FACTORS THAT CONTRIBUTE TO DRY EYE SYNDROME
The single most important risk factor for Dry Eye. Dry Eye Syndrome affects 75% of people over the age of 65.
- Computer Users: Computer users spend hours staring at their terminal ignoring their normal blinking process which is necessary for refreshing the tear film.
- Contact Lenses: Dry Eye is a leading cause of contact lens discomfort or intolerance. Soft contacts in particular rapidly evaporate the tears from the eye, causing irritation with possible other effects such as protein deposits and infection.
- Disease: Many diseases can result in side effects of Dry Eye Syndrome: Asthma, Sjogren's Syndrome, Lupus, Rheumatoid Arthritis, Diabetes, Thyroid Abnormality, Acne Rosacea, etc.
- Environmental Conditions: smoke, fluorescent lights, air pollution, wind, heaters, air conditioning, and dry climates/low humidity can increase tear evaporation.
- Medications: Antibiotics, antidepressants, antihistamines, appetite suppressants, beta blockers, blood pressure medication, decongestants, diuretics, oral contraceptives, tranquilizers, over-the-counter vasoconstrictors, and ulcer medication can also decrease the body's ability to produce lubricating tears.
- Specific to Women: Hormonal changes brought on by pregnancy, lactation, oral contraceptives, menstruation, and post menopause can cause dry eye conditions.
FACTORS THAT CONTRIBUTE TO DRY EYE SYMPTOMS
- Larger flaps in treating hyperopia
9.5 mm as opposed to 8.5 mm are thought to be creating drier eyes
- Decreased blink rate - The normal blink interval is every 5 seconds. When there is unilateral de-innervation there is no change in blink rate. When a patient experiences a bilateral decrease in corneal sensation, there's a decrease in the blink rate of about 30%. Since the corneal nerves are cut during LASIK, there is an expected decrease in sensory stimulation which results in subnormal tear production as well a decreased blink rate.
- Long time contact lens wearers experience a much lower corneal sensation than normal preoperatively, which also results in decreased blinking. Since the patient blinks less they have poor spreading of tears over the eye, usually resulting in decreased tear clearance from the reduced pump action of the lids. This creates a change in the tear composition which results in inflammation and contributes to the dry eye syndrome.
- Antidepressants can cause extreme dryness in a lot of patients as well as causing mydriasis (an enlargement if pupil size). A patient can undergo the LASIK procedure with one pupil size and a few months after taking antidepressants have complaints of glare, halos and other previously nonexistant symptoms which are attributed to a large pupil size.