Peripheral ulcerative keratitis: a sight-threatening corneal condition

The cornea is the clear front window of the eye. In peripheral ulcerative keratitis the outer rim of the cornea, next to the white of the eye, becomes inflamed, thins and breaks down. EyeWiki describes PUK as a group of inflammatory diseases whose final common pathway is peripheral corneal thinning, and says the lesion is a crescent-shaped destructive area of the corneal stroma near the limbus with an overlying epithelial defect.

The mechanism is immune rather than infective. EyeWiki explains that immune complexes activate the complement system, drawing inflammatory cells that release enzymes which destroy corneal tissue. In Mooren ulcer, a related condition of unknown cause, there is no associated systemic autoimmune disease. PUK is therefore both an eye problem and often a signal of disease elsewhere in the body.

EyeWiki lists autoimmune disorders as the primary risk factors: rheumatoid arthritis, present in 34 to 42 percent of patients with PUK, polyarteritis nodosa, inflammatory bowel disease, systemic lupus erythematosus, relapsing polychondritis and the ANCA-associated vasculitides including granulomatosis with polyangiitis and microscopic polyangiitis. It says 36 percent of patients also have scleritis, which is inflammation of the white of the eye.

The NHS rheumatoid arthritis page lists inflammation of other areas of the body, such as the lungs, heart and eyes, among possible complications. People with rheumatoid arthritis or another connective tissue disease who develop a painful red eye should therefore mention their condition and seek assessment rather than assume it is simple conjunctivitis.

EyeWiki says patients may present with pain, redness, tearing, photophobia and decreased vision, and may have a history of autoimmune disorders. Progressive thinning can lead to a descemetocele and perforation of the cornea.

The NHS red eye page advises an urgent appointment with a GP or optician, or NHS 111, for a very painful red eye or a red eye in someone who wears contact lenses, and says to call 999 or go to A&E for a red eye with changes to your sight, pain on looking at light, a severe headache and sickness, or very dark red eyes. Do not drive yourself to A&E with a painful eye and altered vision; ask someone else to drive you or call 999.

• A very painful red eye that does not settle.

• Reduced or blurred vision, light sensitivity or watering.

• A crescent-shaped area of thinning at the edge of the cornea, which is found on examination.

• Known rheumatoid arthritis or vasculitis with new eye symptoms.

EyeWiki says diagnosis is based on history and examination, with a full eye examination including slit lamp assessment focused on the peripheral cornea to see the depth of thinning, the epithelial defect and the degree of inflammation. Corneal scrapings may be taken for culture if infection is suspected, and an ultrasound may be used to look for posterior scleritis.

Patients should also be evaluated for underlying systemic autoimmune disease with laboratory tests and referral to a rheumatologist. The list in EyeWiki includes a full blood count, metabolic profile, urinalysis, antinuclear antibodies, ANCA, rheumatoid factor and anti-CCP, tests for syphilis and tuberculosis, hepatitis screening and a chest X-ray. Other conditions that can resemble PUK include Mooren ulcer, rheumatoid furrow, Terrien marginal degeneration and pellucid marginal degeneration, as well as infective ulcers.

EyeWiki lists the goals as minimising inflammation, preventing infection, promoting healing of the ulcer and preventing perforation. Eye treatment includes preservative-free lubricants and ointments, punctal plugs, topical cyclosporine to reduce inflammation, oral doxycycline for its anti-collagenase effect with vitamin C, topical antibiotics for infection, and, in impending perforation, cyanoacrylate glue. It says topical steroids should be used with extreme caution because they may accelerate corneal melting.

Because the disease is usually part of a systemic condition, systemic immunosuppression is often required. EyeWiki says initial treatment is typically with oral or intravenous steroids, with steroid-sparing agents such as methotrexate, azathioprine, mycophenolate, ciclosporin, tacrolimus, cyclophosphamide and biologic agents used in impending perforation, disease uncontrolled with steroids or associated rheumatoid arthritis. Treatment is shared between ophthalmology and rheumatology or another medical specialty. Surgery, such as lamellar or penetrating keratoplasty, is indicated for perforation or impending perforation.

EyeWiki says visual prognosis is related to the severity of disease and that complications include infection and perforation of the ulcer. It also notes that patients with associated systemic disease have an increased risk of death from vascular events, which is why identifying and treating the underlying disease matters as much as treating the eye.

Regular follow-up is needed, because medication doses are adjusted to the clinical response and the disease can recur. People on immunosuppressants need monitoring for side effects and infection risk, and should seek advice promptly for fever or new symptoms.

On the NHS, PUK is managed by hospital ophthalmology, often a cornea or uveitis clinic, with rheumatology involved. Urgent cases are seen through eye casualty. Private ophthalmology is available, but the need for combined eye and medical specialist care applies in either setting. No UK patient leaflet specific to PUK was found while preparing this page, and the main source is clinician-facing and from the American Academy of Ophthalmology.