Scientists have recently discovered that due to the fact that exercising causes eye pressure to fluctuate, it may increase the risk of glaucoma and other related eyesight disorders. Pumping out heavy iron leads to an increased eye pressure, especially when weightlifters hold their breath. The study was carried out by Brazilian researchers at the Institute of Specialized Ophthalmology and UNIPLAC School of Medicine, Brasília and their findings are published in the Archives of Ophthalmology journal.

The team found that individuals who regularly engage in activities which decrease or, on the contrary, increase the intraocular pressure are more likely to develop eyesight disorders and even blindness. Brazilian scientists noted that the continual change in the pressure within the eyeball brings about glaucoma or other eye sight problems.

"Prolonged weightlifting could be a potential risk factor for the development or progression of glaucoma. Intermittent intraocular pressure increases during weightlifting should be suspected in patients with normal-tension glaucoma who perform such exercises. Patients with normal-tension glaucoma should be questioned as to a history of regular weightlifting," reported leader of the study Dr Geraldo Magela Vieira and his colleagues in the Archives of Ophthalmology journal.

Permanent fluctuation of the intraocular pressure can damage the optic nerve and consequently damage the eyesight. But in the trial, scientists observed that the key-factor which causes eye pressure to become higher when exercising relates to the Valsalva manoeuvre. This manoeuvre describes the breathing process in which air is forced against a closed windpipe and pressure increases in the chest. Therefore, Brazilian experts recommend breathing continuously throughout training in order to keep the chest pressure constant. This could prevent weightlifters and other people prone to experience intermittent pressure in the eyeball from developing eyesight disorders later in life.

"Any fluctuation in pressure within the eye can cause problems. The optic nerve tolerates steady pressure much better than it tolerates fluctuating pressure," confirmed for BBC News David Wright, Chief Executive of the International Glaucoma Association.