What is the aim of the review?
The aim of this Cochrane Review was to find out if blue-light filtering artifical lenses, also known as intraocular lenses (IOLs) protect the back of the eye. Cochrane Review authors collected and analysed all relevant studies to answer this question and found 51 studies.

Key messages
There is little evidence of any important differences between blue-light filtering and non-blue-light filtering lenses. However, studies have been too small and too short-term to provide a reliable answer to this question.

What was studied in the review?
Sometimes the lens in the eye becomes cloudy, often as people become older. Cataract surgery involves removing the cloudy lens and replacing it with an artificial one. This artificial lens is known as an ‘intraocular lens’ or IOL. These IOLs contain a filter to block harmful ultra-violet (UV) light. Some lenses also have a filter to block visible blue light. In theory, high levels of blue light could damage the back of the eye that controls central vision (the macula). It has been suggested that blue-light filtering IOLs may help to protect the macula and prevent a common cause of visual loss in older people, age-related macular degeneration.

What are the main results of the review?
Cochrane Review authors included 51 studies from 17 different countries in this review. The review showed that:

• there is probably no important difference in distance vision between blue-light filtering artificial lenses and non-blue-light filtering lenses 12 months after surgery (we are moderately certain about this evidence);
• there were no relevant data on contrast sensitivity (being a person’s ability to differentiate an object from its background) and colour discrimination, being two measures of macular health;
• none of the people taking part in these studies developed age-related macular degeneration within the follow-up period (we are very uncertain about this evidence);
• there was no evidence on adverse outcomes that may be related to the blue-light filtering IOLs (for example, sleep disturbance).

How up-to-date is this review?
Cochrane Review authors searched for studies that had been published up to 25 October 2017.