Different retinal microvascular response to flicker light between normal-tension glaucoma and high-tension primary open-angle glaucoma detected with optical coherence tomography angiography.

PURPOSE

To compare the visual task-evoked microvascular response in the macula between normal-tension glaucoma (NTG) and high-tension primary open-angle glaucoma [i.e., high-tension glaucoma (HTG)] by using optical coherence tomography angiography (OCTA).

METHODS

In this case-control observational study, ten eyes of 10 patients with HTG, twelve eyes of 12 patients with NTG and eleven eyes of 11 healthy participants were included. All glaucoma eyes had a preserved central visual field of at least 10° and best corrected visual acuity of 20/40 or better. Macular superficial vessel density (VD) was measured by OCTA at baseline and then immediately after a 12.5 Hz white light flicker stimulation.

RESULTS

Flicker light stimulation evoked significant increase in macular superficial VD of HTG (baseline vs. poststimulation:35.31% ± 4.31% vs. 36.07% ± 4.35%, P = 0.048) and control eyes (46.21% ± 2.94% vs. 47.09% ± 2.68%, P = 0.028) but not the eyes with NTG (37.98% ± 5.99% vs. 37.44% ± 5.69%, P = 0.622). The absolute change in VD (ΔVD) was significantly smaller in NTG eyes compared to control eyes (-0.54% ± 1.40% vs. 0.88% ± 1.14%, P = 0.026). NTG eyes also had a lower VD change percentage in the temporal macula than that in HTG eyes (-1.17% ± 5.53% vs. 4.01% ± 4.73%, P = 0.042).

CONCLUSIONS

Visual task-evoked vasoreactivity changes provide additional information in the understanding and assessment of the pathophysiological mechanisms of glaucoma. Discrepancies in the retinal vasoreactivity between HTG and NTG imply that vascular factors may play different roles in the onset and progression of these diseases.

KEY MESSAGES

What is known Vessel density (VD) of the macular superficial retina has been proven to be reduced in individuals suffering from primary open-angle glaucoma (POAG). The reduction of VD has been found to be correlated with the progressive development of glaucoma. What is new Patients with normal-tension glaucoma (NTG) has impaired vasoreactivity to visual stimulation compared with high-tension POAG. The visual stimulation-assisted dynamic optical coherence tomography angiography (OCTA) technique can provide additional information for the vascular dysregulation in the pathophysiology of subtypes of POAG.