Corneal thickness and visual field damage in glaucoma patients

PURPOSE: To verify whether there was a significant correlation between central corneal thickness (CCT) and visual field damage in patients with primary open angle glaucoma (POAG). METHODS: A total of 99 eyes with POAG were consecutively recruited. Patients were classified as glaucomatous based on visual field and optic nerve head damage. All underwent applanation tonometry, Humphrey perimetry, and measurement of CCT with ultrasonic pachymetry. Based on CCT value, the sample was split at the mode in two groups (group 1<535 microm, n=49; group 2>or=535 microm, n=50). RESULTS: Entire cohort: mean CCT 554 microm+/-45.03; mean deviation (MD) -6.68 dB+/-7.32; pattern standard deviation (PSD) 5.33+/-3.75; intraocular pressure (IOP) 17.91+/-4.16 mmHg with treatment. Group 1: CCT was 504.8 microm+/-30.8; MD -9.01 dB+/-8.72; PSD 6.38+/-3.99; IOP 18.02 mmHg+/-4.66. Group 2: mean CCT 574.6 microm+/-35.03; MD -4.39 dB+/-4.70; PSD 4.25+/-3.19; IOP 17.79 mmHg+/-3.57. A significant difference was found between the two groups for both MD and PSD. Linear regression analysis showed a significant correlation between CCT and PSD (P<0.001). CONCLUSIONS: Our data show that patients with a thinner cornea had a worse MD and PSD. As a thinner CCT causes an underestimation of the true IOP, there may be a delay in the diagnosis of POAG or an inadequate estimate of the clinical course despite apparently desirable IOP applanation readings.     

Long-term intraocular pressure fluctuation and visual field progression in glaucoma patients with low intraocular pressure after post-trabeculectomy phacoemulsification.

BACKGROUND: The aim of this study was to evaluate the association of long-term intraocular pressure (IOP) fluctuation and visual field progression in glaucoma patients with low IOP after post-trabeculectomy phacoemulsification. METHODS: A total of 688 eyes with primary open-angle glaucoma (POAG) and chronic primary angle-closure glaucoma (CPACG) were included in this study. The patients always had an IOP below 18 mmHg after post-trabeculectomy phacoemulsification. Visual field testing using the standard automated perimetry was periodically performed at 3 months and for at least 3 years postoperatively. The mean deviation on visual field was compared according to the standard deviation (SD) of the postoperative IOP (SD < or = 2 mmHg group vs. SD > 2 mmHg group). RESULTS: Preoperative and postoperative IOPs during the follow-up period did not differ significantly between the two study groups. Even though the mean deviations on visual field at postoperative 3 months were not different between the two groups, the mean deviations at the last follow-up were significantly worse in the postoperative IOP SD > 2 mmHg group than the postoperative IOP SD < or = 2 mmHg group. CONCLUSIONS: Less postoperative IOP fluctuation was statistically associated with a slower progression of visual field damage in POAG and CPACG patients who kept low IOPs after the post-trabeculectomy phacoemulsification.     

Effects of central corneal thickness on the efficacy of topical ocular hypotensive medications

PURPOSE: To determine the effect of central corneal thickness (CCT) on the efficacy of intraocular pressure (IOP)-reducing drugs in patients with ocular hypertension (OHT). METHODS: This retrospective study analyzed research records of 115 OHT patients and 97 ocular normotensive (ONT) volunteers. CCT was measured by slit-lamp pachymetry and IOP by pneumatonometry. The OHT patients were divided into Thick (>540 microm, n=52) and Thin (相似文献   

Comparison of dynamic contour tonometry with goldman applanation tonometry over a wide range of central corneal thickness

PURPOSE: To compare dynamic contour tonometry with Goldmann applanation tonometry in structurally normal corneas over a wide range of central corneal thickness (CCT). PATIENTS AND METHODS: Twenty-five patients each with normal CCT (group A), thin corneas (group B), and thick corneas (group C) had IOP measured with the Goldmann (GAT) and dynamic contour tonometer (DCT). RESULTS: In group A (mean CCT = 552 +/- 16 microm) the mean GAT was 15.9 +/- 3.1 mm Hg and mean DCT was 16 +/- 3.3 mm Hg (P = 0.91). In group B (mean CCT = 491 +/- 19 microm) the mean GAT was 13.2 +/- 3.5 mm Hg and the mean DCT was 15.9 +/- 3.5 mm Hg (P = 0.009). For group C (mean CCT = 615 +/- 22 microm), the mean GAT was 17.4 +/- 3.8 mm Hg and the mean DCT was 17.4 +/- 3.5 mm Hg (P = 0.95). The 95% agreement limits for DCT were -3.1 mm Hg to 2.9 mm Hg. The mean GAT-DCT difference was -2.6 mm Hg in thin corneas and -0.06 mm Hg in thick corneas. Below 520 microm reduction of 10 microm in CCT appears to result in a significant underestimation of the GAT IOP by 0.7 mm Hg (P < .001) and above 580 microm a non-significant overestimation of 0.2 mm Hg per 10 microm increase in CCT (P = 0.27). CONCLUSION: Dynamic contour tonometer agrees well on average with GAT but the agreement limits are wide. In structurally normal thin corneas DCT may give a more accurate assessment of the true IOP but it does not appear to have any benefit over GAT in thick corneas.     

相干光断层扫描仪检测正常人及青光眼患者中央角膜厚度

目的探讨相干光断层扫描仪(OCT)测量正常人、原发性开角型青光眼(POAG)、正常眼压性青光眼(NTG)、高眼压症(OHT)患者的中央角膜厚度(CCT)。方法采用OCT3测量正常人143例(143只眼)、POAG患者36例(36只眼)、NTG患者39例(39只眼)及OHT患者40例(40只眼)的CCT,并进行单因素4水平设计定量资料的方差分析;用线性回归方法分析正常人CCT与Goldmann压平眼压测量值的相关关系;对OCT测量CCT观察者间和观察者内的一致性进行类内相关系数(ICC)分析。结果正常组、POAG组、NTG组及OHT组的平均CCT值分别为(523.66±32.13)μm、(530.92±27.32)μm、(506.92±21.49)μm及(573.13±27.39)μm。POAG组与正常人组的平均CCT值差异无统计学意义(P=0.099);OHT组的平均CCT值大于其他各组,均P<0.01;NTG组的平均CCT值小于其他各组,均P<0.01。正常组CCT与眼压值呈正相关(r=0.318,R2=0.101,P<0.01)。OCT测量CCT的测量者间和测量者内的ICC值分别为0.995和0.996。结论OCT可以准确地测量CCT;NTG患者平均CCT比正常人薄,而OHT患者比正常人厚;CCT可以影响Goldmann压平眼压计的测量值,但贡献率较小。(中华眼科杂志,2006,42:199-203)     

Central corneal thickness and corneal hysteresis associated with glaucoma damage

PURPOSE: We sought to measure the impact of central corneal thickness (CCT), a possible risk factor for glaucoma damage, and corneal hysteresis, a proposed measure of corneal resistance to deformation, on various indicators of glaucoma damage. DESIGN: Observational study. METHODS: Adult patients of the Wilmer Glaucoma Service underwent measurement of hysteresis on the Reichert Ocular Response Analyzer and measurement of CCT by ultrasonic pachymetry. Two glaucoma specialists (H.A.Q., N.G.C.) reviewed the chart to determine highest known intraocular pressure (IOP), target IOP, diagnosis, years with glaucoma, cup-to-disk ratio (CDR), mean defect (MD), pattern standard deviation (PSD), glaucoma hemifield test (GHT), and presence or absence of visual field progression. RESULTS: Among 230 subjects, the mean age was 65 +/- 14 years, 127 (55%) were female, 161 (70%) were white, and 194 (85%) had a diagnosis of primary open-angle glaucoma (POAG) or suspected POAG. In multivariate generalized estimating equation models, lower corneal hysteresis value (P = .03), but not CCT, was associated with visual field progression. When axial length was included in the model, hysteresis was not a significant risk factor (P = .09). A thinner CCT (P = .02), but not hysteresis, was associated with a higher CDR at the most recent examination. Neither CCT nor hysteresis was associated with MD, PSD, or GHT "outside normal limits." CONCLUSIONS: Thinner CCT was associated with the state of glaucoma damage as indicated by CDR. Axial length and corneal hysteresis were associated with progressive field worsening.     

Corneal thickness determination and correlates in Singaporean schoolchildren

PURPOSE: To determine the central cornea thickness (CCT) in Singaporean children and to examine the possible relationship between intraocular pressure (IOP) and other biometric factors and CCT. METHODS: This was a cross-sectional study. The subjects (N=652) were obtained from the Singapore Cohort Study of the Risk Factors for Myopia (SCORM). The subjects' ages ranged from 9 to 11 years. There were 485 Chinese, 92 Malayan, and 75 Asian Indian children. Measurement procedures included air-puff tonometry, noncontact slit lamp optical pachymetry, cycloplegic autorefraction, and autokeratometry. RESULTS: The mean CCT was 543.6 +/- 32.0 microm. Chinese children had thicker corneas than Malayan or Indian children (P=0.002). The boys had thicker corneas than girls (P=0.011), but the mean difference was only 6.4 microm. There was high correlation of CCT (r=0.98) and IOP (r=0.88) between right and left eyes. IOP was correlated with CCT (r=0.45, P <0.001). In a multiple linear regression model, each millimeter of mercury of IOP was associated with a CCT difference of 5.90 microm (95% confidence interval [CI], 4.98-6.82). The radius of corneal curvature correlated with CCT (r=0.19, P <0.001). The following parameters were not significantly (P >0.05) associated with CCT: age, family income, father's education, axial length, and spherical equivalent. CONCLUSIONS: The mean CCT in Singaporean children aged 9 to 11 years was 543.6 microm and showed ethnic and gender variation. CCT affected measured IOP and correlated weakly with corneal curvature. Compared with data in adults, a change in CCT was associated with a greater difference in measured IOP.     

角膜厚度与高眼压症及青光眼的眼压

目的 探讨高眼压症、正常眼压性青光眼、原发性开角型青光眼患者及正常人的角膜厚度差异,分析角膜厚度与眼压间的关系,以及角膜厚度的测定对各型青光眼的诊断意见。方法 用超声波角膜测厚仪检测７３例（７３只眼）高眼压症、７９例（７９只眼）正常人的中央角膜厚度,并将其测定结果进行比较。回顾性分析每只青光眼治疗前的最高眼压（Ｇｏｌｄｍａｎｎ）,包括２４ｈ眼压曲线,用Ｅｈｌｅｒ法通过中央角膜厚度对眼压进行校正。结     

原发性开角型青光眼非对称性视野损害的影响因素

目的：探讨原发性开角型青光眼（POAG）非对称性视野损害的相关因素，并了解非对称性视野损害者双眼间眼部参数的差异。方法：横断面研究。收集2014年1月至2018年12月温州青光眼进展研究 （WGPS）中确诊的POAG患者，分析双眼眼部参数，包括眼压、眼轴长度（AL）、中央角膜厚度（CCT）、 前房深度（ACD）、晶状体厚度（LT）、视野平均偏差（MD）、视网膜神经纤维层厚度（RNFLT）、盘沿 面积、视盘面积、杯盘比、视杯容积。非对称性视野损害定义为双眼视野MD的绝对差值≥5 dB， 根据此标准将受检者分为对称组和非对称组，分析2组眼部参数与非对称性视野损害的关系。非对称组进一步行双眼间眼部参数的比较。采用独立样本t检验、Mann-Whitney U检验、配对t检验、 Wilcoxon检验、Logistic回归分析对数据进行分析。结果：共纳入POAG患者142例（284眼），对称组 92例（64.8%），男39例（42.4%），年龄（65.3±1.0）岁；非对称组50例（35.2%），男32例（64.0%），年 龄（67.6±9.1）岁。男性[OR=4.52，95%可信区间（CI）：1.90～10.73，P=0.001]、较差眼的CCT较薄 （OR=0.97，95%CI：0.95～0.99，P=0.003）、双眼平均RNFLT差值增大（OR=1.10，95%CI：1.04～1.15， P<0.001）为非对称性视野损害的危险因素。非对称组中，视野损害较重眼相比对侧眼，其平均 RNFLT较薄（Z=-7.80，P<0.001），盘沿较窄（t=-4.97，P<0.001），视盘面积较大（t=2.38，P=0.02）， 平均杯盘比（Z=-4.51，P<0.001）和垂直杯盘比（Z=5.16，P<0.001）均较大，视杯容积较大（Z=-3.31， P<0.001），但双眼间眼压、等效球镜度（SE）、AL、CCT、LT和ACD的差异均无统计学意义。结论：男性、CCT较薄、双眼平均RNFLT差值增大为POAG非对称性视野损害的独立危险因素，而非对称性视野损害者其双眼中的较大视盘眼，更容易发生视神经损害。     

Central corneal thickness of normal tension glaucoma patients in Japan

PURPOSE: To compare central corneal thickness (CCT) of patients with normal tension glaucoma (NTG) with that of age-matched normal subjects, patients with open-angle glaucoma (POAG) and ocular hypertension (OH) subjects in Japan. METHODS: Central corneal thickness was measured in 79 NTG, 61 POAG, 73 OH, and 50 normal subjects with an ultrasonic pachymeter. One eye for 1 subject randomly selected in each group was used for inter-group comparison. The relationship between CCT and the maximum intraocular pressure (IOP) measured by Goldmann applanation tonometer with no ocular hypotensive medication (NTG, OH, and normal subjects) or under medication (POAG patients) was analyzed. RESULTS: The CCT of OH subjects (582 +/- 32 microm; mean +/- SD) was significantly greater than that of the other groups (P <.001), while no difference was seen in CCT among normal (552 +/- 36 microm), NTG (548 +/- 33 microm) and POAG (550 +/- 33 microm) subjects. In normal subjects, CCT and the maximum IOP were significantly correlated but the correlation coefficient was small (r = 0.420, P <.05). CONCLUSIONS: Central corneal thickness shows no significant difference among NTG, POAG, and normal subjects in Japan, while it is significantly greater in OH subjects. The CCT has little influence on the diagnosis of NTG in Japan.     

Effect of a new cohesive ophthalmic viscosurgical device on corneal protection and intraocular pressure in small-incision cataract surgery

PURPOSE: To compare the corneal protective and intraocular pressure (IOP) effects of a new cohesive ophthalmic viscosurgical (OVD), Neocrom Cohesive (sodium hyaluronate 1.4%), with those of Healon (sodium hyaluronate 1.0%) in cataract surgery. SETTING: Department of Ophthalmology, Medical University of Vienna, Vienna, Austria. METHODS: This randomized patient-masked examiner-masked study with fellow-eye comparison comprised 29 cataract surgery patients. Surgery was performed with Neocrom Cohesive in 1 eye and Healon in the other eye. Central corneal thickness (CCT) was measured preoperatively and 1 day and 3 months postoperatively; endothelial cell density (ECD), preoperatively and 3 months postoperatively; and IOP, preoperatively and 6 hours and 1 day postoperatively. RESULTS: The mean CCT change from preoperatively to postoperatively in the Neocrom Cohesive, respectively, group and Healon group was +16.0 microm +/- 25.7 (SD) (P<.01) and +7.0 +/- 17.1 microm (P<.05), respectively, at 1 day and -5.7 +/- 10.8 microm (P<.01) and -4.7 microm +/- 9.5 microm) (P<.01), respectively, at 3 months. The mean ECD change at 3 months was 8 +/- 155 cells/mm(2) in the Neocrom Cohesive group (P = .8) and -46 +/- 139 cells/mm(2) in the Healon group (P = .08). The mean IOP increase was +2.2 +/- 3.5 mm Hg (P<.01) and +1.4 +/- 4.2 mm Hg (P = .14), respectively, 6 hours postoperatively and +0.9 +/- 4.3 mm Hg (P = .37) and 0.0 +/- 3.5 mm Hg (P = .77), respectively, at 1 day. CONCLUSION: There was no significant difference between Neocrom Cohesive and Healon in the changes in CCT, ECD, and IOP after cataract surgery.     

Diurnal variation of ocular hysteresis in normal subjects: relevance in clinical context

BACKGROUND: This study was conducted to assess the diurnal variation in ocular hysteresis, as measured by the Ocular Response Analyser to establish a relationship between diurnal hysteresis variation and diurnal intraocular pressure (IOP) variation. METHODS: Forty-two normal eyes of 21 colleagues and staff in a teaching hospital in Birmingham, UK, were recruited. The IOP and hysteresis were measured by the Ocular Response Analyser. The central corneal thickness (CCT) was measured using a hand-held ultrasonic pachymeter in the mid-pupillary axis. RESULTS: The mean ocular hysteresis at 8 am was 12.7 +/- 2.3 mmHg, at 11 am was 12.2 +/- 2.0 mmHg, at 2 PM was 12.7 +/- 2.1 mmHg and at 5 PM was 12.7 +/- 1.7 mmHg; the difference between the values at any time of measurement was not statistically significant (P > 0.9, repeated measures). IOP as measured by non-contact tonometry was 18.4 +/- 2.8 mmHg, 17.9 +/- 3.3 mmHg, 16.9 +/- 3.1 mmHg and 16.8 +/- 3.2 mmHg, respectively, for the same time period; the difference between the values in the morning and afternoon was statistically significant (P < 0.0001, repeated measures). The CCT was 548.8 +/- 29.5 microm, 547.0 +/- 31.4 microm, 548.2 +/- 29.6 microm and 548.6 +/- 29.4 microm, respectively; the difference between the values was not statistically significant at any time points. Multiple regression analysis showed the relationship between IOP and hysteresis was not statistically significant (P = 0.9). CONCLUSION: The ocular hysteresis reading was almost constant throughout the day, whereas the IOP readings showed highest values in the morning with a reducing trend being lowest in the afternoon. The CCT values were almost stable throughout the day. IOP appears to vary independently of a variation in hysteresis or CCT.     

Long-term evaluation of trabeculectomy in primary open angle glaucoma and chronic primary angle closure glaucoma in an Asian population

Purpose: A retrospective cohort study was undertaken to evaluate and compare the long‐term results of trabeculectomy in primary open angle glaucoma (POAG) and chronic primary angle closure glaucoma (CPACG) in an Asian population. Methods: Yearly diurnal measurements of intraocular pressure (IOP), best‐corrected visual acuity, optic disc and visual field records of patients having primary adult glaucomas who had undergone trabeculectomy, without anti­mitotic agents, with a minimum of 5 years follow up were evaluated. Only one eye of each patient was studied. The success rates for IOP control in POAG and CPACG were statistically analysed. Results: Sixty‐four eyes of 64 patients were studied. The overall probability of success of trabeculectomy in controlling IOP to ≤21 mmHg with or without additional topical antiglaucoma medication was 0.94 and 0.88 at 5 and 10 years, respectively. There was no statistically significant difference in the qualified and absolute success rates for IOP control between POAG and CPACG eyes (log rank test P= 0.6, 0.88, respectively). Twelve of 38 CPACG eyes had a two‐line decrease in visual acuity as compared to four of 26 POAG eyes (P = 0.17). Progression or development of a cataract was the most common cause of visual decline. Conclusions: Trabeculectomy without antimetabolite use appears to be efficacious in lowering IOP and in visual field preservation over a period of 10 years in both POAG and CPACG. Development/progression of cataract especially in eyes with chronic angle closure glaucoma after trabeculectomy must be considered an important issue.     

The relationship among race, iris color, central corneal thickness, and intraocular pressure.

PURPOSE: Central corneal thickness (CCT) influences applanation intraocular pressure (IOP) measurement. The present study sought to determine whether iris color might represent a qualitative surrogate for CCT or race, and therefore differential risk for elevated IOP and, consequently, developing glaucoma. METHODS: Eligible patients included those with best-corrected visual acuity (BCVA) better than 20/40 and who had not worn contact lenses within 24 hours. Exclusion criteria were prior ophthalmic surgery, topical ocular or systemic medication that would influence IOP, previous ocular inflammatory conditions, or current treatment for ophthalmic treatment. Data collection included demographic (name, date of birth, race), BCVA, and iris color. Iris color was judged according to a purpose-developed chart (white: blue, green, brown or black: brown) and patients were assigned to one of four groups. Goldmann applanation tonometry and pachymetry measurements were performed consecutively. To attain a power of 90% to find a difference of 40 microm with alpha < 0.05, we examined at least 14 subjects (28 eyes) for each group. RESULTS: Comparing pachymetry measurements among iris colors revealed no statistically significant difference among the three groups of whites: blue (552 microm), green (552 microm), and brown (562 microm). The same held true when comparing IOP and CCT-adjusted IOP with iris color: blue-15.2, 15.1, green-15.4, 15.2, and brown-14.7, 14.0. When comparing CCT between whites and blacks, CCT was significantly thinner in blacks (533 microm), whether evaluating all whites (555 microm, p = 0.03) or comparing only the brown-iris white group with the black group (562 microm vs. 533 microm, p = 0.03). Mean CCT-adjusted IOP was barely significantly different between whites (14.8) and blacks (16.7) (p = 0.04). CONCLUSION: These results suggest that iris color is not associated with CCT and apparently iris color does not influence measured IOP. We were able to establish a relationship between race and IOP when adjusting IOP for CCT. Our data show a significantly higher CCT-adjusted IOP for blacks than whites demonstrating a racial difference in CCT-corrected IOP.     

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.     

Central corneal thickness in children: Racial differences (black vs. white) and correlation with measured intraocular pressure

PURPOSE: To test the hypotheses that the mean central corneal thickness (CCT) of healthy black children is thinner than that of healthy white children and to confirm the relationship between increased CCT and measured intraocular pressure (IOP) in children. METHODS: This prospective observational case series included 178 eyes of 92 children aged 9 months to 17 years without anterior segment abnormalities or a clinical diagnosis of glaucoma. CCT was measured by ultrasonic pachymetry and IOP was measured by Goldmann or Tono-pen technique. RESULTS: The mean CCT for the 102 eyes of 52 white children was 562+/-35 microm versus 543+/-37 microm for the 66 eyes of 35 black children (P = 0.02). There was a positive relationship between CCT and IOP (P = 0.0002). For every 100 mum increase in CCT, the IOP increased by 2.2+/-0.6 mm Hg. CONCLUSIONS: The mean CCT of black children is thinner than that of white children. There is a positive relationship between increasing measured IOP and CCT among children with normal corneas and anterior segments. The interpretation of elevated IOP in eyes with abnormal anterior segment anatomy and thickened corneas awaits further study.     

Central corneal thickness in individuals with intellectual disabilities

PURPOSE: To assess central corneal thickness (CCT) values in individuals with intellectual disabilities (ID). METHODS: The study group was made up of 25 participants with ID (mean age, 36.9 +/- 8.7 years). The control group was made up of 25 healthy individuals (mean age, 37.1 +/- 10.1 years) with normal intellectual capacity and without any systemic or intraocular pathology. CCT value was measured by ultrasound pachymetry. Ten consecutive measurements were made at the center of the cornea of each eye. RESULTS: In the ID group, mean CCT value was 554.0 +/- 39.7 microm in the right eye and 556.8 +/- 38.7 microm in the left eye. In the control group, mean CCT value was 535.7 +/- 24.2 microm in the right eye and 536.5 +/- 24.8 microm in the left eye. CCT value in the ID group was significantly greater than in the control group for both right (P < 0.05) and left eyes (P < 0.02). CONCLUSIONS: CCT should be kept in mind during measurements of intraocular pressure (IOP) in individuals with ID because their CCTs may be greater than those in the general population.     

Comparison of Pentacam Scheimpflug camera with ultrasound pachymetry and noncontact specular microscopy in measuring central corneal thickness

PURPOSE: Although central corneal thickness (CCT) can be measured by several methods, interchangeability of different modalities has not been fully investigated. CCT is known to correlate with intraocular pressure (IOP). The aim of this study was to evaluate the agreement of Pentacam Scheimpflug system with noncontact specular microscopy (NCSM) and ultrasound (US) pachymetry in measuring CCT and the relation between IOP taken with Goldmann applanation tonometer (GAT) and the CCT measured with these three methods. METHODS: The right eyes of 135 enrolled persons without antiglaucoma drug use (100 females and 35 males), who comprised 32 patients with primary open-angle glaucoma, 14 with ocular hypertension, 45 with primary angle-closure glaucoma, and 44 controls, were studied. Intermethod comparison of CCT was made by the 95% limits of agreement analysis according to Bland and Altman. Linear regression analysis was used to assess the relationship between IOP and CCT taken with each modality. RESULTS: The mean CCT (+/-SD) taken with Scheimpflug, US, and NCSM was 559.49 +/- 38.44 microm, 553.01 +/- 39.33 microm, and 552.04 +/- 42.95 microm, respectively. The average values of CCT taken with the three instruments were not significantly different (one-factor ANOVA; p = 0.26), although the marginal mean difference between Scheimpflug and US or NCSM was statistically significant (paired t test; p = 0.0009 and 0.005, respectively). The 95% limits of agreement were 6.47 +/- 43.21 microm between Scheimpflug and US, 7.45 +/- 58.86 microm between Scheimpflug and NCSM, and 0.98 +/- 51.69 microm between US and NCSM. There was a positive association between IOP and CCT measured with US or NCSM, whereas there was no correlation between IOP and CCT measured with Scheimpflug. CONCLUSIONS: Although CCT values measured with Scheimpflug, US, and NCSM are closely similar, clinicians should keep in mind that these methods are not simply interchangeable.     

Pediatric central corneal thickness variation among major ethnic populations.

PURPOSE: To investigate differences in central corneal thickness (CCT) among African-American, Caucasian, and Hispanic pediatric populations with respect to race, age, and gender. SUBJECTS AND METHODS: Ultrasound pachymetry measurements were obtained on 208 eyes of 106 patients. Measurements from left eyes were used in data analysis. Analysis of variance (ANOVA) and two-tailed t-test were performed to determine the effect of race, age, and gender on CCT variation. RESULTS: Mean central corneal thickness of left eyes in each ethnic group was African-Americans, 523 +/- 40 microm; Caucasians, 563 +/- 36 microm; and Hispanics, 568 +/- 44 microm. ANOVA performed on pachymetry values showed a significant effect of race on CCT (P = 0.00002). Mean Hispanic CCT was greater than mean African-American CCT (P = 0.0003), but was not significantly different from Caucasian CCT (P = 0.56). Mean Caucasian CCT was also greater than mean African-American CCT (P = 0.0001). The difference between mean male CCT (548 +/- 41 microm) and mean female CCT (563 +/- 44 microm) did not reach statistical significance (P = 0.07). When patients were stratified into age groups (<2 years, 2 to 4 years, 5 to 9 years, 10 to 18 years), CCT did not vary with age (P = 0.16). CONCLUSIONS: Our study suggests there may be differences in CCT among different ethnic groups in the pediatric population, with African-Americans having thinner corneas than Caucasians and Hispanics.     

Comparison of localized retinal nerve fiber layer defects between a low-teen intraocular pressure group and a high-teen intraocular pressure group in normal-tension glaucoma patients

PURPOSE: To compare the features of localized retinal nerve fiber layer (RNFL) defects between a low-teen intraocular pressure (IOP) group and a high-teen IOP group in normal-tension glaucoma (NTG) patients. METHODS: Seventy-seven eyes of 77 NTG patients showing localized RNFL defects on RNFL photographs and corresponding visual filed defects at the initial visit to a glaucoma specialist were selected for this study. Patients with range of diurnal IOP within low-teen or high-teen in both eyes were included. All participants completed refraction, diurnal IOP measurement, central corneal thickness (CCT) measurement, stereoscopic disc photography, RNFL photography, and automated perimetry. On RNFL photograph, approximation of the defect to the macula (angle alpha) and width of the defects (angle beta) were measured to represent RNFL defects. The patients were divided into 2 groups according to the level of IOP. A low-teen group had highest IOP of 15 mm Hg (group B). Age at diagnosis, percentage of male patients, systemic disease, refraction, CCT, highest IOP, angle alpha, angle beta, and mean deviation and pattern standard deviation of visual field were compared between the 2 groups. RESULTS: Age at diagnosis of NTG, age distribution, percentage of male patients, systemic disease, spherical equivalent of refraction, CCT, mean deviation, and pattern standard deviation were not different between the 2 groups. Highest IOP was 13.8+/-1.2 mm Hg in group A and 19.2+/-1.4 mm Hg in group B (P<0.001). Angle alpha was significantly smaller in group A than in group B (37.0+/-14.0 vs. 56.5+/-21.2 degrees, P<0.001), whereas angle beta was not different between the 2 groups (39.9+/-17.9 vs. 37.5+/-15.9 degrees, P=0.54). There were no significant correlations between spherical equivalent and angle alpha (r=-0.03, P=0.82), between spherical equivalent and angle beta (r=-0.04, P=0.74), and between angle alpha and angle beta (r=-0.21, P=0.07). CONCLUSIONS: Localized RNFL defect was closer to the center of the macula in group A than in group B, whereas width of defects was not different between the 2 groups. These findings provide indirect evidence to suggest that more than one pathogenic mechanism may exist in the development of RNFL defects in NTG.