Respiratory Muscle Training and Intraocular Pressure: A Prospective Study in Individuals With Normal and High-Normal...

Expiratory resistance training with the AiroFit PRO device causes a dose-dependent, temporary increase in intraocular pressure (IOP) of about 3 mm Hg, with individuals with high-normal IOP reaching values that approach clinically concerning thresholds at maximum resistance.

To examine the acute effects of graded expiratory resistance using the AiroFit PRO breathing trainer on intraocular pressure (IOP) in healthy individuals with normal and high-normal IOP, and to evaluate the agreement between noncontact and applanation tonometry during respiratory strain.

This prospective study included 60 healthy participants (120 eyes): 40 with normal IOP (group 1) and 20 with high-normal IOP (group 2). IOP was measured at baseline and during expiratory efforts at 6 progressively increasing resistance levels (10-200 cmH 2 O/(L/s)) using both noncontact tonometry (NCT) and Goldmann applanation tonometry (GAT). Statistical analyses included the Friedman test for repeated measures, correlation analysis, and multiple linear regressions.

IOP demonstrated a significant progressive increase across all resistance levels (Friedman χ 2 (6)=442.86, P <0.001). The mean IOP increased from 16.57±4.22 mm Hg at baseline to 19.58±4.20 mm Hg at maximum resistance, representing a mean increase of 3.01 mm Hg (18.2%). The magnitude of IOP change did not differ significantly between the normal and high-normal IOP groups (Cohen d=0.055). Baseline IOP was a strong predictor of Level 6 IOP ( R2 =0.845). The NCT and GAT results showed excellent agreement ( r =0.870-0.929) between the 2 methods.

Respiratory training with the AiroFit device results in dose-dependent increases in IOP. While the relative magnitude of IOP change is similar regardless of baseline IOP status, individuals with high-normal IOP reach absolute values approaching clinically concerning thresholds. These findings have implications for glaucoma risk counseling among users of respiratory training devices.