Refractive Surgery and Dry Eyes

Saturday, November 01, 2008

Dr. Michael Rosenberg, one of our fine surgeons here at Northwestern LASIK Physicians, discusses the relationship between refractive surgery and symptoms of dry eyes:

Many kinds of eye conditions give rise to irritative symptoms that patients describe as "dry eyes." True dry eye results from either an inadequate production of tears or an abnormal tear quality that prevents the tears from staying on the eyeball as long as they should. This is distinct from dryness resulting from eyelid inflammation, as well as from the symptoms most commonly found in recipients of LASIK surgery and PRK. Some physicians feel that PRK causes less dry eye symptoms than LASIK.

For reasons we do not fully understand, the nerves in the cornea responsible for sensation (feeling) also affect the amount of time that tears remain on the cornea after we blink. Due to the effects of LASIK flap creation upon these nerves, patients having laser refractive surgery will experience faster evaporation of tears and slight numbness of the cornea. As the nerves regenerate over several months, the tear behavior improves. The tears remain on the cornea longer and the symptoms of dry eye improve. Because of the initial numbness, patients may not be aware of a dry feeling and will tend not to use the drops as directed.

Scientific studies measuring volume of tears after laser surgery are inconclusive. Some studies have shown no effect on tear production; others have shown a decrease. In the latter cases, dry eyes have been shown to have improved over time. If a patient has a dry eye syndrome prior to laser surgery, it may be temporarily worse after the procedure, but will improve to its pre-surgery level.

Dryness is worse in cold or windy weather because of low humidity and increased evaporation. Dryness improves in humid weather or in areas with humidifiers. Some systemic medications may worsen the symptoms. Patients who are concentrating, for instance at work, blink less frequently causing faster evaporation. Dry eyes rarely affects vision significantly. It is more common in women and in older patients. Discomfort is usually mild with appropriate treatment.

Treatment of dry eye includes artificial tears, occlusion (blockage) of the tear drainage system, treatment to improve the quality of the tears (such as Omega 3 fish oil or flaxseed oil), antibiotics to control eyelid inflammation and Restasis, an eye drop, which has the potential to improve tear volume and quality. Your doctor will tailor any treatment to the severity of any symptoms.

There is significant individual variability, but if a patient has no dry eye symptoms prior to laser surgery, and if the physician finds no corneal irritation in the pre-operative examination, dry eye would not be expected to be a significant post-operative problem.

Labels: artificial tears, cornea, dry eye, dry eye syndrome, eye drops, LASIK, PRK, refractive surgery, tear drainage

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