Keratoconus - Cone-Like Cornea

Keratoconus

Keratoconus is a progressive eye disease in which the cornea begins to thin out and bulge into a cone-like shape. The change in shape of the cornea cause deflection in light traveling to the retina. The out of focus light causes blurry and distorted vision making daily tasks difficult to
perform. Keratoconus affects both genders and all ethnicities. It is the most common primary corneal ectasia. It is a bilateral and asymmetric corneal degeneration characterized by localized corneal thinning. This causes high myopia and irregular astigmatism which affects the visual
quality.

The cause of keratoconus is uncertain. However, genetics may play a role in some cases. Initially, keratoconus can go unnoticed by patients since it doesn’t produce any symptoms. According to research studies, the prevalence in general population has been estimated to be
54 per 100,000.

Patients with keratoconus usually experience blurring of vision, slightly distorted vision, increase in light sensitivity and eye redness or swelling. These symptoms between two eyes can be similar or they can differ. The symptoms may exacerbate in severe cases of keratoconus. In
contact lens wearers, they may feel that the contact lens no longer fit properly or it may feel uncomfortable in the very severe cases.

Keratoconus can be diagnosed at the routine exam. The clinical signs to look out for keratoconic patients are Fleischer’s ring, Vogt’s striae, Munson’s sign, and Rizzuti’s sign. The topography shows asymmetric bow-tie pattern.

Keratoconus management varies depending on the disease severity. Traditionally, initial cases of keratoconus are treated with spectacles. However, as the disease progresses, irregular astigmatism develops and optimum vision can’t be obtained with spectacle lenses. Mild-to-
moderate keratoconus are managed with contact lenses. Contact lens is proven to be the most common and successful treatment option. Different types of contact lenses are available such as soft contact lens, gas-permeable rigid contact lens, scleral lenses and hybrid contact lens. There are many different designs treating for keratoconus within these categories of contact lenses.

Keratoplasty is usually performed on the very severe cases of keratoconus. There are many types of keratoplasty. In penetrating keratoplasty, full thickness of cornea is removed and
replaced by a transparent corneal tissue. Other surgical options include intracorneal rings segments (Intacs) and corneal cross-linking.

Author
Dr Kambiz Silani & Khusbu Patel Chief Clinical Director & Student Doctor

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