Keratoconus: Causes, Risk Factors, Symptoms and Treatment

Around one in 2,000 people have keratoconus, an eye disease that affects the structure of the cornea. It usually develops during early puberty and can progress until your mid-30s. When untreated, it can potentially lead to vision loss. It is also one of the leading causes of corneal transplants in the U.S. 

A local optician shares what you need to know about this eye disease. 

What Causes Keratoconus?

The cornea is the clear, protective exterior layer of your eye. The thickest part of the cornea is the middle layer, composed of mostly water and collagen. Collagen plays a significant role in the flexibility and strength of the cornea, helping it retain its round shape. A healthy cornea will focus light, allowing you to see clearly. If you have keratoconus, the cornea thins and protrudes into a cone shape, compromising your vision.   

Keratoconus is a condition caused by the thinning of the cornea the irregularities of its surface. It usually affects both eyes, though one may be more affected than the other. This eye condition usually starts developing during puberty and progresses until the patient reaches their mid-30s. It is difficult to foresee how fast it will progress or whether it will advance. 

While several studies have been made about keratoconus for decades, it remains unclear what causes the eye condition. Its exact cause remains unknown, but experts believe that a person’s susceptibility to keratoconus is present at birth. A common factor in many studies involving this eye disease is the loss of collagen in the cornea. It could be potentially due to an imbalance between production and destruction of the corneal tissue by the corneal cells. 

What Are the Risk Factors?

Age

Many cases of keratoconus are diagnosed during the teenage years. Younger individuals with advanced keratoconus are more likely to require surgery as the eye disease progresses. 

Genetics

With a family history of keratoconus, your risk of developing this eye disease increases. Most researchers agree that several complex factors are necessary for this eye disease to develop, including genetic and environmental factors. If this eye condition runs in the family, you need to visit your eye doctor regularly for an eye exam. Routine checks go a long way in detecting and treating keratoconus in its early stages. 

Underlying Disorders

In certain cases, keratoconus may develop due to underlying disorders like Down syndrome, sleep apnea, asthma, Leber congenital amaurosis and other connective tissue disorders. 

Eye Rubbing

Another risk factor for keratoconus is chronic eye rubbing. This may also increase the likelihood of the progression of this eye disease. If you have this eye condition, you should do your best to avoid rubbing your eyes. Doing so can cause serious damage to the corneal tissue, making symptoms worse. 

Chronic Eye Inflammation

Eye inflammation can occur due to irritants or allergies. Constant inflammation can harm the corneal tissue, which can lead to the development of keratoconus. 

What Are the Common Symptoms?

Keratoconus is often asymptomatic in the early stages, with many patients not immediately noticing any changes in their vision. As the eye condition progresses, it can cause minor blurring and distortion of vision. Patients may become more sensitive to light and glare as well. 

Other symptoms of keratoconus include sudden clouding of vision, seeing glares and halos around lights and poor night vision. Some people may even experience double vision or see partial images around the object they are viewing. These symptoms typically begin in the late teens or early 20s.

Progressive keratoconus is characterized by more distorted and blurred vision. Patients with advanced keratoconus may need to update their eyeglass prescription more frequently due to increased nearsightedness or astigmatism. They may also find that their contact lenses no longer fit their eyes properly and experience discomfort while wearing them.   

Keratoconus may affect each eye differently and slowly progress for 10 to 20 years. As the eye disease advances, the cornea bulges more, and vision worsens. In some cases, the cornea swells and causes sudden decreased vision. The cornea can swell due to the strain from its protruding cone-like shape, causing the development of a small crack. Your eye care specialist may prescribe eye drops for temporary relief if you experience sudden swelling.

The swelling can remain for weeks to months as the crack heals and is eventually replaced by scar tissue. Once scar tissue forms, the cornea will lose its smoothness and become unclear. As a result, vision will become more blurry and distorted.  

How Do Eye Doctors Diagnose Keratoconus?

Your eye doctor can diagnose keratoconus during a comprehensive eye exam. They will thoroughly examine your cornea and measure its curvature. Besides an eye exam and a complete medical history, they may do more tests for the diagnosis of keratoconus. One such test is corneal topography, the most accurate method to detect early keratoconus and keep track of its progression. This test involves taking a computerized image that forms a map of the cornea’s curvature.

Your eye doctor might do a slit-lamp exam to detect imperfections in the outer and middle layers of the cornea. It may also be necessary to perform a pachymetry to measure the thinnest parts of the cornea. 

What Are the Treatment Options for Keratoconus?

Early Keratoconus

The most common treatment for early keratoconus is prescription glasses for nearsightedness and astigmatism. However, wearing glasses will no longer suffice as the condition progresses. Eye doctors usually prescribe hard contact lenses to keratoconus patients. 

Progressive Keratoconus

Specialists can use corneal collagen cross-linking to treat progressive keratoconus. The Food and Drug Administration (FDA) approved this treatment in 2016 after clinical trials proved that it halted or mildly reversed corneal bulging within three to 12 months following the procedure. It is an in-office procedure where your eye doctor applies vitamin B solution to your eye. Ultraviolet light will then be used to activate it for around 30 minutes. The solution forms new collagen bonds, helping the cornea retain its strength and shape. 

Collagen cross-linking will not restore your cornea, but it can prevent further vision distortion. Sometimes this treatment may also result in better vision. However, during the procedure, your eye doctor might remove a thin layer of the cornea or the epithelium to make it easier for riboflavin to reach the corneal tissue.

Advanced Stages

Wearing contact lenses might be uncomfortable for patients with severe keratoconus. If this is the case, your eye doctor may recommend intacts. They are implantable plastic, C-shaped rings used to flatten the surface of the cornea to help improve vision. Corneal rings may also contribute to more comfortable contact lens wear. It will only take about 15 minutes for an eye care specialist to attach intacts. 

Corneal transplant is another treatment option for more advanced stages of keratoconus. During this procedure, a donor cornea takes the place of the patient’s affected cornea. This outpatient procedure only takes around an hour to accomplish. 

After the procedure, you can expect your vision to remain blurry for at least three to six months. You will need to take medication to prevent transplant rejection. Most times, specialists prescribe eyeglasses or contact lenses to achieve clear vision following the surgery.