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Liu MX, Zhu KY, Li DL, Dong XX, Liang G, Grzybowski A, Pan CW. Corneal Biomechanical Characteristics in Myopes and Emmetropes Measured by Corvis ST: A Meta-Analysis. Am J Ophthalmol 2024; 264:154-161. [PMID: 38556185 DOI: 10.1016/j.ajo.2024.03.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 02/17/2024] [Accepted: 03/25/2024] [Indexed: 04/02/2024]
Abstract
PURPOSE To comprehensively identify the corneal biomechanical differences measured by Corvis ST between different degrees of myopia and emmetropia. DESIGN Systematic review and meta-analysis. METHODS Electronic databases, including PubMed, Embase, and Web of Science, were systematically searched for studies comparing the corneal biomechanics among various degrees of myopes and emmetropes using Corvis ST. The weighted mean differences and 95% confidence intervals were calculated. Meta-analysis was performed in high and nonhigh myopes and in myopes and emmetropes, respectively. RESULTS Eleven studies were included in this study. The meta-analysis among myopes and emmetropes included 1947 myopes and 621 emmetropes, and 443 high myopes and 449 nonhigh myopes were included in the meta-analysis among high and nonhigh myopia. Myopes showed the cornea with significantly longer time at the first applanation (A1t) and lower length at the second applanation (A2L) than emmetropes. High myopes showed significantly greater A1t, velocity at the second applanation (A2v), deformation amplitude at the highest concavity (HC-DA), and peak distance at the highest concavity (HC-PD) and decreased time at the second applanation (A2t) and radius of the highest concavity (HC-R). CONCLUSIONS Corneal biomechanics is different in myopia, especially in high myopia. Compared with nonhigh myopes, the corneas of high myopes deformed slower during the first applanation, faster during the second applanation, and showed greater deformation amplitude, indicating greater elasticity and viscidity.
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Affiliation(s)
- Min-Xin Liu
- School of Public Health (M.X.L., D.L.L., X.X.D., C.W.P.), Suzhou Medical College of Soochow University, Suzhou, China
| | - Ke-Yao Zhu
- Pasteurien College of Soochow University (K.Y.Z.), Suzhou, China
| | - Dan-Lin Li
- School of Public Health (M.X.L., D.L.L., X.X.D., C.W.P.), Suzhou Medical College of Soochow University, Suzhou, China
| | - Xing-Xuan Dong
- School of Public Health (M.X.L., D.L.L., X.X.D., C.W.P.), Suzhou Medical College of Soochow University, Suzhou, China
| | - Gang Liang
- Department of Ophthalmology (G.L.), The Affiliated Hospital of Yunnan University, Kunming, China
| | - Andrzej Grzybowski
- Institute for Research in Ophthalmology (A.G.), Foundation for Ophthalmology Development, Poznan, Poland
| | - Chen-Wei Pan
- School of Public Health (M.X.L., D.L.L., X.X.D., C.W.P.), Suzhou Medical College of Soochow University, Suzhou, China.
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Mascolini MV, Toniolo I, Carniel EL, Fontanella CG. Ex vivo, in vivo and in silico studies of corneal biomechanics: a systematic review. Phys Eng Sci Med 2024; 47:403-441. [PMID: 38598066 PMCID: PMC11166853 DOI: 10.1007/s13246-024-01403-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 02/08/2024] [Indexed: 04/11/2024]
Abstract
Healthy cornea guarantees the refractive power of the eye and the protection of the inner components, but injury, trauma or pathology may impair the tissue shape and/or structural organization and therefore its material properties, compromising its functionality in the ocular visual process. It turns out that biomechanical research assumes an essential role in analysing the morphology and biomechanical response of the cornea, preventing pathology occurrence, and improving/optimising treatments. In this review, ex vivo, in vivo and in silico methods for the corneal mechanical characterization are reported. Experimental techniques are distinct in testing mode (e.g., tensile, inflation tests), samples' species (human or animal), shape and condition (e.g., healthy, treated), preservation methods, setup and test protocol (e.g., preconditioning, strain rate). The meaningful results reported in the pertinent literature are discussed, analysing differences, key features and weaknesses of the methodologies adopted. In addition, numerical techniques based on the finite element method are reported, incorporating the essential steps for the development of corneal models, such as geometry, material characterization and boundary conditions, and their application in the research field to extend the experimental results by including further relevant aspects and in the clinical field for diagnostic procedure, treatment and planning surgery. This review aims to analyse the state-of-art of the bioengineering techniques developed over the years to study the corneal biomechanics, highlighting their potentiality to improve diagnosis, treatment and healing process of the corneal tissue, and, at the same, pointing out the current limits in the experimental equipment and numerical tools that are not able to fully characterize in vivo corneal tissues non-invasively and discourage the use of finite element models in daily clinical practice for surgical planning.
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Affiliation(s)
- Maria Vittoria Mascolini
- Department of Industrial Engineering, University of Padova, Padova, Italy
- Centre for Mechanics of Biological Materials, University of Padova, Padova, Italy
| | - Ilaria Toniolo
- Department of Industrial Engineering, University of Padova, Padova, Italy.
- Centre for Mechanics of Biological Materials, University of Padova, Padova, Italy.
| | - Emanuele Luigi Carniel
- Department of Industrial Engineering, University of Padova, Padova, Italy
- Centre for Mechanics of Biological Materials, University of Padova, Padova, Italy
| | - Chiara Giulia Fontanella
- Department of Industrial Engineering, University of Padova, Padova, Italy
- Centre for Mechanics of Biological Materials, University of Padova, Padova, Italy
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Alanazi R, Esporcatte LPG, White L, Salomão MQ, Lopes BT, Ambrósio R, Abass A. Investigation of How Corneal Densitometry Artefacts Affect the Imaging of Normal and Keratoconic Corneas. Bioengineering (Basel) 2024; 11:148. [PMID: 38391634 PMCID: PMC10886353 DOI: 10.3390/bioengineering11020148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2024] [Revised: 01/27/2024] [Accepted: 01/29/2024] [Indexed: 02/24/2024] Open
Abstract
PURPOSE To investigate corneal densitometry artefacts found in Pentacam Scheimpflug scans and their potential effect on assessing keratoconic (KC) corneas compared to normal (N) corneas. METHODS The current study utilises Pentacam data of 458 N eyes, aged 35.6 ± 15.8 (range 10-87), referred to as the "N group", and 314 KC eyes, aged 31.6 ± 10.8 (range 10-72), referred to as the "KC group", where densitometry data were extracted and analysed via a custom-built MATLAB code. Radial summations of the densitometry were calculated at diameters ranging from 0.5 mm to 5.0 mm. The minimum normalised radial summation of densitometry (NRSD) value and angle were determined at each diameter and then linked. KC cone locations and areas of pathology were determined, and a comparison between N and KC groups was carried out both within the averaged area of pathology and over the corneal surface. RESULTS Joining minimum NRSD trajectory points marked a clear distortion line pointing to the nasal-superior direction at 65° from the nasal meridian. The findings were found to be independent of eye laterality or ocular condition. Consistency was detected in the right and left eyes among both the N and KC groups. The location of the KC cone centre and the area of pathology were determined, and the densitometry output was compared both within the area of pathology and over the whole cornea. When the average densitometry was compared between N and KC eyes within the KC area of pathology, the N group recorded a 16.37 ± 3.15 normalised grey-scale unit (NGSU), and the KC group recorded 17.74 ± 3.4 NGSU (p = 0.0001). However, when the whole cornea was considered, the N group recorded 16.71 ± 5.5 NGSU, and the KC group recorded 15.72 ± 3.98 NGSU (p = 0.0467). A weak correlation was found between the Bad D index and NGSU when the whole measured cornea was considered (R = -0.01); however, a better correlation was recorded within the KC area of pathology (R = 0.21). CONCLUSIONS Nasal-superior artefacts are observed in the densitometry Pentacam maps, and analysis shows no significant differences in their appearance between N or KC corneas. When analysing KC corneas, it was found that the cone positions are mostly on the temporal-inferior side of the cornea, opposite to the densitometry artefact NRSD trajectory. The analysis suggests that the corneal densitometry artefacts do not interfere with the KC area of pathology as it reaches its extreme in the opposite direction; therefore, weighting the densitometry map to increase the contribution of the inferior-temporal cornea and decreasing that of the superior-nasal area would improve the classification or identification of KC if densitometry is to be used as a KC metric.
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Affiliation(s)
- Rami Alanazi
- Department of Materials, Design and Manufacturing Engineering, School of Engineering, University of Liverpool, Liverpool L69 3GH, UK
| | - Louise Pellegrino Gomes Esporcatte
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro 20520-050, Brazil
- Instituto de Olhos Renato Ambrósio, Rio de Janeiro 20520-050, Brazil
- Department of Ophthalmology, Federal University of São Paulo, São Paulo 04017-030, Brazil
| | - Lynn White
- Research and Development Department, LWVision, Leicester LE18 1DF, UK
| | - Marcella Q Salomão
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro 20520-050, Brazil
- Instituto de Olhos Renato Ambrósio, Rio de Janeiro 20520-050, Brazil
- Department of Ophthalmology, Federal University of São Paulo, São Paulo 04017-030, Brazil
- Instituto Benjamin Constant, Rio de Janeiro 22290-255, Brazil
| | - Bernardo T Lopes
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro 20520-050, Brazil
- Department of Ophthalmology, Federal University of São Paulo, São Paulo 04017-030, Brazil
- Ophthalmology Eye Clinic, Alder Hey Children's NHS Foundation Trust, Liverpool L12 2AP, UK
| | - Renato Ambrósio
- Instituto de Olhos Renato Ambrósio, Rio de Janeiro 20520-050, Brazil
- Department of Ophthalmology, Federal University of São Paulo, São Paulo 04017-030, Brazil
- Department of Ophthalmology, Federal University the State of Rio de Janeiro, Rio de Janeiro 22290-240, Brazil
- Brazilian Study Group of Artificial Intelligence and Corneal Analysis-BrAIN, Rio de Janeiro & Maceió, Rio de Janeiro 20520-050, Brazil
| | - Ahmed Abass
- Department of Materials, Design and Manufacturing Engineering, School of Engineering, University of Liverpool, Liverpool L69 3GH, UK
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