Dry eye is an eye condition that occurs when the eyes do not produce enough tears or when the tears evaporate too quickly. It is a common and often chronic problem, particularly in older adults. With each blink of the eyelids, tears spread across the front surface of the eye, known as the cornea. Tears provide lubrication, reduce the risk of eye infection, wash away foreign matter in the eye and keep the surface of the eyes smooth and clear. Excess tears in the eyes flow into small drainage ducts in the inner corners of the eyelids, which drain into the back of the nose. Dry eyes can occur when tear production and drainage is not in balance.
Etiology of Dry Eye
The causes of dry eye can be classified as below:
Even though anyone can have dry eye, this condition becomes more common the older you get. Dry eye tends to affect people over the age of 50 because tear production declines with age. This type of dry eye can’t be prevented, but using artificial tears on a regular basis can provide extra lubrication to coat your eyes and relieve dryness.
2. Computer use
Some people who work on a computer experience eyestrain and tension headaches. In addition to these issues, staring at a computer often can also affect your tears and lead to dry eye. This is because people who work at a computer monitor tend to blink less often. As a result, their tears evaporate more quickly. If you use a computer for work, you can reduce dryness by blinking more frequently. Blinking will help lubricate your eyes. This can prevent dryness and irritation. If you still experience dryness, use artificial tears while working at your computer. Additionally, give your eyes a break every now and then. Look away about every 20 minutes and blink repeatedly to re-wet your eyes.
3. Laser surgery
Some people begin to experience dry eye after laser vision correction surgery. This procedure cuts some of the nerves in the cornea, causing the eyes to produce fewer tears.
This type of dry eye is usually temporary and resolves after a few days or weeks. Until your eyes heal, use lubricating eye drops to keep your eyes moist
Hormones can play a role in dry eye. Thus, some women experience dry eye symptoms during pregnancy, menopause, or while using birth control pills. Hormones stimulate the production of tears, so an imbalance can reduce tear production. Hormone replacement therapy doesn’t seem to improve dry eyes. But you can talk to your doctor about lubricating eye drops to reduce dryness and irritation.
5. Vitamin A deficiency
As we know, Vitamin A promotes healthy eyes. Thus, foods rich in vitamin A include eggs, carrots, fish, spinach, broccoli, and peppers. A diet low in foods that contain this vitamin can lead to dry eye and other vision impairments, such as night blindness.
6. Wind exposure
Cold climates and exposure to high winds can cause tears to evaporate too quickly, leading to dryness. To protect your eyes, use lubricating eye drops and wear sunglasses that wrap around your head to protect your eyes from cold and wind.
7. Sjogren’s syndrome
Sjögren’s syndrome is an autoimmune disorder that causes white blood cells to attack your salivary glands and tear glands, reducing tear production. When dry eyes don’t respond to lubricating eye drops, your doctor may recommend a surgery that involves inserting silicone plugs into your tear ducts to help preserve some of your tears
Blepharitis develops when small oil glands on your inner eyelid become clogged and inflamed. Along with dry eyes, you may have oily flakes around your eyelashes. There’s no cure for this condition. Still, you can reduce inflammation by applying a warm compress over closed eyes for a couple of minutes and cleaning your eyelids with baby shampoo. Until inflammation improves, use artificial tears to reduce dry eyes and redness. If your symptoms don’t improve, see your doctor and ask about treatment with antibiotic eye drops.
9. Contact lenses
Long-term use of contact lenses is another risk factor for chronic dry eye. This is because some lenses obstruct oxygen to the cornea. If your eyes don’t receive enough lubrication, switch to eyeglasses and ask your eye doctor about contacts specifically made for dry eyes. These lenses help your eyes retain moisture.
Symptoms of Dry Eye
- Foreign body sensation
- Feeling of dryness
- Ocular discomfort
Signs of dry eye
- Tear film may show presence of stingy mucous and particulate matter.
- Conjunctiva becomes lustureless, mildly congested, conjunctival xerosis and keratinization may occur.
- Corne may show punctate epithelial erosions, filaments and mucus plaques.
Tear film tests for Dry Eye
1. Tear film break-up time(BUT):
It is the interval between a complete blink and appearance of first randomly distributed dry spot on the cornea. It is noted after instilling a drop of fluorescein and examining in a cobalt-blue light of a slit-lamp. BUT is an indicator of adequacy of mucin component of tears. Its normal values range from 15 to 35 seconds.Values less than 10 seconds imply an unstable tear film.
2. Schirmir test
It measures total tear secretions. It is measured with the help of a 5 × 35 mm strip of Whatmann-41 filter paper which is folded 5 mm from one end and kept in the lower fornix at the junction of lateral one-third and medial two-thirds. The patient is asked to look up and not to blink or close the eyes. After 5 minutes wetting of the filter paper strip fron the bent end is measured. Normal values of schirmer test are more than 15 mm. Values of 10-15 mm are suggestive of moderate to mild dry eye. Less than 5 mm suggests severe dry eye.
3. Rose bengal staining
It is a very useful test for detecting even mild cases of keratoconjunctivitis sicca (KCS). Depending upon the severity of KCS three staining patterns A, B and C have been described: ‘C’ pattern represents mild or early cases with fine punctate stains in the interpalpebral area; ‘B’ the moderate cases with extensive staining; and ‘A’ the severe cases with confluent staining of conjunctiva and cornea.
At present, there is no cure for dry eye. However, The following treatment modalities have been tried with variable results:
- Artificial tears remains the mainstay in the treatment of dry eye. These are available as drops, ointments and slow-release inserts. Mostly available artificial tear drops contain either cellulose derivatives (e.g., 0.25 to 0.7% methyl cellulose and 0.3% hypromellose) or polyvinyl alcohol (1.4%).
- Topical cyclosporine (0.05%, 0.1%) is reported to be very effective drug for dry eye in many recent studies. It helps by reducing the cell-mediated inflammation of the lacrimal tissue.
- Mucolytics such as 5% acetylcystine used four times a day helps by dispersing the mucus threads and decreasing tear viscosity.
- Evaporation can be reduced by decreasing room temperature, use of moist chambers and protective glasses. Punctal occlusion to decrease drainage can be carried out by collagen implants, cynoacrylate tissue adhesives, electrocauterisation, argon laser occlusion and surgical occlusion to decrease the drainage of tears in patients with very severe dry eye.
- Permanent lateral tarsorrhaphy may be required in very severe cases.
- Systemic tetracyclines and lid hygiene in patients with chronic posterior blepharitis.
- Vitamin A supplement for the deficiency.
- Treat the cause of lagophthalmos.
For more information : visit AOA