Cornea

Keratoconus

Overview

Keratoconus is a degenerative disease of the cornea that causes it to gradually thin and bulge into a cone-like shape. This shape prevents light from focusing precisely on the retina. As the disease progresses, the cone becomes more pronounced, causing vision to become even more blurred and distorted. Because of the cornea's irregular shape, patients with keratoconus are usually very nearsighted and have a high degree of astigmatism that is not correctable with glasses.

Keratoconus is sometimes an inherited problem that usually occurs in both eyes. However, one eye is often worse than the other.

KCN scar.jpg

Eye with keratoconus

Symptoms

Symptoms of keratoconus may include:

  • Nearsightedness

  • Astigmatism

  • Blurred vision, even when wearing glasses and contact lenses

  • Glare at night

  • Light sensitivity and irritation

  • Frequent prescription changes in glasses and contact lenses

  • Eye rubbing

  • Scarring of the cornea

Detection and Diagnosis

Keratoconus is usually diagnosed when patients reach their twenties. For some, it may advance over several decades, and for others, the progression may reach a certain point and stop.

Keratoconus is not usually visible to the naked eye until the later stages of the disease. In severe cases, the cone shape is visible to an observer when the patient looks down while the upper lid is lifted. When looking down, the lower lid is no longer shaped like an arc, but bows outward around the pointed cornea. This is called Munson's sign.

Special corneal testing called topography provides the doctor with detail about the cornea's shape and is used to detect and monitor the progression of the disease. A pachymeter may also be used to measure the thickness of the cornea.

Treatment

Mild cases may just require routine observation with or without a new glasses prescription. If the condition worsens, contact lenses such as rigid gas permeable lenses or scleral (e.g. PROSE) lenses may be used to rehabilitate the vision.  Because these type of contacts are not flexible, they creates a smooth, evenly shaped surface to see through. However, because of the cornea's irregular shape, these lenses can be very challenging to fit. This process often requires a great deal of time and patience. In some patients, contact lenses do not provide good, comfortable vision and surgery may be an option. Intacs (plastic corneal inserts) may be a possible treatment for some patients with moderate keratoconus. When vision deteriorates to the point that contact lenses no longer provide satisfactory vision, corneal transplant may be necessary to replace the diseased cornea with a healthy one.  Corneal transplantation (PK) can be very successful for contact intolerant patients with keratoconus. 

 

Progressive keratoconus, or eyes that develop progressive thinning and protrusion after refractive surgery such as LASIK, may be treatable with corneal crosslinking (CXL). 

 

Acute hydrops can develop in advanced cases. This is a condition where the membrane on the back layer of the cornea (Descemet’s membrane) tears and allows fluid to build up in the cornea causing fluid-filled blisters on the corneal surface. When these blisters rupture, they cause excruciating pain and poor vision. Acute corneal hydrops is initially managed with medications and usually resolves on its own over weeks to months, depending on its severity. Care must be taken during this time to prevent bacterial infection. Rarely, surgery may be required for hydrops. 

If you have keratoconus or if you think you have keratoconus, call out office to make an appointment with Dr. Kim who can examine your eyes and provide the best course of action for your eye condition.

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