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dry eyes

Figure 1. Illustration of the Tear gland and duct.  (Reproduced from Patient Pictures: Ophthalmology, Health Press, Oxford 2001. Illustrated by Dee McLean)

wHAT IS dry eyes syndrome?

Dry eyes' is a condition in which the amount of tears in your eyes are either insufficient or dry up too quickly. You may also experience symptoms of dry eyes if certain components of the tears (mucus and lipid) are insufficient. This may occur if you have an eyelid or conjunctival disease, such as blepharitis (inflammation of the eyelids), or when normal blinking is disrupted by neurological or eyelid abnormalities.

about your tears

We tend to start tearing when something is very funny, or very sad. However, if your eyes are healthy, glands in your eye are making tiny amounts of tears all of the time. This is known as the ‘tear layer’. The tear layer helps to protect your eye and also allows you to see clearly. It is made up of 3 main ingredients:


  1. Aqueous (water) – Tears are mostly made of water. This is produced by the lacrimal gland, which is located above your eye, underneath your eyelid. Water is required to moisten the eye, wash away debris and provide a smooth corneal surface to help your eye focus. The lacrimal gland also secretes antibodies and anti-bacterial elements to protect the eye.

  2. An oily outer layer – The oily, outer layer is produced mainly by glands within your eyelids (the meibomian glands). This layer lubricates your eye, which helps you blink. The oil also stops your tears from evaporating too quickly.

  3. An inner mucus layer – This layer is produced by glands within the conjunctiva (the clear layer that covers the white part of your eye and the inside of your eyelids). The mucus layer helps to spread tears over the surface of your eye.

TearsDiagram (2).jpg

Image courtesy of NIH National Eye Institute

what causes dry eyes?

There are a number of potential reasons for your dry eyes. These are listed below:


  • Ageing – Dry eyes occur as a part of the natural aging process, especially after the menopause.


  • Medication – Various drugs can reduce your lacrimal gland secretions such as

    • certain antidepressants

    • some blood pressure drugs (including diuretics)

    • medications for Parkinson’s disease

    • contraceptive pills

    • opiate-based pain relief (such as morphine)

    • isotretinoin-type drugs


  • Laser eye surgery (e.g. LASIK) – Some people who have had certain types of laser eye surgery find they have dry eyes in the weeks after surgery. This is usually a result of damage to the corneal nerves. The nerves usually regenerate and dryness typically improves. Occasionally, it can cause permanent problems, and individuals with significant existing dry eye syndrome should not undergo LASIK treatment.


  • Other medical conditions – Some medical conditions can cause inflammation or destruction of the lacrimal gland, resulting in impaired aqueous production. These include:

    • Sjogren’s syndrome, which may occur on its own or alongside other rheumatological diseases, such as rheumatoid arthritis and systemic lupus erythematosis.

    • Other conditions, such as ocular cicatricial pemphigoid or Stevens-Johnson syndrome can cause conjunctival scarring, which causes dry eyes by blocking the lacrimal gland ducts. Conjunctival scarring can also occur as a result of chemical burns.


  • Blepharitis (a condition that causes inflammation of the eyelids) and other such conditions may cause meibomian gland dysfunction, which impairs the secretion of the other components of tears (lipid and mucous), making the eyes dry.


  • Finally, neurological problems, including stroke and Bell’s palsy, can affect your ability to blink/close your eyelids. This prevents the spread of tears over the eye and allows excessive tear evaporation. This can be a serious problem when you're sleeping and in severe dry eyes you may get a corneal ulcer which will require intensive antibiotics.

what are the symptoms of dry eyes?

There are several symptoms of having dry eyes. You may experience all, or just some of them. Symptoms include:

  • itchy eyes

  • a gritty feeling in your eye

  • a burning sensation in your eye

  • stringy mucus in your eye

  • blurred vision

  • sensitivity to light

  • red eyes

  • lack of tears when you cry


Your symptoms may worsen with:

  • windy weather

  • dusty and smoky environments

  • smoking

  • dehydration

  • air conditioning


Your symptoms may improve by closing your eyes.

how dry eye symptoms is diagnosed?

Dry eye syndrome is diagnosed using a slit-lamp (Figure 2). A slit-lamp is a special microscope that eye doctors (ophthalmologists) use to give a magnified image of your eye. A slit-lamp can enable us to see whether:
  • The tear meniscus on the lower lid margin is reduced in size

  • There are strands of mucus in the tear film

  • There are abnormalities of the cornea, or loss and damage to the corneal epithelium (corneal skin cells)

  • These areas of damage can be highlighted using a special yellow dye called fluorescein (Figure 3).


You may also undergo some special tests to help us with our diagnosis. These include:

  • Tear break-up test – This test helps your eye doctor to see whether you have a healthy tear layer. He or she will put droplets of yellow dye (fluorescein) into your eye, which makes the tear layer visible. Your doctor will then time how long it takes for the tear layer to break-up and dry-out. If this takes less than ten seconds, your eyes are drying out too quickly.


  • Schirmer test – Your doctor will place one end of a thin strip of filter paper inside your lower eyelid. The other end will stick out of your eye. Your doctor will measure the amount of liquid the paper soaks up in five minutes. This test can also be done using special cotton threads.

Fluorescein staining of dry parts on the eye


Schirmer test

Image courtesy of American Academy of Opthalmology

what are the treatments available for dry eyes?

There are three main ways to treat dry eyes:


  1. Tear replacement

  2. Preservation of existing tears

  3. Reducing tear drainage



1. Tear replacement


Tear replacement is the main treatment for dry eye syndrome. You will need to take tear replacement medicines regularly for them to work. They can reduce the symptoms of dry eye syndrome and prevent further damage to your eyes.


There are different types of artificial tears and finding the right one for you may take some trying out:


  • Eye drops – There are many different brands for different types of dry eye. Most are available over the counter without a prescription

  • Preservative-free drops are available in single doses if you become sensitive to preservatives. They are also advisable if you are using artificial tear drops more than four times a day. Eye drops need to be used often to work well, so make sure you follow your doctor’s instructions.

  • Eye gels  – These last longer than eye drops, so you will need to use them less frequently

  • Eye ointments – These can be useful in lubricating the eye overnight. However, eye ointments are sticky and tend to blur vision. This means they have limited use in the daytime.


2. Preservation of existing tears


By controlling your environment, you can help your tears work better and last longer. Below is a list of changes that you can make to help with dry eye syndrome:


  • Avoid air-conditioning (air-conditioners reduce the humidity of the air)

  • Avoid smoking

  • Avoid or reduce your reliance on contact lenses

  • Keep well hydrated with water (NOT fizzy drinks, tea or coffee)

  • Take regular breaks when reading, using a computer or watching TV. You blink less when doing these types of visual activities, so your eyes dry out more quickly. A good rule of thumb is the 20-20-20 rule; take a 20-second break every 20 minutes and look at something at least 20 feet away or just close your eyes and relax.

3. Reducing tear drainage

In more severe cases, tear ducts, which drain away the tears, may be deliberately blocked, partially or completely, to conserve tears. Silicone plugs can be placed in the tear ducts to block them. This helps keep both natural and artificial tears on the eyes for longer.

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