Repeatability of corneal biomechanics waveform signal parameters derived from Ocular Response Analyzer in children

Abstract

Purpose: To investigate the repeatability of waveform signal parameters, measured with the Ocular Response Analyzer (ORA), in children.Methods: Two sets of ORA measurements, with a 10-min break between them, were performed on children, aged six to <11 years old, either wearing single-vision spectacles (SVS) or orthokeratology (ortho-k) lenses. Intraclass correlation coefficients (ICCs) were used to assess agreements between two sets of measurements (37 waveform signal parameters).Bland-Altman (BA) plots were used to further analyse waveform signal parameters which have ICC 95% confidence interval (95% CI) between 0.50 to >0.90 (regarded as moderate to excellent agreement).Results: A total of 30 subjects [15 SVS, 15 ortho-k (3.6 ± 2.4 months)] completed the study.Since no significant between-group differences were detected in demographic data (p > 0.28) and all waveform signal parameters (p > 0.05), data from the two groups of subjects were pooled for the analysis of repeatability. Six parameters, h2, h21, p1area, p1area1, p2area, and p2area1, achieved ICCs (95% CI) of 0.82 -0.85 (0.61 -0.93). The mean (SD) of these six parameters were 372 (91), 248 (61), 4077 (854), 1762 (399), 2359 (670), and 1020 (300), respectively. Bland-Altman plots and 95% limits of agreement (95% LoA) showed considerable agreement for all six parameters, the mean difference (95% LoA) were -3 (-101 to 94), -2 (-67.56 to 62.70), 111 (-723 to 946), 102 (-334 to 539), 25 (-718 to 768), and -3 (-Page 2 of 19 350 to 343), respectively.Conclusions: Six waveform signal parameters (h2, h21, p1area, p1area1, p2area, and p2area1), which represent or are related to the areas under the waveform at the peaks in the signal, could achieve moderate to excellent agreement in children. Results of the current study provides fundamental information for further studies on the potential clinical application of these waveform signal parameters in children.

Role of waveform signal parameters in the classification of children as relatively slow and fast myopia progressors

“…Only h2, h21, p1area, p1area1, p2area, and p2area1 were used in the analysis since they had been shown to be repeatable (intraclass correlation coefficient > 0.80) in children (Figure 3). 17 Participants with AE of 0.34 mm or above per two years were defined as relatively fast progressors and the remainder as relatively slow progressors. 18 To determine if baseline characteristics could classify between relatively fast and slow progressors over two years, a binomial logistic regression analysis and the classification and regression tree analysis 19,20 were employed.…”

Short and long term corneal biomechanical analysis after overnight orthokeratology

“…One of the main reasons for these limited analyses on corneal biomechanical changes after OK is the limited number of technologies clinically available to measure or estimate the Corneal biomechanics and orthokeratology biomechanical properties of the cornea, mostly based on the analysis of the corneal response to an air puff [12] . Furthermore, some factors may have been related to this variability among studies evaluating the corneal biomechanical changes after OK, including the moderate consistency of measurements obtained with air puff-based devices to characterize the corneal biomechanics [13] and the limited knowledge of the real meaning of those parameters provided by these devices to assess the mechanical properties of the cornea [12] . The aim of the current study was to investigate the short and long term corneal biomechanical changes after OK and compare them with those occurring in subjects not wearing contact lenses.…”