Blood flow through a blood vessel relies on perfusion pressure
12 and, in the eye, ocular perfusion pressure (OPP) is thought to be the driving force of ocular blood flow.
13 OPP is important for efficient diffusive exchange of oxygen, nutrients, and metabolic waste across the relatively long distance between the choroid and the retina, in which the perfusion pressure in addition to vascularization of the choroid plays a vital role.
14,15 Low OPP can lead to a reduction in ocular blood flow, which may result in ocular ischemia and/or hypoxia.
13 Because there is no retinal vascular supply in the foveal avascular zone, choroidal blood supply plays a significant role in this region.
12 As a result, the fovea may become vulnerable to disturbances in choroidal circulation. By using EDI-OCT to measure CT noninvasively, discovery of correlations between subfoveal CT and OPP might be of clinical significance with regard to assessing the status of choroidal circulation based on in vivo CT, given that OPP is believed to be an indirect indicator of choroidal blood flow.
16 In the past, histologic studies have been performed in animal models to investigate the physiology of choroid and its blood flow,
16 but due to limitation in reflecting the in vivo choroid in humans, their interpretation and application to the human eye are limited. Using EDI-OCT, a recent study by Maul et al.
11 showed that diastolic OPP was significantly associated with CT in glaucoma suspects and glaucoma patients, whereas another group suggested no correlation.
5 Considering the high vascularity of the choroid, we hypothesized that OPP would be one of the major parameters associated with CT.