It is an atopic condition of the external ocular surface that characteristically affects young men in hot and dry climates on a seasonal basis.
History of the disease
The first description of VKC (known by its acronym in English) is attributed to Arlt, who described 3 cases of peri-limbal inflammation in young patients in 1846.
In 1899 Trantas described the limbal white spots that Horner had previously demonstrated. In 1908, Gabrielides identified eosinophils in the conjunctival secretions and the peripheral blood of patients with Keratoconjunctivitis. In 1910, Trans characterized the spectrum of corneal changes seen in VKC.
Keratoconjunctivitis is characterized by severe itching, photophobia, foreign body sensation, mucous discharge (often described as “ropy”), blepharospasm, and blurred vision.
In a 1988 review, Buckley coined the term “morning misery,” which described the active disease status of patients with severe discomfort, blepharospasm, and mucous discharge that left them unable to wake up and “often resulted in late school.”
It is usually bilateral but may be asymmetric. While Keratoconjunctivitis is typically seasonal and recurrent (hence the vernal name meaning spring), 23% of patients may have a perennial form of the disease, and many may have recurrences outside of spring.
Keratoconjunctivitis signs can be divided into conjunctival, limbal, and corneal signs.
Conjunctival signs include diffuse conjunctival injection and superior tarsal giant papillae. These are discrete 1 mm in diameter that characteristically have flat tops that sometimes show spots with fluorescein.
In addition, these giant papillae can sometimes be seen near the limbus, and while relatively uncommon sympathetic formation and conjunctival fibrosis may occur.
Limbal signs include thickening and opacification of the limbal conjunctiva, the gelatinous appearance, and sometimes the confluent limbal papillae.
The Peri-limbal points of Horner-Trantas are white limbic focal points consisting of degenerated epithelial cells and eosinophils.
The limbal disease can result in a deficiency of limbal stem cells, leading to pannus formation with corneal neovascularization.
Corneal signs vary according to the severity of the disease process. Punctate epithelial erosions or keratitis may fuse into macro erosions of the epithelium.
Plaques containing fibrin and mucosa can accumulate in macro erosions forming Shield ulcers. Corneal neovascularization may follow, and resolution may leave a characteristic ring-shaped scar.
A grayish-white lipid deposition may occur in discoloration and the peripheral stroma, known as pseudogerontoxon.
It has been shown that keratoconus is also more prominent in VKC patients, possibly due to an increase in the rubbing of the eyes of patients with chronic irritation.
Differential diagnosis of Keratoconjunctivitis
The primary differential diagnosis to consider is atopic Keratoconjunctivitis (AKC). The AKC usually has a more advanced age of appearance in the second to the fifth decade, compared to the beginning before ten years with Keratoconjunctivitis.
The conjunctival involvement is classically in the superior tarsi in VKC and the inferior tarsus in AKC. In addition, AKC is typically more chronic and more commonly results in corneal scarring and conjunctival scarring, while VKC is typically more self-limited.
Additional differential diagnoses to be considered depending on history and physical state would be seasonal allergic conjunctivitis and giant papillary conjunctivitis.
Demography and Epidemiology
Keratoconjunctivitis is a condition that is observed mainly in hot and dry climates, most commonly in West Africa and the Mediterranean basin. It is also widely seen in the Middle East, Japan, India, and South America.
It is believed to be relatively unusual in North America and Western Europe. It is speculated that the higher incidence in warm regions is secondary to a higher level of contamination by pollen and other allergens.
Men are more affected than women, but this difference decreases as age increases.
It is difficult to obtain a precise prevalence since many patients may not present themselves in the clinics since they may have a mild form of the disease, and the condition is mainly self-limited.
Depending on the region and climate, the prevalence of Keratoconjunctivitis can vary widely. In addition, the majority in the endemic areas is much higher when adolescents are observed compared to the general population.
For example, a European study showed that the prevalence was between 1.2-10.6 / 10,000. At least one study showed a prevalence of 4% in African schoolchildren.