Dr's Casebook with Dr Keith Souter: Diet may be a key factor in the rise and prevention of near-sightedness
For some years it has been apparent that myopia, or near-sightedness is increasing. It is affecting people of all ages, but particularly young people. The International Myopia Institute state that the number of 17 year-olds with myopia has doubled in the last decade, and it is predicted that by 2050 half of the world’s population may be affected.
To understand myopia, think of the eye as being like a camera. In a normal healthy eye light enters through the cornea, passes through the lens, and focuses on the retina at the back of the eye. A myopic eye consistently grows, either longer or curvier, causing light to focus in front of the retina. This results in distant objects appearing out of focus, hence it is near-sighted.
The main risk factors are thought to include excessive screen time and too little time spent outdoors, as well as an inherited tendency. However, recent research published in the British Journal of Ophthalmology studied over one thousand children and found that diet may play a significant role and that it offers a possible way of preventing it.
They found that a diet rich in omega-3 fatty acids, found predominantly in fish oils, may help prevent the development of myopia in children. Conversely, a high intake of saturated fats, found in foods such as butter, fatty food and red meat, increases the risk of it.
They drew studied over a thousand children aged 6 to 8 years who had been randomly recruited from the population based on the Hong Kong Children Eye Study. Their eyesight was assessed, and their diet was measured with the parents help using a food frequency questionnaire. They also looked at risk factors like the amount of time they spent outdoors, playing, reading, writing and screen time.
About one quarter of them had myopia. They measured the axial length of their eyes, the distance from the front of the cornea to the retina at the back of the eye. This length was greatest in the quarter of the children with the lowest intake of omega-3 fatty acids.
Remember the camera model, this would tend to throw the image in front of the retina to produce a blurred image.
They suggest that omega-3 fatty acids may prevent myopia by increasing blood flow through the vascular layer in the eye, so increasing nutrients and reducing oxygen deficiency in the white of the eye which seems to be a key factor in the development of near-sightedness.