Dry eye is a disorder of the tear film, which occurs due to tear deficiency or excessive tear evaporation.
Our eyes have a direct relation to our external environment � especially, the front side of our eyes, which is affected by sunlight, wind, dust, smoke, humidity, etc. Both the upper and lower lids have some glands called lacrimal glands, accessory lacrimal glands and meibomian glands, which secrete the tear. Tears help keep the front surface of our eyes moist, which in turn helps:
* To open and close the eyelids easily
* In washing dust or any other substances out of the eye
* In keeping clarity of vision
* In protecting the eyes from infections due to its anti-bacterial properties
Tear is spread in a thin film-like arrangement in front of the cornea, called the tear film. It provides nutrition to the cornea and maintains its transparency too. This tear film contains three layers. The first is the lipid layer, which is an oily layer, and it prevents evaporation of the tear. The second is the aqueous layer, composed of salts and proteins. The third and last layer, which is in direct contact with the ocular surface, is the mucin layer, which helps the other two layers stay adhered to the cornea.
When there is a qualitative or quantitative disturbance in the tear, then the tear film breaks, and the bare corneal surface is exposed. This results in drying of the eye.
Symptoms of dry eye
* Dryness of the eyes or decreased tearing, resulting in frequent blinks
* White thread-like or foamy discharge from the eyes
* Redness of the eyes
* Irritation or grittiness
* Itching of eyes
* Inability in keeping the eyes open in bright light
* Eye ache
* Infection of eyes or eyelids
* Tiredness of the eyes and headache
* Difficulty in opening the eyes in the morning
Causes of dry eye
* Diseases of lacrimal glands
* Blepharitis or infection in the eyelid margin
* Some systemic disorders like joint pain and skin diseases, e.g. rheumatoid arthritis, SLE, thyroid disorder, psoriasis, Sjogren syndrome, seborrhoeic dermatitis, etc.
* Hormonal changes commonly seen in elderly women
* Old age
* Malnutrition, mainly vitamin A deficiency
* Vitamin D deficiency
* Dry climate and staying for a long time in an air-conditioned area
* Cataract and refractive surgeries
* Prolonged use of computer and mobile phones
* Chemical injury to eyes
* Use of certain medications like anti-allergic drugs
* Neurological disorder leading to inability of eye closure
Diagnosis is based mainly on the symptoms and relevant clinical history. In the clinics, the ophthalmologist commonly does the Tear Film Break Up Time (TBUT) and Schirmer�s test. There are other sophisticated tests too, available nowadays, which are a bit costlier.
Dry eye is managed primarily by avoiding the precipitating factors. We should keep ourselves well hydrated always � take a nutritious diet, rich in green leafy vegetables and fruits. Smoking should be avoided. Eyes should be cleaned with cold water 2-3 times daily, especially after coming from outside.
For those who need to work on the computer for long hours, should keep the computer monitor in a lower position than the eye and they should consciously blink every 15-20 minutes.
Mild dry eyes, where no damage to the ocular surface has occurred, are cured by application of tear substitute. Proper treatment of the specific cause should be done.
For any eye symptoms, over the counter medications are to be avoided and they should be always treated by an experienced eye specialist.
Infection of the cornea and lids is very common in dry eye disease, if not treated properly. In extreme cases, cornea may become opaque resulting in permanent blindness.