Dry Eye
What is Dry Eye?
In our air conditioned and polluted environment nowadays Dry Eye is a much more common condition. Dry eyes is caused by a lack of tears on the eye or tears of poor quality (which may even lead to a watery eye that feels dry). The symptoms of dry eye may be sore or tired eyes, they may feel itchy or may burn, you may feel that you cannot see clearly and need to blink to make your vision clear.
The tear film at the front of the eye is actually the most important for being able to see clearly it provides a smooth film over the front of the eye and allows the light to pass through easily. Tears are actually made up of several components and when on the eye they form into three layers. The lipid layer is the outermost layer, made up of oils produced by the meibomian glands on the lids. This layer stops the watery layers underneath from evaporating too quickly. The next layer is the aqueous (or watery) layer that keeps the eye well lubricated and supplies oxygen to the front of the eye, it is released by the lacrimal glands (which are also stimulated when we cry). The layer closest the eye is the mucin layer. Mucins are sticky substances released by the goblet cells of the lids and conjunctiva, they help stick the tears to the front of the eye. A deficiency in any of these three layers can cause dry eye.
The Tear Film has three layers, the lipid layer, aqueous later and mucin layer
Diagnosing dry eye.
Dry eye can be diagnosed using your symptoms and also by looking at the tear quality using the slit lamp and flourescein dye. A normal tear film will not break up on the eye for at least ten seconds, in dry eye the tear film breaks up (leaving uncovered areas) in less than five seconds. The dye will also show up any areas of the eye that are not getting enough tears on them and are drying up. The glands that release the oil onto the eye will be inspected to see if there are any blockages.
Tear Break Up Time
The tearscope can be used to measure the osmolarity of the tears which gives a good indication of whether the eye is dry even if there appear to be a lot of tears.
The Tearscope from TearLab measures the osmorality of the eye
Treating Dry Eye
Once dry eye has been diagnosed it can be treated in several ways. It is usual to start with artificial tear drops, such as Theratears, Systane, Clinitas Soothe, which replace the tear fluid on the eye. It is better to choose a non-preserved drop as these can be used with contact lenses and are a little bit better for the eye. Artificial tears can be used many times a day as necessary. If the oily layer of the tears is deficient there are now sprays such as Clarimyst which replace the lipid layer specifically.
If there is staining often a gel will be given as well such as Lacrilube or Viscotears, that can be used at night (the gel blurs the vision temporarily so it is best to use it just before bed).
In rare cases the dry eye is severe and caused by a syndrome called Sjögren’s syndrome. In this syndrome the body has an immune response against its own tear glands which reduces the watery layer of the eye and causes the front of the eye to dry out. This is a very painful condition and usually the saliva glands of the mouth are affected too, giving a very dry mouth. Sjögren’s syndrome is more common in middle aged women.
Blepharitis
Often dry eye is caused by a condition called Blepharitis. Blepharitis is an inflammation of the eyelids usually caused by a reaction to toxins released by the bacteria that live on the skin – usually Stapphylococcus Aureus. Blepharitis can be diagnosed using the slit lamp by the observation of crusting on the eye lids, red eye lid margins, this is called anterior blepharitis.
If there are blocked meibomian glands (the little glands that release the oil onto the eye) then this is called posterior blepharitis.
Blepharitis can give symptoms like those of dry eye and if the meibomian glands are blocked may reduce the quality of the tears.
Treating Blepharitis
Unfortunately blepharitis cannot be cured but the symptoms can be alleviated. For anterior blepharitis the easiest way to do this is by taking lid hygiene measures. This involves cleaning the margins of the eye lids with either a cotton bud dipped in a mild solution of baby shampoo or using eye lid scrubs such as Supranettes.
To use the cotton bud method you will need a clean dish containing one part of baby shampoo diluted in ten parts of cool, boiled water.
Try to gently remove all the crusts from the eye lid edges and from between the eye lashes -
- Using a cotton bud, dip the bud into the shampoo then gently but firmly, rub the soaked tip of the bud along the lid edges and between the lashes.
- Repeat this on upper and lower lid edges.
Rinse your face with clean water and dry gently.
- Carry out this procedure twice daily at first - as the condition improves it can be done less often. Use a clean cotton bud for each eye.
If the anterior blepharitis is severe then a course of antibiotics may help. People with Acne Rosacea are unfortunately more likely to suffer from blepharitis.
If you have posterior blepharitis – otherwise known as meibomian gland dysfunction then hot compresses are the first line of treatment. Hot compresses help to melt the oil that is blocking the glands.
- Take a flannel and dip in clean hot (but comfortable on the skin) water.
- Hold the compress against each eye for two minutes.
- Then, if you can, squeeze the lids gently to help express the oil.
- Repeat this twice a day until symptoms improve then periodically to maintain comfort.