Effects of Acute Atmospheric Pressure Changes on Dynamic Contour Tonometry and Goldmann Applanation Tonometry in Normal Individuals: A Pilot Study

Abstract

Précis: Intraocular pressure (IOP) measurement differences with Goldmann applanation tonometry (GAT) and dynamic contour tonometry (DCT) are affected by atmospheric pressure inside a hyperbaric chamber. Purpose: To compare IOP measurements obtained with GAT and DCT in 22 normal individuals at different atmospheric pressures simulated in a hyperbaric chamber. Methods: The IOP of both eyes of 22 healthy volunteers was measured using GAT and DCT at 4 different atmospheric pressure levels. Starting at 1 Queretaro atmospheric pressure (QATM), the IOP was measured with GAT and DCT. The atmospheric pressure was then increased to 1.1 QATM (equivalent to 1032 m above sea level), 1.2 QATM (equivalent to 315 m above sea level), and 1.25 QATM (equivalent to sea level), starting 5 minutes after reaching each level. The limits of agreement between various measurements with each tonometer were calculated using the Bland-Altman plots. Results: The first 4 subjects were used to measure feasibility, consistency, variability, and the time needed for IOP to return to baseline after each atmospheric pressure increase. For the entire 44 eyes, the mean GAT IOP at 1 QATM was 12.23 mm Hg (range, 8 to 20 mm Hg; SD, 2.84) and mean DCT was 16.36 (range, 12.1 to 25.3; SD, 2.84), with a mean 4.14 mm Hg difference (range, −0.1 to 7.5 mm Hg; SD, 1.62; P<0.001). Using the second measurements of the first 4 subjects and those after 5 minutes of adaptation for the rest of the group at 1.1 QATM, mean GAT IOP was 11.05±2.68 mm Hg and mean DCT IOP was 15.60±3.02 mm Hg, for a mean difference between instruments of 4.56±1.81 mm Hg (P<0.001). At 1.2 QATM, mean GAT IOP was 11.14±2.53 mm Hg and mean DCT IOP was 15.39±2.91 mm Hg. The difference between instruments was 4.25±2.12 mm Hg (P<0.001). At 1.25 QATM, the mean GAT IOP was 12.39±3.11 mm Hg and mean DCT IOP was 14.91±2.73 mm Hg. The difference between instruments after 5 minutes of adaptation was 2.53±1.62 mm Hg (P<0.001). Generalized estimating equations for performing linear regression multivariable analysis using atmospheric pressure, expressed as altitude, and age as covariates, shows that the difference between GAT and DCT increases by 1 mm Hg per 673 m of increase of altitude above sea level. Age was not a significant predictor. Conclusions: Acute changes in atmospheric pressure induce changes in IOP measurements for both GAT and DCT and in different directions. Despite the limitation of sample size, it may be postulated that the difference of IOP measurements between the 2 tonometers increases with lower atmospheric pressures.

The Effect of Negative Pressure on IOP in the Living Human Eye

“…Albis-Donado et al 15 more recently evaluated the changes in IOP with exposure to increase atmospheric pressure within a hyperbaric chamber with both Goldman applanation tonometry and dynamic contour tonometry. Their study found that with increasing atmospheric pressure, IOP was reduced.…”

“…However, if negative pressure is mostly distributed Albis-Donado et al 15 more recently evaluated the changes in IOP with exposure to increase atmospheric pressure within a hyperbaric chamber with both Goldman applanation tonometry and dynamic contour tonometry.…”

“…Associations between changes in atmospheric and orbital pressure with IOP, and the forces IOP imparts to the retina, vasculature and ONH have been observed in aviators 9 and divers 10 for over fifty years. 9,[11][12][13] Atmospheric and orbital pressures represent additional mechanical forces, [14][15][16] along with IOP and CSFP, that impact all ocular tissues. While changes in atmospheric pressure occur mostly in specialized conditions (e.g., diving, altitude changes), alteration in atmospheric pressure around the eye has been proposed as a novel treatment of glaucoma to non-invasively reduce IOP.…”

Agreement of rebound and applanation tonometry intraocular pressure measurements during atmospheric pressure change

“…Previous research of IOP in hyperbaric chambers is limited to a 2020 study from Albis-Donado et al, which compared IOP measurements from AP and dynamic contour tonometry (DCT) at varying ATM of 1, 1.1, 1.2, and 1.25. They found that DCT was influenced by ATM changes in an inverse relationship to AP [ 15 ]. RB, therefore, may potentially present an avenue by which researchers can overcome some of the critical technical difficulties of using AP, and by extension DCT, to measure IOP within hyperbaric chambers.…”

Physiology-Enhanced Data Analytics to Evaluate the Effect of Altitude on Intraocular Pressure and Ocular Hemodynamics

“…In comparison, the literature regarding altitude-related alterations in IOP and ocular hemodynamics is much less clear. While several studies have indicated IOP may increase with altitude [6,[12][13][14][15][16][17][18][19][20][21][22], many have also found an opposing decrease in IOP with altitude [7,8,[23][24][25][26][27][28][29][30][31][32]. Additionally, studies have shown that short-term exposure to high altitudes can alter the retinal microcirculation in young, healthy subjects secondary to hypoxic endothelial dysfunction [33].…”