Eye Care Centre

Dry Eye Syndrome

A Common eye condition

The majority of us do not realise that we have often experienced the symptoms of this condition. We say that our eyes become "tired" after sitting in front of a computer for hours or a session of all night studying or driving long distances.
Dry eyes is certainly the most common eye condition and the incidence is increasing rapidly.

Symptoms:

• Grittiness – as though a particle of dust or a hair got in your eye 
  
• Burning sensation 
  
• Redness 
  
• Light sensitivity 
  
• Tearing – Yes! Dryness stimulates reflex watery tear production in the same way a foreign body would 
  
• Puffy eyes 
  
• Blurred vision 
  
• Eye ache - or some experience headache behind the eyes 
  
• Droopy eyelids 
  

Tears and the Tearfilm:

It is important to understand the function of the tearfilm. The ultra thin layer of wetness covering the surface of the eye has a mucin (protein) layer on the inside in contact with the cornea and a oily outer layer on the outside to reduce evaporation with a watery layer sandwiched in-between. Hundreds of little glands in the lids and conjunctiva have to contribute to its formation in a controlled way.
We blink our eyes regularly to maintain this complicated layer. It lubricates the eye and lid movements and provides the clear corneal surface that makes vision possible – to mention only two of its many functions. If the tearfilm does not function properly, dry spots develop producing friction between the eye surface and the lid which causes grittiness, burning, tearing etc. Dry spots on the cornea spoil good vision and incoming light (sunlight, headlights when driving at night) striking dry spots is scattered inside the eye causing glare. Increased friction between eye and lid makes the eye and lid muscles work harder causing them to ache and the lids to droop.
Watery tears are produced in response to emotional disturbance and irritations and has a detrimental effect on the function of the tearfilm.

Causes of Dry Eyes:

• Concentrating (staring) for long periods
– reading, computer work, driving, watching TV etc. We blink less frequently under these circumstances and this leaves more time for evaporation 

• Environmental factors increasing evaporation
– wind, sun, heaters, fans, air-conditioners, fluorescent lighting, reading (study) lamps too close to the face generating heat and convection etc. The modern office environment is designed to produce dry eyes! 

• Diseases
– rheumatoid arthritis, thyroid conditions, allergies, lupus, etc 

• Drugs
– Beta-blocking agents, anti-depressants, anti-histaminics, diuretics, decongestants (e.g. drops used to whiten red eyes), etc. 

• Contact lenses
require more tears and people with dryness tendencies often become symptomatic. Dryness is the most common reason for contact lens failure. 

• Females
have to cope with various hormonal fluctuations throughout life which can cause dryness: menarche, menstruation, contraceptive pills and especially menopause. 

• Age
– our eyes tend to become drier with age 

• Sleep!
– we do not blink our eyes while sleeping. Evaporation continues and mucussy deposit (matter) collects in the inner angle of the eyes. We wake up with irritated eyes especially if we went to bed with dry eyes (TV or reading late before retiring). 

• Our genes
– some people have the tendency towards dry or oily skin or hair. They were born that way. The same applies to our eyes. 

• Rubbing the eyes
disturbs the delicate three-layered stucture of the tearfilm and causes it to break up forming dry spots. 

Treatment:

The first aim should be to avoid as many as possible of the causes mentioned above.

• Sometimes it only requires switching off a ceiling fan in the bedroom! Or, worse, a heater or air-conditioner. 
  
• Make sure ventilation in the car is not directed at your face. Air-conditioning extracts moisture from the atmosphere and your tears end up in a puddle under your car on the garage floor! 
  
• Many students use too bright study lamps positioned too close to the face. 
  
• Coping with computers and their tiring (read: drying) effect on the eyes is an ever increasing problem. The problem is caused by staring in one direction for long periods. This reduces the blinking frequency and increases evaporation time. Develop the habit of frequently looking away. Every time you change your direction of gaze, you blink your eyes. 
  
• Changing treatment for glaucoma, hipertension, hormone replacement, contraception, allergies, etc. often has a beneficial effect. Talk to your medical practitioner. 
  

Unfortunately these measures do not always solve the problem.

More and more sufferers need artificial tears to supplement the tearfilm. A wide variety of products are available.

Drops dispensed in bottles contain preservatives which limits the frequency of use because they can harm the surface of the eye. These cannot be used with contact lenses and has to be discarded 30 days after being opened.

Preservative free drops can be instilled more frequently and can be kept until it expires because it remains sealed and sterile until opened. Can be used with contact lenses.

Gel preparations has a longer lasting effect and is the treatment of choice for many. Not with contact lenses.

Important: Treatment with artificial tears is preventive and cannot reverse symptoms once dryness has set in. Use the drops before you start reading, switch on the computer or TV etc. The drop is effective for only an hour or perhaps two after instillation. It evaporates and drains away towards the nose and throat along the tear ducts. Now you know why you can taste certain drop at the back of your throat a while after instillation and why your nose runs when you cry!

In selected cases it may be necessary to concider partially blocking the tear ducts to conserve tears on the surface of the eye and to slow down the drainage of artificial tears towards the nose and throat. Punctum plugs can be inserted in the ducts as a minor procedure. Usually temporary plugs that dissolve after about 5 days are used to determine the effectiveness before the more permanent (but removeable) silicone plugs are inserted.

Useful Links:

Dry eye syndrome

When eyes turn desert dry