Abstract
Purpose :
To compare the presence of diabetic macular ischemia (DMI) through the foveal avascular zone (FAZ) using Fluorescein Angiography (FA) and Optical Coherence Tomography Angiography (OCTA) in patients with diabetes mellitus (DM).
Methods :
Observational, ambispective, transverse study in 49 patients who underwent traditional FA and OCTA (Spectralis) for DMI over eight months. Two raters independently graded the quantity and quality of the FAZ according to Early Treatment Diabetic Retinopathy Study (ETDRS) protocols, using the ImageJ software. To measure the FAZ in the OCTA, the superficial vascular plexus was used. An intra-class correlation coefficient (ICC) was obtained to assess the level of agreement and reproducibility between the FA and the OCTA to establish DMI. Retinal vessels caliber and area, and thickness of subfoveal and choroid layers were measured using OCTA images. Spearman and a rank-biserial correlational analysis were used to evaluate the relationship between the variables, the presence of neovascularization and visual acuity (VA) in LogMar scale.
Results :
The study included 75 eyes; based on the OCTA and FA, the mean FAZ was 0.86 ±1.15 and 0.875±1.11 mm2, respectively. The level of agreement in the OCTA and FA between raters had an ICC of 0.99 and 0.907 respectively (p<.001). The reproducibility analysis between them had an ICC of 0.85 (p<.001), suggesting that the OCTA may be used to establish the DMI through the FAZ. A negative correlation was found between the central subfield thickness (CST) and years of DM (r=-0.25, p=0.031). The LogMar VA correlated positively with the FAZ (r=0.24, p=0.035) and the CST (r=-0.3, p=0.009). The FAZ, through the OCTA, correlated negatively with the subfoveal choroidal thickness (r=-0.23, p=0.049), with photoreceptor layers (r=-0.33, p=0.003), the length between the outer limiting membrane (OLM) to the outer nuclear layer (ONL) (r=-0.23, p=0.043), and the CST (r=-0.3, p=0.009). The length between the outer plexiform layer (OPL) to the inner limiting membrane correlated positively with the presence of neovascularization (r=0.27, p=0.021).
Conclusions :
High agreement was obtained between DMI grading results for OCTA and conventional FA using standard ETDRS protocols. We also found evidence that the enlargement of the FAZ leads to thinning of the photoreceptor layer and the OLM to the ONL.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.