Seeing the light on eye-rubbing

WHAT common human activity, performed frequently, can make you go blind?

No, not that one. It’s rubbing the eyes.

An Australian professor of optometry warns that habitual rubbing of the eyes can cause spikes in intraocular pressure.

In a person with healthy eyes it is likely to make no difference, but for people with a family history of certain diseases, such as glaucoma, repeated spikes in pressure may be sufficient to cause damage.

Professor Charles McMonnies, from the University of NSW School of Optometry and Vision Science, concluded after a review of the subject that diverse activities – from blowing trumpets to doing yoga headstands – might cause sufficient intraocular pressure to threaten vision.

Intraocular pressure spikes of long duration and frequent occurrence might contribute to the development or worsening of conditions such as keratectasia, axial myopia and glaucoma.

Even a light touch that pushed the eyelid against the eye raised the fluid pressure inside the eye, and a firmer touch could raise pressure three- to five-fold. Closing the eyes and rubbing them could elevate pressure 10-fold, Professor McMonnies said.

Unfortunately for people with itchy eyes, rubbing could become habitual and they should be counselled to treat dryness or irritation, he said.

Common activities which can raise pressure include removing eye make-up, lying face-down into a pillow or wearing an eye-mask touching the eye, wearing swimming goggles, reading in bed instead of sitting up, and lifting weights.

Interestingly, professional musicians who play instruments such as the trumpet, bassoon or French horn, are at higher risk for loss of vision.

That’s because taking a deep breath raises pressure by around 33 per cent. Over a lifetime this could take its toll, Professor McMonnies said.

Inverting the body doubles intraocular pressure, so people already at risk of shortsightedness or glaucoma should probably avoid bench presses, push-ups where the feet are raised, and standing on their head.

Optometry & Vision Science 2008; 85:1018-26.