Keeping a pet cat puts owners at greater risk of going blind, but a dog appears to protect eyesight, a new study suggests.

Scientists have discovered that dogs and cats carry antigens which can prompt different immune responses in humans.

Many pet owners suffer mild allergic reactions to their pets but still choose to keep them. However, the new study suggests that even a small immune response could lead to blindness.

The study by the University of California, Los Angeles, found that cat owners who reacted to their pet allergen had a 90 percent increased risk of glaucoma compared with non-pet owners. But dog owners were 20 percent less likely to develop the debilitation condition.

Keeping a dog also has the added benefit that owners are outside more which has been proven to protect against short-sightedness.

“Not only is Fido man’s best friend, he may also save your sight,” said British laser eye surgeon David Allamby.

“Cats could cause our immune system to react in a way that predispose eyes to the development of glaucoma. Exposure to dogs appears to be linked to the opposite effect and could be protective against the disease.”

Glaucoma occurs when fluid in the eyeball stops draining efficiently, causing a buildup of pressure which damages the optic nerve and nerve fibers from the retina. Previous studies have suggested that inflammation can drive the disease and the researchers wanted to find out if that could be triggered by pet allergens.

Animals frequently groom themselves so allergens from saliva and secretions spread throughout the home, becoming airborne easily where they can be inhaled by humans. The researchers believe that dogs are healthier for humans because they spend more time outdoors.

“The protective effect of dogs could be due to their natural antigens in their dead skin, but might also be because they spend more time outdoors and are happy to get dirty, whereas cats are cleaner animals,” said Anne Coleman of UCLA.

一项新研究表明，养猫会增加主人失明的风险，养狗却能保护主人的视力。科学家发现狗和猫身上携带能激起人体不同免疫反应的抗原。

许多宠物主人对他们的宠物都有轻微的过敏反应，却坚持养宠物。然而研究表明，即使很小的免疫反应都有导致失明的风险。

加州大学洛杉矶分校的这项研究发现，如果猫的主人对他们的宠物过

敏，其患青光眼的风险比没养宠物的人高90%。但是，宠物狗主人出现罹患这种疾病的几率却可能比一般人低20%。养狗的主人需要经常在户外活动，这也有助于保护视力，不会近视。英国激光眼科医生大卫·阿兰比说：“宠物狗不仅是人类最好的朋友，还可以保护你的视力。”

“而宠物猫却会诱发我们的免疫系统做出不同反应，导致青光眼。与狗接触却会产生相反的作用，能预防青光眼。”

青光眼是由于眼球中的液体不能有效排出，导致眼内压增加，从而导致视网膜的视神经和神经纤维受损。早前的研究表明炎症能引起青光眼，研究人员想弄清楚，宠物过敏原是否也会导致青光眼。由于动物频繁地梳理它们自己，所以来自唾液和分泌物的过敏原很快就扩散到整个屋子里，又通过空气传播，容易被人类吸入体内。研究人员认为，对人类来说，狗更健康一些，因为它们大多数时间在户外。

加州大学洛杉矶分校的安妮·科尔曼表示：“狗的防护作用可能来自于它们死皮内的天然抗原，但也可能由于它们更多时间在户外，把自己弄脏也很开心，而猫却是种爱干净的动物。”

   Words to Learn 相关词汇

    【抗原】kàngyuán antigen a substance that stimulates the production of antibodies

    【青光眼】qīngguāngyǎn glaucoma a disease of the eye in which pressure within the eyeball damages the optic disc, impairing vision, sometimes progressing to blindness