Keratoconjunctivitis sicca

Definition/diagnostic criteria Keratoconjunctivitis sicca (KCS), commonly known as dry eye syndrome, is characterised by a deficiency in tear production or tear film instability, leading to ocular discomfort and potential damage to the ocular surface. Diagnostic criteria include subjective symptoms of ocular discomfort, such as dryness, burning or a gritty sensation, and objective signs including reduced tear break-up time (TBUT), low Schirmer test scores, and ocular surface staining.

Epidemiology
KCS is common, particularly among older adults. In the UK, it is estimated that 15-33% of individuals aged over 65 suffer from dry-eye symptoms. The condition is more common in women, particularly post-menopausal women, due to hormonal changes affecting tear production.

Usually the condition is related to ageing, but can have an underlying cause such as Sjogren’s syndrome. It can also occur as a medication side-effect.

Diagnosis
Clinical features: Patients typically present with symptoms of ocular irritation, such as dryness, redness, sensitivity to light, blurred vision, and discomfort in windy or dry conditions. Examination may reveal conjunctival hyperaemia, corneal epithelial defects, and reduced blinking frequency.

Investigations: Diagnosis is often clinical. Possible investigations include:

• Schirmer test to measure tear production.
• TBUT to assess tear film stability.
• Tear osmolarity can also be measured, with higher levels indicative of KCS.
• Ocular surface staining can reveal damage to the corneal and conjunctival epithelium.

Treatment
The mainstay of treatment for KCS involves the use of artificial tears, which are available over the counter and by prescription. These vary in viscosity, with thicker preparations providing longer-lasting relief but potentially causing blurred vision. Preservative-free formulations are recommended for frequent use to reduce the risk of preservative-induced irritation.

• In more severe cases, topical anti-inflammatory medications may be considered.
• Environmental modifications, including avoiding dry or windy conditions and using humidifiers, can also provide symptomatic relief.

Prognosis
KCS is typically a chronic condition requiring ongoing management. With appropriate treatment, most patients achieve good control of symptoms and prevent progression to more serious ocular surface disease. In some cases, untreated severe KCS can lead to complications such as corneal ulceration and vision loss.