Other meanings of Keratoconus
Ophthalmology
Keratoconus is a progressive eye disorder in which the cornea thins and bulges into a cone shape, causing blurred and distorted vision. It typically begins in adolescence or early adulthood and can worsen over time, though it often stabilizes by middle age. The condition is bilateral in most cases, though one eye may be more severely affected than the other.
Keratoconus is characterized by progressive thinning and steepening of the cornea, leading to irregular astigmatism and myopia. The condition is often bilateral but asymmetric, with one eye typically more affected. Early symptoms include mild blurring and increased sensitivity to light, while advanced cases may show corneal scarring and marked visual distortion. The classic sign is the Munson's sign, a V-shaped indentation of the lower eyelid when the patient looks down, and Fleischer's ring, an iron deposit around the base of the cone. Diagnosis is confirmed by corneal topography, which reveals characteristic inferior steepening and thinning.
The exact cause of keratoconus is unknown, but it is considered multifactorial, involving genetic, environmental, and biochemical factors. A family history is present in about 10% of cases, and several genes have been associated, including VSX1 and LOX. Chronic eye rubbing is a strong environmental risk factor, particularly in patients with allergic conditions such as atopic dermatitis and hay fever. Other associations include Down syndrome, connective tissue disorders like Ehlers–Danlos syndrome, and sleep apnea. Hormonal changes during pregnancy have been reported to accelerate progression in some women.
Treatment depends on the severity and rate of progression. In early stages, glasses or soft contact lenses may suffice, but as the cornea steepens, rigid gas-permeable lenses are often required to provide a smooth refractive surface. For progressive cases, corneal collagen cross-linking (CXL) is the mainstay to halt progression by strengthening the corneal stroma. Intracorneal ring segments (e.g., Intacs) can be implanted to flatten the cone and improve lens tolerance. In advanced cases where scarring or extreme thinning occurs, corneal transplantation—either deep anterior lamellar keratoplasty (DALK) or penetrating keratoplasty—may be necessary. Topography-guided photorefractive keratectomy (PRK) combined with CXL is an emerging option for selected patients.
Beyond the common clinical picture, keratoconus has several notable nuances. The condition was first described in detail by the German physician Burchard Mauchart in 1748, but it was not until 1854 that John Nottingham gave it the name "keratoconus." Historically, patients were often misdiagnosed with high myopia or astigmatism before topography became widely available. Keratoconus is also a leading indication for corneal transplantation worldwide, yet many patients never require surgery. Interestingly, the condition is more prevalent in certain populations, such as those of Middle Eastern and South Asian descent, and has been linked to higher rates in patients with a history of eye rubbing due to vernal keratoconjunctivitis. Research into the role of oxidative stress and enzyme imbalances in the cornea is ongoing, and some studies suggest that riboflavin-based CXL may also have a role in treating infectious keratitis, a potential off-label application.
This article is for informational purposes only and does not replace professional medical advice.
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