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Management of dry eyes
Consultant Ophthalmologist, Southampton Eye Hospital, Hampshire, UK
Executive Editor, InnovAiT
E-mail: one{at}rbnewsom.plus.com
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Abstract |
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 TOP Abstract The GP curriculum and...The normal tear filmProduction of tears and...Symptoms of dry eyeExamination of the dry...Treatment of dry eyeReferences |
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A dry eye (sometimes called keratoconjunctivitis sicca) is an eye where there are insufficient or inadequate tears to keep the front surface of the eye moist. Patients usually complain of grittiness or irritation which often worsens towards the end of the day.
Dry eye is a common condition, affecting 10–30% of the population. It is more common in women than men and particularly affects older people. The symptoms can be exacerbated by drugs and eye surgery such as LASIK. Patients with connective tissue diseases, such as rheumatoid arthritis or Sjögren's syndrome, may also present with dry eye. In its severest form, dry eye can lead to sight-threatening corneal disease.
Dry eye is listed as an important topic within the knowledge base of statement 15.5 of the GP curriculum (eye problems). With respect to this, GPs must be able to:
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The normal tear film |
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TOPAbstractThe GP curriculum and...The normal tear filmProduction of tears and...Symptoms of dry eyeExamination of the dry...Treatment of dry eyeReferences |
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The normal tear film (Fig. 1) has three distinct layers. Disruption to any of these layers can cause the symptom of dry eye:
- A lipid layer—produced by the meibomian glands. Prevents evaporation.
- An aqueous layer—produced by the lacrimal glands. Provides lubrication and cleans the eye. Also contains proteins (such as lysozyme) which help to protect the eye from infection.
- A thin, hydrophobic, mucinous layer—produced by the goblet cells in the conjunctiva. Helps the tears to spread evenly over the cornea.
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Production of tears and an abnormal tear film |
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TOPAbstractThe GP curriculum and...The normal tear filmProduction of tears and...Symptoms of dry eyeExamination of the dry...Treatment of dry eyeReferences |
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The major causes of dry eye syndrome are summarized in Fig. 2. Production of the aqueous layer depends on two forms of tear secretion:
- Basal tear secretion—this keeps the eye moist regularly
- Reflex tear secretion—this occurs when the eye becomes irritable or in extreme emotion
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It is possible for an individual to lose basal tear secretion, making the eye irritable. In turn, this produces reflex tear secretion. Thus, it is possible that a dry eye may present paradoxically as a watery eye.
Additionally, in patients with reduced tear production, the concentration (osmolarity) of the tears increases, and there may also be a slight reduction in tear pH. Tear stability can also be reduced due to a lack of water, fat or mucus and this can lead to exposure and damage to the underlying corneal cells.
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Symptoms of dry eye |
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TOPAbstractThe GP curriculum and...The normal tear filmProduction of tears and...Symptoms of dry eyeExamination of the dry...Treatment of dry eyeReferences |
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Diagnosis of dry eye can usually be made on history. A dry eye presents with irritation of the eye, burning and gritty pain. These are generally exacerbated by driving, reading or looking at a computer screen and central heating. They are typically worse in the evening and can lead to paradoxical watering of the eye. A history of autoimmune or connective tissue disease, eye trauma or chemical injury can be contributing factors.
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Examination of the dry eye |
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TOPAbstractThe GP curriculum and...The normal tear filmProduction of tears and...Symptoms of dry eyeExamination of the dry...Treatment of dry eyeReferences |
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In patients with dry eye, the lids should be inspected carefully for signs of blepharitis, inflammation or poor function (such as facial nerve palsy or trigeminal nerve palsy). There may be reddening of the eye. Schirmer's test is rarely used in general practice, but can be helpful to test aqueous production. This test consists of placing a small strip of filter paper inside the lower eyelid of each eye. The eyes are closed for 5 minutes. The paper is then removed and the amount of moisture is measured. Less than 5 mm is abnormal.
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Treatment of dry eye |
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TOPAbstractThe GP curriculum and...The normal tear filmProduction of tears and...Symptoms of dry eyeExamination of the dry...Treatment of dry eyeReferences |
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Before treatment of dry eye, treat any underlying blepharitis. Consider and treat any underlying allergic eye disease. Review the patient's medication. Drugs that commonly cause dry eye include: antidepressants, decongestants, antihistamines, blood pressure medication, diuretics, proton pump inhibitors, tranquilisers, beta blockers and oral contraceptives.
Non-drug measures
Advise patients to avoid dry, dusty and smoky environments. Domestic humidifiers may help symptoms. There is also some evidence that increasing the amount of omega-3 in the diet may help. This can be done by eating oily fish. Advise patients to eat two portions of oily fish a week. Other food sources of omega-3 include soya, flax and pumpkin seeds/oils, walnuts and leafy green vegetables. Concentrated omega-3 supplements are also available to purchase over-the-counter.
Artificial tears and lubricant ointments
In order to relieve the symptoms of dry eye it is best to keep the eyes moist by instilling artificial tears. The amount of tears that are retained in the eye depends upon varying factors, such as the ambient temperature, the humidity and wind speed. As this may vary from one environment to another, symptoms can vary significantly day-to-day and even within a day, particularly if the patient is moving around between different locations.
Table 1 summarizes the preparations currently available for treatment of dry eye. Artificial tears act by increasing the aqueous volume of the tears and reducing the osmolarity. They only work while in contact with the eye. Hydrogels are added to increase the contact time with the eye and reduce the frequency of application needed. The more viscous the drop the longer the benefit. However, blurring of vision can occur with viscous drops. A long acting ointment at night (such as Lacri-lube®) can also provide some relief particularly if there is poor lid closure.
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Choice of drop depends on the severity of symptoms and individual patient:
- Mild dry eye—intermittent symptoms that do not affect quality of life. A simple combination of environmental change with occasional, short acting drops may be all that is necessary.
- Moderate to severe dry eye—continuous symptoms or intermittent symptoms that do affect quality of life. Long-acting drops or a combination of drops (for example, a combination of a short-acting drop such as Liquifilm® with a long acting drop such as Celluvisc®) together with a lubricating eye ointment at night may be necessary.
- Severe dry eye—continuous symptoms with associated eye damage. Seek specialist help. It is essential to ensure careful assessment and moderation of every risk factor, as well as meticulous treatment of eye symptoms and signs, in order to stabilize corneal health and prevent visual loss.
If application of eye drops is needed more than four times daily, in general, preservative-free drops are recommended. Benzalkonium chloride (BAC) is the most commonly used preservative; however, it can become an irritant with prolonged use. If sensitivity to BAC occurs, then the ability to treat other eye conditions with drops is affected. Preservatives such as sodium perborate and polyquaternium-1 are less damaging to the eye surface than BAC.
Immune-modulating drops
For patients with immune-based dry eye (for example, patients with Sjögren's syndrome or rheumatoid arthritis), topical cyclosporine may have a role to play in improving lacrimal function. It should only be initiated under consultant supervision. It is thought to act as a T-cell immunosuppressant, although the exact mechanism is not known. The effect may take weeks to become apparent. Cyclosporine drops have also been shown to be useful in other forms of dry eye, for example dry eye as a result of LASIK surgery. Currently drops (Restasis®) are not available in Europe although they are licensed and widely available in North America. Many patients, who might benefit from them, obtain supplies via the Internet.
Mechanical occlusion of the tear duct
Punctal (or punctual) plugs may be used to obstruct the tear duct. These are particularly useful for patients with dry eyes who wear contact lenses. Plugs can be inserted by either an optometrist or ophthalmologist. Temporary punctal plugs are made of collagen. These plugs dissolve in about a week and are useful as a trial treatment. Silicon plugs provide a longer lasting occlusion. The major problem with punctual plugs is excess watering of the eye. Surgery to permanently occlude the tear duct is rarely needed.
Key points
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References |
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TOPAbstractThe GP curriculum and...The normal tear filmProduction of tears and...Symptoms of dry eyeExamination of the dry...Treatment of dry eyeReferences |
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British National Formulary. (2008) 55. Accessed via www.bnf.org [date last accessed 22.08.2008].
Clinical Knowledge Summaries: Dry Eye Syndrome. Accessed via cks.library.nhs.uk/dry_eye_syndrome [date last accessed 22.082008].
DEWS. 2007 report of the International Dry Eye Workshop (DEWS). Ocular Surface (2007) 5(2):65–204.
Khaw PT, Shah P, Elkington AR, eds. ABC of eyes (2004) 4th edition. London: BMJ Books ISBN: 0727916599.
RCGP. The GP Curriculum: Statement 15.5— Eye Problems. Accessed via www.rcgp-curriculum.org.uk/PDF/curr_15_5_Eye_problems.pdf [date last accessed 22.08.2008].
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