Evaluation of optic disc microcirculation by optical coherence tomography angiography in patients with primary open angle glaucoma

Aim
To assess the vascular network length and area using optical coherence tomography angiography in patients with primary open angle glaucoma and healthy subjects.

Material and methods
The study group included 31 eyes of 21 patients with primary open angle glaucoma: 13 men (42%) and 18 women (58%), at the age of 31–86 years (mean age of 66 ± 12 years). The control group included 34 eyes of 21 healthy volunteers: 4 men (12%) and 30 women (88%), at the age of 35–70 years (mean age of 52 ± 9 years). All patients were examined using optical coherence tomography angiography.

Results
Within the superficial vascular layer, the mean vessel area was 30633 pixels and 3057 pixels in the study and control group, respectively (p>.05), whereas the mean vessel length was 16321 pixels and 15425 pixels in the study and control group, respectively (p>.05). Within the medium layer, the mean vessel area was 20117 pixels and 24675 pixels in the study and control group, respectively (p<.05), whereas the mean vessel length was 8880 pixels and 11111 pixels in the study and control group, respectively (p<.05). Within the choriocapillaris layer, the mean vessel area was 33175 pixels and 35417 pixels in the study and control group, respectively (p<.05), whereas the mean vessel length was 18243 pixels and 18114 pixels in the study and control group, respectively (p>.05).

Conclusions
In glaucoma patients, vascular abnormalities of the optic disc microcirculation can be observed. There was no significant difference in the superficial optic disc vascular network area and length between the groups. The middle depth vessel area was significantly smaller and capillary network shorter in glaucoma patients. Within the deep layer, the vessel area was significantly smaller in glaucoma patients, however, there was no significant difference in the vessel length between the groups. Optical coherence tomography angiography may be a useful tool for non-invasive monitoring of glaucoma patients.