What is dry eyes?
Dry eyes is a multifactor condition which affects the tears and ocular surface. The tears film consists of three componenents:
- A mucus layer which covers the ocular surface and facilitates wetting of the eye.
- An aqueous (watery) layer.
- A lipid (oily) layer covers the tear film to prevent the tears from evaporating.
A deficiency or disruption in any one of these components can result in tear-film instability and lead to dryness of the ocular surface. This is referred to as dry eye. Severe dry eyes can potentially damage the cornea an ocular surface.
What causes dry eyes?
Mucous deficiency is a rare cause of dry eyes and usually leads to particularly severe disease. It results from goblet cell destruction secondary to causes of conjunctival scarring (eg. chemical burns) and Vitamin A deficiency.
Aqueous deficiency is referred to as Keratoconjunctivitis Sicca. More severe forms are often associated with other conditions such as rheumatoid arthritis, Sjogren’s syndrome (dry eye and dry mouth), or following Herpes Zoster Ophthalmicus. Several drugs can cause or exacerbate dry eyes, including antidepressants and the contraceptive pill. A minor degree of aqueous deficiency is common in post-menopausal women.
Lipid anomaly: Chronic blepharitis with an alteration in the lipid component of the tear film may lead to a dry eyes through instability of the tear film.
Dysfunction of tear film distribution: Ocular surface dryness can result from dysfunction of the normal wetting action of the eyelids as occurs with a decreased blinking rate (eg. with Alzheimer’s disease) and malposition of the lids (eg. Ectropion). It may also occur with ocular surface irregularities like a pterygium or pingueculum.
Environmental factors: The symptoms of dry eyes are frequently exacerbated on exposure to conditions associated with increased tear evaporation (eg. air-conditioning or wind) or prolonged reading or computer work when the blink reflex is reduced.
- Burning sensation
- Foreign body sensation
- Unstable vision
- Sensitivity to light
Treatment of dry eyes
Tear substitutes form the mainstay of treatment in mild-to-moderate Keratoconjunctivitis Sicca. It is crucial that the patient uses them frequently and regularly.
- Drops. Avoid preservatives found in bottles by using preservative free single dose units, such as TheraTears Lubricant Eyedrops.
- Gels are slightly thicker, which can blur the vision for a few seconds. It stays in the eye longer and are instilled less frequently. TheraTears Liquid Gel is preservative free and perfect for night time use or during the day in moderate to severe dry eye.
- Ointments containing petrolatum mineral oil can be used at bedtime.
Reduction of tear drainage
Punctal occlusion preserve the natural tears and prolongs the effect of artificial tears. Punctal plugs can be inserted by optometrists and ophthalmologists and may be appropriate for an aqueous tear deficiency.
Avoidance of drying situations
Avoid being in hot or cold winds, near air-conditioners, and being too close to radiant heaters such as fires. Protective glasses may be useful in such situations.
Regular cleaning of the lids is important in the management of Blepharitis, which can cause instability of the tear film. The meibomian glands in the lid secrete oils which help stabilize the tear film. Removing scales and crusts from the lid margins help to promote lipid secretion and keep the lid clear from bacteria that can cause blepharitis. Cleaning should be supplemented with warm compresses to melt solidified oils followed by lid massage to express the meibomian gland secretions.
Studies have shown that a diet rich in Omega 3 fatty acids can aid in the management of dry eye. TheraTears Nutrition contains a combination of fish oil and flaxseed oil and is very effective in managing dry eye conditions.
- Kanski. Clinical Ophthalmology
- Bruce AS and Loughnan MS. Anterior Eye Disease and Therapeutics A-Z 2003