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Repeatability of Scheimpflug based corneal tomography parameters in advanced keratoconus with thin corneas

Eye volume 37, pages 3429–3434 (2023)Cite this article

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Abstract

Objective

To determine the repeatability limits of corneal tomography parameters in patients with advanced and moderately thin keratoconic corneas to assist in planning thickness-based procedural interventions.

Methods

Prospective, single-centre, repeatability study. Three tomography scans using the Pentacam AXL were obtained from patients with keratoconus with thinnest corneal thickness (TCT) ≦400 µm (sub-400 group) and compared to those with TCT = 450–500 µm (450-plus group). Eyes with previous crosslinking, intraocular surgery, or acute corneal hydrops were excluded. Eyes were age and gender-matched. The within-subject standard deviations for flat keratometry (K1), steep keratometry (K2), maximal keratometry (Kmax), astigmatism and TCT were used to calculate respective repeatability limits (r). Intra-class correlation coefficients (ICC) were also analysed.

Results

The sub-400 group comprised 114 eyes from 114 participants, and the 450-plus group comprised 114 eyes from 114 participants. In the sub-400 group, TCT was amongst the least repeatable parameters (33.92 µm; ICC 0.96), compared with the 450-plus group (14.32 µm; ICC 0.99, p < 0.01). In the sub-400 group, K1 and K2 of the anterior surface were the most repeatable parameters (r 3.79 and 3.22 respectively; ICC 0.97 and 0.98 respectively) compared with the 450-plus group (r 1.17 and 0.92 respectively; and ICC 0.98 and 0.99 respectively, p < 0.01).

Conclusions

The repeatability of corneal tomography measurements is significantly reduced in sub-400 keratoconic corneas when compared to 450-plus corneas. Repeatability limits should be carefully considered when surgical interventions are planned for such patients.

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Fig. 1: Pearson’s correlation analysis in various degrees of keratoconus.

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Data availability

The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.

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Authors and Affiliations

  1. Department of Ophthalmology, University of Auckland, Auckland, New Zealand

    Himanshu Wadhwa, Akilesh Gokul, Ye Li, Isabella Cheung, Lize Angelo, Charles N. J. McGhee & Mohammed Ziaei

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  1. Himanshu Wadhwa
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  2. Akilesh Gokul
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  6. Charles N. J. McGhee
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  7. Mohammed Ziaei
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Contributions

AG, CM and MZ were responsible for study design. HW, AG, LA were responsible for data collection. HW was responsible for data collation. HW, AG and YL were responsible for statistical analyses. HW was responsible for manuscript preparation. HW, AG, IC, LA, CN, MZ were responsible for manuscript refinement.

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Correspondence to Mohammed Ziaei.

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Wadhwa, H., Gokul, A., Li, Y. et al. Repeatability of Scheimpflug based corneal tomography parameters in advanced keratoconus with thin corneas. Eye 37, 3429–3434 (2023). https://doi.org/10.1038/s41433-023-02528-6

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