Keratoconus is more common than you think
Keratoconus is an asymmetric, bilateral, frequently progressive corneal disease that is more common than you think. Back in the mid-1980’s studies were developed to roughly and likely inaccurately estimate the incidence and prevalence of the disease.
More specifically, it was published as recently as 1998 by Yaron Rabinowitz, MD, (keratoconus expert from Los Angeles, California), to be approximately 1:2000. While this number seems alarmingly high, it is nowhere near what we know it is today.
A recent study
A recent paper (2017) from the American Journal of Ophthalmology titled “Age-specific Incidence and Prevalence of Keratoconus: A Nationwide Registration Study” performed an epidemiological study based off a total of 4.4 million patients set out to establish prevalence and incidence in the 21st century.
So where did they get the data on that many people you ask? According to the abstract, data was extracted from the largest health insurance provider in the Netherlands, the Netherlands mandatory health insurance database.
Patients aged 10-40 years were defined as the relevant age category for newly diagnosed keratoconus and the annual incidence of newly diagnosed keratoconus was determined.
The prevalence of keratoconus was estimated based on the annual incidence, mean age at diagnosis, and average life expectancy. Main outcome measure was the annual incidence and prevalence of keratoconus.
The annual incidence of keratoconus was 1:7500 in the relevant age category (13.3 cases per 100 000, 95% confidence interval [CI]: 11.6-15.2) and the estimated prevalence of keratoconus in the general population was 1:375 (265 cases per 100 000, 95% CI: 260-270).
These values are 5-fold to 10-fold higher than previously reported values in population studies. The mean age at diagnosis was 28.3 years and 60.6% of diagnosed patients were male.
Yes, You read it correctly…Both the annual incidence and the prevalence of keratoconus were 5-fold to 10-fold higher than previously reported. So how can these numbers in prevalence and incidence be so wildly different from the late 20th century till now?
The screening for keratoconus in the earlier time frame was done only with retinoscopes, keratometers and very rudimentary placido disc imagers. Today, we use much more advanced and sensitive equipment that amongst many other bits of data, can image and analyze corneal elevation values of not only the anterior surface of the cornea but of the posterior cornea as well.
Devices with Scheimpflug cameras or Ocular Coherence Tomography (OCT) able to properly assess anterior/posterior corneal elevation and pachymetric progression have been a necessity in early detection and recognition of this all-to-common corneal disease.
Early detection is essential
Now that we understand the incidence and prevalence AND have an FDA approved drug and device to halt the progression of corneal ectatic diseases such as keratoconus and post-refractive surgery ectasia, identification, and detection of the disease as early as possible is essential to saving as much vision as possible for our patients.
A clinical best practice and strong clinical recommendation from the International Keratoconus Academy of Eye Care Professionals (IKA) is for clinicians to utilize current and modern technology with the inclusion of Scheimpflug or OCT technology to identify patients with progressive corneal ectatic disease and treat them with corneal cross-linking (assuming proper candidates and no contra-indications) to halt the progression of the disease as early as possible.