According to a recent article, a new study has developed a novel index that differentiates eyes with subclinical keratoconus and normal eyes.
Keratoconus
Keratoconus is a disorder affecting the cornea of the eye. It is characterized by progressive thinning of the cornea, often resulting in a conical bulge toward the center of the eye.
Subclinical keratoconus is keratoconus that does not show any clinical signs.
Symptoms:
Keratoconus typically affects both eyes, though the disease may progress at different rates in each. Symptoms tend to begin around the ages of 10 to 25 and may last 10 years or longer. The most common and earliest symptoms are blurred vision, and increased sensitivity to light. People affected by keratoconus may also notice a frequent need to update their eye prescription, and may also experience sudden worsening or clouding of their vision.
Creating the Index
A research team looked at 252 eyes using a Schneimpflug-based tomography system. This system allowed researchers to simultaneously image the various parts of the eye (cornea, anterior chamber, and lens). Of the 252 eye images, 78 were normal eyes, 71 eyes had subclinical keratoconus, and 103 had keratoconus.
Researchers used curvature, elevation, and pachymetry maps of the eyes to create coordinates and magnitudes of the maximum corneal protrusion alterations. Then, the Euclidean distances among these locations were calculated using a location consistency index (LCI). The LCI and the magnitudes of the maximum alterations were combined to create a logistic regression model that was named the location consistency enhanced scores (LCES). The researchers then trained and tested the LCES.
Conclusions
The LCES showed that eyes with subclinical keratoconus had an LCI of 7.8 ± 2.6 µm (micrometer). This result was substantially different from normal eyes that were 11.8 ± 3.9 µm, and eyes with keratoconus that were 5.8 ± 2.4 µm. Furthermore, the LCI was able to distinguish between eyes with subclinical keratoconus and normal eyes with a sensitivity of 67.6%, a specificity of 83.3%, and area under the receiver operating characteristic curve (AUC) of 0.81. Then, combining the magnitudes of the maximum alternations with the LCI for the LCES generated a sensitivity of 90% and a specificity of 74.4% (AUC of 0.91).
The LCES proved to be a possible new index with the ability to assist in confirming if eyes have subclinical keratoconus. In addition, the LCI can assist in differentiating eyes without subclinical keratoconus and eyes without.
