Obesity can put people's eyesight at risk, scientists warned today.
As the British public overindulged during the Christmas period, two Israeli ophthalmologists published a review showing that people who are clinically obese have an increased chance of eye disease.
Expanding waistlines are already linked to conditions such as diabetes, heart disease and cancer, but the researchers said the link between obesity and failing eyesight is the "risk factor that no one talks about".
Professor Michael Belkin and Dr Zohar Habot-Wilner, from the Goldschleger eye institute at the Sheba medical centre, reviewed more than 20 studies involving thousands of patients worldwide.
They said they found a consistently strong link between obesity and the occurrence and development of four major eye diseases that cause blindness: age-related macular degeneration (AMD), cataracts, glaucoma and diabetic retinopathy.
Prof Belkin, a professor of ophthalmology at Tel Aviv University, said: "The purpose behind this review was to acquaint physicians and laypeople with the dangers of being fat as related to ophthalmology. All of this existing research had never been pulled together in a comprehensive way."
All the common eye diseases can affect sight to some extent, with most sufferers experiencing deterioration over time.
Glaucoma is a group of diseases that can damage the eye's optic nerve, resulting in vision loss and blindness, while AMD causes the sharp, central vision to blur, making some activities such as reading difficult.
Cataracts is a clouding of the lens in the eye that affects vision, while diabetic retinopathy is a complication of diabetes, and a leading cause of blindness. The condition occurs when diabetes damages the tiny blood vessels inside the retina - the light-sensitive tissue at the back of the eye.
The researchers said that although the evidence was out there suggesting a link between obesity and these conditions, the results were not well known by the public and should motivate people to lose weight.
The researchers said that in some cases the reason for the link between obesity and the diseases was unclear.
"Nobody has the faintest idea why cataracts are affected since it is a disease of the lens of the eye," Professor Belkin said.
Dr Habot-Wilner said it was likely that the link had something to do with the fact that obese people face a greater chance of developing gout - a disease in which the development of cataracts is more common.
But she stressed that in their study they wanted to raise awareness of the risks of sight problems linked to obesity, rather than why these conditions occur more often and cause more damage in obese people.
"The message we want to send is that obesity can cause not just cancer and hypertension but also ocular disease.
"While this is something that most ophthalmologists know, it's not common knowledge and it should be. It's the risk factor that no one talks about."
