The Effect of Graded Forced Expiration on Intraocular Pressure

The primary objective of this study is to utilize the Airofit device to systematically measure and characterize the changes in intraocular pressure across its six different levels of forced expiration. This investigation will provide crucial quantitative data on the IOP-respiratory effort relationship, enhancing our understanding of IOP dynamics during controlled respiratory stress and establishing a new, standardized paradigm for such research.

Inclusion Criteria: * Aged 18 years or older. * Willing and able to provide informed consent. * Have a best-corrected visual acuity of 6/12 or better. * Able to understand and follow instructions for using the Airofit device. * Have an optic nerve cup/disc ratio not exceeding 0.5, and have a c/d difference between both eyes not exceeding 0.2. * Did not have taken any anticholinergic medication, systemic beta-blockers, or corticosteroids within the last 3 months that could affect intraocular pressure levels. Exclusion Criteria: * a history of intraocular surgery, * a history of uveitis, * a spherical refractive error exceeding 3D, * a history of regular topical treatment other than artificial tears