Dry eye is a chronic, progressive disease affecting both tears and the ocular surface resulting in discomfort, visual changes and possible damage to the ocular surface. Dry eye is a result of poor quality/ quantity produced tears or the evaporation of tears. This condition is more prevalent in women. Patients may experience foreign body sensation, light sensitivity, watery eyes, reduced contact lens tolerance and tired eyes.
Dry eye is classified into two categories namely aqueous deficient dry eye; a reduction in tear production, and evaporative dry eye; an increase in tear evaporation.
Who is at Risk:
Dry eye is a result of various factors such as ageing, hormonal changes in women, smoking, deficiency in vitamin A and omega 3 fatty acids, environmental factors such as air conditioning, prolonged near vision tasks and long term contact lens wear. Medication such as anti-depressants, anti-histamines and beta blockers can increase ones risk for dry eye disease. Rheumatoid arthritis and Sjorgens disease are contributing factors to dry eyes. Patients generally experience dry eyes after LASIK and other refractive surgeries but this usually resolves within several months.
Function of the Tear Layer:
Tears are a very important aspect of the ocular system and serve as a barrier against infections, they wash out debris and lubricate the eye. Tears consist of 3 layers:
- The outermost oil layer is produced by the meibomian glands in the eyelid and protects against evaporation.
- The middle aqueous layer is produced by the lacrimal gland and provides nourishment to the cornea.
- The innermost layer is the mucin layer providing lubrication.
Investigations to Detect Dry Eye:
The tests that are designed to diagnose dry eye evaluate the osmolarity, quantity and quality of tears. Patients with dry eyes have an increased tear osmolarity. Tear break time is a very frequent measure of determining dry eye, however tests such as Schirmer test, Lisamine green and Tear Lab will all evaluate the stability of the tear film. These tests are painless and doctors obtain the results immediately.
Treatment of Dry Eye:
The treatment of dry eye disease is very individualized, depending on the cause of dry eye. Ocular lubricants, omega 3 essential fatty acids, eyelid scrubs and warm compresses are more frequently prescribed. Autologus serum eye drops are prescribed in certain cases. In more severe cases lacrimal punctal occlusion may be recommended to occlude the tear drainage ducts.