Diabetic Macular Ischemia In Type 1 Diabetes

Abstract

Purpose: To investigate the relationship between fundus fluorescein angiography (FA) derived measurements of retinal vascular morphology and visual acuity (VA) in Diabetic Macular Ischaemia (DMI).

Methods: Data were retrospectively collected over a period of 6 months. FAs were analysed using the Early Treatment Diabetic Retinopathy Study (EDTRS) protocol for DMI. The Foveal Avascular Zone (FAZ), capillary non-perfusion areas- temporal to the fovea, and the overlying the papillomacular (PM) nerve fibre bundle were quantified using custom software.

Results: 51 patients with type 1 diabetes (DM) who had undergone a FA were included in the analysis. The mean age of 40 years (SD:13.2) with a 3:2 male to female ratio. 17 eyes (33.3%) had “no DMI”, 10 (19.6%) “questionable”, 13 (25.5%) “mild”, 8 (15.6%) “moderate”, and 3 (5.9%) “severe” ischemia. Median FAZ area (mm2) was 0.15mm2 (IQR: 0.10-0.17) in no DMI, 0.25mm2 (IQR: 0.19-0.30) in questionable, 0.30mm2 (IQR: 0.23-0.37), and 0.44mm2 (IQR: 0.35-0.52) in severe DMI (p<0.001). VA was reduced moderate and severe (0.2 LogMar [IQR: 0.10-0.55]) compared to those with none, questionable, and mild ETDRS-DMI grades (0.0 LogMar [IQR: 0.0-0.2]) (p=0.03). Temporal and PM ischemia was observed both in eyes without DMI (35.3% and 17.6% respectively), as well as across all ETDRS-DMI grades (67.6% and 47.1%) (p=0.16, p=0.82).

Conclusions: The prevalence of DMI in patients with type 1 DM (66.7%) was greater than in type 2 DM (54.6%), observed in a previous study. The pattern of DMI in type 1 DM also differs to that observed in type 2 DM. Temporal and PM ischemia was present across all ETDRS-DMI grades, unlike type 2 DM, where it was present only in more severe ETDRS-DMI grades. Functional outcomes of both DM types are similar, where a reduction of visual acuity was only observed in eyes with moderate to severe ETDRS-DMI grades.

Keywords: 499 diabetic retinopathy • 688 retina • 754 visual acuity