Introduction
Dry eye is a common presenting complaint, especially in older patients. It affects 15-30% of people aged over 50. It is usually not indicative of any serious underlying disease, but be aware of Sjögren’s syndrome – an autoimmune disorder causing dry eyes, often associated with another underlying autoimmune diagnosis.
As we age, the natural tears we produce become less oily. As a result, they are less able to keep the surface of the eye moist. As a result, dry eyes can occur – particularly in dry or arid conditions (including air conditioned environments) or when outdoors – especially when windy. Patients may paroxysmally present with watery eyes – as there is compensation for the dry eye and production of excessively watery tears.
The typical presentation will be purely dry eyes, without pain and without visual acuity being affected. In severe cases the yes may become red, but this is not common.
Differentials might include allergy, conjunctivitis (especially if viral and not purulent), glaucoma, herpes simplex or zoster infection, thyroid disease and, as mentioned above, Sjögren’s Syndrome. In some patients deformities of the eyelids preventing proper closure may exacerbate or be the undying cause of the issue.
Often simple measures such as use of artificial tears is all that is required for management.
Physiology
Tears are more complex than it might first appear. The lacrimal glands produce much of the liquid and electrolytes, but mebomian glands produce oils and fats, and the conjunctival goblets cells produce mucins which all come together to format eh constituent parts of the tears.
Once inflammation has been established it can contribute to a vicious circle of ongoing dry eyes and further inflammation if one of the three producers of tears constituents is not able to performs its function to the best of its ability.
Causes
- Common in the elderly – reduced tear secretion
- May have a genetic component
- Persistent gritty sensation without red eye
- Contact lens wearing
- Long periods of time staring at screens – causes decreased blinking which can lead to dry eyes
- More common in diabetes or after previous cataract surgery
- More common in women
- Diuretics, beta-blockers and anticholinergic agents may exacerbate dry eye
- May be associated with blepharitis
- Sjögren’s syndrome: autoimmune condition, dry eyes and mouth which often accompanies connective tissue disorders e.g. rheumatoid arthritis
Presentation
- Dry, gritty sensation in eyes
- Often worse towards the end of the day
- Eyelids may appear red and feel sticky
- Usually bilateral, but not necessarily equally affected
Red flags that suggest a more serious cause include:
- Eye pain
- Altered visual acuity
- Photophobia
- Significant redness of the eye
- Diplopia
- Acute onset
Examination
Examination is often normal. There may be come conjunctival inflammation or in severe cases there could be evidence of corneal ulceration.
A thorough examination of the eyes should be performed including:
- Visual acuity
- Eye movements
- Eye lid movements and closing
- Examination of conjunctiva and sclera with and without fluorescein
- Fundoscopy
- Check for tenderness and firmness of the globe on palpation (glaucoma)
- Consider checking pressures if available
Also consider checking for signs of thyroid eye disease and checking any painful joints.
Investigations
- Staining of the cornea with fluorescein and slit lamp examination
- Schrimer’s test (strip of filter paper in fornix, measure advancing edge of tears)
- Consider TFTs
Treatment
- Artificial tear drops or simple ointments
- Beware that some artificial tears with certain preservatives may exacerbate the issue – especially if used more than 4-6x daily for prolonged periods – advise to use preservative free preparations
- Use 3-4x daily
- If using any other eye drops be careful about manufacturer instructions on when to use
- Acetylcysteine drops can be used to disperse thick mucus
- Medication review – considering ceasing any pro active medications
- Smoking cessation and avoidance of second-hand smoke
- Minimise contact lens wear
- Lifestyle factors:
- Take regular breaks from time staring at screens
- Encourage patient to try to blink more frequently!
- Acetylcysteine drops (in filamentary keratitis)
- Treatment of blepharitis
- Temporary punctal plugs or permanent punctal occlusion (tear conservation)
- Blocks the lacrimal duct either temporarily or permanently
Consider ophthalmology referral or discussion of case via telephone if any red flags or other concerns.
Be aware that dry eyes predisposes to conjunctivitis, keratitis, ulceration and other eye infections