Abstract
PurposeTo assess the repeatability and reproducibility of swept-source optical coherence tomography (SS-OCT) and Scheimpflug system and evaluate the agreement between the two systems in measuring multiple corneal regions in children.MethodsPachymetric and keratometric maps for both systems were evaluated. Central, midperipheral and peripheral corneal thickness (CT), keratometry and astigmatism power vectors were recorded. The three outcomes yielded by the same observer were used to assess intraobserver repeatability. The differences in the mean values provided by each observer were used to evaluate interobserver reproducibility. Within-subject standard deviation, test-retest repeatability (TRT) and coefficient of variation (CoV) were used to analyze the intraobserver repeatability and interobserver reproducibility. Paired T-test and Bland-Altman were used to appraise interdevice agreement.ResultsSeventy-eight eyes of 78 children were included. The CoV was ≤2.12 and 1.10%, respectively, for repeatability and reproducibility. TRT and CoV were lower for central and paracentral CT measurements than for peripheral measurements. The SS-OCT device generated higher precision when acquiring CT data, whereas Scheimpflug system showed higher reliability when measuring corneal keratometry. Although the CT readings measured using SS-OCT were significantly thinner than Scheimpflug device (P < 0.001), the central and thinnest CT values were still of high agreement. The interdevice agreement of keratometry measurement was high for the central corneal region and moderate for the paracentral and peripheral areas.ConclusionsThe precision of CT measurements by SS-OCT was higher, while the reliability of keratometry measurements by the Scheimpflug system was higher in children. Apart from the measured values in the central corneal region, the thickness and keratometry readings should not be considered interchangeable between the two systems.
Highlights
Precise measurement of corneal thickness (CT) and refractive power in children is vital for screening corneal ectasia, monitoring myopia progression, and planning orthokeratology [1, 2]
Regarding the paracentral and peripheral CT measurements, most of the test-retest repeatability (TRT) and coefficient of variation (CoV) yielded by CASIA were about one-third of those rendered by Pentacam HR
Intraobserver repeatability of corneal thickness measurements For intraobserver repeatability of CT measurements by both devices, TRT and CoV were lower for central corneal thickness (CCT), thinnest corneal thickness (TCT) and paracentral CT measurements than for peripheral measurements
Summary
Precise measurement of corneal thickness (CT) and refractive power in children is vital for screening corneal ectasia, monitoring myopia progression, and planning orthokeratology [1, 2]. To obtain a topographic map of the cornea, various technologies including Placido disk corneal topography, slit-scanning corneal topography, Scheimpflug imaging and optical coherence tomography (OCT) have been employed. Placido disk imaging does not provide information regarding the posterior corneal surface. Several reports have revealed high precision of rotating Scheimpflug camera, the Pentacam (Oculus Optikgeräte GmbH, Wetzlar, Germany), and an anterior-segment OCT (AS-OCT), the CASIA SS-1000 (Tomey, Nagoya, Japan) in measuring the central corneal thickness (CCT) and power [5,6,7,8,9]. Several studies have reported high precision of anterior segment SS-OCT, CASIA (SS-1000; Tomey, Nagoya, Japan), in acquiring pachymetric and keratometric data of the central cornea [17,18,19]. There are no published papers that measured corneal topography in children, and its extent of cooperation remained low, challenging the reliability of measurement
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