VKC and AKC

VKC

VKC is a recurrent bilateral, external ocular inflammation primarily affecting boys/young adults living in warm/dry climates. It's an allergic disorder in which IgE and cell-mediated immune mechanisms play an important role. About 3/4 of patients have a family history of atopy. Such patients often develop asthma and eczema in infancy. The onset of VKC is usually after five years and the condition eventually resolves around puberty, rarely persisting beyond the age of 25 years. It may occur on a seasonal basis w/peak incidence over late spring and summer.

SYMPTOMS - intense ocular itching which may be assoc w/lacrimation, photophobia, foreign body sensation and burning. Thick mucous discharge and ptosis also occur. There are three main types: Palpebral, Limbal and Mixed. Limbal signs are far more common in dark skinned races while tarsal and conjunctival signs are more common in lighter skinned races.

CLINICAL FEATURES

• Palpebral VKC - diffuse papillary hypertrophy, most marked on superior tarsus. The papillae enlarge and have a flat-topped polygonal appearance reminiscent of cobblestones. In severe cases the connective tissue ruptures giving rise to giant papillae which may be coated with copious mucus. As the inflammation settles the papillae shrink and become more separated but often do not disappear.
• Limbal VKC is characterised by mucoid nodules scattered around the limbus with discrete white superficial spots composed mostly of eosinophils at the apices of the lesions

KERATOPATHY

• Punctate epithelial erosions involving the superior cornea are the earliest findings
• Shield ulceration is a serious problem which may be complicated by bacterial keratitis and rarely perforation.
• Plaque formation may occur when the base of the ulcer becomes coated w/desiccated mucus. This results in defective wetting by tears, prevents re-epithelialisation and predisposes to subepithelial scarring and vascularisation

TREATMENT

Topical

• Steroids are indicated for keratopathy but may be required as short-term therapy for severe discomfort in px w/only conjunctivitis. Fluorometholone should be used since it has a weaker ocular hypertensive effect that dexamethasone or prednisolone.
• Mast cell stabilisers such and nedocromil and lodoxamide are used as prophylactic therapy that reduces the need for steroids. They don't have the side effects of steroids but are no good at controlling acute exacerbations.
• Antihistamines are also effective
• Acetylcysteine 0.5% has mucolytic properties and is useful in the treatment of early plaque formation

Supratarsal steroid injection of betamethasone or triamcinolone is effective in patients with severe disease unresponsive to conventional therapy.

Surgical treatment might be necessary for severe shield ulcers that are resistant to medical therapy. This may involve debridement, superficial keratectomy, excimer lase phototherapeutic keratectomy as well as amniotic membrane transplantation to enhance re-epithelialisation.

ATOPIC KERATOCONJUNCTIVITIS

A relatively rare, but potentially serious condition which most often affects young men w/atopic dermatitis.

CLINICAL FEATURES

• Lids are red, thickened and fissured, w/staph. bleph also common
• Conjunctivitis primarily involves the inferior forniceal and tarsal conjunctiva. Infiltration of the tarsal conjunctiva results in a pale and featureless appearance. During exacerbations there may be chemosis, limbal hyperaemia and papillary hypertrophy. In advanced cases cicatrizing conjunctivitis many develop
• Keratopathy is the main cause of visual impairment and is characterised by punctate epithelial erosions. More advanced lesions include persistent epithelial defects, shield-shaped anterior stromal scars and peripheral vascularisation.
• Complications inculde aggressive herpes simplex keratitis and microbial keratitis

TREATMENT

Similar to that of VKC but more prolonged.

• Topically antibiotics and lid hygiene, preservative free lubricants may prove useful during exacerbations, steroids are affective for short term treatment of inflammatory exacerbations and for keratopathy, mast cell stabilisers such as sodium cromoglycate are effective and should be used throughout the year as prophylaxis against exacerbation and as steroid-sparing agents. NSAIDs such as ketorolac are also effective and may be used in combination w/a mast cell stabiliser. Antihistamines are less effective in AKC than VKC.
• Supratarsal steroid injections when topical treatment is ineffective
• Systemic antihistamines for severe itching, antibiotics such as azithromycin 500mg once daily for three days may be effective in reducing inflammation. Cyclosporin may be useful in severe cases.