Factors Associated with Retinal Microvasculature Dropout Induced by Elevation of Intraocular Pressure in Primary Open-Angle Glaucoma.

PURPOSE

To investigate the risk factors related to decrease in vessel density (VD) observed in primary open-angle glaucoma (POAG), due to acute increase in intraocular pressure (IOP) by an ophthalmodynamometer (OPD).

METHODS

This cross-sectional study involved 42 eyes of participants (22 Controls and 20 POAG patients) that underwent optical coherence tomography angiography (OCT-A) to assess VD in the peripapillary region in three examination sets: primary gaze position (1), 25-degree adduction (2) and 25-degree adduction with OPD compression (3). Individual relationships between IOP levels and changes in the superficial complex VD were evaluated after image processing and exclusion of large retinal vessels. Multivariable regression analysis was used to verify factors associated with differences in VD induced by IOP elevation.

RESULTS

A significant increase in IOP was induced by OPD compression during adduction (mean ± SD, Control: + 13.8 ± 2.8;

POAG

+ 13.4 ± 2.1 mmHg). Only during IOP elevation (set 3), a significant VD decrease was observed both in POAG eyes (p = 0.008) and controls (p = 0.022). Baseline IOP (p = 0.022), maximum IOP (p = 0.003), and scleral rigidity (p = 0.029) were significantly associated with VD decreases in eyes with POAG. No changes were observed in VD during adduction gaze exclusively.

CONCLUSION

Acute IOP elevation induced with OPD, but not adduction gaze, decreased peripapillary VD measured with OCT-A imaging. IOP levels and scleral rigidity significantly affected VD reduction in POAG patients. Thus, high scleral rigidity may decrease the ability of the globe to dampen the well-known effects of IOP fluctuation on glaucoma onset and progression.

KEY MESSAGES

What is known Decrease vascular density in the peripapillary retina was associated with POAG, but factors related to the vascular response to elevated IOP are unexplored. What is new OCT-A quantification shows decreases in vascular density of the superficial layers of the peripapillary retina during an acute elevation in IOP. High IOP levels and scleral rigidity significantly affected vascular density reduction in POAG patients.