Abstract
Purpose :
Central Retinal Artery Occlusions (CRAOs) is are occlusions of the central retinal artery, which often presents clinically as sudden, painless loss of vision in one eye. The central retinal artery is the primary blood supply to the inner retinal layers of the macula, and therefore CRAOS result in irreversible loss of vision in the affected eyes. Currently, there is no established treatment that can alter the course progression of the disease other than to prevent subsequent neovascularization. The purpose of this study is to use the imaging instrument Laser Speckle Flowgraphy (LSFG), a relatively novel diagnostic tool to help quantify the degree of loss of blood flow in CRAO patients, using the metric relative blood flow (RBF). RBF allows for a unitless ratio comparison of blood flow from the patients’ healthy eye to the affected eye and establish the degree of ischemia.
Methods :
Three separate LSFG scans were performed on seven patients with clinical history of CRAOs and twenty control patients to measure the mean blur rate (MBR) in the optic nerve head (ONH) of both healthy and affected eyes. MBR is a measurement of laser scatter directly correlated with the flow of red blood cells though tissue and vasculature. RBF, a unitless ratio of respective MBRs was then calculated to measure the average loss of blood flow through the ONH due to the CRAO.
Results :
A Welch two sample t-test was used to calculate statistical significance, resulting in a indicating strong significant difference in RBF between healthy control patients and CRAO patients. In control patient’s RBF was calculated to be 1.021332 (p= 0.6843) indicating no significant difference in RBF between healthy eyes. In CRAO patients, RBF was calculated to be 0.503304 ± 0.1433871 (p = 1.06 * 10-5), indicating on average a 50 percent loss in blood flow to the ONH in eyes with CRAOs.
Conclusions :
These results support our current understanding of the pathophysiology of CRAOS, and provides researchers and clinicians with a diagnostic tool capable of truly quantifying loss of blood flow. RBF measurements of CRAO patients confirm a dramatic loss in blood flow in affected eyes due to occlusive injury. Prospective studies could utilize LSFG measurements to longitudinally analyze blood flow in affected eyes throughout disease progression and determine the possibility of a correlation between the return of blood flow and a return of visual acuity.
This is a 2021 ARVO Annual Meeting abstract.