Why does laser eye surgery make eyes dry?

LASIK and PRK work on the cornea (the transparent dome over the pupil) to thin and reshape it in a way calculated to better focus an image on the retina at the back of the eye. This reshaping process necessarily removes corneal tissue. In so doing, some of the many, fine sensory nerves of the cornea are unavoidably damaged.

It is the constant, minute-by-minute stimulation of these nerves in blinking, looking around, and from external irritation (e.g. smoke) that messages the lacrimal glands nearby to produce tears. If this "signal" is muted, as in the case of the damaged nerves, the lacrimal glands will not produce as much tears.

Fortunately, the nerves do grow back, but this can take as long as 1-2 years and in some cases, never to the same degree as was the case before the laser surgery. If this is a problem, the patient may need to be prescribed a tear-producing medicine such as Restasis® or Xiidra.®

_Written by J. Trevor Woodhams, M.D. - Chief of Surgery, Woodhams Eye Clinic