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The Role of Corneal Biomechanics in the Assessment of Ectasia Susceptibility Before Laser Vision Correction

Authors Baptista PM, Marta AA, Marques JH, Abreu AC, Monteiro S, Menéres P, Pinto MDC

Received 10 December 2020

Accepted for publication 20 January 2021

Published 19 February 2021 Volume 2021:15 Pages 745—758


Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 3

Editor who approved publication: Dr Scott Fraser

Pedro Manuel Baptista,1,2 Ana Ambrósio Marta,1 João Heitor Marques,1 Ana Carolina Abreu,1 Sílvia Monteiro,1 Pedro Menéres,1,2 Maria do Céu Pinto1

1Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal; 2Instituto de Ciências Biomédicas Abel Salazar, Porto, Portugal

Correspondence: Pedro Manuel Baptista
Centro Hospitalar Universitário do Porto, Largo Prof. Abel Salazar, Porto, 4099-001, Portugal
Tel + 35-1917868372

Purpose: To describe the tomographic and corneal biomechanical status of a sample of eyes excluded from LVC and to present the differences in biomechanical behavior in relation to cutoffs of clinical- and tomography-based screening methods used in clinical practice.
Patients and Methods: Observational cross-sectional study including 61 eyes from 32 consecutive patients who were excluded from LVC in our department. Clinical and demographic data were collected from the patients’ clinical records. Tomographic data was assessed with a Scheimpflug camera (Pentacam, OCULUS®). Ablation depth (μm) and residual stromal bed (μm) were calculated by the WaveLight® EX500 laser system software (Alcon, EUA). The corneal biomechanical assessment was made through ultra-high speed Scheimpflug imaging during noncontact tonometry (Corvis ST, OCULUS®). Several ectasia risk scores were analyzed.
Results: Mean age was 31.0± 6 years old and mean manifest spherical equivalent was − 2.01 ± 2.3D. Belin–Ambrósio deviation index was the tomographic parameter with higher proportion of eyes within the ectasia high risk interval. In the biomechanical assessment, more than 95% of eyes met the criteria for ectasia susceptibility in four of the first generation and in two of the second generation parameters. In a cutoff based comparative analysis, eyes with Kmax ≥ 45.5 D, eyes with VCOMA < 0 and eyes with ARTmax ≤ 350 presented significantly softer corneal biomechanical behavior.
Conclusion: The majority of eyes excluded from LVC in the present study met the criteria for ectasia susceptibility in several biomechanical parameters, validating the clinical and tomographic based screening prior to LVC in our center. Differences found in the biomechanical assessment regarding cutoffs used in clinical practice highlight its differential role in characterizing risk profile of these patients. Tomography should not be overlooked and the integration of all data, including treatment-related parameters, can be the future of risk ectasia screening prior LVC.

Keywords: keratorefractive surgery, ectasia, ultra-high speed Scheimpflug camera, Corvis, tomography, corneal biomechanics

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