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KERATOCONUS

Introduction

The curvature of the cornea (the clear tissue at the front of your eye) is measured to determine your prescription. Keratoconus is a progressive cornea condition that causes thinning and protrusion of the cornea.  This results in irregular astigmatism, fluctuating vision, corneal scarring and prevents you from maximizing your functional vision.

Keratoconus is the most common corneal disease and generally affects both eyes at different rates.  It occurs in the second decade, affects both genders and all ethnicities.  Due to the progressive nature of the condition, early eye exams and monitoring is recommended.  In the general population, it has been estimated that 54 out of 100,000 people have a form of keratoconus.

The conical shape of the cornea causes fluctuating vision due to the irregular reflection of light (light scattering).  This is the reason vision correction with spectacles is limited and correction with custom contact lenses, such as scleral lenses is crucial.

Eye diagram normal vs keratoconus

Keratoconus is a progressive condition that causes thinning and protrusion of the cornea. This results in irregular astigmatism, fluctuating vision, corneal scarring which all affect best corrected vision.

Causes

The exact or main cause of keratoconus is unknown at this time.  However, there are three different types of suspected causes.  They include: genetic, environment and hormonal.

  1. Genetic
    Although there appears to be a familial association, there is a less than 10% chance that a family member of a person with keratoconus with also have the condition.  However, analysis of keratoconus corneas have shown a structual defect in the anchoring fibers of the anterior (front) cornea.  This causes a more flexible cornea, which represents the bulge or conical appearance of the cornea.
  2. Environment
    The environment thought is due to eye rubbing and free radicals.  In general, it is thought that minor trauma such as eye rubbing further damages the anchoring fibers.  When coupled with allergies, such as hay fever, eczema, asthma and food allergies, eye allergies are common, which causes an increase in eye rubbing.Some studies have suggested that the keratoconus cornea processes free radicals poorly and as a result, the ability to self-repair is impaired.  Over time this leads to further tissue damage and degradation by affecting the structural fibers.
  3.  Hormonal
    This is a newer theory that has not been proven.  But as keratoconus occurs in the second decade, it is thought that the hormonal system plays a part during puberty.
    To learn more visit the National Keratoconus Foundation.

Management

Management of keratoconus involve treating the disease and improving the vision. Treating the disease include collagen cross-linking, INTACS, and corneal transplants.  The Cornea Research Foundation has further information for surgical options.

Improving vision of patients with keratconus is crucial for improved quality of life and includes glasses and contact lenses.  Glasses and contact lenses are still needed even with the above surgical procedures as these treatments are intended to delay or halt disease progression.  Glasses tend to be difficult due to the fluctuating vision most patients experience.  Contact lenses are an excellent option!  Many options exist including traditional soft lenses and more custom lenses, the gas permeable lenses (“hard lenses”).

Gas permeable lenses are not just the typical corneal lenses, but include piggy-back, hybrid and scleral lenses.  Although not many people know about scleral contact lenses, they are often the lens of choice due to their comfort and quality of vision.

scleral-lens-diagram

Scleral lenses “vault” over the keratoconus cornea and uses liquid underneath to correct and stabilize vision.

Scleral lenses provide excellent comfort because they sit on the sclera.  The sclera compared with the cornea has far fewer nerve endings, which means an increase in comfort when wearing.  The scleral lens traps liquid (sterile saline and the natural tears) underneath the lens; this liquid is the key to correct and stabilize the fluctuating vision experience by people with keratoconus.

Dr. Anh Do and Dr. Anthony Huynh

Dr. Anh Do and Dr. Anthony Huynh are experienced in fitting a variety of custom contact lenses, including keratoconus, post-surgical and irregular astigmatism; these lenses may give you back the vision you thought you once lost! Contact us for more information.

See Dr. Anh Do and Dr. Anthony Huynh’s biographies.