Blinking and operating: cognition versus vision
- St Paul's Eye Unit, 8z Link, Royal Liverpool University Hospital, Prescot Street, Liverpool L7 8XP, UK
- Correspondence to: Mr Kaye; stephen.kaye{at}rlbuh-tr.nwest.nhs.uk
- Accepted 21 November 2001
The difference in the refractive indices between the air and the tear film results in the tear film having the greatest optical power of any part of the eye. Eyelid blinks are important for maintenance of the tear film. Between blinks there is progressive thinning of the tear film, which becomes non-uniform on the ocular surface and may break up. This produces an irregular air/tear interface, with a reduction in image quality.1 The longer the period between blinks the greater the effect on the tear film and reduction in vision. Restoration of the tear film occurs immediately following a blink so that the ability to maintain a regular tear film is dependent on the blink rate. A reduction in the blink rate such as, for example, a pause between blinks of 15 seconds has been associated with a change in the shape of the profile of the corneal tear film and up to a 6% …
