“Kerato … What?”
When an optometrist tells a patient they have keratoconus, the common response is, “What is that?” Unfortunately, it is not a clear cut answer. Fully understanding the condition and what causes it can take time and effort.
The basics of keratoconus are that the cornea, the clear tissue overlying the colored part of a person's eye, becomes thinner than normal and begins to bulge in the shape of a cone. When looking at the roots of the term keratoconus, this is exactly what it is describing: kerato in Greek means cornea and conos means cone – describing a cornea shaped like a cone.
In contrast, a normal cornea is more spherical, shaped similarly to a basketball that has been cut in half. Accuracyately determining the shape of the cornea is much easier with today's technology than it was in the past. The Pentacam® is a piece of equipment that simultaneously measures the shape and thickness of a patient's cornea. This is a helpful tool, due to the dual nature of keratoconus, which exhibits a conic shape occurring in an area of thin corneal tissue.
Keratoconus & The Causes
Now that the patient has a basic understanding of what it is, they then ask, “What caused it to happen?” This is when the answer begins to get a little complicated. There are theories as to what contributions to keratoconus, but a definitive reason has not been determined as to the cause. Most people agree there is a genetic component to the condition. Whenever a parent has keratoconus, children are monitored more closely for keratoconus symptoms. There has also been a correlation to people with atopic conditions that are related to allergic hypersensitivity.
These conditions can include allergic dermatitis, allergic asthma and allergic conjunctivitis of the eyes. These situations do not guarantee everyone with an allergy is at a high risk for keratoconus; however, individuals who tend to be highly sensitive may be more at risk for keratoconus development. It is thought that constant eye rubbing can cause keratoconus, and in people with atopic conditions, eye rubbing can be habitual. It is not known whether the condition itself or the act of rubbing the eyes plays a larger role in keratoconus development.
Available Keratoconus Treatment Options
“What can I do about it?” is the last thing the patient asks. The answer to this question depends on the severity of the condition. In the early stages of keratoconus, vision can generally be corrected using contact lenses. The normal type of lens necessary is a rigid gas permeable lens which most people know as a “hard” contact lens. As the condition progresses, keratoconus treatment may call for surgical intervention.
There is a type of corneal implant technology that alters the shape of the cornea that helps decrease the amount the cornea bulges. This type of implant has been shown to aid in vision correction and is also reversible if removal is necessary. Ultimately, if the condition progresses quite enough, a keratoconus corneal transplant can be deemed necessary. Once performed, most people obtain functional vision while wearing a rigid gas permeable lens similar to the type worn in early keratoconus.
New technology is now available! The technology is known as corneal cross-linking (CXL). Corneal cross-linking may help lower the number of people in need of a cornea transplant. This process strengthens corneal tissue, preventing it from thinning or bulging more than it currently does. Corneal cross-linking allows a solution of riboflavin (Vitamin B2) to sit on the cornea while an ultraviolet light strengthens the cornea. This does not cure keratoconus, but halts the progress to a stage that requires a corneal transplant.
There are two different types of corneal cross-linking. The first is known as Epi-OFF, which requires the outer skin layer of the cornea to be removed for the treatment. The second is known as Epi-ON, which is when the outer skin of the cornea is not removed which results in less discomfort, much faster recovery, and significantly reduced risk of infection and scar tissue.
Epi-OFF corneal cross-linking was approved by the FDA in the middle of 2015. However, it took over 5 years to gain governmental approval for Epi-OFF corneal cross-linking. Because of this, it is considered outdated compared to Epi-ON.
Many people diagnosed with keratoconus have a grim outlook for their vision. Fortunately, today's advances help provide people with not only functional, but good vision.