Dry Eye

We talk about dry eye in situations where the quantity and/or quality of tears is not adequate to lubricate the ocular surface. Tears are necessary to keep the ocular surface healthy, maintaining transparency so that vision is clear. Instability of the tears causes inflammation and changes to the ocular surface. It is a common and usually chronic problem.

The eyes become uncomfortable. The patient feels stinging and burning, symptoms that can appear in dry air environments, such as in an air-conditioned room or on board an aeroplane, or after looking at a computer screen after a few hours.

The signs and symptoms of dry eye affecting both eyes are:

• Feeling of stinging, burning and scratching in the eyes
• Accumulation of mucus at the corner of the eyes
• Sensitivity to light
• Red eyes
• Foreign body sensation
• Tearing in response to irritation 
• Blurred vision
• Difficulty in supporting contact lenses

The tear film has 3 layers, oily, aqueous and mucous. This combination keeps the ocular surface lubricated and transparent. O dry eye can have a variety of causes.

Tear changes can be caused by hormonal problems, autoimmunity, inflammation of the eyelid glands or allergic diseases. For some people the cause is insufficient production or increased evaporation.

Decreased production can cause dry keratoconjunctivitis, and can be related to age, some diseases such as Sjorgen's syndrome, allergic diseases, rheumatic diseases (e.g. rheumatoid arthritis), lupus, scleroderma, vitamin A deficiency, and others.

Some medications, such as antihistamines, decongestants, antidepressants, to name a few, that can contribute to dry eyes.

Other situations such as contact lens abuse that causes corneal desensitisation, and laser refractive surgery that causes corneal nerve damage, 

Which indirectly cause a decrease in tear secretion.

On the other hand, we have to consider situations related to increased evaporation. This can be the cause, for example, of the burning sensation, with prologated computer use, the decrease in the frequency of blinking leads to excessive evaporation which can cause the symptoms.

In this case we also include situations, with decreased production of the oil layer due to reduced production or malfunction of the eyelid glands (the meibomius glands):

On blepharitis

In case of decreased blinking frequency, in Parkinson's disease or when concentrating on certain tasks such as reading, driving or working on the computer

In entropion (the palpebral edge turned inwards) and ectropion (the palpebral edge turned outwards. The altered eyelid function in both cases leads to prolonged exposure of the eye with consequent tear evaporation.

In windy, smoky, dry air conditions

As risk factors, of dry eyewe consider age, being over 50 years old, because tear production decreases with age. Women, due to the hormonal changes of pregnancy, use of contraceptives and menopause. Having a diet low in Vitamin A.

Prolonged contact lens wear and a history of laser refractive surgery are also factors.

These changes cause complications such as eye infections, as the protection of the ocular surface is lost due to the absence of tears. In particular the cornea may suffer abrasions and later ulcers with loss of transparency and reduced visual acuity. Quality of life is also diminished by the difficulty in performing certain tasks.

Who has dry eye should therefore avoid situations where there is dry air or air blown directly into the eyes, hairdryers, air conditioning or fans, protect the eyes with glasses with superior and lateral protection, in environments with a lot of wind. Take breaks from tasks where you are going to stare a lot, in the case of the computer or prolonged reading, and put on artificial tears or blink repeatedly. In this case it is also useful if the monitor is below the eyes. This prevents the eyes being so wide open, reducing tear evaporation.

Avoid smoking and use artificial tears frequently.

Diagnosis includes the patient's clinical history that can shed light on the origin of dry eyeby assessing local pathologies, such as eyelid diseases, and general pathologies, such as endocrine changes and autoimmune diseases.

The tear assessment tests are simple. The Schirmmer test which evaluates the quantity of tear produced. It consists of applying a strip of filter paper with markings in mm, placed on the inside of the lower eyelid. After 5 minutes, the doctor can see how wet the strip is and get an idea of the amount of tears. The BUT (breakup time) measures the tear evaporation time by looking under a bio microscope at the tear film rupture after the application of a dye. This gives us an idea of the quality of the tear. These are simple but useful tests for a quick evaluation of the situation at the doctor's office.

The CPO has recently acquired a device that allows the evaluation of tear quantity and quality in a more precise way than the aforementioned tests.

Treatment of dry eye is reduced in mild cases to the frequent use of artificial laps.

In more severe cases, treatment consists of controlling underlying disease situations and also improving the quality or quantity of tears, in the latter case by preventing the rapid elimination of tears from the lacrimal ducts. 

Underlying diseases, treated as eyelid diseases on their own resolve the problem in most cases. Inflammatory conditions of the eyelids are a frequent cause of dry eye and their treatment, including local anti-inflammatories and antibiotics, can remove the cause.

 Identifying a drug that causes an allergic reaction and withdrawing or replacing it solves the problem. This is the case for reactions to long-acting eye drops, such as in the medical treatment of glaucoma. 

Other forms of treatment, such as inserts (small grains of hydroxypropyl cellulose) placed in the lower sac (inside the eyelid) slowly release lubricating substance. 

Drugs that stimulate tear secretion such as pilocarpine in eye drops. In cases where nothing else works, the use of autologous serum eye drops (made from the patient's own blood) may help.

Other ways to improve symptoms:

- Tampons placed in the orifices of the tear ducts (the ducts that drain the tears into the nasal cavities), prevent the elimination of the tear, keeping the tears in the eye for longer.

- Pulsed light (laser) treatment is a way to stimulate the production of the meibomius glands. It has good results in cases where the lipid layer of the tear is reduced.

At CPO we have recently introduced this laser with excellent results.