Ocular Surface Disease

The surface as a system

The ocular surface is the cornea, the conjunctiva, the eyelids and the tear film working together: the lids spread the tears, the meibomian glands supply the oil, the lacrimal gland the water, the conjunctival goblet cells the mucin, and the corneal nerves the signals that coordinate it. Disease in any part disturbs the rest. Blepharitis damages the glands; gland failure dries the surface; the dry surface inflames; inflammation damages the glands and the goblet cells. Ocular surface disease is the name for that interlocking set of problems.

The components

• Dry eye disease: evaporative from meibomian gland dysfunction, aqueous-deficient from low tear production, or mixed
• Eyelid disease: blepharitis, demodex, rosacea, and lids that do not close fully in sleep or after facial palsy
• Conjunctival disease: allergic conjunctivitis, conjunctivochalasis (loose folds of conjunctiva), pinguecula and pterygium
• Medication toxicity: preserved glaucoma drops and other long-term medications that damage the surface
• Systemic disease: Sjogren's syndrome, graft-versus-host disease, thyroid eye disease, rheumatoid arthritis
• Post-surgical: reduced corneal sensation and dryness after LASIK, cataract or corneal surgery
• Neurotrophic keratitis: surface breakdown from loss of corneal nerve function

Assessment

A thorough slit lamp examination of the lids, lashes, gland openings, conjunctiva and cornea, with fluorescein and lissamine green dyes to show damaged cells; tear film break-up time and, where appropriate, osmolarity, inflammation testing and meibography; an assessment of lid closure and blink; and a review of every drop and medication in use. The findings are graded into a picture of which components are affected and how severely.

Treatment in layers

Treatment addresses each component, usually stepwise: the lids first, with hygiene, warm compresses, treatment of demodex or rosacea, and gland treatment; then the tears, with preservative-free lubricants and punctal plugs; then inflammation, with cyclosporine, lifitegrast or short steroid courses; then protection for the most damaged surfaces, with serum tears, scleral lenses, moisture chambers or, for exposure, taping or surgery on the lids. Preserved drops are switched to preservative-free alternatives. Systemic disease is managed with the relevant physician. Improvement is measured at follow-up with the same tests.

Why it matters for surgery

A diseased surface gives inaccurate pre-operative measurements, heals more slowly and sees less clearly after any eye surgery. Patients preparing for LASIK, cataract or lens surgery are checked for ocular surface disease, which is treated before measurements when it is found.