Evaluation of corneal parameter changes under different accommodative stimuli with Scheimpflug imaging-based tomography

AIM:To evaluate the reliability of measurements of corneal changes with accommodation in healthy eyes using a Scheimpflug imaging-based system and how these measurements distribute in the normal population.METHODS:Prospective,non-randomized,comparative study including 27 healthy subjects(54 eyes),including emmetropia(13 eyes),myopia(17 eyes),hyperopia(4 eyes)and astigmatism(20 eyes)groups.In all cases,a complete eye examination was performed,including the analysis of corneal changes with different accommodative stimuli(+2.00,0.00 and-3.00 D)using the Pentacam AXL system.The investigation was structured in 2 phases:repeatability analysis and characterization of accommodation-related corneal changes in healthy populations.RESULTS:In the repeatability analysis,the index of height asymmetry(IHA)showed the greatest variability with the three accommodative stimuli,being the results for the rest of parameters acceptable.The group of emmetropes showed significant differences with accommodative changes in the position of maximum keratometry(Kmax;P<0.05),whereas in the astigmatism group,significant changes were not only observed in the position of Kmax,but also in minimum corneal thickness(MCT),corneal spherical aberration,and total and low order aberration root mean square(all P<0.05).Likewise,a significant difference was found in the displacement of the X position of Kmax with+2.00 D and-3.00 D in the myopia group(P=0.033)as well as in changes with+2.00 D and-3.00 D in the magnitude of the position vector of Kmax in the emmetropia group(P<0.05).No significant changes were found between accommodative stimuli in the displacement of coordinates of MCT(P≥0.109).CONCLUSION:The position of Kmax and MCT in healthy corneas can change significantly when presenting different accommodative stimuli using the accommodation mode of the Pentacam system,with different trends in these accommodation-related corneal changes between refractive errors.Likewise,the consistency of the measurements obtained with Scheimpflug has been confirmed.

Monitoring of central corneal thickness after phacoemulsification—comparison of statical and rotating Scheimpflug pachymetry,and spectral-domain OCT

AIM:To explore the possibility of deploying three contactless devices(static and rotating Scheimpflug technology,spectral domain optical coherence tomography)for measuring central corneal thickness(CCT)in preoperative and postoperative examinations of cataract patients.METHODS:Totally 72 patients who had undergone surgery without complications were selected.The CCT was measured prior to the operation,as well as on the first,5th-7th and 28th day following the operation using the Nidek NT 530-P,Sirius?,and Topcon OCT-2000 devices.RESULTS:A significant postoperative increase and subsequent decrease in CCT was identified with all three devices.The correlations were highly significant and thus reflect a very good degree of comparability at all times with the exception of the rotating Scheimpflug camera.The postoperative results from the latter differed significantly from the other devices.The correlations were Sirius/Topcon(P=0.010)and Sirius/Nidek(P<0.0005).No statistically significant difference could be identified in the comparison between Topcon and Nidek(P=0.056).CONCLUSION:All three devices are suitable for postoperative monitoring of CCT.The measurement results are only comparable to a limited extent and not interchangeable in the course of treating a single patient.This is due to the different imaging technology used in the devices and the resulting modalities for conducting the measurements.

Comment on hydration with Cefuroxime-a method for sealing a small leaking corneal perforation

Dear Editor,In a recent interventional case report,Allon et al ）hydrated corneal stroma with cefuroxime to seal a small traumatic leaky corneal perforation that was unresponsive to prior soft bandage contact lens application for 6d.

Repeatability of 3D OCT Pachymetry in Eyes with and without Contact Lens Induced Corneal Swelling

Introduction: Corneal thickness measurement is an indirect assessment of the physiological corneal function in human eye. This value, especially in the central area, is an important data for clinical diagnosis, treatment and monitoring of anterior segment pathologies. There are several technologies for non-invasively measuring corneal thickness like optical coherence tomography (OCT). However, there is little information available describing the effect of contact lens induced corneal swelling in OCT measures. The purpose of this study was to evaluate the repeatability of OCT corneal pachymetry in eyes with and without contact lens induced corneal swelling. Material and Methods: This study included five visits over one week in six healthy subjects: baseline and after sleeping with four different CL of +0.50 D, +2.00 D, +5.00 D and +8.00 D (Acuvue 2, Johnson & Johnson Vision Care) on four different days. Corneal pachymetry OCT 3D (Topcon) were measured three consecutive times during each visit. Besides, this measurement was repeated in 12 meridians (Scans #1 to #12), between 0°and 165°with 15° intervals. Results: Corneal pachymetry was significant different between before and after contact lens wear (p < 0.001 ANOVA). High repeatability was found without corneal swelling [Coefficient of variation (CV) = 0.68% p = 0.93] and with corneal swelling [CL -0.50 D (CV = 0.78% p = 0.95;590 ± 46 μm CI 95% 548 to 596), with CL + 2.00 D (CV = 0.72% p = 0.97;601 ± 46 μm CI 95% 595 to 607), with CL + 5.00 D (CV = 0.78% p = 0.66;608 ± 50 μm CI 95% 601 to 615) and with CL + 8.00 D (CV = 0.77% p = 0.97;607 ± 44 μm CI 95% 601 to 613)]. There were no differences (p = 1.00) in central corneal thickness along the 12 scans corneal [Scan #0 (593 ± 50 μm CI 95% 582 to 603), #1 (592 ± 50 μm CI 95% 581 to 603), #2 (591 ± 50 μm IC 95% 580 to 602), #3 (590 ± 49 μm CI 95% 579 to 600), #4 (590 ± 50 μm CI 95% 579 to 600), #5 (591 ± 50 μm CI 95% 581 to 602), #6 (590 ± 51 μm CI 95% 580 to 601), #7 (589 ± 50 μm CI 95% 578 to 600), #8 (590 ± 50 μm CI 95% 579 to 600), #9 (589 ± 50 μm CI 95% 579 to 600), #10 (592 ± 50 μm CI 95% 581 to 602) and #11 (591 ± 50 μm CI 95% 580 to 601). Conclusions: 3D OCT showed a high repeatability (CV < 1%) to measure central thickness in corneas with and without contact lens induced corneal swelling. This technology presents advantages over other clinical devices used to measure corneal thickness and could be the “gold standard” for future clinical studies and clinical practice for eye care practitioners.

Comparison of Central Corneal Thickness using Ultrasound Pachymetry during Corneal Collagen Cross-linking

Purpose:To study variation in central corneal thickness (CCT) during corneal collagen cross-linking(CXL) using ultrasound pachymetry. Methods:Twenty patients (26 eyes) with progressing keratoconus undergoing riboflavin-UVA-induced CXL were involved in this study. Intraoperative CCT measurement using ultrasonic pachymetry was performed during the procedure.Measurements were obtained before operation, after epithelial removal, after riboflavin drop instillation, and after UVA irradiation. Results:Mean CCT was 495±56 and 450±52 μm before and after epithelial removal, respectively. Mean CCT was 443±42 and 411±39 μm after riboflavin drop instillation and after UVA irradiation, respectively. Statistically significant decreases in CCT occurred between the preoperative period and after epithelial removal, after riboflavin drop instillation and after UVA irradiation. Twenty-six eyes from 20 patients undergoing CXL were divided into 2 groups (I with CCT≥400 μm after UVA irradiation and II with CCT<400 μm after UVA irradiation). No statistically significant difference was noted between I and II in preoperative endothelial cell count, but a statistically greater postoperative endothelial cell count was noted in I compared to II. A statistically significant difference was evident between preoperative and postoperative endothelial cell counts in Group II (P<0.05). Conclusion:Performing CXL with the use of riboflavin and UVA irradiation resulted in a statistically significant decrease in CCT, to a level where the corneal endothelium may be damaged.(Eye Science 2013; 28:15-19)

Method Optimization and Application Extension of Bovine Corneal Opacity and Permeability Assay

This paper systematically summarizes the improvements in bovine corneal opacity and permeability assay(BCOP),an alternative method of eye irritation test,further explores the usage mode of combinatorial methods with BCOP at the core module,introduces the application of each single method and their combination in the assessment of pesticides,plant extracts,medical devices and medicines.By optimizing traditional methods,the alternative method is more scientific and individually applicable.

智能手机辅助新型标记法在白内障术中标记目标轴位的准确性

目的:评估一种智能手机辅助的新型“任意点两步法”在白内障超声乳化吸出联合人工晶状体植入术中寻找目标轴位的便利性和准确性。方法:前瞻性观察性研究。选取2021-10/2022-04于我院拟行白内障超声乳化吸出联合人工晶状体植入术的年龄相关性白内障患者62例62眼。随机分为两组,对照组31例31眼采用裂隙灯下标记的“传统两步法”标记人工晶状体的目标轴位,试验组31例31眼采用智能手机辅助的“任意点两步法”标记人工晶状体的目标轴位。术中均采用Callisto eye导航系统作为标准参照,计算参照标记点的偏差值(偏差-1)、目标轴位标记点的偏差值(偏差-总)和参照标记点到目标轴位标记点夹角的偏差值(偏差-2),并记录术前轴位标记用时。结果:试验组偏差-1值和偏差-总值均低于对照组(1.06°±1.39°vs 2.48°±2.23°,1.77°±1.54°vs 2.81°±1.58°,均P<0.01),但两组偏差-2值无明显差异(1.35°±1.40°vs 1.48°±1.79°,P>0.05)。试验组术前轴位标记用时短于对照组(1.77±1.70 min vs 2.88±3.20 min,P<0.01)。结论:与“传统两步法”相比,智能手机辅助的“任意点两步法”在白内障超声乳化吸出联合人工晶状体植入术中寻找目标轴位的过程操作简便省时、准确性高。

Comparison of corneal measurements in keratoconic eyes using rotating Scheimpflug camera and scanning-slit topography

AIM: To compare the anterior segment measurements obtained by rotating Scheimpflug camera(Pentacam) and Scanning-slit topography(Orbscan IIz) in keratoconic eyes.METHODS: A total of 121 patients, 71 males(58.7%)and 50 females(41.3%)(214 eyes) with the diagnosis of keratoconus(KC) were enrolled in this study. Following diagnosis of KC by slit-lamp biomicroscopic examination, central corneal thickness(CCT), thinnest corneal thickness(TCT), anterior chamber depth(ACD),and pupil diameter(PD) were measured by a single examiner using successive instrumentation by Pentacam and Orbscan.RESULTS: There was no significant difference between the two instruments for the measurement of CCT and TCT. In contrast, scanning-slit topography measured ACD(3.46±0.40 mm vs 3.38±0.33 mm, P =0.019) and PD(4.97 ±1.26 mm vs 4.08 ±1.19 mm, P 【0.001) significantly larger than rotating Scheimpflug camera.The two devices made similar measurements for CCT(95% CI:-2.94 to5.06, P =0.602). However, the mean difference for TCT was-6.28(95% CI:-10.51 to-2.06, P =0.004) showing a thinner measurement by Orbscan than by Pentacam. In terms of the ACD, the mean difference was 0.08 mm(95%CI: 0.04 to 0.12, P 【0.001) with Orbscan giving a slightly larger value than Pentacam. Similarly, Orbscan measurement for PD was longer than Pentacam(95% CI:0.68 to 1.08, P 【0.001).CONCLUSION: A good agreement was found between Pentacam and Orbscan concerning CCT measurement while comparing scanning-slit topography and rotatingScheimpflug camera there was an underestimation for TCT and overestimation for ACD and PD.

Repeatability and agreement of CCT measurement in myopia using entacam and ultrasound pachymetry

AIM: To evaluate the repeatability of central corneal thickness (CCT) measurement by entacam, and agreement of CCT measured by Pentacam and ultrasound pachymetry (USP) in Chinese myopia. Thereby investigate the possibility of Pentacam as a substitute for USP in CCT measurement before refractive surgery. The effects of corneal curvature measured by Pentacam on CCT were also evaluated. METHODS: One hundred and forty-eight right eyes of 148 individual with myopia were included in this study. Three successive Pentacam CCT measurements followed by 10 successive ultrasound pachymetry were carried out in the 148 eyes. Mean of CCT taken by each device was calculated for comparison. According to the CCT measured by USP, all the 148 eyes were divided into 3 groups: <520 mu m, 520-560 mu m, >560 mu m. For all eyes and each group the CCT obtained by Pentacam and USP were compared. Anterior corneal curvature of the 148 eyes was also adopted for correlation analysis with CCT obtained by ultrasound pachymetry. In addition, CCT measurement using 60 random selected Scheimpflug images was performed by 3 skilled investigators at different time, and this was repeated for 3 times by a forth investigator to assess repeatability of Pentacam CCT measurement using Scheimpflug images. RESULTS: Intraclass correlation coefficient (ICC) analysis revealed high intraobserver repeatability (ICC=0.994, F=158.60, P<0.001) for CCT measurement by Pentacam. The interobserver (ICC=0.998, F =494.73, P <0.001) and intraobserver (ICC=0.997, F=383.98, P<0.001) repeatability for Pentacam CCT measurements using Scheimpflug images were also excellent. There was high positive correlation between the CCT values measured by Pentacam and ultrasound pachymetry (r=0.963, P<0.001). Bland-altman plots showed that the Pentacam underestimate the CCT by 8.02 mu m compared with ultrasouond pachymetry.The differences between Pentacam and USP increased as the CCT readings by USP increased (Pentacam vs USP: slope=-0.04, P< 0.05). The 95% upper and lower limits of agreement between CCT values obtained from the two devices were +9. 33 mu m and -25.37 mu m. No significant association could be found between CCT and anterior corneal curvature. CONCLUSION: Inter- and intraobserver variability for CCT measurements by Pentacam was considerably below clinically significant levels. CCT of myopia obtained by Scheimpflug camera, Pentacam, were highly correlated to that by ultrasound pachymetry. However, the values obtained are not directly interchangeable between Pentacam and ultrasound pachymetry as the 95% limits of agreement are relatively wide. Pentacam can be a useful instrument for measuring CCT in candidates to refractive surgery in clinic.

Eye rubbing-induced changes in intraocular pressure and corneal thickness measured at five locations, in subjects with ocular allergy

AIM: To assess the effects of eye rubbing on corneal thickness(CT) and intraocular pressure(IOP)measurements obtained 0-30 min after habitual eye rubbing in symptomatic patients.METHODS: Measurements of IOP and CT were obtained at five locations(central, temporal, superior,nasal and inferior) before, and every 5min for 30 min interval after 30 s of eye rubbing, for 25 randomly selected eyes of 14 subjects with ocular allergy and 11age-matched normals. Differences in measurements were calculated in each group [Baseline measurements minus measurements recorded at each time interval after eye rubbing(for IOP), and for each corneal location(for CT)]and comparison were then made between groups(allergic versus control) for differences in any observed effects.RESULTS: Within groups, baseline mean IOPs in the allergic patient-group(14.2 ±3.0 mm Hg) and in the control group(13.1±1.9 mm Hg) were similar at all times,after eye rubbing(P 】0.05, for all). The maximum reduction in IOP was 0.8 mm Hg in the control subjects and the maximum increase was also 0.8 mm Hg in the allergic subjects. Between groups(allergic versus control), the changes in IOP remained under 1 mm Hg at all times(P =0.2) after 30 min of eye rubbing. Between 0and 30 min of CT measurements after eye rubbing, the mean central CT(CCT), inferior CT(ICT), superior CT(SCT), temporal CT(TCT) and nasal CT(NCT) did not vary significantly from baseline values in the control and allergic-subject groups(P 】0.05, for both). Between both groups, changes in CT were similar at all locations(P 】0.05)except for the TC which was minimally thinner by about4.4 μm(P =0.001) in the allergic subjects than in the control subjects, 30 min following 30 s of eye rubbing.CONCLUSION: IOP measured in allergic subjects after30 s of habitual eye rubbing was comparable with that obtained in normal subjects at all times between 0 and30 min. Although, CT in the allergic subjects were similar to those of the control subjects at all times, it varied between +10 and-7.5 μm following eye rubbing, with the temporal cornea showing consistent reductions in thickness in the subjects with allergy. However, this reduction was minimal and was considered to not be clinically relevant.

Short and long term corneal biomechanical analysis after overnight orthokeratology

AIM: To investigate the short and long term corneal biomechanical changes after overnight orthokeratology(OK) and compare them with those occurring in subjects not wearing contact lenses.METHODS: Retrospective case control study enrolling 54 subjects that were divided into three groups 18 subjects each: control group(CG), short term(15 nights) OK(STOK) group, and long term(more than 1 y of OK wear) OK(LTOK) group. Corneal biomechanics were characterized using the Cor Vis? ST system(Oculus), recording parameters such as time [first/second applanation time(AT1, AT2)], speed [velocity of corneal apex at the first/second applanation time(AV1, AV2)], and amplitude of deformation(AD1, AD2) in the first and second corneal flattening, corneal stiffness(SPA1), biomechanically corrected intraocular pressure(b IOP) and corneal(CBI) and tomographic biomechanical indices(TBI).RESULTS: Significantly lower AD1 and standard deviate on of Ambrosio’s relational average thickness related to the horizontal profile(ARTh) values were found in the OK groups compared to CG(P<0.05). Likewise, significantly higher values of CBI were found in STOK and LTOK groups compared to CG(P<0.01). No significant differences between groups were found in integrated radius index(P=0.24), strain stress index(P=0.22), tomographic biomechanical index(P=0.91) and corneal stif fness parameter(SPA1, P=0.97). Significant inverse correlations were found between corneal thickness and CBI in STOK(r=-0.90, P<0.01) and LTOK groups(r=-0.71, P<0.01).CONCLUSION: OK does not seem to alter significantly the corneal biomechanical properties, but special care should be taken when analyzing biomechanical parameters influenced by corneal thickness such as amplitude of deformation, ARTh or CBI, because they change significantly after treatment but mainly due to the reduction and pachymetric progression induced by the corneal molding secondary to OK treatment.

Three-year follow-up in advanced pediatric keratoconus:thin corneas may not have pachymetry properly assessed after crosslinking

AIM:To analyze the crosslinking(CXL)effects in pediatric keratoconus,and to identify the patients’corneal characteristics whose pachymetry could not be adequately evaluated by Scheimpflug method after procedure.METHODS:Consecutive pediatric patients with progressive keratoconus underwent CXL were included.Best-corrected visual acuity(BCVA)and spheric equivalent(SE)were measured before and after CXL.After CXL,groups 1 and 2 were divided based on the posterior surface Pentacam quality specifications(QS):"OK"(Group 1)and"not OK"(Group 2).The mean(RmF and RmB)and minimum(RminF and RminB)radius of curvatures of the anterior and posterior corneal surfaces,and the thinnest pachymetry(Pmin)were measured preoperatively at 3,6,12,24,and 36 mo.Haze was annotated.RESULTS:Twenty-six patients(14 men,mean age 14±1.8 y)and median Kmax of 59.9 D initially and 61.4 D preoperatively were treated.BCVA was not different before and 24 mo after CXL.Group 2 statistically differed to group 1 in that SE was more myopic before and with no difference 24 mo after CXL;RmF and RmB were steeper and Pmin was thinner pre-surgically.Group 2,in which pachymetric changes could not be adequately evaluated after surgery,presented with significant RmF flattening,a shift to hyperopia,and more haze after CXL.CONCLUSION:Patients whose pachymetry could not be adequately evaluated after CXL had steeper and thinner corneas before surgery.The predictive factors for impaired QS after CXL are RmF,RmB,and Pmin.In advanced keratoconus,alternative methods to analyze pachymetry and the posterior surface should be considered.

Optimization of Linear Filtering Model to Predict Post-LASIK Corneal Smoothing Based on Training Data Sets

Laser vision correction is a rapidly growing field for correcting nearsightedness, farsightedness as well as astigmatism with dominating laser-assisted in situ keratomileusis (LASIK) procedures. While the technique works well for correcting spherocylindrical aberrations, it does not fully correct high order aberrations (HOAs), in particular spherical aberration (SA), due to unexpected induction of HOAs post-surgery. Corneal epithelial remodeling was proposed as one source to account for such HOA induction process. This work proposes a dual-scale linear filtering kernel to model such a process. Several retrospective clinical data sets were used as training data sets to construct the model, with a downhill simplex algorithm to optimize the two free parameters of the kernel. The performance of the optimized kernel was testedon new clinical data sets that were not previously used for the optimization.

Anterior Segment Optical Coherence Tomography Indices and Their Value in Diagnosing Corneal Ectasia

Purpose: To determine the diagnostic value of the anterior segment optical coherence tomography (AS-OCT) indices in differentiating normal from ectatic corneas. Material and Methods: Two groups of patients—with corneal ectasia and normal controls were compared. Each group consists of 80 eyes of 43 age and sex-matched patients. All of them underwent corneal topography with OCULUS Keratograph 5M and corneal pachymetry with AS-OCT with RTVue-100. The indices generated by the AS-OCT pachymetric scans were analyzed. Results: There was a statistically significant difference for all the examined indices between the two groups with p values <0.001 and a confidence interval of 95%. The minimal corneal thickness (Min) was the best performing index according to the ROC analysis with an area under the curve of 0.976 and a combination of sensitivity and specificity of 0.925 and 0.911 respectively, and a “cut-off” value of 484 microns, followed by the indices of focal thinning—Min-Med and Min-Max with an area under the curve of 0.973 and 0.971 and sensitivity/specificity of 0.938/0.962 and 0.938/0.937 respectively. The rest of the examined parameters had an area under the curve in the range between 0.950 for the central corneal thickness and 0.814 for the outer superior segment. Conclusion: The anterior segment OCT indices showed excellent capability in differentiating ectatic from normal corneas.

Determination of Central Corneal Thickness in Patients with Refractive Anomalies and Emmetropy

Aim: The purpose of this study was to compare measurements of CCT in emmetropia and patient with refractive anomalies. Methods: We represent a retrospective research which was conducted at the University Clinical Center of Kosovo (UCCK). In this study were included 80 patients, divided into two groups: test and a control group. Mean age was (M = 25.90, DS = 7.16), men (N = 41% or 51.3%) and women (N = 39% or 48%). Results: Results show that there were no differences in the CCT, Hyperopic (M = 545.21 DS = 52.24), Myopic (M = 547.90 DS = 47.93) and Emmetropic (M = 550.75 DS = 41.29). After measuring of the longitudinal axis and analyzing the data by means of Anova test, it appeared to be a significant difference between the analyzed groups, Hyperopic (M = 21.99, DS = 1.27), Myopics (M = 23.21, DS = 1.24), Emmetropic (M = 22.36, DS = 0.81). Results also revealed that there is correlation between the CCT and IOP, where increase CCT decreases IOP and vice versa (r = -0.26, p = 0.01). Conclusion: The results have shown that CCT is thinner in myopic but does not show correlation with hypermetropic and emmetropic. While during the measurement of central corneal thickness and eye tension it is found that there is a negative correlation between them. Keratometry has a negative correlation with CCT. While there was no correlation between CCT and age. Given the role of CCT in interpreting IOP values, it is recommended to perform a systematic CCT measurement in routine clinical practice, which would assist in the diagnosis of ocular hypertension.

飞秒激光小切口角膜基质透镜取出术来源的角膜基质透镜保存方法的研究进展

飞秒激光小切口角膜基质透镜取出术(SMILE)为屈光手术的主流术式。SMILE术中取出的大量新鲜角膜基质透镜组织可被回收再利用于临床,治疗远视、老视、角膜溃疡、圆锥角膜和边缘性角膜变性等眼科疾病,早期已取得良好的治疗效果。但因时间、地点等因素限制,大多新鲜透镜组织无法立即使用,且缺乏简单有效的保存方法,致使大部分新鲜透镜被丢弃。因此,探索角膜基质透镜的保存方法,提高其利用率具有重要意义。目前,角膜基质透镜的保存方法主要有超低温冷冻保存、介质保存、超低温冷冻联合介质保存、去细胞化保存和新型营养胶囊保存法。本文就SMILE来源的角膜基质透镜保存方法的研究进展进行综述,以期为角膜基质透镜的临床深入研究及应用提供参考。

Sirius Scheimpflug-Placido versus. ultrasound pachymetry for central corneal thickness: meta-analysis

Background:To compare the difference in central corneal thickness(CCT)measurements in normal eyes between a rotating Scheimpflug camera combined with a Placido-disk corneal topographer(Sirius,CSO,Italy)and ultrasound pachymetry(USP).Methods:A systematic literature search was conducted for relevant studies published on PubMed,Medline,EMBASE,and the Cochrane Library and ClinicalTrials.gov from inception to August 1st,2019.Primary outcome measures were CCT measurements between Sirius and USP.A random effects model was used to pool CCT measurements.Results:A total of twelve studies involving 862 eyes were included in this meta-analysis.The meta-analysis found CCT measurements between Sirius and USP to be statistically significantly different(P<0.0001).The mean difference between Sirius and USP was-11.26μm with a 95%confidence interval(CI)(-16.92μm,-5.60μm).The heterogeneity Was IP=60%(P=0.004).Conclusion:CCT measurements with the Sirius Scheimpflug-Placido topographer were statistically significantly lower than USP.However,it may be argued that the mean difference of 11.26μm is not a clinically significant difference.

眼眶异物DR角膜缝环定位法与CT三维重建定位法临床价值评估

【目的】探讨眼眶异物数字化放射摄影(DR)角膜缝环定位法与CT三维重建定位法临床价值。【方法】回顾性分析我院2016年1月至2020年12月收治的疑为眼部异物的患者作为研究对象,拟研究数量51例。同时做眼眶异物DR角膜缝环定位法和CT三维重建定位法,统计两种方法异物检出率,分析眼部异物的定位情况。【结果】采用眼眶异物DR角膜缝环定位法能分辨眼眶内异物者38例,采用CT三维重建定位法能分辨眼眶内异物者46例,CT三维重建定位法准确率90.20%高于眼眶异物DR角膜缝环定位法准确率74.51%(P<0.05)。眼眶异物DR角膜缝环定位法能分辨出球内异物23例,CT三维重建定位法能分辨球内异物25例,其中CT三维重建定位法能分辨的球内异物最大径为(2.65±0.14)mm,低于眼眶异物DR角膜缝环定位法能分辨的球内异物直径(2.94±0.36)mm(P<0.05)。眼眶异物DR角膜缝环定位法显示异物点钟位、异物到水平面距离、异物到矢状面距离及异物到两侧角巩膜缘连线距离与CT三维重建定位法结果相比无差异(P>0.05)。采用CT三维重建定位法能比较清楚地分辨出眼内、外的40例高密度影;采用眼眶异物DR角膜缝环定位法有23例确定为眼球内高密度影,有15例高密度影无法确定是眼球内外(P<0.05)。【结论】对于眼眶内异物定位来说,CT三维重建定位法分辨率高,定位准确,能检测眼球内部细微金属颗粒,可做眼部异物定位的常规方法,同时对于少数在虹膜根部、睫状体部、悬韧带外侧部的小异物定位,需配合眼眶异物DR角膜缝环定位法来定位。

Sirius角膜地形图仪和A型超声角膜测厚仪测量三种角膜激光屈光术前后中央角膜厚度的比较分析

目的 比较Sirius与A超测量SMART、SMILE和FS-LASIK三种手术前后中央角膜厚度(CCT)的差异性、相关性和一致性。方法 分别用Sirius及A超测量125例(249只眼)患者术前及术后3个月的CCT值。结果 三组患者术前Sirius和A超CCT值比较,差异均具有统计学意义(均P<0.001)。术后除SMART组外,Sirius和A超CCT值比较,差异具有统计学意义(P=0.755,P=0.04,P=0.000)。手术方式对术后两种仪器测量差异的影响具有统计学意义(F=28.504,P<0.001),且FS-LASIK组的差异明显大于SMART组和SMILE组(均P<0.001)。手术前后,两种仪器的相关性和一致性较好。结论 Sirius和A超在测量SMART、SMILE和FS-LASIK三种手术前后中央角膜厚度时显示了高度的相关性及一致性,结合使用可提高手术前后评估角膜参数的准确性。

角膜生物力学分析仪测量近视患者中央角膜厚度和眼压的准确性评价

背景CorvisST角膜生物力学分析仪（CorvisST）能测量角膜生物力学指标、眼压和中央角膜厚度（CCT），且测量的眼压值为校正CCT和生物力学因素的修正值，在国外已用于临床，但目前对中国人群CCT和眼压测量准确性的研究报道较少。目的评估CorvisST测量近视患者CCT和眼压的准确性，为其临床应用提供参考。方法采用诊断性试验方法，对2012年11—12月在广西视光中心准分子激光门诊行术前检查的56例近视患者进行CorvisST、Goldmann压平式眼压计（GAT）和A型超声检查，采用配对t检验法比较CorvisST测量CCT值与A型超声测量结果的差异及CorvisST测量眼压值与GAT测量结果的差异，采用Bland·Altman法评价不同测量方法测量结果的一致性。结果CorvisST测得的CCT值为（539．82±19．79）μm，高于A型超声测量的CCT值（535．34±19．41）μm，两者比较差异有统计学意义（￡：4．19，P〈O．01）。CorvisST测得CCT均值较A型超声测量均值高4．5μm，95％的一致性界限为-11．2～20．2Ixm，7．1％（4／56）的点在95％的一致性界限以外。CorvisST和GAT测得的眼压值分别为（15．75±1．60）mmHg（1mmHg=0．133kPa）和（16．23±2．40）mmHg，两者比较差异有统计学意义（t=2．15，P=0．04）。CorvisST测得的眼压均值较GAT测得均值低0．5mmHg，95％一致性界限为-3．8—2．8mmHg，3．57％（2／56）的点在95％一致性界限以外。结论CorvisST测量的CCT稍高于A型超声，2种检测仪器测量的CCT结果一致性较差，临床上不可互相代替。CorvisST测量的眼压值稍低于GAT，二者测量值具有较好的一致性，临床上可以互相替代。