Dry eyes

    Written by Seamus Flynn, Optometrist

This can often be a chronic problem and leads to inflammation and over the long term can damage our eyes.Dry eyes occurs when our eyes don’t produce enough tears or when the tears that are produced are of insufficient quality to lubricate and protect the cornea.

When tears are produced they lubricate the eye and then drain out of the corner of the eye and along a tube into the back of the nose.

Whenever there is an imbalance between the production of tears and the drainage, dry eye occurs.

Dry eyes generally causes a gritty, burning and uncomfortable sensation which in most cases responds well to over the counter lubricating eye drops.

Causes

Dry eye is caused when there is an insufficient quantity of tears produced or when the tears that are produced are of insufficient quality

-Insufficient quantity of tears produced

Tears are formed in the lacrimal gland above the eye and in most cases are produced in sufficient amounts to protect the front surface of the eyes and keep them lubricated.

There are a number of different reasons why an insufficient amount of tears may be produced. As we age the lacrimal glands naturally produce less tears and this is why dry eye is very common amongst the elderly.

Medications such as diuretics, antihistamines and decongestants as well as certain anti depressants cause a decrease in the production of tears from the lacrimal glands. 

Certain inflammatory and auto immune disorders can affect the lacrimal gland and result in insufficient tear production.

-Environmental factors

Environment factors such as high humidity and air conditioned environments can cause the tear film to evaporate from the surface of the eye resulting in dry eye.

-Insufficient tear quality

The tear film is made up of three main layers, an oil layer, a water layer and a mucus layer.

The mucus layer helps spread the tear across the cornea and the oil layer creates a barrier that help prevent the tears evaporating from the front surface of the eye.

Deficiencies in any of the three layers can cause the tears to evapourate too quickly or the existing tears to not lubricate the eyes sufficiently resulting in dry eye.

-Other Causes

Long term use of contact lenses can cause dry eye especially if they are over worn.

Dry is is one of the most common side effects of LASIK eye surgery with some estimates having it as occurring in 75% of procedures.

Symptoms

Symptoms of dry eye include

• a burning sensation
• grittiness
• uncomfortable eyes
• stringing
• mucus in the eye
• foreign body sensation
• excess watering. 

Diagnosis

An optometrist can diagnose dry eye by carrying out a comprehensive eye examination and taking an extensive patient medical history. 

A medical history is used to determine any genetic or environmental factors that could cause dry eyes.

An examination of the external structures and observation of the blink rate will then be carried out followed by a detailed look at the tear film under magnification using dies such as fluorescein which helps evaluate both the quantity and the quality of the tear film

If also helps determine if the cornea has been affected by insufficient lubrication and protection caused by dry eye. The optometrist will also measure the tear breakup time and which is the time in seconds from a blink to the two years breaking up. Hello value tear breakup time is diagnostic of dry eye. 

Treatment

The goal of treating dry eye is to provide a stable tear film that both lubricates and protects the eyes.

This can be done by a number of methods and in some cases using multiple of these methods.

Lubricating Eye drops

The first step is to use lubricating eye drops. These mimic natural tears and are often sufficient to both offer relief of dry eye symptoms and to protect the cornea.

They do not replace natural tears but rather compliment existing tears to provide a more stable tear film.

This method does not work for everyone particularly if there is a severe case of dry eye.

Conserving existing tears

Tears are produced in the lacrimal gland and drain out of the edge of the eyes through the puncta and into the lacrimal sac. In order to conserve the tears on the eye a punctal plug can be placed in the corner of the eye. Rather than draining out of the eye it remains at the eye surface and keeps the eye lubricated for longer.

The punctal plugs are temporary and can be removed but there are also more permanent surgical options to block the puncta long term.

Other treatments

Other treatments include treating the underlying couse of the dry eye whether that is inflammation, meibomian gland dysfunction etc.                                                                     Drugs called cholinergics such as pilocarpine can be used to increase tear production.

Supplements to improve Dry Eye

Omega 3

Omega 3 is a very effective supplement for dry eye.

It helps the meibomian glands produce the oily layer of the tear film which helps spread the tear evenly over the eye and prevent evaporation which is a leading cause of dry eye.

Flaxseed Oil

Flaxseed oil is an important supplement for dry eye as it contains high levels of alpha-linolenic acid. These are very helpful at preventing dry eyes.

Helpful Tips to Prevent Dry Eye

Avoid air-conditioned environment where possible as it can dry out the eyes.

If you are doing close concentrated work remember to blink on a regular basis to reestablish the tear film. We naturally blink less when doing concentrated work.

Drink eight to ten glasses of water a day to keep hydrated as this also keeps the eyes hydrated and tear film stable.

Wear sunglasses when outdoors to prevent your tears evaporating due to exposure to the wind and the sun.

Latest developments in Dry Eye Treatment

Recently there has been a lot of research into secretagogue treatments for dry eye. These formulations are designed to simulate aqueous and mucus production which are vital elements of the tear film. Producing these elements of the tear film rather than trying to conserve existing tears has the potential to be a game changer in dry eye treatments. 

Another exciting development is the use of contact lenses as a treatment. 

TRaditionally contact lenses, especially when badly fitted or overworn were a contributing factor to dry eye but with advances in contact lens technology specialised soft contact lenses can alleviate the symptoms of dry eyes and the latest ones can actually treat some of the underlying causes.