Evaluation of retinal neurodegeneration and microvascular changes in diabetic retinopathy: An OCT angiography study

Author: Slim Salmi (Tunisia)

Co-authors: Asma Khallouli, Rahma Saidane, Racem Choura, Ahmed Arfaoui, Afef Maalej, Riadh Rannen

Purpose

To assess the macular ganglion cell changes of and macular microvascular parameters in early-stage diabetic retinopathy (DR) using Spectral Domain optical coherence tomography angiography (SD OCT-A).

Setting/Venue

Department of Ophthalmology of the Military Hospital of Tunis, Tunisia.

Methods

We conducted an observational study including 40 eyes of 20 patients presenting with no DR or mild non-proliferative DR at baseline and 40 healthy controls were included. All included individuals underwent a complete ophthalmic examination including visual acuity, anterior and posterior segment examination as well as SD OCT and OCT-A at baseline and 3 months .The study enrollment was led between January 2020 and February 2021. Ganglion Cell Complex (GCC) thickness was evaluated in all subjects .OCTA was performed using Optovue RTVue XR Avanti, AngioVue. 6 mm x 6 mm macular scans with measurement of the foveal avascular zone (FAZ) and vessel densities (VD) in both superficial (SCP) and deep (DCP) capillary plexus were analyzed.

Results

Mean age was 61 ± 4.5 years in DR group and 60.3 ± 3.2 years and healthy controls group (p=0.42). BCVA was 20/20 for all subjects.HbA1c (%) was 7.5 ± 1.2 in DR group .Progressive GCC thinnig was 2 ± 0.42µm at 3 months.The microvascular parameters which have significantly changed at the end of the study compared to baseline were : the FAZ area: 0.32-0.34 mm2, VDs SCP and : 3.4 % -4.9 % and VD DCP:4.1 % -10,6 % . A strong positive correlation was found between loss of GCC and VD from baseline to 3 months. (r = 0,65, p < 0.05). Multivariable regression analysis showed that thinner baseline GCC and greater loss of GCC thickness (B = 0.658, p < 0.001) were significantly associated with VD changes.

Conlusions

In the early stage of DR, progressive structural retinal neurodegeneration and macular microvascular alterations seem to be highly linked. Advanced CCG thinning might precede microvascular impairment in early DR.

Financial Disclosure

The authors declare no conflict of interest.