Vernal Keratoconjunctivitis (VKC) – Definition, Treatment and Prevention

Definition

Vernal Keratoconjunctivitis (VKC) is a severe bilateral chronic allergic inflammatory disease of the ocular surface. In most of the cases, the disease is limited to the tarsal conjunctiva and to the limbus. However, in the more severe cases, the cornea may be involved, leading to potentially sight threatening complications. Prompt recognition of these complications is crucial in the management of VKC, which is one of the most severe ocular allergic diseases.

In mild cases of VKC this inflammation causes itching and redness. In more severe cases the surface under the top eye lid can become inflamed and swollen bumps (called papillae) can form. These are sometimes known as cobblestones because of their appearance. When the eye closes these can rub on the front of the eye causing pain and irritation.

Children with VKC often have other allergic conditions like asthma, eczema or food allergies. In most cases children grow out of VKC by the time they reach adulthood.

Anatomy of Eye

Pathophysiology

A personal or family history of atopy is seen in a large proportion of VKC patients. VKC was originally thought to be due to a solely IgE mediate reaction via mast cell release. It has now been shown that IgE is not enough to cause the varied inflammatory response that is seen with VKC. Activated eosinophils are thought to play a significant role and these can be shown consistently in conjunctival scrapings; however mononuclear cells and neutrophils are also seen. Additional attention has been given to the CD4 T-helper-2 driven type IV hypersensitivity with immunomodulators such as IL-4, IL-5, and bFGF. Thought has been given to a possible endocrine method as well as there is a decrease in symptoms and prevalence after puberty.

Types

There are three types of VKC are as follows:

• Palpebral – Papillae primarily involving upper tarsal conjunctiva
• Limbal – Papillae located at limbus
• Mixed – Components of both palpebral and limbal types

Risk factors of vernal keratoconjunctivitis

There are several factors that may make an individual more likely to develop VKC.

The use of kerosene/firewood for cooking, dust exposure, and the presence of non-ocular allergic disease in the child or family members of the child, are statistically significant risk factors for vernal keratoconjunctivitis.

Family and personal history

Your family and personal history are important to consider. Up to 75% of people VKC have experienced allergic diseases previously, such as asthma, eczema or hayfever (allergic rhinitis). In addition, about 40–60% of people with VKC have one or more family members affected by these allergic conditions.

Environment and season

The environment, including geographical location and season is also important. For example, people living in warmer tropical and temperate areas, such as in Mediterranean areas, the Middle East and Africa, are more likely to experience VKC than those in cooler zones. VKC is also more common in the summer.

Age

VKC is more often experienced in childhood and adolescence and it is most common between 4 and 20 years of age. It is estimated that about 80% of people affected by VKC experience symptoms before the age of 10 years.

Gender

VKC is more common in boys and young adult men. The risk of VKC in boys compared to girls is 2–4 times higher. However, in older persons, the male to female ratio is approximately equal.

Causes of Vernal Keratoconjunctivitis

The cause of VKC is a hypersensitivity or allergic reaction of the eyes to airborne allergens. The pathogenesis of ocular allergies is related to a complex exchange of information between tissues through cell-to-cell communications, chemical mediators, cytokines, and adhesion molecules. It is also possible that the neural and endocrine systems may influence ocular allergic responses.

The longer a patient suffers from seasonal VKC, the more likely he or she is to develop the disease chronically. That is why it is important to obtain a swift diagnosis and treat the disease as soon as possible.

Vernal Keratoconjunctivitis Symptoms

Symptoms include:

• Burning eyes.
• Discomfort in bright light (photophobia).
• Itching eyes.
• The area around the cornea where the white of the eye and the cornea meet (limbus) may become rough and swollen.
• The inside of the eyelids (most often the upper ones) may become rough and covered with bumps and white mucus.
• Watering eyes.

Complications of Vernal Keratoconjunctivitis

Complications of VKC may include:

• Corneal scaring
• Microbial keratitis (inflammation of cornea)
• Corneal ulcer
• Corneal opacity
• Hyperplasia of limbal tissue
• Steroid induced cataract and glaucoma
• Visual impairment
• Amylopia may be caused by corneal opacity, irregular corneal astigmatism or keratoconus

Glaucoma or cataract may be caused by unsupervised use of topical corticosteroids.

Diagnosis and test

There are no established diagnostic criteria for VKC. The diagnosis of VKC is based upon the typical epidemiology and clinical features of VKC (eg, young boys living in warm climates who present with ocular pruritus and giant papillae on the conjunctival lining of the upper eyelid).

The typical, characteristic signs and symptoms of this disease render the diagnosis of VKC fairly straightforward, even for the general ophthalmologist.

• Atypical presentations or incomplete forms of VKC may, however, lead to an underestimation of its incidence.
• The identification of both the major and minor signs and symptoms of VKC allows an early and accurate diagnosis of this disease.
• At present, total and specific IgE determination, as well as skin tests cannot be considered useful additional laboratory tests, because more than 50% of patients with VKC are negative.
• In case of a diagnostic dilemma, a conjunctival scrapings or tear cytology can be useful in demonstrating the presence of eosinophils infiltrating the conjunctival epithelium.

Treatment and medications

There are some treatments for VKC that address the inflammation by altering the immune response, including cyclosporine and tacrolimus. Other anti-allergy pharmacological therapies for VKC have been shown to be effective in mild to moderate forms of the disease, but they do not target the underlying inflammatory process, therefore are less effective in severe VKC. These include:

• Vasoconstrictors
• Mast cell stabilisers
• Antihistamines
• Non-steroidal anti-inflammatory drugs
• Corticosteroids
• Surgical intervention

There are limitations to some therapies such as short duration of action, poor efficacy in controlling the condition and risks associated with long-term use

Prevention of Vernal Keratoconjunctivitis

The general principle for preventing all allergies is to avoid the triggers. Triggers for eye allergies can be avoided by:

• Using sunglasses to act as a barrier for airborne allergens;
• Using hypoallergenic bedding;
• Washing sheets in hot water; and
• Minimising animal exposure, if animals are believed to trigger allergic symptoms.

Avoiding allergies may be difficult for people with VKC, because they are often sensitive to a large number of allergens. Relocating to cooler climates is frequently helpful, although this may not be the most feasible solution.

People who do not know what causes their allergic conjunctivitis may consider consulting an allergy specialist. The specialist may do allergy testing to find out what triggers their symptoms.