Circumpapillary Structure in Eyes with Glaucoma Altered with Negative Pressure Induction

The effects of pressure changes induced by a multipressure dial on circumpapillary retinal nerve fiber layer (RNFL) and capillary density measurements in patients with glaucoma was investigated in recent research.

Using optical coherence tomography angiography (OCTA), the findings indicate circumpapillary capillary density (CD) measurements showed a dose-dependent increase with the induction of negative pressure, while RNFL thickness measurements were unchanged.

Led by Robert N. Weinreb, MD, the prospective intervention study included twenty-four patients with primary open-angle glaucoma. A single eye of each patient underwent negative pressure application with the MPD.

The multipressure dial altered intraocular pressure (IOP) relative to atmospheric pressure by generating a negative pressure vacuum within a goggle chamber that is placed over the eye. Serial high-density OCTA imaging of the optic nerve head at different negative pressure increments of –5mmHg in each study participant. They started from 0 mmHg, ending at –20mmHg, and then returning to baseline.

Images were acquired after 2 minutes of sustained negative pressure at each target pressure in order to allow for stabilization of the retinal structures and microvasculature. For analysis, the RNFL thickness and capillary density measurements were automatically calculated using the native high-density OCTA imaging software, and then exported.

The influence of different levels of negative pressure on circumpapillary RNFL thickness and capillary density measurements, assessed by a linear mixed-effects model with repeated measures, was calculated for the main outcome.

The study population had a mean age of 71.0 years, the baseline intraocular pressure (IOP) was 17.5 mmHg, and data show a mean 24-2 mean deviation of –2.80 dB.

Serial circumpapillary capillary density measurements indicated a statistically significant dose-dependent increase from baseline, without negative pressure application, to the maximum negative pressure application of –20 mmHg (difference, 2.27%; P = .010).

Moreover, the research shows capillary density measurements decreased symmetrically when lowering the negative pressure to baseline. Circumpapillary capillary density measurements at target negative pressures of –10 mmHg, –15 mmHg, and –20mmHg were significantly higher than baseline measurements (all P values, <0.05).

Investigators noted “circumpapillary RNFL thickness remained the same throughout different levels of negative pressure.”

The abstract, “Multipressure Dial Goggle Effects on Circumpapillary Structure and Microvasculature in Glaucoma Patients,” was published in Ophthalmology Glaucoma.