Abstract
Purpose :
Changes in retinal vascular caliber, oxygenation and tortuosity have been reported in subjects with diabetic retinopathy (DR). African Americans (AA) have a prevalence of diagnosed diabetes 1.6-fold higher than white Americans. Furthermore, diabetic AA exhibit excess mortality, morbidity and disability relative to white Americans with the same condition, in particular regarding diabetes-related microvascular complications. The purpose of the current study was to investigate alterations in retinal vascular SO2 and tortuosity in diabetic AA with no clinical DR and moderate/severe non-proliferative DR (NPDR).
Methods :
The study was performed in 56 subjects (female/male=60%/40%), ages ranging between 40 and 87 years. Right eyes were grouped according to DR severity as non-diabetic (N=26), no clinical DR (N=19), and moderate/severe NPDR (N=11). DR severity was determined by grading stereoscopic fundus photographs using the Modified Airlie House classification. Imaging was performed using a scanning laser ophthalmoscope (Optos Daytona) at wavelengths 532 nm and 633 nm. Customized software was developed to analyze the images and measure vascular hemoglobin SO2, diameter, vessel tortuosity index (VTI), and number of inflection points (IP) in retinal arteries and veins. Statistical analysis was performed by general linear models adjusting for age, mean arterial pressure, glycated hemoglobin (HbA1C), intraocular pressure (IOP), and axial length (AL).
Results :
Arterial maximum VTI increased from 0.29 ± 0.09 in non-diabetics to 0.86 ± 0.14 in moderate/severe NPDR (P=0.003), while venous diameter increased from 105 ± 3.0 μm in non-diabetics to 124 ± 4.7 μm in moderate/severe NPDR (P=0.001). Arterial maximum VTI also increased with HbA1C (P=0.02). Arterial diameter decreased with age (P=0.007), but did not change with DR severity (P=0.9). Similarly, arterial SO2 increased with HbA1C (P=0.03), but did not change with DR severity (P=0.3). Venous SO2 increased from 55.7% ± 3.4% in non-diabetics to 61.2% ± 5.0% in moderate/severe NPDR (P=0.05). Venous maximum VTI did not change with DR stage.
Conclusions :
DR progression was associated with increased venous diameter, venous oxygen saturation, and arterial tortuosity in AA. These findings advance the understanding of how retinal vascular structure and oxygenation are affected in AA with DR and can lead to improved diagnosis and disease monitoring.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.