Peripheral Ulcerative Keratitis
Peripheral ulcerative keratitis
Description, Causes and Risk Factors:
Peripheral ulcerative keratitis is also called marginal keratolysis or peripheral rheumatoid ulceration. This condition is often associated with active or chronic rheumatoid arthritis, relapsing-polychondritis (connective-tissue in?ammation) and Wegerner's granulomatosis, a rare condition characterised by kidney disease and development of nodules in the respiratory tract.
Peripheral ulcerative keratitis refers to a crescent shaped destructive inflammation of the juxtalimbal corneal stroma associated with an epithelial defect, presence of stromal inflammatory cells, and stromal degradation. The ulceration may progress both centrally and circumferentially, relentlessly, unresponsive to topical or conservative local therapy. The conjunctiva, episclera and/or sclera are usually inflamed. Vascularized corneal pannus is absent in the active phase. The signs of resolution of active PUK include resolution of the conjunctival inflammation, epithelialization of the corneal surface with residual corneal thinning and a vascularized scar. Whatever the etiology, PUK is always a local destructive process mediated by the final pathway of collagenolytic and proteolytic enzymes released from neutrophils and/or macrophages. The end result is peripheral corneal stromal degradation.
Peripheral ulcerative keratitis occurs when immune complexes activate the complement system resulting in chemotaxis of inflammatory cells (neutrophils & macrophages). These neutrophils and macrophages release collagenase and protease that destroy corneal stroma. Proinflammatory cytokines induce stromal keratocytes to produce matrix metalloproteases which contribute to the breakdown of the cornea.
Other causes and risk factors:
Peripheral ulcerative keratitis may be caused by:
Giant cell arteritis.
Diseases of the digestive tract inflammation.
Disorders of metabolism.
The use of contact lenses.
Injury to the eye due to chemicals, trauma or surgery.
Keratitis (due to viruses, bacteria, fungi and acanthamoeba).
Major risk factors for this disease is a connective tissue disease and vascular disease.
Among patients with rheumatic disease and peripheral ulcerative keratitis, the 10-yr mortality rate is about 40% (usually due to MI) without treatment and about 8% with systemic cytotoxic therapy.
Patients with PUK frequently present with pain, tearing and photophobia. In contrast, patients with non-inflammatory peripheral thinning disorders such as Pellucid or Terrien's marginal degeneration are usually asymptomatic except for decreased vision. Visual acuity may be decreased in patients with PUK if there is central corneal involvement or significant astigmatism. On slit lamp biomicroscopy, one finds variable degrees of stromal loss or thinning adjacent to the limbus. As in all true ulceration, there is an epithelial defect with an underlying subepithelial inflammatory infiltrate. Non-ulcerative peripheral corneal thinning such as Terrien's degeneration will have intact epithelium.The conjunctiva and episclera are usually inflamed. Associated scleritis, especially the necrotizing form, is a highly significant finding because its presence signals an underlying systemic vasculitic process. In the appropriate clinical setting, the detection of scleritis may rule out Mooren's ulcer, which classically has no associated scleritis.
Evaluation of patients with suspected peripheral ulcerative keratitis includes a complete ophthalmological exam. The Ophthalmologist will assess patient's vision, intraocular pressure, pupils, and examine the eyes with a slit lamp. Examination will focus on the peripheral cornea to assess the degree of involvement, depth of corneal thinning, extent of epithelial defect, and degree of inflammation.
Laboratory tests should focus on the suspected systemic disease.
Urinalysis (UA), blood urea nitrogen (BUN), and creatinine.
Erythrocyte sedimentation rate (ESR).
Rheumatoid factor (RF); positive in 80% of patients with associated RA.
Angiotensin-converting enzyme (ACE); elevated in sarcoidosis.
Antinuclear antibodies (ANA); positive in patients with SLE and RA.
Antibody to double-stranded DNA (anti-dsDNA); associated with SLE.
Antibodies to small nuclear ribonucleoprotein-Sm (anti-Sm); associated with SLE.
Antibodies to small nuclear ribonucleoproteins(anti-RNP); associated with SLE.
Antineutrophil cytoplasmic antibodies (ANCA); C-ANCA sensitivity of 96% for active generalized WG (Wegener granulomatosis), 67% for active regional disease, and 32% for WG in full remission after initial regional symptoms.
Circulating immune complex (CIC) - Raji cell assay; C-1q binding assay.
Anti-type II antibodies; associated with RP.
Complement - C3 and C4, CH50; consumed in patients with SLE.
Hepatitis B surface antigen (HBsAg); present in 40% of patients with PAN (polyarteritis nodosa).
Fluorescent treponemal antibody-absorption (FTA-ABS) for syphilis.
Complete blood cell (CBC) count.
A combination of local and systemic therapy may be indicated in autoimmune mediated or vasculitic PUK. Aggressive topical steroids, topical cyclosporine A 2%, collagenase inhibitors or collagenase synthetase inhibitors have been used with varying results as adjunct therapy. Treatment with topical corticosteroids may be harmful in a subset of vasculitic PUK because they inhibit new collagen production. Local surgical therapy such as conjunctival resection, ulcer debridement, application of tissue adhesive to the ulcer bed and to a small rim of surrounding normal cornea and sclera, and application of continuous wear bandage soft contact lens can be used to delay the disease process while the patient is being immunosuppressed. The indications for the use of systemic immunomodulatory agents including methotrexate, cyclophosphamide, cyclosporine and azathioprine are : (1) PUK associated with potentially lethal systemic vasculitic syndromes such as PAN, RA, SLE, PSS, Sjögren's syndrome, RP, Wegener's granulomatosis, allergic angiitis of Churg-Strauss, and giant cell arteritis. (2) PUK associated with necrotizing scleritis and vasculitis is found by histopathologic analysis of ocular tissue. (3) Bilateral and/or progressive Mooren's ulcer. (4) PUK unresponsive to aggressive conventional medical and surgical therapy. A combination of oral prednisone and an immunomodulatory agent such as methotrexate is usually initiated at the same time. It may take about 4 to 6 weeks for the immunomodulatory agents to take effect. Oral prednisone is used in the interim to stabilize the patient and control the active inflammatory process until the immunomodulatory agent takes effect. Prednisone is subsequently tapered and the patient maintained on the systemic immunomodulatory agent. If the initial combination of therapy is ineffective after several months, the patient will be switched to a different agent such as cyclophosphamide. The methotrexate is stopped and the oral prednisone increased in the crossover period. In patients with PUK associated with Wegener's granulomatosis and polyarteritis nodosa, cyclophosphamide at a daily dosage of 2 mg/Kg orally together with corticosteroids (1mg/Kg) may be the initial therapy of choice. Oral cyclosporine is more effective in intraocular inflammation and is rarely used in PUK. Treatment of patients with non-autoimmune associated PUK such as rosacea may include systemic doxycycline or minocycline, lid hygiene and lubrication, and metronidazale for the dermatologic findings.
NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
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