Correlates of acute exercise-induced ocular hypotension

Area of Science:

• Ophthalmology
• Exercise Physiology
• Cardiovascular Research

Background:

• Intraocular pressure (IOP) regulation during exercise is complex.
• Understanding factors influencing IOP during physical activity is crucial for eye health.
• Acute dynamic exercise is known to affect IOP, but the precise mechanisms require further elucidation.

Purpose of the Study:

• To investigate the factors influencing the decrease in intraocular pressure (IOP) during acute dynamic exercise.
• To determine the relationship between exercise intensity, physiological responses, and IOP changes.
• To examine the role of beta-adrenoceptor blockade in modulating exercise-induced IOP reduction.

Main Methods:

• Studied graded exercise (30-90 watts) and exercise to exhaustion on a cycle ergometer.
• Compared IOP response in trained versus sedentary individuals under a fixed workload.
• Investigated the effects of selective (betaxolol) and nonselective (levobunolol) beta-adrenoceptor blockade during graded exercise.
• Measured intraocular pressure using applanation tonometry and monitored blood lactate, PCO2, and plasma osmolarity.

Main Results:

• Intraocular pressure decreased proportionally to exercise intensity during graded exercise.
• Sedentary subjects exhibited a greater IOP decrease than trained subjects, correlated with blood lactate levels.
• Beta-adrenoceptor blockade (both selective and nonselective) lowered baseline IOP and potentiated the ocular hypotensive effects of exercise.

Conclusions:

• Acute dynamic exercise lowers IOP in a graded manner, related to relative workload.
• The IOP decline during exercise is linked to blood lactate accumulation, independent of PCO2 or plasma osmolarity.
• Exercise augments the IOP-lowering effects of beta-adrenoceptor blockade, suggesting additive hypotensive mechanisms.