Dry eye is a condition in which there is an insufficient amount of tears needed to lubricate and nourish the eye. This process is essential for providing clear vision and for protecting the eye’s sensitive surface tissues. Other common names for dry eye include chronic dry eye, dry eye syndrome, dry eye disease, and kerato-conjunctivitis sicca.
Having dry eye does not mean that your eyes are actually “dry.” In fact, many sufferers of dry eye experience persistent watery eyes. Dry eye simply refers to an abnormality of the tear film.
The tear film of the human eye is complex, and includes an aqueous (watery) layer covered by a lipid (oily) layer to prevent evaporation. Underneath the tear film, a mucus (sticky) layer is present to help the tear film adhere to the eye’s surface. If any of these three tear film layers are disturbed, it can interfere with the eye’s natural lubrication process. If these disruptions continue, the person can develop dry eye.
Causes of Dry Eye
From various environmental factors to the aging process, there are numerous causes of dry eye. The most common causes of mild to moderate dry eye include computer use, contact lens wear, and aging, especially in women who are peri-or-postmenopausal. Moderate to severe dry eye is often associated with Sjogren’s syndrome. This auto-immune disease can not only cause dry eyes, but also dry mouth and nose. LASIK vision correction surgery can also contribute to dry eyes.
Aging: The aging process can cause a decrease in lipid production, resulting in a condition known as evaporative dry eye.
Environmental Factors: Indoor and outdoor climate, wind, humidity levels, and the presence of various irritants can result in dry eye. Environmental factors that can contribute to this condition include:
- High altitudes
- Air conditioning
- Hair dryers
- Central heating
- Dry, hot and/or windy climates
- Excessive sun exposure
- Cigarette smoke
- Air travel
- Air pollution
Contact Lens Wear: Many people who wear contact lenses complain of dry eyes. As contact lenses rub against the conjunctiva in the eyelids and absorb the tear film, this action can cause or contribute to dry eye. In some instances, long-term contact lens wearers may experience a reduction in epithelial nerve sensation, which can help reduce the stimulus to produce tears.
- Auto-immune diseases (Sjogren’s rheumatoid arthritis, lupus)
- Lacrimal gland deficiency
- Parkinson’s disease
- Rheumatoid arthritis
- Rosacea (Facial rosacea is directly linked with ocular rosacea, which can cause eye conditions like blepharitis.)
- Stevens-Johnson syndrome
Eye Injuries and Eye Surgeries:
- Chemical burns
- Corneal transplants
- Laser refractive surgery, e.g. LASIK, epi LASIK, LASEK, PRK, etc. The most commonly known for dry eye is LASIK surgery, as it ablates or severs more nerves than other types of laser refractive surgery.
Conditions of the Eyelid/Anatomical Abnormalities:
- Bell’s palsy
- Bulging eye
- Droopy eyelid
- Lagophthalmos (Inability to close the eyelids, which can be caused by LASIK, hypothyroidism, blepharoplasty, or other causes, or can occur naturally.)
- Noncturnal lagophthalmos
Eye Diseases that Affect the Meibomian Glands:
- Meibomian gland dysfunction (also referred to as meibomiantis or meibomitis)
- Ocular rosacea (Believed to be present in up to 75 percent of perimenopausal women with facial rosacea)
Hormonal Changes or Deficiencies:
- Decreased androgen production
- Hormonal changes due to menopause
- Estrogen supplementation (which can improve or worsen dry eye)
- Thyroid conditions
Low Blink Rate
The act of blinking is necessary to properly spread tears over the surface of the eye, and therefore stimulating tear production. Having a low blink rate can affect eye lubrication and cause dry eye symptoms.
When you focus on a nearby object for a prolonged period of time, you are most likely blinking less than you normally would. For example, looking at a computer, watching television, or reading can cause you to blink less frequently. In fact, computer use has been shown to decrease the blink rate from 22 blinks per minute to just 7 blinks per minute.
Certain medications have been known to exacerbate dry eye. If you believe that the medication you are taken is causing or contributing to your dry eyes, consult with your doctor. He or she may be able to prescribe an alternative medication to eliminate this side effect. Note that it’s important not to stop using a medication without consulting your doctor first.
- Allergy medications (especially antihistamines)
- Antidepressants (e.g. diazepam, amitriptyline)
- Beta blocks
- Birth control pills
- Certain medications used to regular heart rhythm abnormalities
- Many pain medications
- Parkinson’s medications
- Sleeping pills
- Some blood pressure medications
Smoking, radiation therapy, and vitamin A deficiencies can also cause or contribute to dry eye disease.
Role of Artificial Tears
As it’s crucial to the health of the eye for its surface to maintain lubrication, artificial tears in the form of liquids, gels and ointments can be used to lubricate the eye. As dry eye can result in eye injuries which can compromise vision, it’s important to keep your eyes properly lubricated. A treatment option such as Crocodile Tears can help sufferers of dry eye have less discomfort. Find out if Crocodile Tears can help you.