculature. The purpose of this prospective study was to compare imaging of posterior segment vasculature in normal dogs and cats using OCT-A, fluorescein angiography (FA), and indocyanine green angiography (ICGA). METHODS: Eight adult funduscopically normal dogs and 13 funduscopically normal cats were included in the study. Retinal vasculature was assessed by OCT-A followed by ICGA then FA. Regular fundus imaging was also performed. RESULTS: High-resolution images of the different vascular layers within the retina and choroid could be acquired using OCT-A in both dogs and cats. The technique provided more detail than obtained with FA/ICGA. However, artifacts/errors can occur during OCT-A image acquisition/analysis/interpretation and must be considered. Furthermore, OCT-A only allows for a limited field of view compared to FA/ICGA. CONCLUSIONS: Optical coherence tomography angiography is a new non-invasive posterior segment imaging technique that is complementary to traditional dye-based angiographic techniques. Detailed imaging of the dog and cat posterior segment can be achieved under general anesthesia. OCT-A provides additional detail of the vasculature and can clearly demonstrate the anatomical depth of the imaged vessels. There are, however, some limitations to this new technique that may be overcome by future technological advances.