Does championship-level accuracy stem from genetics, or from eyes trained to their limits? Researchers from the Faculty of Fundamental Problems of Technology at Wrocław University of Science and Technology have investigated how long-term sports shooting training affects visual parameters.

A research team composed of Dr Izabela Garaszczuk, Dr hab. Eng. Magdalena Asejczyk, University Professor, and optometrist Wiktoria Jenczewska studied the eyesight of national-level sports shooters over the course of a year. The results were clear: shooters see and “stabilise their gaze” better than most people, but years of aiming with one eye may weaken binocular cooperation.

The design, course and findings of this first-of-its-kind study were published in the prestigious journal Scientific Reports, issued by Nature Portfolio..

From scepticism to a research gap

The origins of the project were unexpected. The initial impulse was not a competition or a record, but an optometry conference – specifically a panel devoted to visual training in athletes.

“In Poland, such training is not yet common practice, but internationally it is used by, for example, goalkeepers and tennis players. Coaches believe it improves performance,” recalls Dr Izabela Garaszczuk from the Faculty of Fundamental Problems of Technology, admitting that she was initially sceptical.

Most existing research focused on popular sports such as football, hockey or golf. Sports shooting – especially static shooting – was virtually absent from scientific literature.

“Studies on sports shooters rarely include detailed analyses of visual parameters. That meant athletes could have been training ‘blindly’, unaware of both the full potential and the limitations of their vision,” explains Prof. Magdalena Asejczyk.

In Search of “Twin Eyes”

After the conference, Dr Garaszczuk, together with Prof. Asejczyk and then master’s student Wiktoria Jenczewska, established contact with the Polish national shooting team. The goal was to encourage athletes to examine how they actually see.

The research itself lasted nearly a year and posed significant logistical challenges. The athletes came from across the country, and the delicate diagnostic equipment could not be transported. Shooters therefore had to attend the Wrocław Tech laboratory within a very limited time window.

This was made possible during a national team training camp in Wrocław. “A key role was played by Natalia Król – multiple medallist, coach and sports referee from WKS Śląsk Wrocław – who coordinated our cooperation with the athletes,” says Dr Garaszczuk.

An even greater challenge emerged at the next stage: creating an optimal control group.

“Vision is not only about age. Refractive error, its correction, and even eyeball geometry all matter,” explains Dr Garaszczuk.

The team therefore searched for individuals with almost identical visual parameters to those of the shooters – so-called “twin eyes”. Only such a comparison could eliminate the classic scientific error of comparing “apples and oranges”.

The “Quiet Eye” – the secret of champions

Each examination lasted over an hour and went far beyond a standard eye test.

“We assessed refractive error and visual acuity, analysed binocular cooperation, measured vernier acuity (the ability to detect microscopic spatial displacements), examined gaze stability, and conducted ocular biometry and visual field tests,” lists Dr Garaszczuk. “Wiktoria Jenczewska, then a student and now an optometrist, carried out an enormous amount of work during the time-consuming experimental phase.”

The results left no doubt: sports shooters are true visual specialists. The key phenomenon observed in them is the so-called “quiet eye” – a state in which eye movements are almost “switched off” just before the shot.

“Although it may seem that our eyes are motionless when we fixate on a target, they constantly perform micro-movements. If these stopped completely, we would stop seeing,” explains Dr Garaszczuk. “Shooters are able to drastically reduce the amplitude of these movements and maintain this state longer than untrained individuals. Even on a macro scale, their eyes appear calmer and more focused.”

When one eye does the work of two

The most surprising findings concerned long-term consequences. In sports shooting, athletes aim with one eye while the other is systematically covered. Over time, the brain begins to favour the dominant eye, and binocular cooperation weakens.

“Our study clearly demonstrated deterioration in certain binocular vision parameters – including convergence – particularly in the most experienced athletes,” says Dr Garaszczuk. “Importantly, these changes correlated with years of training, not with age.”

“I see well, but something feels off”

Although these are not overt clinical disorders, many shooters described a vague discomfort: faster eye fatigue, sensitivity to glare, or difficulty “locking onto” a single image after training.

“They often said they simply felt ‘strange’ after practice,” notes Wiktoria Jenczewska.

This is a typical sign of neuronal-level strain. The eyes still see clearly, but the brain must exert increasing effort to process visual information. Fortunately, for occasional shooters the risk remains low.

“What matters most is the intensity and long-term exposure to monocular aiming,” emphasises Jenczewska.

How to “reset” the eyes after training

The researchers stress that simple measures can help maintain visual health. These include convergence exercises (alternating focus between near and distant objects), binocular or dichoptic exercises engaging both eyes, consciously uncovering the non-aiming eye during training, and properly adjusted corrective lenses for shooting (similar to computer glasses).

Binocular shooting training – although more demanding – is also increasingly discussed as a way to limit negative adaptations.

Beyond shooting

The mechanism identified in shooters may also apply to other professions involving enforced monocularity, such as surgeons, dentists or watchmakers.

“Shooting is an ideal research model because monocularity is imposed deliberately and systematically,” explains Dr Garaszczuk, who is already planning further research. “Our next step will be longitudinal studies to determine whether visual parameters return to normal after an athlete ends their career, and if so, how quickly.”

The team also plans to use ultra-precise eye-trackers and investigate the impact of visual training on actual sports performance.

Garaszczuk I. K., Jenczewska W. Asejczyk M. „Superior monocular visual function but compromised binocular balance in precision shooters compared to age and refraction matched controls”. Scientific Reports. Volume 15, Article number: 28816 (2025).