## 2 Factors Affecting the IOP Response to Exercise
### Breathing Pattern  
The breathing pattern adopted during exercise plays a crucial role in both physical performance and the physiological responses to exercise. Proper breathing techniques are essential for maintaining stability, optimizing energy delivery, and minimizing the strain on the cardiovascular system. For example, the Valsalva maneuver, in which an individual exhales forcefully with a closed airway, is commonly used in high-intensity exercises such as powerlifting. This maneuver enhances trunk stability and allows for greater force production during demanding physical efforts. However, while the Valsalva maneuver can enhance performance, it may also have detrimental effects on hemodynamic function, including significant increases in blood pressure and intrathoracic pressure [48; 49]. Regarding IOP, there has been limited research investigating the specific impact of breathing patterns during exercise. However, recent studies suggest that the pattern of breathing can modulate IOP responses. In particular, restricted breathing or compromised gas exchange during exercise appears to result in higher IOP levels. Two studies, one involving dynamic resistance training and the other examining isometric resistance exercises, demonstrated that, when gas exchange is hindered, such as through the Valsalva maneuver, greater increases in IOP are observed [50; 51]. This suggests that IOP increases are linked to alterations in breathing that impair normal respiration, potentially contributing to higher IOP during intense exercise. In addition, the eruption of the COVID-19 pandemic and the use of face masks to reduce its transmission led to assess the effects of wearing face masks on IOP. In this regard, [PERSON] and colleagues (2021) [52] investigated the short-term effects of using surgical and FFP2/N95 masks on IOP levels during low-intensity endurance exercise in primary open-angle glaucoma patients. Although the magnitude of the increase was relatively small, this finding suggests that restricted airflow from wearing masks could influence IOP, particularly during exercise. This highlights the importance of considering breathing dynamics and the potential for mask-induced airflow restriction when assessing exercise safety for individuals with glaucoma or those at risk. Additionally, research on high-altitude exposure, where oxygen levels are lower and breathing patterns naturally change, has provided further insight into the relationship between breathing and IOP. Numerous studies have investigated the effects of high-altitude exposure on IOP, and, while most agree that high-altitude conditions result in a statistically significant increase in IOP, these changes are generally considered clinically insignificant in healthy individuals [53; 54; 55; 56; 57; 58; 59; 60]. However, this effect may be more pronounced in individuals with glaucoma, where even small increases in IOP could pose a risk to optic nerve health [61]. In the context of airflow restriction as a performance enhancement tool, certain studies have explored the use of specialized masks designed to limit airflow during exercise, simulating the effects of high-altitude training [62]. These masks are thought to improve physical performance by increasing the body's efficiency in oxygen utilization. However, recent research on the effects of airflow restriction masks has shown that they can counteract the IOP-lowering effects typically observed during low-intensity endurance exercise [63]. The study found that the use of airflow restriction masks resulted in higher IOP during exercise, highlighting that any manipulation of normal breathing, whether through masks or other means, may negatively affect IOP regulation. Taken together, these findings suggest that the manipulation of breathing patterns--whether through the Valsalva maneuver, face masks, or other interventions that restrict airflow--can lead to an increase in IOP during exercise.