Vernal Keratoconjunctivitis

By Stuart Macfarlane

Abstract

Vernal Keratoconjunctivitis (VKC) is a recurrent, bilateral, external inflammation primarily affecting boys and young adults living in warm, dry climates. More than 90% of patients with VKC exhibit one or more atopic conditions such as asthma, eczema, or seasonal allergic rhinitis. The onset is usually after five years old and can resolve around puberty. It rarely persists in patients more than 25 years old.

Introduction

VKC is an allergic condition which is IgE-mediated, and was thought to be the only ocular disease to involve solely Type I (immediate) hypersensitivity. Evidence has been found that supports some involvement of type IV hypersensitivity reaction.1

Type I hypersensitivity reactions occur when a sensitised individual comes in contact with a specific antigen. Immunoglobulin E (IgE) has a strong affinity for mast cells, and the cross-linking of 2 adjacent IgE molecules by the antigen triggers mast cell degranulation. This in turn causes the release of various preformed and newly formed mediators of the inflammatory cascade, including histamine, tryptase, chymase, heparin, chondroitin sulfate, prostaglandins, thromboxanes, and leukotrienes. This results in increased vascular permeability and migration of eosinophils and neutrophils.

The involvement of inflammatory cells - particularly eosinophils and mast cells -can produce sequelae. Conjunctival papillae with epithelial downgrowth form crypts, at the base of which lie mucus-producing goblet cells. Plasma cells and lymphocytes collect inside papillae stroma. Vernal shield ulcers develop in the upper regions of the cornea.

Case Report

A 19 year old dark-skinned female presented to MM with chronically irritated, severely itchy, red eyes. The symptoms were more severe in the right eye. She noticed a mucoid discharge. She had a history of allergies and had previously been diagnosed with allergic conjunctivitis.

Lid eversion showed large papillae worse in the right eye. Slitlamp examination showed Trantas dots and mild superior punctate epithelial erosions. She had moderate conjunctival injection.

Her GP had previously prescribed Pred Forte qid for 5 days followed by Lomide qid. She had relief with the topical steroid however her GP would not allow her to instil the drops more than 5 days. She ceased Lomide after 2 weeks when she decided it was not helping and was then prescribed Opticrom qid, which she was currently using.

Primarily limbal VKC was diagnosed by MM and Maxidex qid was prescribed. She was advised to continue the Opticrom qid and review in 3 weeks at which time the steroid would be ceased. MM made the comment that he would usually prescribe Patanol in conjunction with topical steroids however she had recently filled a prescription for Opticrom and had a newly opened bottle.

The chronicity of the disease was impressed upon her. She was advised that Opticrom was a prophylactic medication.

Differential

VKC signs are similar but must be differentiated from Atopic Keratoconjunctivitis (AKC).
-AKC typically affects young males with atopic dermatitis.
-VKC presents at a younger age than AKC and is more commonly found in males.2
-VKC is more common in Spring and AKC is generally perennial.
-VKC is associated with a thick mucoid discharge whereas AKC has a clear watery discharge.
-Trantas dots and shield ulcers are commonly found in VKC and rarely found in AKC.
-Corneal neovascularisation and conjunctival scarring is not found in VKC wheras AKC tends to develop deep corneal neovascularization.
-Conjunctival scraping reveals eosinophils to a greater degree in VKC.1

Discussion

VKC can be divided into three main clinical types:

Palpebral VKC, which is characterised by diffuse papillary hypertrophy particularly on the superior tarsus. The papillae enlarge and develop a cobblestone appearance. In severe cases giant papillae develop which may be coated in copious mucous. In severe cases large papillae may cause mechanical ptosis.2 With treatment the papillae shrink however often do not disappear.

Limbal VKC is characterised by Trantas dots, which are limbal mucoid nodules composed predominantly of eosinophils. It is more common in dark-skinned individuals. As the name implies, papillae tend to occur at the limbus and have a thick gelatinous appearance. They commonly are associated with multiple white spots (Horner-Trantas dots), which are collections of degenerated epithelial cells and eosinophils.1 Horner-Trantas dots are transient, with each appearance rarely lasting more than 1 week.

Mixed VKC, which is a combination of the palpebral and limbal variations.

Keratopathy is common and may involve punctate epithelial erosion (PEE) from a combination of the toxic effect of inflammatory mediators released from the conjunctiva, and direct mechanical action of the papillae on the cornea.

Severe PEE may result in shield ulceration, which is typically shallow with white irregular epithelial borders. This ulcer has the potential to develop microbial infection.

A potential sequela of shield ulceration is plaque formation. The base of the ulcer is composed of abnormal mucus, fibrin and serum, deposited as a grey plaque.3 This results in defective wetting by tears, thus preventing re-epithelialisation. Sub-epithelial scarring and vascularisation may develop.

Inflammation of the limbus can settle leaving a pseudogerontoxon, which resembles an arcus.

Treatment

Allergen avoidance should be emphasised, however often this is impractical. Moving to a more temperate climate is also effective. Air-conditioning and control of dust may help. Cold packs and ocular lubricants can offer temporary relief.

Mast cell stabilisers instilled long term are the mainstay of treatment of VKC with the newer drugs such as Patanol with a combination antihistamine/mast cell stabiliser action preferred.4,5 A short course of topical steroids such as Maxidex or Predneferin Forte generally become necessary for most patients with significant symptoms.

Several reports have shown that topical cyclosporin (Restasis) may be effective in reducing some of the signs and symptoms of VKC.6 Oral aspirin has been shown to be effective.7

Treatment of corneal shield ulcer may require a antibiotic-steroid combination. Mucomyst (acetylcsteine) has been prescribed as a mucolytic. Severe cases of corneal shield ulcer may require superficial keratectomy to promote epithelial regeneration. There have been reports of excimer laser phototherapeutic keratectomy (PTK) being used to remove fibrin deposits on the Bowman layer and theoretically facilitate epithelial healing.8 Also a low water content, thin hydrogel lens can reduce the interaction between the lid and cornea.

References

1. Abelson MB, Madiwale N, Weston JH. Conjunctival eosinophils in allergic ocular disease. Arch Ophthalmol 1983; 101: 555-6.
2. Buckley RJ. Vernal keratoconjunctivitis. Int Ophthalmol Clin 1988; 28: 303-8.
3. O'Connor GR, Chandler JW, eds. Advances in Immunology and Immunopathology of the Eye. Chicago: Year Book Medical Publishers; 1985.
4. Allansmith MR, Ross RN. Ocular allergy and mast cell stabilizers. Surv Ophthalmol 1986; 30: 229-44.
5. Azevedo M, Castel-Branco MG, Oliveira JF, et al. Double-blind comparison of levocabastine eye drops with sodium cromoglycate and placebo in the treatment of seasonal allergic conjunctivitis. Clin Exp Allergy 1991; 21: 689-94.
6. Bleik JH, Tabbara KF. Topical cyclosporine in vernal keratoconjunctivitis. Ophthalmology 1991; 98: 1679-84.
7. Abelson MB, Butrus SI, Weston JH. Aspirin therapy in vernal conjunctivitis. Am J Ophthalmol 1983; 95: 502-5.
8. Cameron JA, Antonios SR, Badr IA. Excimer laser phototherapeutic keratectomy for shield ulcers and corneal plaques in vernal keratoconjunctivitis. J Refract Surg 1995; 11: 31-5.
9. Gormaz A, Eggers C. Vernal keratoconjunctivitis and keratoconus. Am J Ophthalmol 1983; 96: 555-6.