The UK Biobank assessment expanded significantly during the three years that people joined the project.

One of the biggest developments was the collection of eye measures for the last 100,000 participants in Croydon, Sheffield and Birmingham.

The addition of the sight test, eye pressure measures (testing for glaucoma, a common and avoidable cause of blindness) and a photo and scan of the back of the eye (able to detect problems like retinal detachment) created the biggest study of eyes ever undertaken.

Poor eye-sight reduces quality of life as people age, and can be a risk factor for other major health problems (such as hip fracture).

Professor Peng Tee Khaw at the NIHR Biomedical Research Centre, Moorfields Eye Hospital and UCL Institute of Ophthalmology, London, said scientists were very much looking forward to using this extensive collection of information.

Loss of vision is a major health issue that affects about 2 million people in the UK and, although the vast majority are older, it is estimated that about 80,000 working-age people are affected.

• Evidence suggests that over 50% of these cases are due to preventable or treatable causes.
• Vision loss is associated with increased risk of physical injury, emotional distress and loss of independence. Vision loss increases the chances of falling, and can effect quality of life in many ways, such as becoming dependent on others to prepare meals.
• The commonest registered cause of blindness and visual impairment in the UK (accounting for over 56% of the total) is age-related macular degeneration. Glaucoma (11%) and diabetic retinopathy (6%) are the next most commonly registered causes of significant visual loss.
• Some of the genes that may contribute to inherited eye disorders (including glaucoma and cataracts) have been identified – which may lead to new treatments.
• Dementia is caused by damage in the brain, but research suggests it may be possible to monitor the illness by looking for changes that also occur in the eye.

With all these issues in mind, the UK Biobank Resource will become a powerful study tool in understanding much more about eye disorders, how they affect health and whether or not the eyes can provide an early warning system for other disorders.