Background
Diabetic retinopathy (DR) represents the leading cause of blindness in working-age
people. It affects about one in every three diabetic patients. This visual loss can be
prevented by early detection and proper management.
Purpose
The aim of this study was to assess the ability of optical coherence tomography
angiography (OCTA) to detect subclinical changes in parafoveal capillaries in
diabetic patients without DR.
Patients and methods
This prospective case–control study was conducted upon 50 participants who were
divided into two groups: group A (25 diabetic patients without clinical manifestation
of DR) and group B (25 healthy control participants of matched age and sex with
group A). The two groups were compared regarding the parameters of the foveal
avascular zone (FAZ) area, perimeter, and FD (flow density of retinal capillaries
within 300 μm surrounding the FAZ) in addition to the parafoveal vessel density of
superficial and deep capillary plexuses (SCP and DCP) on macular scans (3×3 mm)
centered on the fovea by OCTA.
Results
There were statistically significant differences in FAZ area, perimeter, and FD
together with parafoveal vessel density of SCP and DCP between healthy controls
and diabetic patients without DR. The mean FAZ area of the healthy control group B
was 0.27±0.08 mm2 compared with 0.32±0.11 mm2 in the diabetic group A
(P=0.01). In addition, the FAZ perimeter was significantly increased (P=0.003)
in the diabetic patients without DR (2.39±0.56 mm) compared with the control (2.11
±31 mm). Statistically significant decreases of vessel density in the FD-300, SCP,
and DCP were observed in diabetic patients without DR compared with controls (all
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