Pentacam measurement errors in keratoconus

• Grant number: 16/17706-1
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: November 01, 2016
• End date: October 31, 2017
• Field of knowledge: Health Sciences - Medicine
• Principal Investigator: Sidney Julio de Faria e Sousa
• Grantee: Felipe Alves de Oliveira
• Host Institution: Faculdade de Medicina de Ribeirão Preto (FMRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

In the keratoconus evaluation is fundamental the measurement of corneal curvatures, conducted by eye tomograph Pentacam®, but this is liable to errors, as any other instrument. This project proposes to quantify this measurement error, since there is no consensus in the specialized current literature. Know a reliable measurement error would provide greater accuracy to identify and track the progression of keratoconus, and set an appropriate course of treatment, reducing the chance of false positives.130 patients diagnosed with keratoconus, according to the criteria of CLEK group (Collaborative Longitudinal Evaluation of Keratoconus) will have the cornea of each eye measured with Pentacam® between 10 (M1) and 20 minutes (M2). The parameters as simulated keratometry (K1 and k2) and keratometry mean (KM) of the posterior and anterior corneas, the maximum keratometry (kmax) of the anterior cornea, as well pachymetry, cornea apex, pupillary center and the thinnest point will be analyzed. The discrepancy between the measurements in the same eye will be given subtracting M1 to M2, and will be considered only one cornea per patient, randomly chosen. The measurement error is calculated by the coefficient of repeatability (CR) as proposed by Bland and Altman, taking into account the standard deviation within subject and the CR standard error. (AU)