So say Geraldo Magela Vieira, MD, and colleagues in the Archives of Ophthalmology.
Vieira works at the Institute of Specialized Ophthalmology and UNIPLAC medical school in Brasilia, Brazil.
He and his colleagues studied 30 healthy young men aged 18-40 (average age: nearly 26) at the health club of the Catholic University of Brasilia.
First, the researchers established the maximum amount of weight each man could bench press. The group's average maximum bench-press weight was 145 pounds.
Next, the men bench-pressed 80% of their maximum bench-press weight four times.
On the first three lifts, the men exhaled while hoisting the weight and inhaled as they lowered it. On the last lift, they didn't exhale, holding their breath for about eight seconds.
After a five-minute break, the men bench-pressed the same amount of weight four more times without holding their breath on any of the lifts.
Each man was tested with an electronic device that measured the pressure inside his eyes (intraocular pressure).
Intraocular pressure rose for 90% of the men during the hold-your-breath bench-pressing session and for 62% of the men when they didn't hold their breath.
The rise in intraocular pressure might raise glaucoma risk, Vieira's team notes.
But this study doesn't prove that. The men were only studied once, so it's not clear if they later developed glaucoma.
The researchers are currently doing more studies on glaucoma and weightlifting.