Background: OCT angiography (OCTA) and laser speckle flowgraphy (LSFG) are novel and noninvasive imaging modalities which could evaluate fundus blood flow quantitatively. However, the role of OCTA and LSFG as diagnostic tools has not been widely investigated. Previous reports indicated that NO, reduced by hyperglycemia, exerts a key role for the autoregulation of retinal blood flow. We designed this study to evaluate the retinal blood flow by OCTA and LSFG in hyperglycemic DM.
Method: 10 patients with extreme hyperglycemia at our outpatient clinic (FPG>250mg/dL, or casual PG>350mg/dL, age 58±5, 7 males, HbA1c 11.1±0.5%) and 32 healthy volunteers (age 48±2, 17 males) were included. Vascular density was calculated using OCTA. LSFG measured relative blood velocity (mean blur rate: MBR) in the optic nerve head (ONH). MBR-A (the mean of all area), MBR-V (the vessel mean) and MBR-T (the tissue mean) were analyzed.
Result: OCTA revealed no difference between two groups in the vascular density at macula (47.37±1.14% for DM and 47.44±0.67% for NDM) and a tendency of decrease in the diabetic vascular density at ONH (40.14±3.56% for DM and 42.48±1.25% for NDM) without statistical significance. With LSFG, MBR-A and MBR-T did not exhibit significant differences, while MBR-V significantly decreased in DM compared to the healthy (42.85±2.05% for DM, 49.25±1.34% for NDM, p = 0.025).
Discussion: Our results demonstrated that vascular hypoperfusion at ONH was associated with extreme hyperglycemia in DM with tendency to decrease in vascular density. It is generally supposed that the retinal blood flow decreases in DM and acute hyperglycemia. In DM actually presented physiological changes in the retina. Besides, there is a report that autoregulation of blood flow in the ONH is disrupted in diabetic rabbits, as well as in healthy ones with uncoupled gap junctions. It is possible that the similar mechanisms are involved in ONH blood flow decrease observed in this study.
T. Mitsumatsu: None. F. Yagi: None. Y. Kondo: None. A. Anraku: None. S. Okahata: None. K. Sakamoto: None. G. Tomita: None. T. Shiba: Speaker's Bureau; Self; Shionogi & Co., Ltd., Pfizer Inc., Merck Sharp & Dohme Corp., Kowa Company, Ltd., Daiichi Sankyo Company, Limited.