青年女性生理周期期间角膜生物力学性能和眼压的节律性变化

目的探讨中国青年女性生理周期期间角膜生物力学性能和眼压的节律性变化以及两者之间的关系。方法前瞻性研究。41例健康青年女性分别在月经周期初期、排卵期和月经周期末期用眼反应分析仪（ORA）对角膜补偿眼压（IOPcc）、可重复模拟Goldmman眼压（IOPg）、角膜滞后量（CH）和角膜阻力因子（CRF）进行测量。采用Pentacam对CCT进行测量。采用重复测量方差分析法分析测量参数在不同时间点的变化以及Pearson相关进行相关性分析。结果在女性生理周期的不同阶段,CCT、CH和CRF存在波动,但差异无统计学意义,在月经周期末期IOPcc和IOPg均较初期显著下降（P<0.01）。△IOPg与△CRF呈低度正相关（r=0.356,P<0.05）,与△CH呈低度负相关（r=-0.336,P<0.05）,△IOPcc则与△CH呈中度负相关（r=-0.702,P<0.01）,与△CRF不相关（r=-0.069,P>0.05）。△CRF、△CH、△IOPg和△IOPcc均与△CCT无明显相关性（│r│均<0.3,P均>0.05）。结论在女性生理周期期间,角膜生物力学性能无明显变化但眼压在月经周期末期发生了显著下降。IOPg的变化与CH、CRF低度相关,而IOPcc则与CH中度相关,与CRF不相关。角膜生物力学性能可能是眼压的影响因素之一。     

翼状胬肉对角膜生物力学特性的影响

ObjectiveThe aim of this study is to investigate the influence of pterygium on corneal biomechanical properties by comparing the corneal hysteresis （CH） and the corneal resistance factor （CRF） measured by an ocular response analyzer （ORA） in normal and pterygium eyes. MethodsIn a case control study， 40 patients with monocular nasal simple pterygiums were randomly selected. The contralateral eyes were used for comparison. CH，CRF， IOPg and IOPcc were measured with an ORA and corneal curvature were measured with an corneal curvemeter. A paired t test， linear correlation and regression analysis were used in this study. ResultsBoth the mean CH and CRF in pterygium eyes were both lower than in normal eyes and the differences were statistically significant （t=2.637， 2.415， P<0.05）. Both the mean horizontal corneal curvature and vertical curvature in pterygium eyes were lower than in normal eyes and the differences were statistically significant （t=12.447， P<0.01； t=2.578， P<0.05）. In linear correlation and regression analysis， the D-values of CH and CRF between normal and pterygium eyes were both positively correlated with that of corneal horizontal curvature （r=0.622， 0.678， P<0.01）， and corneal astigmatism （r=0.525， 0.515， P<0.01）. ConclusionThe CH and CRF were significantly lower in pterygium eyesthan in normal eyes， and the D-values of CH and CRF betweennormal and pterygium eyes werecorrelated with horizontal corneal curvature. Using the measurements of CH， CRF and corneal curvature is helpful to assess the severity of pterygium′s influence on the cornea.     

LASIK术后角膜生物力学变化与眼压测量值的相关性

目的 观察LASIK术后角膜生物力学参数和眼压测量值的变化及角膜生物力学变化与眼压的相关性。设计 前瞻性病例系列。研究对象 哈尔滨医科大学附属第一医院2014年1-12月LASIK手术患者81例（162眼）。方法 应用非接触眼压计（non-contact tonometer,NCT）分别在术前及术后3个月测量眼压。同时应用眼反应分析仪（ocular response analyzer,ORA）测量角膜滞后量（corneal hysteresis,CH）、角膜阻力因子（corneal resistance factor, CRF）、模拟Goldmann 眼压（Goldmann intraocular pressure,IOPg）和角膜补偿眼压（corneal-compensated intraocular pressure,IOPcc）。比较手术前后各参数的变化并分析术后角膜生物力学参数变化与眼压测量值的相关性。 主要指标 手术前后NCT、IOPcc、IOPg、CH、CRF。 结果 LASIK术后3个月CH、CRF、IOPcc、IOPg、NCT测量值与术前比较均显著降低,术后IOPcc与IOPg和NCT之间比较差异均有统计学意义（P<0.05）;△CH、△CRF与△IOPcc、△IOPcc- IOPg和△IOPcc-△NCT均成负相关,△CH、△CRF与△IOPg和△NCT均成正相关（P<0.05）;CH和CRF的减少量与眼压测量值下降具有相关性（P<0.05）。结论 LASIK术后角膜生物力学参数和眼压测量值均较术前显著降低,眼压测量值下降与CH和CRF的减少量具有相关性,说明眼压下降的程度可能受角膜生物力学特性的影响。     

Reproducibility of viscoelastic property and intraocular pressure measurements obtained with the Ocular Response Analyzer

Purpose: To analyse the reproducibility of corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann‐correlated intraocular pressure (IOPg) and corneal‐compensated intraocular pressure (IOPcc) obtained with the ocular response analyzer (ORA). Methods: This is a prospective study, nonmasked, of eight successive examinations with the ORA device in 60 normal eyes. Using 30 eyes (one eye per subject), the reproducibility was assessed by comparing the first series of four examinations to the second four and by calculating the within‐subject coefficient of variation. The correlation and difference with the fellow eye were analysed, respectively. Results: The mean values were 10.7 ± 1.8 mmHg, CRF; 10.6 ± 1.6 mmHg, CH; 15.9 ± 3.9 mmHg, IOPg and 16.2 ± 3.7 mmHg, IOPcc. The reproducibility was significantly different for CRF (5.2 ± 5.9%), CH (7.3 ± 8.6%), IOPg (7.7 ± 6.7%) and IOPcc (10.1 ± 8.0%); p < 0.001. Considering the reproducibility, CRF correlated with CH (rs = 0.55; p < 0.001) and showed to be independent of IOPg and IOPcc. The score spread was best for CRF (2.6 ± 1.5 mmHg; 24.0%) compared to IOPg (4.3 ± 1.5 mmHg; 28.1%) and CH (3.1 ± 1.7 mmHg; 29.9%) and worst for IOPcc (5.5 ± 2.5 mmHg; 34.4%). The lowest difference with the fellow eye was observed for CRF (5.0%; p = 0.09). The correlation with the fellow eye was high, especially for IOPcc and CRF (rs > 0.9; p < 0.001) followed by IOPg and CH (rs > 0.8; p < 0.001). Conclusion: The ORA device provides reproducible information on viscoelastic properties of the cornea in normal eyes notably CRF and CH. IOPcc was less reproducible. Four measurements per eye were necessary to reach a 10% precision and six for 5%.     

Corneal biomechanical changes and intraocular pressure in patients with thyroid orbitopathy

AIM: To determine the relevance of the objective parameters addressing the altered biomechanical properties of cornea for glaucoma monitoring in patients with mild or moderate thyroid associated orbitopathy (TAO), and in healthy individuals. METHODS: Twenty-five patients with TAO (group 1) and 25 healthy adults (group 2) were included to the study. Both groups were of a similar age and the ratio women:man. For each patient, the following parameters of both eyes were measured with ocular response analyzer (ORA): corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann correlated intraocular pressure (IOPg) and corneal compensated intraocular pressure (IOPcc). In both groups participating in our study, all measurements were performed within minutes to reduce the diurnal effects. RESULTS: The mean age in group 1 was 56±11y and 76% were women, 24% were men. The mean age in group 2 was 64±11y and 68% were women, 32% were men. CH correlated negatively with IOPg in group 1 (r2=0.10, P<0.05). IOPg strongly correlated with IOPcc in both groups (group 1: r2=0.79, P<0.0001; group 2: r2=0.85, P<0.0001). There was positive correlation between CRF and IOPg in group 1 (r2=0.12, P<0.05) and in group 2 (r2=0.31, P<0.0001). Statistical analysis revealed no significant correlation between CRF and IOPcc in group 1 (r2=0.009, P>0.05) and also no significant correlation in group 2 (r2=0.04, P>0.05). CRF mean value in group 2 (11.51±1.72 mm Hg) was higher than in group 1 (10.85±1.45 mm Hg) (P<0.05). IOPg strongly correlated with IOPcc in both groups (group 1: r2=0.79, P<0.0001; group 2: r2=0.85, P<0.0001). There was also strong correlation between CRF and CH in both populations: group 1: (r2=0.58, P<0.0001), group 2: (r2=0.41, P<0.0001). CONCLUSION: Biomechanical parameters of cornea, as quantified by CH and CRF, and measured together with IOPcc, precisely reveal glaucoma staging in TAO and thus are reliable for diagnosing and follow-up in clinical practice.     

近视人群中角膜生物力学特性的分布

目的：分析伊朗近视眼及散光人群中角膜生物力学参数的分布特征。

方法：对接受激光矫正手术的近视眼及散光患者180眼进行前后节、显然验光等效球镜度、Orbscan II和Zywave全面的术前检查。用眼反应分析仪测量角膜滞后量,角膜阻力因子,模拟Goldmann眼压值及角膜补偿后眼压值。分析所有角膜生物力学的分布特性及其与显然验光等效球镜度、性别和年龄的相关性。数据采用SPSS 17软件进行统计学分析,以P<0.05为有显著性差异。

结果：平均年龄为28.20±6.78岁。平均显然验光等效球镜为-4.21±1.19D。平均角膜滞后量,角膜阻力因子,模拟Goldmann眼压值和角膜补偿后眼压值分别为10.00±1.28mmHg,10.17±1.45mmHg,15.71±2.67mmHg和 16.68±2.41mmHg。近视人群中,28.4%角膜滞后量约为10mmHg,71%从9mmHg增长到11mmHg。25.9%的近视人群的角膜阻力因子为10mmHg,48.7%为9mmHg增长到11mmHg。显然验光等效球镜与角膜滞后量(Rs=0.001,P=0.71)和显然验光等效球镜与角膜阻力因子(Rs=0.01,P=0.18)之间正相关性不明显。

结论：研究显示了伊朗近视眼人群中角膜生物力学的分布特征(角膜滞后量,角膜阻力因子,模拟Goldmann眼压值及角膜补偿后眼压值),并证实了角膜生物力学特性参数和显然验光等效球镜,年龄及性别之间没有统计学相关性。     

Corneal biomechanical properties in normal‐tension glaucoma

Purpose: To investigate the intraocular pressure (IOP) and corneal biomechanical properties of normal and normal‐tension glaucoma (NTG) eyes. Methods: This study included 83 normal and 83 NTG eyes. We measured corneal‐compensated IOP (IOPcc), Goldmann‐correlated IOP (IOPg), corneal resistance factor (CRF), corneal hysteresis (CH) and central corneal thickness (CCT) three times each for normal and NTG eyes using an Ocular Response Analyzer (ORA). Results: No significant difference in CCT was seen between normal eyes (541.4 ± 26.8 μm) and NTG eyes (535.4 ± 24.9 μm; p = 0.16). IOPcc was significantly higher in NTG eyes (16.1 ± 2.6 mmHg) than in normal eyes (15.1 ± 2.9 mmHg; p = 0.01), while IOPg was significantly lower in NTG eyes (14.1 ± 2.7 mmHg) than in normal eyes (15.1 ± 3.0 mmHg; p = 0.04). CRF and CH were significantly lower in NTG eyes (CRF, 8.9 ± 1.5 mmHg; CH, 9.2 ± 1.3 mmHg) than in normal eyes (CRF, 10.6 ± 1.4 mmHg; CH, 10.8 ± 1.3 mmHg; p < 0.0001 each). Conclusion: IOPcc was significantly higher in NTG eyes than in normal eyes. The ORA may be useful for distinguishing between the IOPcc of NTG eyes with normal IOP and that of normal eyes. In addition, the ORA enables CRF and CH to be measured in vivo, and weakness of the lamina cribrosa may be clinically inferred from the fact that CRF and CH were reduced in NTG eyes in our study. Low CRF and CH may be clues to the pathology of NTG.     

Are There Any Changes in Corneal Biomechanics and Central Corneal Thickness in Fuchs’ Uveitis?

Purpose: To compare corneal biomechanics, intraocular pressure (IOP) and central corneal thickness (CCT) of 38 patients with unilateral Fuchs’ uveitis (FU) with 42 healthy controls.

Methods: Corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated and corneal-compensated IOP (IOPg and IOPcc, respectively) and CCT were measured.

Results: The mean CH, CRF, and IOPg of the involved FU eyes were significantly lower (9.5?±?1.6, 9.0?±?1.9 and 13.1?±?4.3?mmHg) than contralateral eyes (10.1?±?1.7, 9.9?±?1.7 and 14.6?±?3.4?mmHg), and controls (10.5?±?1.5, 10.3?±?1.5 and 14.8?±?2.5?mmHg), respectively. There was no significant difference for mean IOPcc between involved FU or contralateral eyes and controls (14.8?±?4.1, 15.5?±?3.4 and 15.0?±?2.7?mmHg). The CCT values correlated with CH and CRF in the involved and contralateral eyes.

Conclusions: Involved FU eyes had lower CH, CRF, and IOPg than contralateral eyes and controls, with no difference regarding IOPcc.     

Age-related change in corneal biomechanical parameters in a healthy Caucasian population

Purpose: To determine the effect of aging on corneal biomechanical parameters measured via ocular response analyzer in a homogenous healthy Caucasian population.

Methods: A total of 2039 Caucasian adults were consecutively recruited and divided into seven groups according to decades of age. The difference in mean corneal hysteresis (CH), mean corneal resistance factor (CRF), mean Goldmann-correlated intraocular pressure (IOPg), and mean corneal-compensated IOP (IOPcc) between decades of age were investigated. The strength of the correlations between corneal biomechanical parameters, and between each biomechanical parameter and age were evaluated. The effect of age on each corneal biomechanical parameter was analyzed.

Results: Mean age of the participants (1173 female and 866 male) was 43.30 ± 14.64 years. Mean CH, CRF, IOPcc, and IOPg were 11.49 ± 1.89 mmHg, 11.40 ± 2.30 mmHg, 15.01 ± 3.11 mmHg, and 15.72 ± 3.80 mmHg, respectively. There were significant differences in mean CH, CRF, IOPcc, and IOPg between groups (p < 0.001 for all parameters). There was a significant negative correlation between age and CH (r = –0.067 and p = 0.003), and a significant negative correlation between age and CRF (r = –0.053 and p = 0.017). There was a significant positive correlation between age and IOPg (r = 0.25 and p < 0.001), and between age and IOPcc (r = 0.20 and p < 0.001). Linear regression analysis showed that for every 1-year increase CH decreased 0.011 mmHg, CRF decreased 0.004 mmHg, IOPcc increased 0.053 mmHg, and IOPg increased 0.047 mmHg.

Conclusions: Aging can cause significant changes in corneal biomechanical parameters. Corneal biomechanical parameters were correlated with each other, and each was correlated with aging.     

Evaluation of corneal biomechanical properties following penetrating keratoplasty using ocular response analyzer

Purpose:

To evaluate corneal biomechanical properties in eyes that has undergone penetrating keratoplasty (PK).

Materials and Methods:

Retrospective observational study in a tertiary care centre. Data recorded included ocular response analyzer (ORA) values of normal and post-keratoplasty eyes [corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg), and cornea-compensated intraocular pressure (IOPcc)], corneal topography, and central corneal thickness (CCT). Wilcoxon signed rank test was used to analyze the difference in ORA parameter between post-PK eyes and normal eyes. Correlation between parameters was evaluated with Spearman''s rho correlation.

Results:

The ORA study of 100 eyes of 50 normal subjects and 54 post-keratoplasty eyes of 51 patients showed CH of 8.340 ± 1.85 and 9.923 ± 1.558, CRF of 8.846 ± 2.39 and 9.577 ± 1.631 in post-PK eyes and normal eyes, respectively. CH and CRF did not correlate with post-keratoplasty astigmatism (P =0.311 and 0.276, respectively) while a significant correlation was observed with IOPg (P =0.004) and IOPcc (P < 0.001).

Conclusion:

Biomechanical profiles were significantly decreased in post-keratoplasty eyes with significant correlation with higher IOP as compared with that in normal eyes.     

Correlating Corneal Biomechanics and Ocular Biometric Properties with Lamina Cribrosa Measurements in Healthy Subjects

Purpose: To examine interrelations between corneal biomechanics, ocular biometric variables and optic disc size (ODS), lamina cribosa depth (LCD) or thickness (LCT) in a healthy population. Material and Methods: In a cross-sectional case-control study, the following measurements were made in 81 eyes of 81 participants: axial length, anterior chamber depth, lens thickness, and central corneal thickness using the optical biometer Lenstar LS900; and corneal hysteresis (CH), corneal resistance factor (CRF), Goldman-correlated intraocular pressure (IOPg), and corneal-compensated IOP (IOPcc) using the Ocular Response Analyzer. Serial horizontal enhanced depth imaging optical coherence tomography (EDI OCT) B-scans of the optic nerve head were obtained in each participant. Mean ODS, mean LCD, and mean LCT were measured in 11 equally spaced horizontal B-scans, excluding the LC insertion area under Bruch’s membrane and scleral rim. Results: LCD was measured in 74 of 81 eyes (91.36%); LCT in 60/81 (75.3%); ODS in 81/81 (100%). CRF was poorly, but significantly, correlated with LCT (Pearson’s R = 0.264; P = 0.045). IOPcc, IOPg, CH, and ocular biometrics variables were poorly (non-significantly) correlated with LCD, LCT, and ODS. Conclusions: CRF was poorly but directly correlated with LCT. No association was detected between CH or ocular biometric variables and ODS, LCD, or LCT.     

Corneal Biomechanical Characteristics in Patıents with Behçet Disease

Aim: To examine corneal biomechanical properties, intraocular pressure, and central corneal thickness in uveitic eyes with Behçet disease (BD) and to compare them with healthy controls. Methods: This study included 40 eyes of 34 patients with ocular BD and 20 eyes of 20 healthy controls. Eyes with ocular BD were subdivided into active and inactive groups. Ocular response analyzer (ORA) measurements were performed on the 20 eyes of 16 patients with active BD (group 1), 20 eyes of 18 patients with inactive BD (group 2), and 20 eyes of 20 healthy volunteers who served as the control group (group 3). Corneal hysteresis (CH), corneal resistance factor (CRF), intraocular pressure (Goldmann correlated [IOPg], and corneal compensated [IOPcc]) and central corneal thickness (CCT) values were recorded. Results: Mean age of patients in groups 1, 2, and 3 was 33.81?±?9.36, 32.38?±?9.08, and 31.05?±?5.85 years, respectively (p?=?0.76). Mean CH, CRF, IOPg, IOPcc, and CCT values in groups 1, 2, and 3 were [8.51?±?1.88, 9.72?±?2.11, 19.87?±?2.92, 16.13?±?3.29, and 592.50?±?39.95], [8.46?±?1.82, 8.45?±?1.98, 15.89?±?2.68, 15.35?±?2.91, and 528.35?±?19.18], and [8.47?±?1.48, 8.43?±?1.58, 15.59?±?2.74, 15.42?±?3.19, and 526.30?±?18.21], respectively [(p₁?=?0.040, 0.904, <0.001, 0.495 and <0.001 for CRF, CH, IOPg, IOPcc and CCT in group 1, respectively), (p₂?=?0.989, 0.904, 0.659, 0.989, and 0.989 for CRF, CH, IOPg, IOPcc and CCT in group 2, respectively), (p₃?=?0.989, 0.904, 0.660, 0.989, and 0.989 for CRF, CH, IOPg, IOPcc and CCT in group 3, respectively)]. Conclusion: CRF, IOPg, and CCT values altered in active BD group when compared with inactive BD and control group (p?相似文献   

Effect of biometric characteristics on biomechanical properties of the cornea in cataract patient

AIM: To determine the impact of biometric characteristics on the biomechanical properties of the human cornea using the ocular response analyzer (ORA) and standard comprehensive ophthalmic examinations before and after standard phacoemulsification. METHODS: This study comprised 54 eyes with cataract with significant lens opacification in stages I or II that underwent phacoemulsification (2.8 mm incision). Corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg), and corneal-compensated intraocular pressure (IOPcc) were measured by ORA preoperatively and at 1mo postoperatively. Biometric characteristics were derived from corneal topography [TMS-5, anterior equivalent (EQTMS) and cylindric (CYLTMS) power], corneal tomography [Casia, anterior and posterior equivalent (EQaCASIC, EQpCASIA) and cylindric (CYLaCASIA, CYLpCASIA) power], keratometry [IOLMaster, anterior equivalent (EQIOL) and cylindric (CYLIOL) power] and autorefractor [anterior equivalent (EQAR)]. Results from ORA were analyzed and correlated with those from all other examinations taken at the same time point. RESULTS: Preoperatively, CH correlated with EQpCASIA and CYLpCASIA only (P=0.001, P=0.002). Postoperatively, IOPg and IOPcc correlated with all equivalent powers (EQTMS, EQIOL, EQAR, EQaCASIA and EQpCASIA) (P=0.001, P=0.007, P=0.001, P=0.015, P=0.03 for IOPg and P<0.001, P=0.003, P<0.001, P=0.009, P=0.014 for IOPcc). CH correlated postoperatively with EQaCASIA and EQpCASIC only (P=0.021, P=0.022). CONCLUSION: Biometric characteristics may significantly affect biomechanical properties of the cornea in terms of CH, IOPcc and IOPg before, but even more after cataract surgery.     

Corneal biomechanical properties changes after coaxial 2.2-mm microincision and standard 3.0-mm phacoemulsification

AIM: To compare the changes in corneal biomechanics measured by ocular response analyzer (ORA) after 2.2-mm microincision cataract surgery and 3.0-mm standard coaxial phacoemulsification. METHODS: The prospective nonrandomized study comprised eyes with cataract that had 2.2-mm coaxial microincision or 3.0-mm standard incision phacoemulsification. The corneal hysteresis (CH), corneal resistance factor (CRF), corneal-compensated intraocular pressure (IOPcc) and Goldmann-correlated intraocular pressure (IOPg) were measured by ORA preoperatively and at 1d, 1-, 2-, 3- and 4-week postoperatively. Results were analyzed and compared between groups. RESULTS: In both groups, CH decreased in the immediate postoperative period (P<0.05), returned to the preoperative level at one week (P=0.249) in the 2.2-mm group, and at two weeks in the 3.0-mm group (P=0.264); there was no significant change in CRF values. In 2.2-mm group, mean IOPcc and IOPg increased at 1d postoperatively (both P<0.05), and returned to preoperative level at one week (P=0.491 and P=0.923, respectively). In 3.0-mm group, mean IOPcc and IOPg increased at 1d and 1wk postoperatively (P=0.005 and P=0.029, respectively), and returned to preoperative level at 2wk (P=0.347 and P=0.887, respectively). CONCLUSION: Significant differences between preoperative and postoperative corneal biomechanical values were found for CH, IOPcc and IOPg. But the recovery time courses were different between the two groups. The 2.2-mm coaxial microincision cataract surgery group seemed recovery faster compared to the 3.0-mm standard coaxial phacoemulsification group.     

Internal limiting membrane dragging and peeling: a modified technique for macular holes closure surgery

AIM: To introduce a modified technique of internal limiting membrane (ILM) centripetal dragging and peeling to treat idiopathic macular hole (IMH) and to observe the ILM-retina adhesive forces. METHODS: Twenty-six consecutive patients with stage 3 to 4 IMH and followed up at least six months were enrolled. All patients underwent complete par plana vitrectomy, ILM dragging and peeling, fluid and gas exchange, 15% C3F8 tamponade and 2-week prone position. The best corrected visual acuity, macular hole evaluation by optical coherence tomography, and complications were evaluated. RESULTS: The mean diameter of IMH was 524±148 μm (range: 201-683 μm), with 21 cases (80.8%) greater than 400 μm. ILM dragging and peeling were successfully performed in all cases. Most of the ILM-retina adhesive forces are severe (42.3%, 11/26), followed by mild (38.5%, 10/26), and moderate (19.2%, 5/26). The mean follow-up duration was 21.2±6.1mo. The IMH was closed in 25 (96.3%) eyes. Visual acuity (logMAR) improved significantly from 1.2±0.6 preoperatively to 0.7±0.5 postoperatively (P<0.001). CONCLUSION: Preexisting ILM-retina adhesive force is found in IMH patients. With assistance of this force, this modified technique may help to release the IMH edges and improve the closure rate of large IMH.     

Changes in corneal biomechanics and intraocular pressure following Femto-LASIK using Goldman applanation tonometry and ocular response analyzer

AIM:To compare intraocular pressure(IOP)measurements before and after laser in situ keratomileusis(LASIK)with a femtosecond laser for flap creation using ocular response analyzer(ORA)and Goldmann applanation tonometry,and to identify factors that may influence the preoperative and postoperative IOP.METHODS:A prospective study conducted on myopic patients who underwent LASIK using a femtosecond laser for flap fashioning.Enrolled patients were evaluated preoperatively,6 wk and 3 mo postoperatively for manifest refraction(MR),keratometric(K)readings and central corneal thickness(CCT)using a scheimpflug-based topography.Corneal resistance factor(CRF),corneal hysteresis(CH),Goldmann correlated IOP(IOPg)and corneal compensated IOP(IOPcc)were measured using ORA besides IOP assessment by Goldman applanation tonometry(GAT).RESULTS:There was a statistically significant decrease in measures of IOPg by 3.35±0.83 mm Hg,followed by GAT which decreased by 2.2±0.44 mm Hg,and the least affected by operation was IOPcc which decreased only by 0.87±0.1 mm Hg after 6 wk.After 3 mo follow up there was a statistically significant decrease in IOPcc which decreased only by 0.76±0.4 mm Hg,followed by IOP GAT by 1.6±0.5 mm Hg,and the most affected by operation was IOPg which decreased by 2.3±0.3 mm Hg.Correspondingly,there was a statistically significant decrease in CH and CRF after 6 wk and 3 mo.At 3 mo,the preoperative MR and preoperative GAT were prominent significant predictors of the postoperative GAT changes.The prediction equation was subsumed.CONCLUSION:IOP measurements and corneal biomechanical factors reduce significantly after LASIK with a femtosecond laser for flap creation.The IOPcc values are less influenced by changes in corneal properties than IOPg and GAT,indicating that IOPcc may provide the most reliable measurement of IOP after this procedure.     

Relationship Between Corneal Hysteresis and Corneal Resistance Factor with Other Ocular Parameters

Abstract

Purpose: To evaluate the relationship between corneal hysteresis (CH) and corneal resistance factor (CRF) with age, central corneal thickness (CCT), corneal curvature (KM), corneal volume (CV), and refractive error in naïve eyes. Methods: 105 healthy subjects (58 male and 47 female) were included in this study. The ages ranged from 19 to 82 years (mean 43.1?±?15.4 years) and refraction between ?11?D and +6?D (mean ?0.79?±?2.95?D). CH and CRF obtained with the Ocular Response Analyzer (ORA) were correlated with age, refractive error, Goldmann Applanation Tonometry (GAT), and with CCT, KM, CV obtained with the Pentacam, and with Corneal-Compensated Intraocular Pressure (IOPcc) and Goldmann-correlated intraocular pressure measurement (IOPg) obtained with ORA. A multivariable mixed effect model was used to evaluate associations among these parameters. Results: CH ranged from 6.9 to 14.6?mmHg (mean 10.26?±?1.49?mmHg); CRF ranged from 5.8 to 17?mmHg (mean 10.38?±?1.64?mmHg). Multivariate analysis showed a statistically significant correlation between CH with CCT (p?<?0.001), and KM (p?<?0.001), and between CRF with CCT (p?<?0.001) and GAT (p?<?0.001). Conclusions: Our findings support the hypothesis that CH and CRF are related to the corneal shape and thickness, and show a decrease of CH with age.     

Biomechanical properties of the cornea measured by the Ocular Response Analyzer and their association with intraocular pressure and the central corneal curvature

Background: The aim of this study was to investigate the biomechanical properties of the cornea and their association with intraocular pressure (IOP), central corneal thickness (CCT) and the central corneal radius of curvature (Rc). Methods: Eighty‐three eyes were divided into two groups. The biomechanical properties of the cornea were measured in 63 normal eyes and in 20 post‐laser in situ keratomileusis (LASIK) eyes. The IOP, corneal hysteresis (CH) and corneal resistance factor (CRF) were measured by the Ocular Response Analyzer (ORA). The Rc and CCT were measured using the corneal topographer Medmont E‐300 and the Tomey SP‐100 Handy ultrasonic pachymeter. Other parameters measured by the ORA, such as TimeIn and TimeOut, were also studied. Results: A mean corneal hysteresis of 10.8 mmHg and CRF of 10.6 mmHg were recorded for the normal eyes. There was no significant association with central curvature. All parameters measured by the ORA showed a significant correlation with the CCT, except for the corneal‐compensated intraocular pressure (IOPcc). Both IOPs measured by the ORA had the same values for the mean CH and CRF. For the post‐LASIK eyes, the CH and CRF were lower than in the normal non‐operated eyes. The TimeIn and the TimeOut also presented lower values for the post‐LASIK eyes, suggesting that additional data can be obtained with the ORA measurements. Conclusions: The results of this study indicate that there is no correlation between the parameters measured with the Ocular Response Analyzer and central corneal radius of curvature. Some of the biomechanical properties of the cornea studied were found to differ in the normal eyes compared to the post‐LASIK eyes.     

FS-LASIK联合胶原交联术后的早期临床观察

目的：探讨飞秒激光辅助准分子激光原位角膜磨镶术(femtosecond laser-assisted excimer laser in situ keratomileusis,FS-LASIK)联合胶原交联术后的早期安全性和有效性。

方法：选取2016-07/2017-08我院接受飞秒辅助LASIK联合胶原交联术近视患者30例60眼,分别于术前、术后1、3mo检查裸眼视力。应用角膜地形图(TMS)测量陡峭K值(Ks)、平坦K值(Kf)、角膜规则指数(SRI)、角膜非对称指数(SAI)。眼反应分析仪(ocular response analyzer,ORA)检测角膜补偿眼压(corneal compensated intraocular pressure,IOPcc)、模拟Goldmann眼压(Goldmann correlated IOP value,IOPg)、角膜阻力因子(corneal resistance factor,CRF)、角膜滞后量(corneal hysteresis,CH)。伽利略眼前节分析值包括前后表面屈光度和角膜厚度分布。角膜内皮细胞计数仪器进行内皮计数检查,比较手术前后各指标的差异。

结果：术后1d 26眼(43%)、1mo 55眼(92%)、3mo 50眼(83%)裸眼视力保持0.8以上。术后1mo与术前比较,IOPcc、IOPg、CRF、CH较术前显著降低,差异均有统计学意义(P<0.01)。术后3mo与1mo比较,IOPcc、IOPg、CRF、CH值无统计学差异(P>0.05)。角膜地形图参数：术后1mo与术前比较,Ks、Kf显著下降(P<0.01),SRI、SAI显著上升(P<0.01); 术后3mo与1mo比较,Ks有显著升高(P<0.05),Kf变化无统计学差异(P>0.05),SRI、SAI有显著下降(P<0.05)。伽利略眼前节分析中：模拟角膜曲率计陡峭K值(Sim Ks)、模拟角膜曲率计平坦K值(Sim Kf)在3mo较1mo有0.94D和0.95D的增长。另外,前后表面Kf值3mo较1mo明显增加,差异有统计学意义(P<0.01); 而Ks值差异无统计学意义(P>0.05)。同时,中心点、厚度最薄点,术后3mo与1mo角膜厚度差异无统计学意义(P>0.05)。角膜内皮计数检查：术前(3059.95±247.87/mm²)与术后1mo(3052.87±267.71/mm²)比较,差异无统计学意义(t=0.279,P>0.05)。

结论：屈光角膜手术联合胶原交联术对于度数高和角膜薄、角膜厚度分布不均、地形图异常(除外圆锥角膜)的患者治疗安全有效。     

Corneal properties in children with congenital isolated growth hormone deficiency

AIM:To compare the corneal parameters of children with congenital isolated growth hormone deficiency and healthy subjects.METHODS: In this cross-sectional, prospective study, 50 cases with growth hormone (GH) deficiency treated with recombinant GH and 71 healthy children underwent a complete ophthalmic examination. The corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg) and corneal-compensated intraocular pressure (IOPcc) were measured with the Ocular Response Analyzer (ORA). Central corneal thickness (CCT) was measured by a ultrasonic pachymeter.RESULTS: The mean age was 13.0±3.0 years in the GH deficiency group consisting of 21 females and 29 males and 13.4±2.4 years in the healthy children group consisting of 41 females and 30 males. There was no statistically significant difference between the groups for gender or age (Chi-square test, P=0.09; independent t-test, P=0.28, respectively). The mean duration of recombinant GH therapy was 3.8±2.4y in the study group. The mean CH, CRF, IOPg and IOPcc values were 11.0±2.0, 10.9±1.9, 15.1±3.3, and 15.1±3.2 mm Hg respectively in the study group. The same values were 10.7±1.7, 10.5±1.7, 15.2±3.3, and 15.3±3.4 mm Hg respectively in the control group. The mean CCT values were 555.7±40.6, 545.1±32.5 μm in the study and control groups respectively. There was no statistically significant difference between the two groups for CH, CRF, IOPg, IOPcc measurements or CCT values (independent t-test, P=0.315, 0.286, 0.145, 0.747, 0.13 respectively).CONCLUSION: Our study suggests that GH deficiency does not have an effect on the corneal parameters and CCT values. This observation could be because of the duration between the beginning of disease and the diagnosis and beginning of GH therapy.