Keratoconus: More Common Than You Think

Age-Specific Incidence and Prevalence of Keratoconus: A Nationwide Registration Study

Godefrooij DA, de Wit GA, Uiterwaal CS, Imhof SM, Wisse RP
Am J Ophthalmol. 2017;175:169-172

Study Summary

The commonly quoted number for the prevalence of keratoconus is 1:2000, which is pretty rare, although it varies by region of the world. Using mandatory health insurance data on 4.4 million patients from 2011 to 2014 from the largest health insurance provider in The Netherlands, the authors of this study determined that the prevalence in their general population was higher at 1:375.

Viewpoint

The incidence or prevalence of a disease is an important number to keep in mind when considering whether a particular patient has that disease. A common adage in medicine is: "When you hear hoof beats, think of horses and not zebras," as horses are more common than zebras (at least in most areas). If a condition is commonly found in your patient population, there is a greater chance that any given patient will have that specific disease compared with a rarer condition.

This new study finding is important. Making the diagnosis of keratoconus at an earlier age is much more critical now than it was just a decade or so ago because corneal collagen crosslinking is well-documented to slow down or stop the progression of keratoconus when treated in its mild-to-moderate stages,^[1,2] and it is available in many, if not most, countries of the world.

Prior to the advent of corneal collagen crosslinking, diagnosing the patient at age 15 or 20 or 25 years really did not affect the long-term prognosis. The condition was going to progress at its own rate, although we have known for many years that eye rubbing likely encourages progression and should be avoided.

We now want to diagnose keratoconus as early as possible. If the keratoconus is progressing, we want to be able to offer the patient corneal collagen crosslinking at an earlier stage to prevent worsening, which is associated with decreased vision, decreased contact lens tolerance, and increased need for corneal surgery (eg, corneal transplant).

This study indicates that keratoconus is now more of a "horse" and less of a "zebra" and should be considered higher in the list of differential diagnoses of young patients with progressive myopia and rapidly changing astigmatism.

Abstract

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Cite this: Keratoconus: More Common Than You Think - Medscape - Apr 05, 2017.

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