· It is a chronic, progressive and painful peripheral keratitis of idiopathic/unknown etiology and no systemic associations.
Autoimmune process - a Type 3 hypersensitivity reaction has been implicated - antigen antibody reaction to infectious toxin deposited in the peripheral cornea causes inflammation and ulceration
More common in adult males
Infectious associations have been reported- helminthiasis, hepatitis C
TYPES:
1. Limited/Typical
Unilateral, older patients, mild to moderate symptoms, responded well to medical and surgical treatment
2. Malignant/Atypical
Bilateral, younger patients, severe symptoms, poor response to therapy
Three zones of involvement:
Superficial stroma:
1. Vascularised and infiltrated with plasma cells and lymphocytes
2. Destruction of collagen matrix
3. Absent epithelium and Bowman’s
Mid stroma:
1. Fibroblast hyperactivity
2. Collagen lamellae are disorganized
Deep stroma:
1. Heavy macrophage infiltrate
2. Sparing of Descemet’s membrane and endothelium
SYMPTOMS:
Pain is excruciating - out of proportion to the inflammation
Redness, lacrimation, photophobia
Reduced vision - irregular astigmatism due to peripheral corneal thinning, associated uveitis, central corneal involvement
SIGNS:
Progressive, peripheral, crescentic corneal ulceration that is slightly central to the corneoscleral limbus
Patchy peripheral stromal infiltrates → Coalesce → spreads circumferentially and then centrally → involves limbus and entire cornea eventually
Anterior ⅓ to ½ of corneal stroma involved with a steep, overhanging edge
Leading and central edge is typically undermined
Adjacent conjunctiva - inflamed
Lab investigations to rule out other peripheral ulcerative keratitis (PUK):
1. CBC with differential count
2. Platelet count
3. ESR
4. Rheumatoid factor
5. ANA
6. ANCA
7. Complement fixation
8. Circulating immune complexes
9. VDRL/FTA-ABS
10.BUN and creatinine
TREATMENT:
Stepwise Approach
The goal of therapy is to arrest the destructive process and to promote healing and reepithelialization of the corneal surface
1. Topical corticosteroids to control the inflammation
2. Conjunctival resection
3. Systemic immunosuppression
4. Surgical procedures:
· Superfical lamellar keratectomy
· Small perforations can be sealed with glue and bandage contact lens
· Patch graft/ penetrating keratoplasty is necessary in larger perforations not amenable to glue
Image from Rajan Eye Care Hospital