- People diagnosed with glaucoma found to have 'significantly higher levels' of an allergic antibody to cats and cockroaches
- Raise possibility the immune system plays a role in the eye disease
- Second-leading cause of blindness globally and is caused by a build-up of pressure in the eyeball, triggering damage to the optic nerve or retina
(Daily Mail) Owning a cat can increase a person's risk of developing the eye disease glaucoma, experts have warned.
In contrast, however, having a pet dog could protect against the disease, which can cause blindness.
Scientists at the University of California, Los Angeles, discovered those people diagnosed with glaucoma had 'significantly higher levels' of immunoglobulin E.
This is a type of allergic antibody produced by the body in response to cats and cockroaches.
Levels of the allergic antibody are elevated in those people who suffer hay fever and asthma.
Researchers said their findings raise the possibility that the immune system plays a role in glaucoma.
The condition is the second-leading cause of blindness across the world.
Often affecting both eyes, it develops when fluid, which is constantly produced by the eye, cannot drain properly and pressure builds up in the eyeball.
The pressure can cause damage to the optic nerve - which connects the eye to the brain - and the nerve fibres from the retina.
As part of the study, experts examined data from 1,678 people, aged in their 50s and 60s.
Each volunteer underwent an allergy test for dust mites, cats, dogs, cockroaches and rodents, the Wall Street Journal reported.
Around five per cent of those taking part were diagnosed as having the eye disease.
Of those, 14.3 per cent had significantly higher levels of immunoglobulin E, to cats and 19.1 per cent to cockroaches.
That was compared with 10 per cent in non-glaucoma patients.
Levels associated with dogs were elevated in just six per cent of glaucoma patients, compared with nine per cent of those without the eye disease.
The report stated: 'Participants with glaucoma had significantly higher odds of sensitisation to the cockroach and cat allergens compared to those without glaucoma.'
The authors suggest that the difference in cat and cockroach allergens and those of dogs may have different effects because dogs spend more time outdoors.
The study was published in the American Journal of Ophthalmology.