First Author: W.Ngo SINGAPORE
Co Author(s): C. Tan T. Lim
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To describe quantitative vessel density measurements captured using optical coherence tomography angiography (OCT-A) in a cohort of patients with centre-involving diabetic macular edema and to investigate its relationship with central foveal thickness and severity of background diabetic retinopathy.
Tertiary ophthalmology referral centre in central Singapore
In a prospective study, a cohort of 14 consecutive patients with centre-involving diabetic macular edema (DME) referred to the medical retina service were recruited. All patients had OCT-A and spectral-domain optical coherence tomography (SD-OCT) performed at baseline. The 3x3 mm retinal images on the OCT-A were used in the analysis. Superficial plexus vessel density measurements generated using OCT-A were analysed to investigate its relationship with the central foveal thickness (CFT) in the central 1-mm Early Treatment Diabetic Retinopathy Study (ETDRS) standard subfield measured using SD-OCT. Vessel density measurements were also correlated with baseline patient demographics and disease parameters such as the severity of diabetic retinopathy to investigate their relationships.
The mean age for the 14 patients was 61.2 years (range 50-69 years). Nine (64.3%) were males and 5 females (35.7%). Twenty eyes of 14 patients had centre-involving diabetic macular edema. Of these, 3 (15%) had background mild non-proliferative diabetic retinopathy (NPDR), 12 (60%) had moderate NPDR, 2 (10%) had severe NPDR status post panretinal photocoagulation (PRP) and 3 (15%) had proliferative diabetic retinopathy status post PRP. The size of fovea avascular zone (FAZ) measured using OCT-A was larger in the group with severe NPDR and PDR, compared to the group with mild-moderate NPDR (0.479 mm2 vs. 0.381 mm2, p=0.09). However, average superficial plexus vessel density was similar in the group with severe NPDR and PDR compared to the group with mild-moderate NPDR (43.0% vs. 44.0%, p=0.59). In DME eyes with CFT greater than 400 µm, the FAZ was larger than eyes with CFT less than 400 µm (0.410 mm2 vs. 0.383 mm2, p=0.56). The average superficial plexus vessel density was also lower in eyes with CFT greater than 400 µm when compared with eyes with CFT less than 400 µm (42.8% vs. 44.4%, p=0.41).
There is an association between the size of the FAZ and vessel density of the superficial capillary plexus with the severity of diabetic macular edema and background retinopathy. This suggests that retinal perfusion at the macula has an association with the severity of diabetic macular edema and may have a role in its pathophysiology.