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Wan K, Wolffsohn JS, Cho P. Role of waveform signal parameters in the classification of children as relatively slow and fast myopia progressors. Clin Exp Optom 2024; 107:402-408. [PMID: 36797056 DOI: 10.1080/08164622.2023.2177098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 01/14/2023] [Accepted: 02/01/2023] [Indexed: 02/18/2023] Open
Abstract
CLINICAL RELEVANCE Identification of the baseline chracteristics for children undergoing orthokeratology with relatively fast myopia progression can allow a more accurate determination of the risk/benefit ratio. BACKGROUND This study aimed to investigate if baseline corneal biomechanics can classify relatively slow and fast myopia progression in children. METHODS Children aged six to 12 years with low myopia (0.50 to 4.00 D) and astigmatism (less than or equal to 1.25 D), were recruited. Participants were randomised to be fitted with orthokeratology contact lenses with a conventional compression factor (0.75 D, n = 29) or an increased compression factor (1.75 D, n = 33). Relatively fast progressors were defined as participants who had axial elongation of 0.34 mm or above per 2 years. A binomial logistic regression analysis and a classification and regression tree model were used in the data analysis. The corneal biomechanics were measured with a bidirectional applanation device. The axial length was measured by a masked examiner. RESULTS As there were no significant between-group differences in the baseline data (all p > 0.05), data were combined for analysis. The mean ± SD axial elongation for relatively slow (n = 27) and fast (n = 35) progressors were 0.18 ± 0.14 mm and 0.64 ± 0.23 mm per 2 years, respectively. The area under the curve (p2area1) was significantly higher in relatively fast progressors (p = 0.018). The binomial logistic regression and classification and regression tree model analysis showed that baseline age and p2area1 could differentiate between slow and fast progressors over 2 years. CONCLUSIONS Corneal biomechanics could be a potential predictor of axial elongation in orthokeratology contact lens-wearing children.
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Affiliation(s)
- Kin Wan
- School of Optometry, The Hong Kong Polytechnic University, HKSAR, Hong Kong, China
| | | | - Pauline Cho
- School of Optometry, The Hong Kong Polytechnic University, HKSAR, Hong Kong, China
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Benavente-Perez A. Evidence of vascular involvement in myopia: a review. Front Med (Lausanne) 2023; 10:1112996. [PMID: 37275358 PMCID: PMC10232763 DOI: 10.3389/fmed.2023.1112996] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 05/02/2023] [Indexed: 06/07/2023] Open
Abstract
The benign public perception of myopia (nearsightedness) as a visual inconvenience masks the severity of its sight-threatening consequences. Myopia is a significant risk factor for posterior pole conditions such as maculopathy, choroidal neovascularization and glaucoma, all of which have a vascular component. These associations strongly suggest that myopic eyes might experience vascular alterations prior to the development of complications. Myopic eyes are out of focus because they are larger in size, which in turn affects their overall structure and function, including those of the vascular beds. By reviewing the vascular changes that characterize myopia, this review aims to provide an understanding of the gross, cellular and molecular alterations identified at the structural and functional levels with the goal to provide an understanding of the latest evidence in the field of experimental and clinical myopia vascular research. From the evidence presented, we hypothesize that the interaction between excessive myopic eye growth and vascular alterations are tipping-points for the development of sight-threatening changes.
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Chu Z, Ren Q, Chen M, Cheng L, Cheng H, Cui W, Bi W, Wu J. The relationship between axial length/corneal radius of curvature ratio and stress–strain index in myopic eyeballs: Using Corvis ST tonometry. Front Bioeng Biotechnol 2022; 10:939129. [PMID: 36046672 PMCID: PMC9420864 DOI: 10.3389/fbioe.2022.939129] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Accepted: 07/13/2022] [Indexed: 11/13/2022] Open
Abstract
Purpose: This study aimed to investigate the correlation of axial length/corneal radius of curvature ratio with stress–strain index (SSI).Methods: Retrospective analysis was conducted to compare the right eyes of those with high myopia (HM, n = 132; age and 10–48 years) with those without high myopia (NHM, n = 135; age and 7–48 years), where the baseline axial length, corneal radius of curvature ratio, and central corneal thickness were analyzed; the differences in two groups were compared; and the relationship of axial length and axial length/corneal radius of curvature ratio with SSI were explored.Results: Compared with AL < 26mm, SSI significantly decreased when AL ≥ 26 mm (p = 0.001), while there was no correlation with AL in the NHM group (r = -0.14, p = 0.12) or HM group (r = -0.09, p = 0.32). AL/CR was significantly associated with SSI in both the NHM (r = -0.4, p < 0.001) and HM (r = -0.18, p = 0.04) groups. In the NHM group, AL/CR was significantly associated with SSI (unstandardized beta = -0.514, se = 0.109, p < 0.001) with the adjustment of age and gender. Additionally, a significant association of SSI with AL/CR was also found after adjusting for age and gender (unstandardized beta = -0.258, se = 0.096, and p = 0.0082) in the HM group.Conclusion: SSI showed a significant negative correlation with AL/CR in patients without high myopia and in patients with high myopia. However, SSI exhibited no decrease with the worsening of myopia, but it gradually remained stable at a low level. The findings of this study validate, to some extent, the possibility of analyzing the dynamic changes in ocular wall stiffness during the development of myopia by measuring in vivo corneal biomechanical parameters.
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Affiliation(s)
- Zhe Chu
- Eye Institute of Shandong First Medical University, Qingdao Eye Hospital of Shandong First Medical University, State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, School of Ophthalmology, Shandong First Medical University, Qingdao, China
| | - Qi Ren
- Eye Institute of Shandong First Medical University, Qingdao Eye Hospital of Shandong First Medical University, State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, School of Ophthalmology, Shandong First Medical University, Qingdao, China
| | - Meizhen Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University Guangzhou, Guangzhou, China
| | - Lu Cheng
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University Guangzhou, Guangzhou, China
| | - Hao Cheng
- Department of Ophthalmology, the First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Wei Cui
- Eye Institute of Shandong First Medical University, Qingdao Eye Hospital of Shandong First Medical University, State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, School of Ophthalmology, Shandong First Medical University, Qingdao, China
| | - Wenjiao Bi
- Eye Institute of Shandong First Medical University, Qingdao Eye Hospital of Shandong First Medical University, State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, School of Ophthalmology, Shandong First Medical University, Qingdao, China
| | - Jie Wu
- Eye Institute of Shandong First Medical University, Qingdao Eye Hospital of Shandong First Medical University, State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, School of Ophthalmology, Shandong First Medical University, Qingdao, China
- *Correspondence: Jie Wu,
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Zhao M, Lam AK, Cheong AM. Structural and haemodynamic properties of ocular vasculature in axial myopia. Clin Exp Optom 2021; 105:247-262. [PMID: 34343434 DOI: 10.1080/08164622.2021.1943320] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
The high prevalence of myopia has become a global concern, especially in East and Southeast Asia. Alarmingly, the prevalence of high myopia is increasing. Mechanical stretching caused by excessive eyeball elongation leads to various anatomical changes in the fundus. This stretching force may also lead to the development of vascular abnormalities, which tend to be subtle and easily overlooked. A healthy ocular vasculature is a prerequisite of adequate oxygen supply for normal retinal functions. This review summarises previous findings on structural and haemodynamic aspects of myopia-related vascular changes.
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Affiliation(s)
- Mei Zhao
- Centre for Myopia Research, School of Optometry, Faculty of Health and Social Science, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Andrew Kc Lam
- Centre for Myopia Research, School of Optometry, Faculty of Health and Social Science, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Allen My Cheong
- Centre for Myopia Research, School of Optometry, Faculty of Health and Social Science, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
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Mcmonnies CW. An examination of the baropathic nature of axial myopia. Clin Exp Optom 2021; 97:116-24. [DOI: 10.1111/cxo.12101] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 04/17/2013] [Accepted: 05/05/2013] [Indexed: 11/29/2022] Open
Affiliation(s)
- Charles W Mcmonnies
- School of Optometry and Vision Science, University of New South Wales, Kensington, New South Wales, Australia,
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Sedaghat MR, Momeni-Moghaddam H, Azimi A, Fakhimi Z, Ziaei M, Danesh Z, Roberts CJ, Monfared N, Jamali A. Corneal Biomechanical Properties in Varying Severities of Myopia. Front Bioeng Biotechnol 2021; 8:595330. [PMID: 33553113 PMCID: PMC7859342 DOI: 10.3389/fbioe.2020.595330] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Accepted: 12/21/2020] [Indexed: 11/20/2022] Open
Abstract
Purpose: To investigate corneal biomechanical response parameters in varying degrees of myopia and their correlation with corneal geometrical parameters and axial length. Methods: In this prospective cross-sectional study, 172 eyes of 172 subjects, the severity degree of myopia was categorized into mild, moderate, severe, and extreme myopia. Cycloplegic refraction, corneal tomography using Pentacam HR, corneal biomechanical assessment using Corvis ST and Ocular Response Analyser (ORA), and ocular biometry using IOLMaster 700 were performed for all subjects. A general linear model was used to compare biomechanical parameters in various degrees of myopia, while central corneal thickness (CCT) and biomechanically corrected intraocular pressure (bIOP) were considered as covariates. Multiple linear regression was used to investigate the relationship between corneal biomechanical parameters with spherical equivalent (SE), axial length (AXL), bIOP, mean keratometry (Mean KR), and CCT. Results: Corneal biomechanical parameters assessed by Corvis ST that showed significant differences among the groups were second applanation length (AL2, p = 0.035), highest concavity radius (HCR, p < 0.001), deformation amplitude (DA, p < 0.001), peak distance (PD, p = 0.022), integrated inverse radius (IR, p < 0.001) and DA ratio (DAR, p = 0.004), while there were no significant differences in the means of pressure-derived parameters of ORA between groups. Multiple regression analysis showed all parameters of Corvis ST have significant relationships with level of myopia (SE, AXL, Mean KR), except AL1 and AL2. Significant biomechanical parameters showed progressive reduction in corneal stiffness with increasing myopia (either with greater negative SE or greater AXL), independent of IOP and CCT. Also, corneal hysteresis (CH) or ability to dissipate energy from the ORA decreased with increasing level of myopia. Conclusions: Dynamic corneal response assessed by Corvis ST shows evidence of biomechanical changes consistent with decreasing stiffness with increasing levels of myopia in multiple parameters. The strongest correlations were with highest concavity parameters where the sclera influence is maximal.
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Affiliation(s)
| | | | - Abbas Azimi
- Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran.,Refractive Errors Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Zohreh Fakhimi
- Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Mohammed Ziaei
- Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Zeynad Danesh
- Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Cynthia J Roberts
- Ophthalmology & Visual Science, Biomedical Engineering, The Ohio State University, Columbus, OH, United States
| | - Naeemeh Monfared
- Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Alireza Jamali
- Department of Optometry, School of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, Iran
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Yu AY, Shao H, Pan A, Wang Q, Huang Z, Song B, McAlinden C, Huang J, Chen S. Corneal biomechanical properties in myopic eyes evaluated via Scheimpflug imaging. BMC Ophthalmol 2020; 20:279. [PMID: 32652982 PMCID: PMC7353814 DOI: 10.1186/s12886-020-01530-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Accepted: 06/26/2020] [Indexed: 12/20/2022] Open
Abstract
Background To investigate the biomechanical properties of the cornea in myopic eyes using corneal visualization Scheimpflug technology (Corvis ST). The relationships between the biomechanical properties of the cornea and the degree of myopia were also investigated. Methods 265 eyes of 265 subjects were included. Based on spherical equivalent (SE) in diopters (D), participants were divided into four groups: low myopia/control (SE: − 0.50 to − 3.00D), moderate myopia (SE: − 3.00 to − 6.00D), high myopia (SE: − 6.00 to − 10.00D) and severe myopia (SE greater than − 10.00D). Axial length (AL), anterior segment parameters, and corneal biomechanical properties were obtained with the Lenstar LS900, Pentacam HR and Corvis ST, respectively. Results Mean (±SD) SE was − 7.29 ± 4.31D (range: − 0.63 to − 25.75D). Mean AL was 26.31 ± 1.82 mm (range: 21.87 to 31.94 mm). Significant differences were detected within the four groups in terms of six corneal biomechanical parameters: deformation amplitude (DA), time from start until second applanation (A2-time), length of flattened cornea at the second applanation (A2-length), corneal velocity during the first and second applanation (A2-velocity), time from start to highest concavity (HC-time), and central curvature at highest concavity (HC radius). AL was positively associated with DA whereas negatively associated with A1-velocity and A2-length. SE was positively associated with A2-time, HC-time and A2-velocity, whereas negatively associated with DA. IOP was positively associated with four corneal biomechanical parameters and negatively associated with three parameters. Conclusions Eyes with severe myopia showed greater DA, lesser A2 time, HC time, and faster A2-velocity compared to low to high myopia. This suggests the cornea becomes weaker and more deformable with elongation of axial length with corresponding increases in myopia. DA, A2-time and A2-velocity could be useful corneal biomechanical indicators in patients with myopia.
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Affiliation(s)
- A-Yong Yu
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China.,Key Laboratory of Vision Science, Ministry of Health Peoples Republic of China, Wenzhou, Zhejiang, China
| | - Hui Shao
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Anpeng Pan
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China.,Key Laboratory of Vision Science, Ministry of Health Peoples Republic of China, Wenzhou, Zhejiang, China
| | - Qinmei Wang
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China.,Key Laboratory of Vision Science, Ministry of Health Peoples Republic of China, Wenzhou, Zhejiang, China
| | - Zixu Huang
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Benhao Song
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Colm McAlinden
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China.,Department of Ophthalmology, Singleton Hospital, Swansea Bay University Health Board, Swansea, UK
| | - Jinhai Huang
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China. .,Key Laboratory of Vision Science, Ministry of Health Peoples Republic of China, Wenzhou, Zhejiang, China. .,Eye Hospital of Wenzhou Medical University, 270 West Xueyuan Road, Wenzhou, Zhejiang, 325027, China.
| | - Sisi Chen
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China. .,Key Laboratory of Vision Science, Ministry of Health Peoples Republic of China, Wenzhou, Zhejiang, China. .,Eye Hospital of Wenzhou Medical University, 270 West Xueyuan Road, Wenzhou, Zhejiang, 325027, China.
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Feola AJ, Nelson ES, Myers J, Ethier CR, Samuels BC. The Impact of Choroidal Swelling on Optic Nerve Head Deformation. ACTA ACUST UNITED AC 2018; 59:4172-4181. [DOI: 10.1167/iovs.18-24463] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Andrew J. Feola
- Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, Georgia, United States
- Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Medical Center, Atlanta, Georgia, United States
| | | | - Jerry Myers
- NASA Glenn Research Center, Cleveland, Ohio, United States
| | - C. Ross Ethier
- Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, Georgia, United States
| | - Brian C. Samuels
- Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, Alabama, United States
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9
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Grudzińska E, Modrzejewska M. Modern Diagnostic Techniques for the Assessment of Ocular Blood Flow in Myopia: Current State of Knowledge. J Ophthalmol 2018; 2018:4694789. [PMID: 29607217 PMCID: PMC5828053 DOI: 10.1155/2018/4694789] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 12/21/2017] [Indexed: 11/17/2022] Open
Abstract
Myopia is the most common refractive error and the subject of interest of various studies assessing ocular blood flow. Increasing refractive error and axial elongation of the eye result in the stretching and thinning of the scleral, choroid, and retinal tissues and the decrease in retinal vessel diameter, disturbing ocular blood flow. Local and systemic factors known to change ocular blood flow include glaucoma, medications and fluctuations in intraocular pressure, and metabolic parameters. Techniques and tools assessing ocular blood flow include, among others, laser Doppler flowmetry (LDF), retinal function imager (RFI), laser speckle contrast imaging (LSCI), magnetic resonance imaging (MRI), optical coherence tomography angiography (OCTA), pulsatile ocular blood flowmeter (POBF), fundus pulsation amplitude (FPA), colour Doppler imaging (CDI), and Doppler optical coherence tomography (DOCT). Many researchers consistently reported lower blood flow parameters in myopic eyes regardless of the used diagnostic method. It is unclear whether this is a primary change that causes secondary thinning of ocular tissues or quite the opposite; that is, the mechanical stretching of the eye wall reduces its thickness and causes a secondary lower demand of tissues for oxygen. This paper presents a review of studies assessing ocular blood flow in myopes.
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Affiliation(s)
- Ewa Grudzińska
- Department of Ophthalmology, Pomeranian Medical University in Szczecin, Szczecin, Poland
| | - Monika Modrzejewska
- Department of Ophthalmology, Pomeranian Medical University in Szczecin, Szczecin, Poland
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11
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Intraocular Pressure, Axial Length, and Refractive Changes after Phacoemulsification and Trabeculectomy for Open-Angle Glaucoma. J Ophthalmol 2017; 2017:1203269. [PMID: 28660076 PMCID: PMC5474260 DOI: 10.1155/2017/1203269] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 04/30/2017] [Indexed: 11/17/2022] Open
Abstract
PURPOSE To compare changes in intraocular pressure (IOP), axial eye length (AEL), and refractive outcome in primary open-angle glaucoma patients undergoing cataract surgery and trabeculectomy in dependence of the sequence of surgeries. MATERIALS AND METHODS We retrospectively analysed 48 eyes. The changes in refraction, intraocular pressure, and axial eye length were analysed after surgery. In group A (21 subjects), phacoemulsification was performed before trabeculectomy, and in group B (27 subjects), trabeculectomy was performed before phacoemulsification with a minimum time span between interventions of 6 months. RESULTS The reduction in IOP and the decrease in AEL after trabeculectomy were significant after 6 and 12 months postsurgery (p < 0.001 each). The decrease in AEL was 0.42 ± 0.11% at 6 months after surgery and 0.40 ± 0.13% after 12 months from surgery; this decrease in AEL was comparable between the groups. The refractive outcome was significantly different between the groups (group A: 0.35 ± 0.75 dpt, group B: -0.05 ± 0.36 dpt, p = 0.018); in group A, trabeculectomy caused a hyperopic shift of 0.34 ± 0.44 dpt (p = 0.002) at 12 months postsurgery. CONCLUSION IOP reduction after trabeculectomy causes AEL shortening. The effect on refractive outcome depends on the sequence of surgeries. Better refractive outcome is achieved if phacoemulsification is performed after trabeculectomy.
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12
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Quantitative Assessment of the Impact of Blood Pulsation on Intraocular Pressure Measurement Results in Healthy Subjects. J Ophthalmol 2017; 2017:9678041. [PMID: 28250983 PMCID: PMC5304312 DOI: 10.1155/2017/9678041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2016] [Accepted: 01/05/2017] [Indexed: 11/18/2022] Open
Abstract
Background. Blood pulsation affects the results obtained using various medical devices in many different ways. Method. The paper proves the effect of blood pulsation on intraocular pressure measurements. Six measurements for each of the 10 healthy subjects were performed in various phases of blood pulsation. A total of 8400 corneal deformation images were recorded. The results of intraocular pressure measurements were related to the results of heartbeat phases measured with a pulse oximeter placed on the index finger of the subject's left hand. Results. The correlation between the heartbeat phase measured with a pulse oximeter and intraocular pressure is 0.69 ± 0.26 (p < 0.05). The phase shift calculated for the maximum correlation is equal to 60 ± 40° (p < 0.05). When the moment of measuring intraocular pressure with an air-puff tonometer is not synchronized, the changes in IOP for the analysed group of subjects can vary in the range of ±2.31 mmHg (p < 0.3). Conclusions. Blood pulsation has a statistically significant effect on the results of intraocular pressure measurement. For this reason, in modern ophthalmic devices, the measurement should be synchronized with the heartbeat phases. The paper proposes an additional method for synchronizing the time of pressure measurement with the blood pulsation phase.
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14
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Beaton L, Mazzaferri J, Lalonde F, Hidalgo-Aguirre M, Descovich D, Lesk MR, Costantino S. Non-invasive measurement of choroidal volume change and ocular rigidity through automated segmentation of high-speed OCT imaging. BIOMEDICAL OPTICS EXPRESS 2015; 6:1694-706. [PMID: 26137373 PMCID: PMC4467714 DOI: 10.1364/boe.6.001694] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 03/17/2015] [Accepted: 03/18/2015] [Indexed: 05/26/2023]
Abstract
We have developed a novel optical approach to determine pulsatile ocular volume changes using automated segmentation of the choroid, which, together with Dynamic Contour Tonometry (DCT) measurements of intraocular pressure (IOP), allows estimation of the ocular rigidity (OR) coefficient. Spectral Domain Optical Coherence Tomography (OCT) videos were acquired with Enhanced Depth Imaging (EDI) at 7Hz during ~50 seconds at the fundus. A novel segmentation algorithm based on graph search with an edge-probability weighting scheme was developed to measure choroidal thickness (CT) at each frame. Global ocular volume fluctuations were derived from frame-to-frame CT variations using an approximate eye model. Immediately after imaging, IOP and ocular pulse amplitude (OPA) were measured using DCT. OR was calculated from these peak pressure and volume changes. Our automated segmentation algorithm provides the first non-invasive method for determining ocular volume change due to pulsatile choroidal filling, and the estimation of the OR constant. Future applications of this method offer an important avenue to understanding the biomechanical basis of ocular pathophysiology.
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Affiliation(s)
- L. Beaton
- Centre de Recherche Hôpital Maisonneuve-Rosemont, Montréal, QC,
Canada
| | - J. Mazzaferri
- Centre de Recherche Hôpital Maisonneuve-Rosemont, Montréal, QC,
Canada
| | - F. Lalonde
- Centre de Recherche Hôpital Maisonneuve-Rosemont, Montréal, QC,
Canada
- Département d’ophtalmologie, Université de Montréal, Montréal, QC,
Canada
| | - M. Hidalgo-Aguirre
- Centre de Recherche Hôpital Maisonneuve-Rosemont, Montréal, QC,
Canada
- Institut National de la Recherche Scientifique – Energie, Matériaux et Télécommunications, Varennes, QC,
Canada
| | - D. Descovich
- Centre de Recherche Hôpital Maisonneuve-Rosemont, Montréal, QC,
Canada
| | - M. R. Lesk
- Centre de Recherche Hôpital Maisonneuve-Rosemont, Montréal, QC,
Canada
- Département d’ophtalmologie, Université de Montréal, Montréal, QC,
Canada
| | - S. Costantino
- Centre de Recherche Hôpital Maisonneuve-Rosemont, Montréal, QC,
Canada
- Département d’ophtalmologie, Université de Montréal, Montréal, QC,
Canada
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15
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Danielewska ME, Krzyżanowska-Berkowska P, Iskander DR. Glaucomatous and age-related changes in corneal pulsation shape. The ocular dicrotism. PLoS One 2014; 9:e102814. [PMID: 25032962 PMCID: PMC4102586 DOI: 10.1371/journal.pone.0102814] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 06/22/2014] [Indexed: 12/04/2022] Open
Abstract
PURPOSE To ascertain whether the incidence of ocular dicrotic pulse (ODP) increases with age, it is more pronounced in glaucomatous than in normal eyes and whether it is related to cardiovascular activity. METHODS 261 subjects aged 47 to 78 years were included in the study and classified into four groups: primary open angle glaucoma (POAG), primary angle-closure glaucoma (PACG), glaucoma suspects with glaucomatous optic disc appearance (GODA) and the controls (CG). Additionally, in each group, subjects with ODP were divided into two age subgroups around the median age. A non-contact ultrasonic method was used to measure corneal indentation pulse (CIP) synchronically with the acquisition of electrocardiography (ECG) and blood pulse signals. ODP was assessed from the acquired signals that were numerically processed in a custom written program. RESULTS ODP incidence was about 78%, 66%, 66% and 84% for CG, GODA, POAG, and PACG group, respectively. With advancing age, the ODP incidence increased for all subjects (Δ = 12%), the highest being for the PACG and POAG groups (Δ = 30%). GODA group did not show an age-related increase in the incidence of ODP. CONCLUSIONS The ocular dicrotism, measured with non-contact ultrasonic method, was found to be a common phenomenon in elderly subjects. The increased ODP incidence in PACG and POAG group may correspond to either higher stiffness of glaucoma eyes, biochemical abnormalities in eye tissues, changes in ocular hemodynamics, may reflect the effect of medications or be a combination of all those factors. The results of GODA group suggest different mechanisms governing their ocular pulse that makes them less susceptible to generating ODP and having decreased predisposition to glaucoma.
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Affiliation(s)
- Monika E. Danielewska
- Institute of Biomedical Engineering and Instrumentation, Wroclaw University of Technology, Wroclaw, Poland
| | | | - D. Robert Iskander
- Institute of Biomedical Engineering and Instrumentation, Wroclaw University of Technology, Wroclaw, Poland
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Abstract
PURPOSE Myopic chorioretinal atrophy is a debilitating condition that causes severe loss of primary vision. However, its mechanisms and pathologic course are not well understood. We performed volumetric measurements of the posterior choroid via three-dimensional analysis of the choroid in patients with high myopia to understand its structure, and we compared the measurements with those of normal subjects. METHODS Twenty-five highly myopic but otherwise normal eyes and 25 nonmyopic eyes were evaluated. Enhanced depth imaging optical coherence tomography (EDI-OCT) was performed using 20 × 20-degree raster scans consisting of 25 high-speed line scans. Three-dimensional retinal and choroidal thickness maps were produced from the EDI-OCT data. For the quantitative analyses, the macula was divided into nine regions, as defined by the Early Treatment Diabetic Retinopathy Study (ETDRS) layout, and the mean retinal and choroidal thicknesses of each region were obtained. RESULTS The choroidal thicknesses at all regions in the high-myopia group were significantly smaller than those in the normal refractive group (p < 0.0001). The foveal choroidal thickness was the greatest in the normal group but not in the high-myopia group. In the high-myopia group, the choroidal thickness at the fovea was significantly greater than that at the outer nasal quadrants (p < 0.0001) but significantly smaller than that at the outer superior (p < 0.0001) quadrants. CONCLUSIONS Three-dimensional choroidal thickness maps obtained via EDI-OCT are useful for quantifying choroid thickness in subjects with high myopia more accurately.
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del Buey MA, Lavilla L, Ascaso FJ, Lanchares E, Huerva V, Cristóbal JA. Assessment of corneal biomechanical properties and intraocular pressure in myopic spanish healthy population. J Ophthalmol 2014; 2014:905129. [PMID: 24719755 PMCID: PMC3955599 DOI: 10.1155/2014/905129] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 01/10/2014] [Indexed: 11/17/2022] Open
Abstract
Purpose. To examine biomechanical parameters of the cornea in myopic eyes and their relationship with the degree of myopia in a western healthy population. Methods. Corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann correlated intraocular pressure (IOP), and corneal compensated IOP (IOPcc) were measured using the ocular response analyzer (ORA) in 312 eyes of 177 Spanish subjects aged between 20 and 56 years. Refraction was expressed as spherical equivalent (SE), which ranged from 0 to -16.50 diopters (D) (mean: -3.88 ± 2.90 D). Subjects were divided into four groups according to their refractive status: group 1 or control group: emmetropia (-0.50 ≤ SE < 0.50); group 2: low myopia (-0.75 ≤ SE < 3.00 D); group 3: moderate myopia (-3.00 ≤ SE ≤ -6.00 D); and group 3: high myopia (SE greater than -6.00 D). We analyzed the relationship between corneal biomechanics measured with ORA and SE. Results. CH in the emmetropia, low myopia, moderate myopia, and high myopia groups was 11.13 ± 0.98, 11.49 ± 1.25, 10.52 ± 1.54, and 10.35 ± 1.33 mmHg, respectively. CH in the highly myopic group was significantly lower than that in the emmetropic group (P = 0.07) and low myopic group (P = 0.035); however, there were no differences with the moderate myopic group (P = 0.872). There were no statistically significant differences regarding IOP among the four groups (P > 0.05); nevertheless, IOPcc was significantly higher in the moderately myopic (15.47 ± 2.47 mmHg) and highly myopic (16.14 ± 2.59 mmHg) groups than in the emmetropia (15.15 ± 2.06 mmHg) and low myopia groups (14.53 ± 2.37 mmHg). No correlation between age and the measured parameters was found. CH and IOPcc were weakly but significantly correlated with SE (r = 0.171, P = 0.002 and r = -0.131, P = 0.021, resp.). Conclusions. Present study showed only a very weak, but significant, correlation between CH and refractive error, with CH being lower in both moderately and highly myopic eyes than that in the emmetropic and low myopic eyes. These changes in biomechanical properties of the cornea may have an impact on IOP measurement, increasing the risk of glaucoma.
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Affiliation(s)
- María A. del Buey
- Department of Ophthalmology, Lozano Blesa University Clinic Hospital, Zaragoza, Spain
- Department of Ophthalmology, Quirón University Hospital, Zaragoza, Spain
- Instituto Aragonés de Ciencias de la Salud (IACS), Zaragoza, Spain
| | - Laura Lavilla
- Department of Ophthalmology, Lozano Blesa University Clinic Hospital, Zaragoza, Spain
- Department of Ophthalmology, Quirón University Hospital, Zaragoza, Spain
| | - Francisco J. Ascaso
- Department of Ophthalmology, Lozano Blesa University Clinic Hospital, Zaragoza, Spain
- Instituto Aragonés de Ciencias de la Salud (IACS), Zaragoza, Spain
| | - Elena Lanchares
- Instituto Aragonés de Ciencias de la Salud (IACS), Zaragoza, Spain
- Aragón Institute for Engineering Research (I3A), University of Zaragoza, CIBER on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Zaragoza, Spain
| | - Valentín Huerva
- Department of Ophthalmology, Arnau de Vilanova University Hospital and IRB-Lleida, Avenida Rovira Roure 80, Lleida, Spain
| | - José A. Cristóbal
- Department of Ophthalmology, Lozano Blesa University Clinic Hospital, Zaragoza, Spain
- Department of Ophthalmology, Quirón University Hospital, Zaragoza, Spain
- Instituto Aragonés de Ciencias de la Salud (IACS), Zaragoza, Spain
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Gogniat F, Steinegger D, Nosch DS, Joos R, Goldschmidt M. The accuracy of dynamic contour tonometry over soft contact lenses. Optom Vis Sci 2013; 90:125-30. [PMID: 23292044 DOI: 10.1097/opx.0b013e31827cdaa7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
PURPOSE Dynamic contour tonometry (DCT) has been shown to measure the intraocular pressure (IOP) independently of corneal thickness. This study aimed to investigate if DCT remains accurate when the IOP measurement is taken over soft contact lenses (CLs) of different thicknesses and material characteristics. METHODS This was a prospective clinical study that included 42 patients. Subject age was 22 to 59 years (26.5 ± 6.3 years). Intraocular pressure and ocular pulse amplitude (OPA) measurements were taken under topical anesthesia without CLs and over various daily disposable CLs with -0.50, +5.00, and -5.00 diopters (D) in hydrogel (Nelfilcon A) and in silicone hydrogel (Narafilcon A) materials. RESULTS No statistically significant differences were found when comparing the IOP measurements obtained using either of the different CL powers of -0.50 or -5.00 D, irrespective of which CL material was being used. However, the difference of 0.62 mm Hg observed when the Nelfilcon A with a power of +5.00 D was used turned out to be highly statistically significant (p = 0.0002), whereas the Narafilcon A with the same power of +5.00 D, with a small difference of -0.16 mm Hg, was not. Regarding OPA measurements, no significant differences were found between measurements with and without CL neither for different materials nor for change in dioptrical power (F = 0, p = 1.000). CONCLUSIONS This study showed good reliability of IOP and OPA measurements over CLs with varying thickness profiles and different soft materials when using the DCT. Only a small but statistically significant difference of 0.62 mm Hg was found for the IOP measurement with the hydrogel CL of +5.00 D compared with "no CL."
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Affiliation(s)
- Fabrice Gogniat
- University of Applied Sciences Northwest of Switzerland, Institute of Optometry, Olten, Switzerland
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Man REK, Sasongko MB, Wang JJ, Lamoureux EL. Association between myopia and diabetic retinopathy: a review of observational findings and potential mechanisms. Clin Exp Ophthalmol 2012; 41:293-301. [PMID: 22958192 DOI: 10.1111/j.1442-9071.2012.02872.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Accepted: 08/10/2012] [Indexed: 01/03/2023]
Abstract
A protective, but inconsistent association between myopia and a decreased risk of diabetic retinopathy (DR) has been suggested in several studies. However, it is unclear whether the structural, or the refractive components of myopia; or both, is the main contributor to this protective relationship. This paper provides a comprehensive review of existing evidence on the association between myopia, and its structural (axial length [AL], anterior chamber depth [ACD]) and refractive (lens biometry and corneal curvature [CC]) components, with DR. 11 studies consisting of 7230 subjects from 1960 to April 2012, were reviewed. A longer AL was the only variable associated with a lower risk and severity of DR. Therefore, the available evidence suggests that AL is the main contributor to the protective influence of myopia on DR observed in earlier studies. Further investigations are now needed to determine the mechanisms by which AL protects against DR.
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Affiliation(s)
- Ryan E K Man
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, University of Melbourne, Melbourne, Victoria
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Longer Axial Length Is Protective of Diabetic Retinopathy and Macular Edema. Ophthalmology 2012; 119:1754-9. [DOI: 10.1016/j.ophtha.2012.03.021] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Revised: 03/12/2012] [Accepted: 03/12/2012] [Indexed: 11/24/2022] Open
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Plange N, Rennings C, Herr A, Weber A, Roessler GF, Mazinani BE, Kaup M, Remky A. Ocular pulse amplitude before and after cataract surgery. Curr Eye Res 2011; 37:115-9. [PMID: 22007729 DOI: 10.3109/02713683.2011.626910] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE To investigate the impact of cataract surgery on the association of the ocular pulse amplitude (OPA) and intraocular pressure (IOP) with respect to the interpretation of OPA as an estimate of ocular blood flow. METHODS Twenty-four patients with cataract were included in a clinical study. OPA was measured using dynamic contour tonometry (DCT, Pascal(®), SMT Swiss Microtechnology AG, Switzerland). IOP was measured by means of Goldmann applanation tonometry (IOP GAT) and DCT (IOP DCT). All measurements were performed before and one day after cataract surgery. RESULTS At baseline, OPA was correlated to IOP GAT (r = 0.67, P = 0.0002) and IOP DCT (r = 0.82, P < 0.0001), but not to age or axial length. Postoperative OPA was correlated to IOP GAT (r = 0.67, P = 0.0002) and IOP DCT (r = 0.65, P = 0.0004). In 17 patients, IOP GAT decreased after surgery (IOP DCT n = 14), whereas an increase was apparent in seven patients (IOP DCT n = 10). The mean absolute deviation of IOP GAT pre- to post-surgery was 4.54 mmHg ± 2.47 (range 1-10 mmHg) and 5.4 mmHg ± 3.2 (range 1.1-13.1 mmHg) for IOP DCT. The changes of OPA were significantly correlated to changes in IOP GAT (r = 0.48, P = 0.017) and IOP DCT (r = 0.60, P = 0.001). IOP GAT and IOP DCT changes were not correlated to changes in corneal thickness. CONCLUSIONS The OPA measured with the Pascal(®) device seems to be dependent on IOP changes. Particular caution should be taken in the interpretation of OPA in estimating pulsatile ocular blood flow.
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Affiliation(s)
- Niklas Plange
- Department of Ophthalmology, RWTH Aachen University, Aachen, Germany.
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Knecht PB, Bosch MM, Michels S, Mannhardt S, Schmid U, Bosch MA, Menke MN. The ocular pulse amplitude at different intraocular pressure: a prospective study. Acta Ophthalmol 2011; 89:e466-71. [PMID: 21401909 DOI: 10.1111/j.1755-3768.2011.02141.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE To investigate changes in ocular pulse amplitude (OPA) during a short-term increase in intraocular pressure (IOP) and to assess possible influences of biometrical properties of the eye, including central corneal thickness (CCT) and axial length. METHODS In a prospective, single centre study, OPA and IOP as measured by dynamic contour tonometry (DCT) were taken before baseline- and post-OPA (delta) intravitreal injection of 0.05 ml anti-vascular endothelial growth factor agents. Analysis was performed employing linear regression with baseline- and post (delta)-OPA differences as the dependent and post-IOP as well as delta IOP as the independent variable. A multilinear regression analysis with delta OPA as the dependent variable and baseline IOP, post-IOP, CCT and axial length as independent variables was conducted. RESULTS Forty eyes of 40 patients were included. IOP and OPA increased significantly after injection (IOP mean increase ± SD: 17.83 ± 9.83 mmHg, p < 0.001; OPA mean increase ± SD: 1.39 ± 1.16 mmHg, p < 0.001). For every mmHg increase in IOP, the OPA showed a linear increase of 0.05 mmHg (slope 0.05, 95% CI: 0.02-0.09, p = 0.003, r(2) = 0.20). Multiple regression analysis with delta OPA as the dependent variable revealed a partial correlation coefficient of 0.47 (p = 0.003) for post-IOP as the only significant contribution. CONCLUSION A clear positive relationship between OPA measurements and IOP levels was shown in a clinical routine setting using DCT focusing on baseline and postinterventional comparisons of OPA values after intravitreal injections in patients with exudative age related macular degeneration. When considering the OPA for diagnostic purposes, we recommend indication of corresponding IOP values.
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Affiliation(s)
- Pascal Bruno Knecht
- Department of Ophthalmology, University Hospital Zurich, Zurich, Switzerland.
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Tabuchi H, Kiuchi Y, Ohsugi H, Nakakura S, Han Z. Effects of corneal thickness and axial length on intraocular pressure and ocular pulse amplitude before and after cataract surgery. Can J Ophthalmol 2011; 46:242-6. [PMID: 21784209 DOI: 10.1016/j.jcjo.2011.05.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2010] [Revised: 10/08/2010] [Accepted: 11/02/2010] [Indexed: 10/26/2022]
Abstract
OBJECTIVE To investigate the relationship between the biophysical properties of the cornea and eye on the intraocular pressure (IOP) and ocular pulse amplitude (OPA) before and after cataract surgery. DESIGN Intervention study. PARTICIPANTS The left eyes of 311 patients. METHODS The left eyes of 338 patients undergoing cataract surgery without other eye pathology were studied. IOP and OPA were recorded by dynamic contour tonometry (DCT) 1 week before and 14 weeks after cataract surgery. The axial length, corneal curvature, central corneal thickness, anterior chamber depth, and anterior chamber angle were measured 1 week before cataract surgery. Multiple regression analyses of these factors to the preoperative OPA were performed. The difference between the pre- and postoperative IOP and OPA were investigated by paired t tests. RESULTS Three hundred and eleven of 338 eyes were analyzed. The preoperative OPA was negatively correlated with axial length (β = -0.24, p < 0.0001) and positively correlated with the preoperative IOP (β = 0.13, p < 0.0001). The average OPA was significantly decreased after cataract surgery (p < 0.0001). The mean change in postoperative OPA was -0.45 ± 0.63 mm Hg (95% CI -0.52 to -0.38 mm Hg). CONCLUSIONS The preoperative OPA was negatively correlated with axial length as reported. A significant decrease in OPA was observed after the cataract surgery.
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Affiliation(s)
- Hitoshi Tabuchi
- Department of Ophthalmology, Tsukazaki Hospital, Himeji, 68-1 Waku, Aboshi-ku, Himeji-City, Hyogo 671-1227, Japan.
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