Circadian variations in central corneal thickness and intraocular pressure in patients with glaucoma

AIM: To analyse 24 hour variations in intraocular pressure (IOP) and central corneal thickness (CCT) in a group of glaucomatous patients. METHODS: 30 patients with primary open angle glaucoma were hospitalised and underwent circadian evaluations (at 8 pm, midnight, 4 am, 8 am, noon, and 4 pm) of supine and sitting IOP, respectively, measured using a Perkins and a Goldmann tonometer, and CCT measured using an ultrasonic pachymeter (the mean value of three measurements within 5 mum). All patients were treated with timolol 0.5% twice daily and latanoprost 0.005% once daily. RESULTS: Mean supine IOP was 15.3 (SD 3.7) mm Hg (range 10-25), with circadian fluctuations of 7.3 (3.3) mm Hg. Mean sitting IOP was 15.1 (3.9) mm Hg (range 8-26), with circadian fluctuations of 5.4 (3.1) mm Hg. Mean CCT was 534 (39) microm (range 443-637 microm) with circadian fluctuations of 16.5 (6.2) microm (range 6-31 microm). Both the within patient and within time point fluctuations in CCT were statistically significant (p<0.0001, ANOVA). CONCLUSIONS: The authors found considerable fluctuations in 24 hour IOP. The circadian fluctuations in CCT were small and, although statistically significant, did not seem to interfere with the circadian IOP assessment.     

Combining corneal hysteresis with central corneal thickness and intraocular pressure for glaucoma risk assessment

Purpose

To determine whether adjusting corneal hysteresis (CH) values for central corneal thickness (CCT) and intraocular pressure (IOP) improves its capability to differentiate primary open-angle glaucoma (POAG) from ocular hypertension (OH).

Methods

This prospective, observational, cross-sectional study included 169 eyes of 169 subjects with a diagnosis of POAG (n=81) or OH (n=88). We utilized the Ocular Response Analyzer (ORA), Pascal Dynamic Contour Tonometer (DCT), Goldmann applanation tonometer (GAT), and ORA ultrasound pachymeter to obtain CH, IOP, and CCT values. Correlational, regression, and t-test analyses were conducted before and after the sample was divided into low, intermediate, and thick CCT subgroups.

Results

In the full sample, CH and CCT were moderately correlated (r=0.44, P<0.001). Although both were related to diagnosis in univariate regression analysis, only CH was independently related to glaucoma diagnosis in multivariate analysis. After the sample was divided into CCT tertiles, CH was significantly lower in POAG vs OH eyes within all three CCT subgroups, and CH was the only multivariate variable that differentiated POAG from OH in each CCT subgroup. Moreover, the relationship between CH and diagnosis was more robust within the CCT subgroups compared with the full sample, suggesting that integrating CCT into CH interpretation is beneficial. Adjusting CH for IOP did not aid diagnostic precision in this study.

Conclusion

Our findings suggest that combining CH and CCT for glaucoma risk assessment improves diagnostic capability compared to using either factor alone. Conversely, adjusting CH for IOP provided no clear clinical benefit in this study.     

Diurnal variation in central corneal thickness and intraocular pressure in eyes with pseudoexfoliation syndrome without glaucoma

Aim:

The aim was to ascertain if any differences exist in diurnal central corneal thickness (CCT) and intra-ocular pressure (IOP) between eyes with pseudoexfoliation (PXF) syndrome without glaucoma and eyes with no ocular pathology. A secondary aim was to determine whether there was a significant relationship between CCT and IOP.

Settings and Design:

This study was a prospective design conducted within a hospital setting.

Materials and Methods:

The experimental group consisted of seven participants with bilateral PXF (14 eyes) and the control group comprised of 15 participants (30 eyes). Testing included CCT and IOP measured at four different times on one given day (8.00 a.m.; 11 a.m.; 2 p.m. and 5 p.m.).

Statistical Analysis:

The data were analyzed with the generalized linear latent mixed model.

Results:

PXF eyes displayed a significantly thinner overall mean CCT (520 μm) compared to controls (530 μm). Furthermore, a significant reduction in CCT and IOP occurred in the PXF group from 8 a.m. to 5 p.m. The mean overall IOP in PXF eyes was significantly lower than the control group. A significant association between IOP and CCT was also found in PXF eyes.

Conclusions:

Displaying a significantly thinner mean CCT highlights the importance of measuring CCT in an ophthalmic clinical setting as to avoid falsely underestimated IOP measurements in such a high-risk glaucoma population. Furthermore, a statistically significant correlation between IOP and CCT in PXF eyes suggests that the reduction in CCT that occurred in PXF eyes between 8 a.m. and 5 p.m. may be partly responsible for the reduction in IOP measurements.     

Diurnal variation of intraocular pressure in suspected glaucoma patients and their outcome

Background A case-controlled prospective study was conducted to evaluate the diurnal variation of intraocular pressure (IOP); the mean, the amplitude of variation and the peak and trough times of pressure readings in the suspected open-angle glaucoma patients as compared with a control group. We also looked at the outcome of these suspects after diurnal variation of IOP measurements. Methods Diurnal variation of intraocular pressure was measured in 202 eyes of suspected open-angle glaucoma patients and 100 control eyes, at 4-hourly intervals for 24 hours (phasing). Based on the phasing results, optic disc changes and visual field defects, the patients were diagnosed as primary open angle glaucoma (POAG), normal tension glaucoma (NTG), ocular hypertension (OHT), or physiologic cup (PC), or still remained as glaucoma suspects due to inconclusive diagnosis. The last group (glaucoma suspects) was then followed up 6-monthly for their eventual outcome. Results The highest percentage of suspected glaucoma patients had peak (maximum) readings in the mid-morning (10–11 a.m.) and trough (minimum) readings after midnight (2–3 a.m.); the highest percentage of control group had peak readings in the late evening (6–7 p.m.) and trough readings after midnight (2–3 a.m.). The mean amplitude of variance was 6 mm Hg in suspected glaucoma group and 4 mm Hg in the control group. After ‘phasing’, 18.8% of the suspected glaucoma patients were diagnosed as POAG, 16.8% as NTG, 5% as OHT, and 28.7% as physiologic cup; 30.9% remained as glaucoma suspects. After 4 years follow-up, 70% of the glaucoma suspects still remained as glaucoma suspects, 6.7% developed NTG and another 6.7% POAG; 16.6% were normal. Conclusions Serial measurement of IOP ( phasing) in a 24-hour period is still needed, in order not to miss the peak and the trough IOP readings in suspected open-angle glaucoma patients, which helps in better management of glaucoma. Among 30.9% of patients who remained as glaucoma suspects after the initial phasing, 13.4% developed NTG/POAG over a period of 4 years. This paper was presented in part at the 19th Congress of Asia Pacific Academy of Ophthalmology (APAO), Bangkok, Thailand, 28 November-3 December 2003. The authors have no financial support in the writing of this paper.     

Assessment of the central corneal thickness and intraocular pressure in premature and full-term newborns

Purpose:

To assess the central corneal thickness (CCT) and intraocular pressure (IOP) in premature and full-term newborns.

Materials and Methods:

In this study, we evaluated measurements of CCT and IOP in 45 premature and 45 full-term newborns. IOP was determined with topical anesthesia using a Tono-Pen AVIA, applanation tonometer and a wire lid retractor in premature newborns undergoing screening for retinopathy. Full-term newborns were used as a control group. CCT was determined with a portable pachymeter after IOP measurements had been made in both groups. Because there was high correlation of CCT and IOP between right and left eyes, only the right eye data were used for further analyses.

Results:

The mean gestational age was 31.5 ± 2.7 weeks (ranging 25-35 weeks) and the mean age at measurement after birth was respectively 36.3 ± 0.9 weeks (ranging 33-37 weeks) in premature newborns and 38.2 ± 0.7 weeks (ranging 38-41 weeks) and 42 ± 2.2 weeks (ranging 39-46 weeks) in full-term newborns. The mean IOP was 16.2 ± 2.7 mmHg (ranging 10-22 mmHg) in premature and 16.6 ± 2.3 mmHg (ranging 10-22 mmHg) in full-term newborns. The mean CCT was found 600 ± 50 μm (ranging 515-790 μm) in the premature group and 586 ± 48 μm (ranging 475-730 μm) in the full-term group. Mean CCT was greater in premature newborns than in full-term newborns, but the difference between groups was not statistically significant (P = 0.7). Mean IOP measurement in two groups was found very similar and the difference also was not statistically significant (P = 0.27). There was no correlation between IOP and CCT, gestational age, gestational weight, age at measurement, weight at measurement neither right nor left eye in both groups in multiple regression analysis.

Conclusion:

We found that premature infants have slightly thicker corneas but no high IOP measurements than full-term newborns. It could be concluded that in premature at the mean gestational age of 36 weeks CCT is not different from that of full-term newborns.     

原发性开角型青光眼患者及正常人的眼压日内波动趋势

目的研究原发性开角型青光眼（POAG）、正常眼压性青光眼（NTG）患者及正常人双眼眼压昼夜波动趋势及其眼压峰值出现的规律，比较双眼眼压波动趋势是否一致。设计前瞻性病例系列。研究对象POAG、NTG患者及正常对照各30例。方法用Goldmann压平眼压计测量眼压日曲线，比较双眼的日眼压波动模式及眼压峰值分布。主要指标眼压测量值。结果眼压峰值出现于非办公时段的正常人为右眼6．7％、左眼10．0％；NTG患者为右眼20．0％、左眼23．3％；POAG患者为右眼23．3％、左眼20.0％。结论POAG、NTG患者和正常人有着不同的眼压昼夜波动模式，且双眼的波动趋势不尽相同，不能完全将双眼等同看待；部分观察对象的峰值眼压分布于非办公时段，办公时段多次眼压测量不能完全代替一日眼压监测。（眼科，2007,16：33．36）     

术后眼压正常的原发性开角型青光眼中央角膜厚度与视神经受损关系

目的 探讨手术后眼压达正常的原发性开角型青光眼(primary open angle glaucoma,POAG)患者中央角膜厚度(Central Corneal Thickness,CCT)与视野、视神经损害进展的关系.方法 对127例施行小梁切除术的原发性开角型青光眼患者进行角膜测厚、视野检查及海德堡视网膜断层扫描(HRT-2).根据CCT将127例患者分成两组:第一组CCT<540μm(n=59),第二组CCT≥540μm(n=68).手术后1个月开始检查,随访2年,对所得数据进行分析.结果 两组术后2年除了视盘面积(DA)无差异外,其平均视野缺损值(MD)、视杯面积(CA)、最大视杯深度(MxCD)、杯盘面积比(C/DAR)、盘沿面积(RA)、视杯形态测量(CSM)、平均视网膜神经纤维厚度(mRNFLT)与首诊比较差异均有统计学意义(P<0.05),且第一组上述指标的进展均较第二组加快(P<0.05).结论 原发性开角型青光眼患者即使手术后眼压控制正常,其视野及视神经仍出现继续损害,角膜厚度薄者视野及视神经的损害更明显.     

Diurnal variation of central corneal thickness and Goldmann applanation tonometry estimates of intraocular pressure

PURPOSE: To determine whether there is a temporal relationship between the diurnal variation of central corneal thickness (CCT) and intraocular pressure (IOP) by Goldmann applanation tonometry in young normal human participants in vivo. METHODS: Twenty-five eyes of 25 young healthy normal participants were examined in a prospective observational cross-sectional study. IOP, CCT and corneal curvature were measured using standard clinical techniques over a 24-hour period, and the temporal interrelationships between these parameters were examined. RESULTS: The overnight change in IOP measured by Goldmann tonometry was 3.1+/-2.4 mm Hg (P<0.001), CCT was 20.1+/-10.9 mum (P=0.016), with no statistical change in central corneal curvature (0.05 mm, P=0.477, paired t test with Bonferroni correction). Both IOP and CCT were highest on awakening at 7:00 then dropped rapidly to baseline levels by 9:00 (linear mixed models), and these two parameters were highly correlated (r=0.978, P<0.001). After 9:00, there was no correlation between these parameters (r=-0.453, P=0.260). CONCLUSIONS: The results of this study have highlighted a potential link between the diurnal variation of CCT and the accuracy of Goldmann tonometry estimates of IOP during the first 2 hours after awakening. Clinicians should be wary of using Goldmann tonometry to estimate IOP until the overnight increase in CCT has resolved.     

角膜中央厚度对高眼压症和开角型青光眼眼内压测量值的影响

目的研究角膜中央厚度对高眼压症和原发性开角型青光眼病人的眼内压测量值的影响.方法对44例(88眼)临床诊断为高眼压症的患者,31例(61眼)原发性开角型青光眼患者及52例(104眼)与高眼压症患者屈光状态相近的正常人的角膜中央厚度及眼内压进行检测,用统计学方法比较3组的角膜中央厚度的差异及高眼压症患者的眼内压值与角膜中央厚度的相关关系.结果①高眼压症组的角膜中央厚度的平均值585.6±35.7μm明显高于原发性开角型青光眼(54.1±38.7μm)(P＜0.01)及正常对照组(535.5±29.4μm)(P＜0.01),而原发性开角型青光眼的角膜中央厚度与正常对照组相比无显著性差异(P＜0.05).②将高眼压症患者的角膜中央厚度与眼内压测量值进行简单线性相关分析,可见角膜中央厚度与眼内压测量值呈明显正相关,相关系数为0.636(P＜0.01).角膜中央厚度每增加50μm可使眼内压测量值升高约2mmHg.结论①高眼压症患者的角膜中央厚度明显大于原发性开角型青光眼和正常眼,高眼压症患者的角膜中央厚度与眼内压呈明显的正相关,提示高眼压症患者是由于角膜中央厚度高于正常范围而造成眼内压测量值的升高.②角膜中央厚度值可作为高眼压症及原发性开角型青光眼的诊断与鉴别诊断的重要依据.提示临床工作中,可将角膜中央厚度检测作为排除青光眼的常规检查手段.③当角膜中央厚度在520±50μm的范围内,眼压读数相对准确,如果角膜中央厚度超过570μm,眼压读数相应增高,这可能是高眼压症患者眼压测量值高于正常范围的重要原因之一.     

近视眼中央角膜厚度与眼压的关系

目的　探讨近视眼中央角膜厚度(centralcornealthickness,CCT)与眼压 ( intraocular pressure,IOP)的关系及其临床意义。方法　检测近视眼患者 6 59例 12 6 4眼的CCT及 IOP进行统计学分析。结果　以 CCT为自变量 X,IOP为应变量 Y,可得直线回归方程 Y =- 2 .36 33+0 .0 34 7X ( P <0 .0 1) ,若根据 CCT将本组病例分为 4组 ,CCT 值分别为 4 86 .18μm ± 12 .10 μm、 52 7.6 9μm ±13.0 4 μm、56 8.87μm± 13.11μm、6 12 .2 5μm± 11.0 7μm,则 4组 IOP分别为 14 .34 m m Hg± 2 .4 8mm Hg ( 1k Pa =7.5mm Hg )、 15.96 m m Hg± 2 .70 m m Hg、 17.4 5m m Hg±2 .39mm Hg、18.4 8mm Hg± 2 .4 1m m Hg,各组间差异均有显著性 ( P<0 .0 1)。若以屈光度分 4组 ,其值分别为 2 .2 6 D±0 .14 D、4 .53D± 0 .87D、 7.2 9D± 0 .91D、12 .75D± 3.53D,则4组 IOP分别为 16 .4 5mm Hg± 2 .4 8m m Hg、16 .52 m m Hg±2 .75mm Hg、 16 .57mm Hg± 2 .83m m Hg、 16 .80 mm Hg±2 .6 6 mm Hg,无组间差异 ( P>0 .0 5)。结论　近视眼 IOP随CCT增加而增高并成正相关 ,与近视屈光度无关。CCT为影响 IOP检测的一个重要因素 ,检查 CCT有助于更正确地估计 IOP,可以作为鉴别某些临床疾病的重要指标     

近视眼角膜厚度与眼压相关因素分析

目的 探讨近视眼角膜中央厚度(CCT)、屈光度、角膜曲率、年龄、性别与眼压(IOP)测量值之间的关系.方法 对219例431只眼用超声角膜测厚仪、Goldmann眼压计、检影镜及电脑验光仪和ObscanⅡ角膜地形图分别测量其数据.结果 近视眼患者CCT与IOP之间具有直线正相关性,CCT每增加10μm,眼压值约增加0.5 mmHg(1 mmHg=0.133 kPa).近视患者CCT与屈光度数具有负相关性.近视患者CCT与角膜曲率、年龄及性别不相关.结论 CCT为影响IOP测量的一个重要因素,检查CCT有助于更好的了解真实IOP值;CCT随近视眼患者屈光度数的增加有变薄的趋势.     

角膜厚度对眼压测定的影响

目的：探讨角膜厚度（CCT）对眼压（IOP）测量的影响及其临床意义。方法：用超声角膜测厚仪吸非接触式眼压计检测288例眼科患者500眼之CCT及IOP进行统计学分析。结果：IOP随CCT增加而增高并成正相关（CCT每增加27μm,IOP将随之增加1mmHg）而与屈光度无关,CCT与患者年龄成负相关。结论：CCT为影响IOP检测的一个重要因素,检查CCT有助于更正确的估计IOP,可以作为鉴别某些临床疾病的重要指标。     

拉坦前列素对闭角型青光眼眼压和角膜中央厚度及内皮细胞密度的影响

目的:探讨拉坦前列素对闭角型青光眼患者眼压和角膜厚度及角膜内皮细胞密度的影响。方法:选取60例60眼原发闭角型青光眼患者住院行患眼小梁切除术期间,对对侧眼进行研究,30眼应用拉坦前列素滴眼1次/d,30眼用透明质酸钠滴眼1次/d作为对照,用药前测定眼压、角膜厚度和内皮细胞密度,用药后4wk内每周测定眼压、角膜厚度和上皮细胞密度。结果:用药4wk后,拉坦前列素组眼压显著降低(P<0.05),拉坦前列素与透明质酸钠对角膜厚度平均值变化统计学无显著性差异,对角膜内皮细胞密度无影响。结论:拉坦前列素显著降低眼压,且对角膜厚度及内皮细胞数无影响。     

Central corneal thickness and visual field progression in patients with chronic primary angle-closure glaucoma with low intraocular pressure

PURPOSE: To determine the association of central corneal thickness (CCT) and visual field progression in patients with chronic primary angle-closure glaucoma (CPACG) with low intraocular pressure (IOP). DESIGN: Retrospective, comparative case series. METHODS: A total of 163 eyes with CPACG and sustained IOP <18 mm Hg were included. Initial and three-year after mean deviation (MD) on Humphrey field analyzer and CCT with ultrasonic pachymetry were recorded. On the basis of the CCT value, the sample was split in two groups (group 1 <540 microm; group 2 > or =540 microm). RESULTS: Mean CCT was 525.8 +/- 11.6 microm in group 1 and 574.4 +/- 24.0 microm in group 2. There was no significant difference for initial MD (P = .979), but a significant difference was found between two groups for follow-up MD (P = .023). CONCLUSIONS: Patients with CPACG with a thinner cornea are at greater risk for visual field progression even if they maintain a low IOP after treatment.     

中央角膜厚度对3种眼压计眼压测量值的影响

目的比较分析不同中央角膜厚度(central corneal thickness,CCT)下Icare回弹式眼压计、Goldmann压平式眼压计(Goldmann applanation tonometer,GAT)和动态轮廓眼压计(dynamic contour tonometry,DCT)的眼压测量结果,探讨CCT对3种眼压计测量值的影响。方法 对78例患者152眼分别用Icare、GAT、DCT3种眼压计进行眼压测量,并进行CCT的测量,对比不同CCT下3种眼压计的测量结果,分析眼压测量值与CCT的关系。结果 在全部受测者中Icare、GAT、DCT测得的眼压均值分别为(19.16±5.03)mmHg(1 kPa=7.5 mmHg)、(18.41±4.52)mmHg和(17.23±3.69)mmHg,三者之间有显著差异(F=7.256,P=0.001)。Icare和GAT的眼压测量值均与CCT显著相关(r=0.341,P<0.001;r=0.333,P<0.001),CCT每改变10μm,Icare的眼压值改变0.47 mmHg,GAT的眼压值改变0.41 mmHg;而DCT的眼压测量值与CCT无显著相关(r=0.032,P=0.699)。结论 Icare、GAT的眼压测量值均明显受CCT的影响,而Icare受CCT影响的程度较GAT的稍大,DCT的眼压测量值基本不受CCT的影响。     

Association of central corneal thickness and 24-hour intraocular pressure fluctuation

PURPOSE: To evaluate the association between office-hour central corneal thickness (CCT) and 24-hour intraocular pressure (IOP) fluctuation in patients with glaucoma. DESIGN: Observational case-control study. METHODS: Measurements of IOP were obtained every 2 hours during a 24-hour period from 52 untreated glaucoma patients and 29 age-matched normal control subjects housed in a sleep laboratory. Habitual IOP measurements were obtained using a pneumatonometer in the sitting positions during the diurnal/wake period (7 AM to 11 PM) and in the supine position during the nocturnal/sleep period (11 PM to 7 AM). CCT was measured in all subjects using ultrasound pachymetry once during office hours. The association between IOP fluctuation (peak IOP-trough IOP) during the 24-hour period and the office-hour CCT was assessed in both glaucoma patients and healthy age-matched controls using Spearman rank order correlation. RESULTS: There was no statistically significant correlation between IOP fluctuation and CCT in glaucomatous (P=0.405) and normal subjects (P=0.456). CONCLUSIONS: Twenty-four-hour IOP fluctuations were not correlated with single CCT measurements taken during office hours in glaucoma patients.