When testing for keratoconus, clinicians don’t necessarily need the latest and greatest imaging tools. All they really need is a retinoscope, according to a new study.
Researchers from Oman investigated the validity and reliability of retinoscopy in screening for keratoconus and used the rotating Pentacam Scheimpflug camera as the gold standard for comparison. They found the tried-and-true tool came through with a high sensitivity and specificity for detecting the condition.
“With the advent of technology, the retinoscope has been overshadowed by the availability of sophisticated machines like tomography scans and machines that are capable of measuring the biomechanical properties of the cornea,” the researchers said in their paper.
Two independent, masked retinoscopists screened patients between the ages of 10 and 30 for scissoring reflex. Patients underwent vision testing, slit lamp examination and Pentacam imaging. Investigators made a diagnosis of keratoconus by Pentacam if the final D index in the Belin and Ambrósio display was greater than or equal to 2.69. Researchers then compared the results of retinoscopy and Pentacam examinations to assess the validity and reliability of the test.
The study enrolled 123 patients and 245 eyes, the majority of which had early keratoconus. Using the Amsler-Krumeich classification, researchers found 67.8% had stage I keratoconus, 26.4% had stage II, 2.3% had stage III and 3.4% had stage IV keratoconus. Retinoscopy had 97.7% sensitivity, 79.9% specificity, 70.8% positive predictive value and 98.4% negative predictive value. Additionally, researchers reported an excellent correlation between the two retinoscopists’ diagnoses.
“Retinoscopy appears to be a very sensitive and reliable test for detecting keratoconus, including early disease,” the study said. “Such a test may be implemented in population-based screening programs for keratoconus.”
|Al-Mahrouqi H, Oraba SB, Al-Habsi S, et al. Retinoscopy as a screening tool for keratoconus. Cornea. January 9, 2019. [Epub ahead of print].|