Abstract
Purpose :
Microaneurysms are a common lesion in diabetic eye disease. It remains unclear, however, why some grow and leak fluid, causing local neural pathology, while others within the same region resolve without sequelae. We evaluated the relationship of blood flow parameters estimated by computational fluid dynamics (CFD) modeling of diabetic microaneurysms (MAs) with vascular and local neural retinal characteristics.
Methods :
MAs in eyes of diabetic study participants were imaged with adaptive optics scanning laser ophthalmoscope (AOSLO) imaging and spectral domain optical coherence tomography (SDOCT). AOSLO and SDOCT images were registered and assessed for MA cross-sectional area and perfusion status. OCT images were graded for disorganization of the retinal inner layers (DRIL) within 500 microns of MAs. CFD modeling estimated shear rate and wall shear stress for the whole MA body and subregions within individual MAs.
Results :
A total of 52 MAs were imaged (30 eyes) from 22 participants with mean±SD age 40.4±11.0 years, diabetes duration 23.1±8.1 years, hemoglobin A1c 8.1±1.1%, who were 82% with type 1 diabetes and 41% female. Mean shear rate drop between the MA feeding vessels and body was higher in larger MAs (p=0.0002) and MAs with decreased perfusion (p=0.003). MAs with greater differences in shear rate drop between subregions were significantly larger (p=0.009), less perfused (p=0.0005) and more likely to have visible clot within the MA (p<0.05). Mean wall shear stress drop was higher in larger (p=0.007) and less perfused MAs (p=0.002). Greater variability in either shear rate (p=0.008) or wall shear stress drop (p=0.0009) was associated with greater extent of local surrounding DRIL. In a small subgroup of 8 MAs imaged in follow-up (7.0±5.1 mo later), MA growth was associated with increasing variability of shear rate drop (r=0.80, p=0.02) and wall shear stress drop (r=0.86, p=0.007).
Conclusions :
Estimation of shear rate and wall shear stress by CFD modeling can identify MAs that are likely to be larger, less perfused, and associated with local neural retinal pathology. Future studies will address whether longitudinal changes in these blood flow parameters predict future anatomic and functional outcomes of MAs in the diabetic eye.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.