London, Aug 19 (IANS): Eating oily fish twice in a week -- equivalent to 500 mg per day of dietary omega-3 polyunsaturated fatty acids -- can decrease the risk of sight-threatening diabetic retinopathy in middle-aged and older individuals with Type 2 diabetes, finds a study.

Diabetic retinopathy is a diabetes complication that affects eyes and has become a leading global cause of vision loss. It is caused by damage to the blood vessels of the light-sensitive tissue at the back of the eye (retina).

The increasing prevalence of Type 2 diabetes mellitus, coupled with an increased lifespan, has resulted in a steady rise of disability in older individuals with diabetes.

The retina is rich in long-chain omega-3 polyunsaturated fatty acids.

Many experimental models have supported dietary long-chain omega-3 polyunsaturated fatty acids' protection against diabetic retinopathy, however, clinical data is lacking, the researchers said, in the paper published online by JAMA Ophthalmology.

The team conducted a prospective study within the randomised clinical trial Prevencion con Dieta Mediterranea (PREDIMED).

From 2003 to 2009, 3,614 individuals aged 55 to 80 years with a previous diagnosis of Type 2 diabetes were recruited in Spain.

Participants meeting the long-chain omega-3 polyunsaturated fatty acids recommendation at baseline (500 mg/d or greater) showed a 48 per cent reduced risk of sight-threatening diabetic retinopathy, than those with lower levels of the fatty acids.

"Our findings, which are consistent with the current model of the pathogenesis of diabetic retinopathy and data from experimental models, add to the notion of fish-derived long-chain omega-3 polyunsaturated fatty acids as a healthy fat," said Aleix Sala-Vila from the Lipid Clinic in Barcelona.