keratoconjunctivitis sicca
Summary
Keratoconjunctivitis sicca (dry eye syndrome) results from decreased tear production or increased tear evaporation, leading to dryness and irritation of the cornea and conjunctiva. It is a hallmark feature of Sjögren syndrome but can also occur independently due to aging, medications, or environmental factors. Classic symptoms include gritty, sandy sensation in the eyes, redness, and photophobia.
Detail
Keratoconjunctivitis sicca occurs due to lymphocytic infiltration and destruction of the lacrimal glands (in Sjögren syndrome) or other causes of tear film dysfunction (aging, antihistamines, anticholinergics, vitamin A deficiency, contact lens use, LASIK surgery). Pathophysiology involves either decreased aqueous tear production or increased evaporation due to meibomian gland dysfunction, leading to hyperosmolar tear film and epithelial damage to the cornea and conjunctiva.
In Sjögren syndrome, this is part of the classic triad with xerostomia (dry mouth) and parotid gland enlargement, caused by autoimmune destruction of exocrine glands. It can be primary or secondary (associated with rheumatoid arthritis, SLE, or other autoimmune diseases). Autoantibodies anti-Ro/SSA and anti-La/SSB are characteristically positive.
Clinical diagnosis involves Schirmer test (measures tear production via filter paper placed in lower eyelid; <10mm wetting in 5 minutes is abnormal) and slit-lamp examination with rose bengal or fluorescein staining showing punctate epithelial erosions. Patients present with foreign body sensation, burning, photophobia, and blurred vision that worsens throughout the day.
Complications include corneal ulceration, scarring, and increased risk of ocular infections due to compromised tear film (which normally has antimicrobial properties via lysozyme and IgA). Chronic untreated cases can lead to vision loss.
Treatment includes artificial tears, punctal plugs to retain natural tears, topical cyclosporine (increases tear production by reducing inflammation), and addressing underlying autoimmune disease. Patients with Sjögren syndrome also have increased risk of non-Hodgkin lymphoma (particularly MALT lymphoma of the parotid gland), making this an important association to remember for boards.
Sources
- First Aid for the USMLE Step 1
- Robbins and Cotran Pathologic Basis of Disease
- UpToDate: Sjögren Syndrome
- Vaughan & Asbury's General Ophthalmology
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