The role of optical coherence tomography angiographyin assessing of the retinal ganglion cells complex in patients with primary open-angle glaucoma
The purpose of this study was to determine the role of the retinal ganglion cell complex (GCC) parameters in assessing the severity of glaucomatous optical neuropathy (GON) in patients with II and III stages of primary open angle glaucoma (POAG) based on optical coherence tomography (OCTA).Material and methods. The study included 24 patients (47 eyes) in the main group with primary open-angle glaucoma (POAG) and 9 healthy individuals (18 eyes) in the control group. The protocol of the complex of ganglion cells (GCC Report) of the OCTA system RTVue-100 "Optovue" was analyzed. The parameters of the thickness (GCC tot, GCC sup, GCC inf ) of the retinal GCC, focal and global losses of the volumes (FLV, GLV), and their percentile comparison with the normative database were evaluated.Results. Significant thinning of the retinal GCC and an increase in its focal and global losses of the volumes in patients with II and III stage of POAG were determined when compared with the control group, as well as in patients with the third stage of disease when compared with the second. The percentile evaluation of retinal GCC in patients with POAG revealed a significant decrease in all parameters of the thickness of the GCC and an increase in the volume of focal and global losses in patients with III stage of POAG compared with the II stage (in the number of eyes with a certain percentile status). At the same time, the increase in the volume of focal and global losses was determined in a more eyes than the thinning of the GCC of the retina, and the most frequent increase was found in the volume of focal losses. More than half of the eyes of patients with II stage of the disease (54.6%) had a percentile evaluation that showed the compliance of the investigated indicators with the norm. One-third of the patients with II stage of POAG have a marked decrease in the studied indicators to a level comparable to the III stage of POAG.Conclusions. OCTA is informative method both in the early diagnosis of GON and in assessing the progression of the glaucomatous process. A significant change in all parameters of the GCC of the retina was determined, as in the comparison of the patients of the II and III stage of the POAG with the control group, and among themselves. The change in the parameters of the protocol of the retinal GCC is in some cases significantly ahead of perimetric losses, which makes it expedient to use them in assessing the degree of progression of GON and determining the stage of the disease.