Study of corneal biomechanical properties in patients with childhood glaucoma

AIM: To study of corneal biomechanical properties and intraocular pressure (IOP) measured with Corvis Scheimpflug Technology (ST) in patients with childhood glaucoma (CG). METHODS: Cross-sectional study in which 89 eyes were included 56 of them with CG. Only one eye per patient was included. The following variables were obtained from the clinical history and the ophthalmological examination: age, sex, IOP, number of surgeries, and the cup/disc ratio (CDR). The following parameters were recorded using Corvis ST: corrected by biomechanics IOP (bIOP), not corrected IOP (nctIOP), central corneal thickness (CCT), maximum concavity [radius, peak distance (PD) and deformation amplitude], applanation 1 and 2 (length and velocity). The mean age was 23±14.55 and 33±19.5 years old for the control group and CG group, respectively. Totally 36 were males and 53 were females. In the CG group, 7 patients were controlled only with medical treatment. Sixteen had at least one previous goniotomy, 19 had at least one trabeculectomy, and 11 had an Ahmed implant. RESULTS: A significant and positive intraclass correlation coefficient was found between Goldman IOP and the IOP measured by Corvis in both groups. No differences were found between the IOP measured with Corvis and Goldman using a student t-test. Regarding biomechanical parameters, there were differences in the applanation length 2 (A-L2), in the applanation velocity 2 (A-V2) and in the PD. By sex, only the applanation length 1 (A-L1) was found to be different in control group. A positive and significant Pearson correlation was found between CDR and the A-L1. CONCLUSION: Corneal biomechanical properties have shown differences between CG and healthy subjects and also between men and women.

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Comparability of three intraocular pressure measurement: iCare pro rebound, non-contact and Goldmann applanation tonometry in different IOP group

BMC Ophthalmology ◽

10.1186/s12886-019-1236-5 ◽

2019 ◽

Vol 19 (1) ◽

Cited By ~ 4

Author(s):

Min Chen ◽

Lina Zhang ◽

Jia Xu ◽

Xinyi Chen ◽

Yuxiang Gu ◽

...

Keyword(s):

Intraocular Pressure ◽

Pearson Correlation ◽

Linear Regression Analysis ◽

Corneal Thickness ◽

Intraclass Correlation ◽

Cross Sectional Study ◽

Applanation Tonometry ◽

Cross Sectional ◽

Wide Range ◽

Iop Measurement

Abstract Background Measurement of intraocular pressure (IOP) is essential for glaucoma patients. Many factors such as central corneal thickness (CCT) can affect the accuracy of IOP measurement. The purpose of this study was to evaluate the agreement of IOP measured by non-contact tonometer (NCT), iCare pro rebound tonometer (iCare), and Goldmann applanation tonometer (GAT) in different IOP group. Methods This was a Hospital-based cross-sectional study. Two hundred subjects were enrolled in this study. All subjects underwent IOP measurement using an NCT–iCare–GAT sequence. Bland-Altman, Pearson correlation and intraclass correlation analysis were performed using SPSS 17.0 software. The influence of CCT on each IOP measurement methods was evaluated by linear regression analysis. Results The mean difference (Δ) of NCT–GAT did not differ from (Δ) iCare–GAT in IOP < 10 and 10–21 mmHg group. However, (Δ) NCT–GAT was significantly higher than (Δ) iCare–GAT in IOP 22–30 and > 30 mmHg group (P < 0.05). Bland–Altman analysis showed significant agreement between the three devices (P < 0.01). IOP measurements of the three methods were significantly correlated with CCT (P < 0.01). Conclusions ICare pro shows a higher agreement with GAT over a wide range of IOP compared with NCT. The consistency between the three tonometers was similar in a low and normal IOP range. However, NCT shows a greater overestimate of IOP in moderate and higher IOP group. The variability of IOP measurement affected by CCT is NCT > iCare pro > GAT.

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Comparison of Corneal Biomechanical Properties among Axial Myopic, Nonaxial Myopic, and Nonmyopic Eyes

BioMed Research International ◽

10.1155/2020/8618615 ◽

2020 ◽

Vol 2020 ◽

pp. 1-7 ◽

Cited By ~ 1

Author(s):

Aratchaporn Tubtimthong ◽

Sunee Chansangpetch ◽

Nitee Ratprasatporn ◽

Anita Manassakorn ◽

Visanee Tantisevi ◽

...

Keyword(s):

High Speed ◽

Pearson Correlation ◽

Corneal Thickness ◽

Normal Subjects ◽

Biomechanical Properties ◽

Cross Sectional Study ◽

Cross Sectional ◽

Linear Mixed Effects ◽

Corneal Deformation ◽

History Of

Purpose. To compare corneal deformation characteristics using ultra-high-speed Scheimpflug camera (Corvis ST) in patients with nonmyopic (NM), mild-to-moderate nonaxial myopic (MM), and high axial myopic (HM) eyes. Methods. In this cross-sectional study, normal subjects aged >40 years with no history of ocular laser/surgery were classified according to axial length (AL) and spherical equivalence (SE) into three groups: (1) NM (SE > −0.50 D and AL < 26 mm), (2) MM (SE −6.00 D to −0.50 D and AL < 26 mm), and (3) HM (SE ≤ −6.00 D and AL ≥ 26 mm). Seven parameters including corneal deformation amplitude (CDA), inward/outward corneal applanation length, inward/outward corneal velocity (ICV and OCV), peak distance, and radius were measured. Pearson correlation and linear mixed-effects model were done. Results. A total of 180 eyes were recruited. 98 eyes were NM, 30 eyes were MM, and 52 eyes were HM. There were significant correlations of OCV to the degree of refractive error (r = 0.203, p<0.001) and AL (r = −0.242, p<0.001). After adjusting for age, sex, intraocular pressure, and corneal thickness, there was significantly higher CDA (β = 0.07, p<0.001), faster OCV (β = −0.08, p<0.001), and smaller radius (β = −0.39, p=0.01) in the HM group compared to the NM group. Conclusion. The higher CDA, faster OCV, and smaller radius found in the HM may suggest that these eyes have reduced ocular stiffness and may be less stable and more prone to stress.

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Pattern ERG as a predictor in ocular hypertensive

Asian Journal of Ophthalmology ◽

10.35119/asjoo.v15i2.215 ◽

2016 ◽

Vol 15 (2) ◽

Author(s):

Paaraj Dave ◽

Jitendra Jethani

Keyword(s):

Amplitude Ratio ◽

Corneal Thickness ◽

Visual Fields ◽

Cross Sectional Study ◽

Control Group ◽

Study Group ◽

Pattern Erg ◽

Check Size ◽

Cross Sectional ◽

The Mean

Purpose: To report the repeatability of Pattern Electrotretinogram (PERG) and its findings in ocular hypertension (OHT) and normal eyes.Methods: A cross-sectional study where PERG responses were compared between the study group comprising of 80 eyes of 80 patients with intraocular pressure (IOP)>21 mmHg and the control group with 80 eyes of 80 normal individuals (IOP≤21mmHg). The optic disc and the visual fields were normal with a visual acuity of ≥ 0.8 in both groups. PERG was recorded twice for each individual in the control group by a single operator on 2 consecutive days to assess the repeatability.Results: The mean age in the study and control groups was 50.05±10.03 and 54.8±7.66 years(p=0.44) respectively. The mean IOP was 26.55±3.9 mmHg for the study group as opposed to 14.45±2.9 mmHg for the controls (p<0.001). The central corneal thickness and the cup-disc ratio was similar between the groups (p>.05). The P50-N95 amplitude (p=0.01) and the P50 latency (p<0.001) was statistically significantly different between both the groups. The intra-class correlation coefficient (ICC) showed poor agreement for all parameters except for N35-P50 0.8 to 16 degree check size amplitude ratio (PERG ratio).Conclusion: Increase in P50 latency emerges as a new candidate for early glaucoma indicator in addition to reduction in P50-N95 amplitude. PERG parameters suffer from high test-retest variability. Deterioration in PERG recordings should be interpreted with caution. The variability is lesser for the PERG ratio which maybe more meaningful while monitoring for change over time.

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Corneal Biomechanical Properties in Varying Severities of Myopia

Frontiers in Bioengineering and Biotechnology ◽

10.3389/fbioe.2020.595330 ◽

2021 ◽

Vol 8 ◽

Author(s):

Mohammad-Reza Sedaghat ◽

Hamed Momeni-Moghaddam ◽

Abbas Azimi ◽

Zohreh Fakhimi ◽

Mohammed Ziaei ◽

...

Keyword(s):

Axial Length ◽

Corneal Thickness ◽

Biomechanical Properties ◽

Cross Sectional Study ◽

Geometrical Parameters ◽

Cross Sectional ◽

Corvis St ◽

Multiple Parameters ◽

Inverse Radius ◽

Biomechanical Parameters

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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A Quantitative Comparison of Multispectral Refraction Topography and Autorefractometer in Young Adults

Frontiers in Medicine ◽

10.3389/fmed.2021.715640 ◽

2021 ◽

Vol 8 ◽

Author(s):

Yunru Liao ◽

Zhenlan Yang ◽

Zijing Li ◽

Rui Zeng ◽

Jing Wang ◽

...

Keyword(s):

Correlation Coefficient ◽

Pearson Correlation ◽

Intraclass Correlation ◽

Correlation Coefficients ◽

Cross Sectional Study ◽

Cross Sectional ◽

High Agreement ◽

Intraclass Correlation Coefficients ◽

Repeatability And Reproducibility ◽

The Mean

Purpose: Purpose of this study is to evaluate the measuring consistency of central refraction between multispectral refraction topography (MRT) and autorefractometry.Methods: This was a descriptive cross-sectional study including subjects in Sun Yat-sen Memorial Hospital from September 1, 2020, to December 31, 2020, ages 20 to 35 years with a best corrected visual acuity of 20/20 or better. All patients underwent cycloplegia, and the refractive status was estimated with autorefractometer, experienced optometrist and MRT. We analyzed the central refraction of the autorefractometer and MRT. The repeatability and reproducibility of values measured using both devices were evaluated using intraclass correlation coefficients (ICCs).Results: A total of 145 subjects ages 20 to 35 (290 eyes) were enrolled. The mean central refraction of the autorefractometer was −4.69 ± 2.64 diopters (D) (range −9.50 to +4.75 D), while the mean central refraction of MRT was −4.49 ± 2.61 diopters (D) (range −8.79 to +5.02 D). Pearson correlation analysis revealed a high correlation between the two devices. The intraclass correlation coefficient (ICC) also showed high agreement. The intrarater and interrater ICC values of central refraction were more than 0.90 in both devices and conditions. At the same time, the mean central refraction of experienced optometrist was −4.74 ± 2.66 diopters (D) (range −9.50 to +4.75D). The intra-class correlation coefficient of central refraction measured by MRT and subjective refraction was 0.939.Conclusions: Results revealed that autorefractometry, experienced optometrist and MRT show high agreement in measuring central refraction. MRT could provide a potential objective method to assess peripheral refraction.

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Does Intramedullary Nailing for Distal Fibular Fractures Restore Anatomic Parameters and Syndesmotic Relationship?

Foot & Ankle Orthopaedics ◽

10.1177/2473011420s00003 ◽

2020 ◽

Vol 5 (2) ◽

pp. 2473011420S0000

Author(s):

Natalio R. Cuchacovich Mikenberg ◽

Francisco J. Bravo Gallardo ◽

Esteban Giannini ◽

Claudia Astudillo ◽

Manuel J. Pellegrini ◽

...

Keyword(s):

Statistical Power ◽

Intraclass Correlation ◽

Total Sample ◽

Cross Sectional Study ◽

Wilcoxon Test ◽

Medium Size ◽

Control Group ◽

Cross Sectional ◽

Rotation Length ◽

Paired Control

Category: Trauma; Ankle Introduction/Purpose: Fibular nailing (FN) is a method of fixation that has proven to be useful for the treatment of distal fibular fractures (DF). FN minimizes soft tissue complications, provides similar stability compared to plating with less hardware related symptoms. Nevertheless, FN has been associated with syndesmotic malreduction and incapacity of restoring length and rotation of the fibula. We aimed to evaluate the fibular and syndesmotic reduction after fixation with FN compared to the uninjured ankle. Methods: Prospective cohort, cross-sectional study with a paired control group. Patients with DF fractures treated with FN between January 2017 and July 2019 were included. Immediate postoperative bilateral Ankle CT was obtained in all cases. Two independent radiologists performed all the measurements on both ankles (fibular rotation, length, translation, and syndesmotic diastasis. Statistical analysis was made using the Wilcoxon Test and Intraclass correlation coefficient (ICC). Considering a medium size sample effect, 95% confidence with .05 alpha error, a total sample of 26 subjects were needed to achieve a .80 of statistical power (G-Power 3.1). All analyses were performed using SPSS V20. Results: Twenty-six patients were included (14 Women). The mean age was 47 years (18-91). No statistically significant differences were identified considering fibular rotation (p:0,694), fibular length (p:0,585) and syndesmotic diastasis (p:0,078) between the injured and uninjured ankle. Fibular translation has statistical differences (p:0,043). The ICC shows an excellent concordance between radiologists except for Fibular translation (ICC 0,47) Conclusion: In this cohort, fixation of DF fractures with FN allows restoration of anatomical parameters of the ankle in terms of fibular rotation, length, and syndesmotic diastasis. However, Fibular translation had significant differences compared with the uninjured ankle.

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Structural and Biomechanical Corneal Differences between Type 2 Diabetic and Nondiabetic Patients

Journal of Ophthalmology ◽

10.1155/2019/3764878 ◽

2019 ◽

Vol 2019 ◽

pp. 1-9 ◽

Cited By ~ 5

Author(s):

João N. Beato ◽

João Esteves-Leandro ◽

David Reis ◽

Manuel Falcão ◽

Vítor Rosas ◽

...

Keyword(s):

Linear Regression ◽

Linear Regression Analysis ◽

Corneal Thickness ◽

Biomechanical Properties ◽

Cross Sectional Study ◽

Applanation Tonometry ◽

Multivariate Linear Regression ◽

Multivariate Linear Regression Analysis ◽

Cross Sectional

Purpose. To analyze and compare corneal structural and biomechanical properties, characterized by corneal hysteresis (CH) and resistance factor (CRF), between patients with and without type 2 diabetes mellitus (DM), and determine the main ocular variables that influence them. Methods. Sixty diabetic and 48 age- and sex-matched non-DM patients were enrolled in this cross-sectional study. The DM group was analyzed according to DM duration (<or ≥ 10 years), HbA1c levels (<or ≥ 7%), and presence of retinopathy. CH and CRF were evaluated using the Ocular Response Analyzer® (ORA). Central corneal thickness (CCT) was determined by Scheimpflug tomography (Pentacam® HR). Intraocular pressure was obtained with ORA (IOPcc) and Goldmann applanation tonometry (IOP-GAT). Univariate and multivariate linear regression analyses were performed to evaluate the relationship between demographical, clinical, and ocular variables with the biomechanical properties. Results. There were no statistically significant differences in the CH and the CRF between DM and non-DM groups (p=0.637 and p=0.439, respectively). Also, there was no statistical difference between groups for the CCT, IOPcc, or IOP-GAT. Multivariate linear regression analysis showed that CH was positively associated with CCT (p<0.001) and negatively associated with IOPcc (p<0.001), while CRF was positively associated with CCT (p<0.001) and IOPcc (p=0.014). Conclusion. The CCT and IOPcc were found to be the main parameters that affect corneal biomechanical properties both in diabetics and controls. In this study, there was no significant effect of DM type 2 on corneal biomechanics.

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Vascular deformation in human atherosclerotic carotid artery evaluated by 2D analysis of ultrasonography

Vascular ◽

10.1177/1708538119890163 ◽

2020 ◽

Vol 28 (4) ◽

pp. 441-449

Author(s):

Mehravar Rafati ◽

Mehrdad Rafati-Rahimzadeh ◽

Hassan Moladoust ◽

Mohammadreza Sehhati

Keyword(s):

Carotid Artery ◽

Pearson Correlation ◽

Intima Media Thickness ◽

Cross Sectional Study ◽

Control Group ◽

Severe Stenosis ◽

Cross Sectional ◽

Automated Method ◽

Age Range ◽

Male Subjects

Objectives Common carotid artery (CCA) remodelling in the atherosclerosis process is an inherent necessary element that decreases the progress of significant lumen compromise. The present study used a semi-automated method to assess relationships of intima-media thickness (IMT), lumen diameter (LD) and inter-adventitial diameter (IAD) using ultrasound B-mode images of atherosclerotic carotid artery. Methods In the cross-sectional study, 120 male subjects (age range: 40–60 years) were classified into four research groups namely control, mild, moderate, and severe stenosis. The maximum near and far wall IMT, mean of both walls’ IMT and IAD, and also LD of the left CCA were extracted for all participants. Pearson correlation coefficient was utilized to investigate relationships of IMT, LD, and IAD. Results Results revealed that the maximum far and near wall IMT, mean of both walls’ IMT and IAD in the CCA were significantly different in stenosis patients and the control group ( p< 0.001). However, there were no significant differences among the four studied groups in terms of LD of CCA ( p = 0.65). There was a stronger correlation between mean of both walls’ IMT and IAD in comparison with mean far wall IMT and IAD ( p < 0.001). Conclusions Results indicated that changes of IAD in the left CCA were associated with carotid deformation, and thus it can be considered as a predictor of atherosclerosis process.

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Evidence of a Down Syndrome Keratopathy: A Three-Dimensional (3-D) Morphogeometric and Volumetric Analysis

Journal of Personalized Medicine ◽

10.3390/jpm11020082 ◽

2021 ◽

Vol 11 (2) ◽

pp. 82

Author(s):

Ibrahim Toprak ◽

Francisco Cavas ◽

Alfredo Vega ◽

José S. Velázquez ◽

Jorge L. Alio del Barrio ◽

...

Keyword(s):

Down Syndrome ◽

Corneal Thickness ◽

Three Dimensional ◽

Normal Karyotype ◽

Volumetric Analysis ◽

Cross Sectional Study ◽

High Order ◽

Control Group ◽

Cross Sectional ◽

Anterior Posterior

The aim of this study was to investigate whether a different and abnormal corneal profile is present in Down syndrome (DS) by personalized three-dimensional (3D) modelling. This single-centre cross-sectional study included 43 patients with DS (43 eyes) and 58 age-sex-matched control subjects (58 eyes) with normal karyotype and topography. Refraction, central corneal thickness (CCT), aberrations (high-order, coma and spherical), asphericity and morphogeometric/volumetric parameters based on a 3D corneal model that was generated from raw topographical data were evaluated. Deviation of anterior/posterior apex (Dapexant/Dapexpost) and thinnest point (Dmctant/Dmctpost) from corneal vertex, anterior/posterior surface area (Aant/Apost), sagittal area passing through the anterior/posterior apex (Aapexant/Aapexpost) and thinnest point (Amctpost), total corneal volume (Vtotal) and volumetric progression for each 0.05 mm step of the radius value centred to the thinnest point (VOLMCT) and anterior/posterior apex (VOLAAP/VOLPAP) comprised the morphogeometric/volumetric parameters. In the DS group, 58.1% of the eyes presented abnormal topography. High-order and coma aberrations, asphericity, Dapexant, Aant, Apost and Aapexant were significantly higher, whereas CCT, Aapexpost, Amctpost, Vtotal, VOLAAP, VOLPAP and VOLMCT were lower in the DS group than in the control group (p < 0.05). Dapexpost did not differ between the groups (p > 0.05). This study demonstrates that corneas of the subjects with DS are different and more aberrated than those of normal age- and sex-matched non-DS controls. Anterior corneal apex appears to be displaced in DS even with normal topography, while posterior apex seems stable although topography is abnormal. These findings may help to modify our approach in the diagnosis of keratopathy in subjects with DS.

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Comparison of ocular biometric parameters between concomitant exotropic and orthotropic eyes

10.21203/rs.3.rs-121911/v1 ◽

2020 ◽

Author(s):

Weifen Gong ◽

Fan Yang ◽

Shibin Lin ◽

Geng Wang

Keyword(s):

Strong Correlation ◽

Partial Correlation ◽

Pearson Correlation ◽

Corneal Thickness ◽

Anterior Chamber Depth ◽

Correlation Coefficients ◽

Cross Sectional Study ◽

Spherical Equivalent ◽

Cross Sectional ◽

Cover Test

Abstract PurposeTo compare the biometric characteristics between concomitant exotropia (XT) and orthotropia (OT) with OA2000.MethodThis cross-sectional study collected 4–18 years old children. All subjects underwent a comprehensive ophthalmic examination and prism alternate cover test for ocular alignment measurement. Included subjects had no any eye surgery, structural ocular anomalies, amblyopia of either eyes, ptosis, cataract and nystagmus. OA-2000 was used for the measurement of ocular biological parameters. Spherical equivalent (SE, spherical power + (cylindrical power)/2), keratometry, central corneal thickness (CCT), white to white distance (WTW), pupil diameter (PD), anterior chamber depth (ACD), lens thickness (LT), axial lengths (AL) and intereye differences in SE, keratometry, CCT, WTW, PD, ACD, LT and AL were analyzed by independent sample t-tests. Pearson correlation was used for correlations assessment. Partial correlation was used to control for intereye differences in SE.ResultsA total of 156 subjects (79 XT and 77 OT) were collected. Intereye differences in spherical equivalent (SE) (t 2.369, P 0.019), AL (t 3.423, P 0.001), ACD (t 3.782, P < 0.001), LT (t 3.136, P 0.002) and PD (t 3.229, P 0.002) were significantly larger in XT patients than OT patients. The correlation coefficient of XT with SE asymmetry was 0.187 (P 0.020), 0.265 with AL asymmetry (P 0.001), 0.289 with ACD asymmetry (P < 0.001), 0.251 with PD asymmetry (P 0.002) and 0.243 with LT asymmetry (P 0.002). Strong correlation (r 0.875) was found between anisometropia and AL asymmetry. After controlling the effect of anisometropia, the correlation coefficients slightly reduced between XT patients and intereye differences in AL (reduced to 0.213), ACD (reduced to 0.266), PD (reduced to 0.230) and LT (reduced to 0.230). Strong correlation (r 0.855) was found between intereye differences in ACD and LT.ConclusionCompared with OT subjects, intereye differences in SE, AL, ACD, LT and PD were significantly larger in XT patients and had positive correlation with XT and may be associated with the pathogenesis of XT.

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