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Placido disk-derived data detect, identify mild forms of keratoconus
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Researchers built a discriminant function combining four corneal wavefront variables and four Placido variables to effectively detect forme fruste keratoconus and keratoconus, according to a study.
Researchers included 119 eyes in a cohort of 176 patients. The patients were split into two groups, normal or forme fruste keratoconus (FFKC), using automated corneal classification software. The study was part of a larger prospective study at the Rothschild Foundation, Paris, France.
The FFKC group consisted of 62 topographically normal eyes of patients with keratoconus in the fellow eye. Researchers compared the anterior topographic parameters between the two groups. These parameters were obtained from specular topography using Placido-based indices and corneal wavefront Zernike coefficients, according to the researchers.
Using a discriminant function that was built by combining four corneal wavefront variables and four Placido variable, researchers found the area under the receiver operating characteristic curve was 0.970.
The function had a 63% sensitivity for detecting FFKC and 100% sensitivity for detecting keratoconus, with a specificity of 82%, researchers found.
“The current study found that indices constructed by discriminant analysis obtained from Zernike coefficients from the anterior corneal surface and Placido-derived indices could detect FFKC with good accuracy. This was also verified in a validation based on a new dataset of eyes,” the researchers wrote in the study.
Disclosure: The researchers report they are consultants for Nidek.
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Saad A, et al. J Refract Surg. 2016;doi:10.3928/1081597X-20160523-01.
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