Keratoconus

Excerpt

Keratoconus is a progressive bilateral corneal ectatic disorder characterized by cone-like steepening of the cornea. This disorder is one of the leading indications for corneal transplantation in Western countries and can be associated with other medical conditions. Keratoconus typically manifests during puberty or early adulthood, leading to irregular stromal thinning. This results in a cone-like bulge or protrusion and significant vision loss.

Keratoconus is derived from the combination of the Greek words kéras ("cornea") and conus ("cone"). During the early 1700s and 1800s, European eye specialists observed several aspects of keratoconus, such as its appearance, characteristics, and impact on vision. However, it was in 1854 that Dr. John Nottingham, a British physician, offered comprehensive insight into the condition. His work was pivotal in distinguishing keratoconus from other corneal shape abnormalities.

Optical effects of keratoconus include a significant and variable reduction in visual acuity, image distortion, and increased sensitivity to glare and light. The significant asymmetry reduces the ability of spherocylindrical spectacle lenses to correct vision adequately. In modern medicine, keratoconus is recognized as a disorder that affects both eyes, although often with uneven severity, leading to gradual thinning and curvature of the cornea. Patients with keratoconus commonly experience decreased visual acuity due to irregular astigmatism and myopia, which results from corneal distortion and scarring. Keratoconus may remain subclinical and be classified as slightly asymmetric oblique astigmatism.

Contrary to the traditional notion that keratoconus is unrelated to inflammation, recent research suggests a connection with alterations in inflammatory substances, implying potential inflammatory changes in affected eyes. More prevalent in individuals with a family history of keratoconus, the condition may present independently or alongside other vision or general health conditions. Although keratoconus is a bilateral disease, symptoms may be more pronounced in one eye than the other. The manifestation and progression of the disease exhibit considerable variability. In severe cases, keratoconus may lead to the development of acute corneal hydrops.

Progression typically ceases by the fourth decade of life. Treatment primarily focuses on vision correction and prevention of disease progression. Early treatment options for progressive keratoconus include corneal collagen cross-linking, which may help slow or halt the disease progression. Many patients manage the disease with the use of rigid gas-permeable contact lenses. In contrast, a minority of patients may eventually require corneal transplantation.