Cataract surgery for congenital cataract: endothelial cell characteristics, corneal thickness, and impact on intraocular pressure.

PURPOSE: To investigate whether central corneal thickness (CCT), endothelial cell characteristics, and intraocular pressure (IOP) are affected in patients with previous congenital cataract surgery and to focus on their clinical significance. METHODS: CCT and IOP measurements and specular microscopy were performed in 31 eyes of 17 cases of extracted congenital cataracts and 40 eyes of 20 age- and sex-matched participants as control group. The mean of three pachymetry measurements of the central cornea was taken as CCT. IOP was checked using an applanation tonometer. RESULTS: The mean corneal thickness of the eyes with extracted congenital cataract (632+/-45 microm) was significantly greater than that of the control eyes (546+/-33 microm; p<0.001). There was no significant difference in the corneal endothelial cell count, coefficient of variation (CV), and mean cell area (AVG) of endothelial cells between operated eyes and the control group. The mean measured IOP in the operated group (22.8+/-3.3 mm Hg) was significantly greater than IOP in controls (14.1+/-1.8 mm Hg, p<0.001). CONCLUSIONS: Although the corneas were clinically clear and there was no significant difference in endothelial characteristics of eyes with extracted congenital cataract and controls, central corneas of operated eyes were significantly thicker than those of controls. To differentiate the actual glaucoma from ocular hypertension in these patients, the central corneal thickness measurement should strongly be considered.     

Limits of agreement between the optical pachymeter and a noncontact specular microscope

PURPOSE: To determine the limits of agreement between central corneal thickness (CCT) measurements made with the slit lamp-attached optical pachymeter and the SP2000P noncontact specular microscope. METHODS: Triplicate readings for CCT were obtained for each of 130 (right) eyes of 130 patients, using the slit lamp-attached optical pachymeter and then the SP2000P noncontact specular microscope. The average CCT measured by each method was compared. Subsequently, the mean difference between both sets of measurements was assessed, and the 95% confidence interval (limits of agreement) between both techniques was determined. RESULTS: The mean +/- SD CCT measured by the optical pachymeter was 543 +/- 34 microm and 532 +/- 34 microm for the specular microscope. We found a statistically significant (P < 0.001) mean bias of 10 mum between CCT values measured with both types of equipment, with the optical pachymeter returning the higher values. The coefficient of variation was 6.3% for the optical pachymeter and 6.4% for the specular microscope. CONCLUSIONS: The right eye CCT measurements made by the optical pachymeter are, on average, 10 mum thicker than those made with the SP2000P specular microscope, which suggests that both pieces of equipment cannot be used interchangeably to monitor CCT changes in patients. Excluding left eye measurements, the reliability of the optical pachymeter is identical to that of the noncontact specular microscope.     

The role of central corneal thickness in the diagnosis of glaucoma

PURPOSE: To determine the effect of central corneal thickness (CCT) on applanation tonometry and any resultant misclassification of normals as ocular hypertension. METHOD: The central corneal thickness was measured using the ultrasound pachometer in 50 normals, 25 glaucoma and 23 ocular hypertensive patients. The student's "t" test was used to determine any significant difference in CCT between the three groups. RESULTS: There was a statistically significant difference in the mean CCT of the ocular hypertensives (0.574 +/- 0.033 mm) as compared to the glaucomas (0.534 +/- 0.030 mm) and normals (0.537 +/- 0.034 mm). Applying the described correction factor for corneal thickness, 39% of eyes with ocular hypertension were found to have a corrected IOP of 21 mmHg or less. CONCLUSIONS: Increased corneal thickness in ocular hypertension may lead to an overestimation of IOP in 39% of cases. Measurement of central corneal thickness is advisable when the clinical findings do not correlate with the applanation IOP.     

Central corneal thickness in primary open angle glaucoma, pseudoexfoliative glaucoma, ocular hypertension, and normal population

PURPOSE: This study was designed to determine the relationship between central corneal thickness (CCT) and intraocular pressure (IOP) measured by applanation tonometer in glaucomatous, ocular hypertensive, and normal eyes. METHODS: A total of 125 subjects were included in the study. Twenty-six had primary open angle glaucoma (POAG), 25 had pseudoexfoliative glaucoma (PXG), 24 had ocular hypertension (OHT), and 50 of them were normal. IOP values were measured by Goldmann applanation tonometer whereas CCT values were measured by ultrasonic pachymeter. RESULTS: CCT values in the OHT group (595.75+/-22.52 microm) were greater than the CCT values of the POAG group (539.92+/-21.50 microm), the PXG group (526.28+/-31.73 microm), and the normal group (533.96+/-29.25 microm) (p<0.05). Eight patients who were diagnosed with OHT showed IOP values of 21 mm Hg or lower with corrected IOP values according to CCT. CONCLUSIONS: Increased CCT may lead to falsely high values of IOP measured with Goldmann applanation tonometer. In this study, when IOP values of the OHT group were redefined according to the formulae regarding the CCT, the authors noted that one third of them were normal. Determination of the CCT in OHT cases is crucial since it has great impact on IOP values, measured with applanation tonometer, which is the main parameter in the diagnosis and follow-up of glaucoma.     

高眼压症中央角膜厚度与眼压关系的临床观察

目的 评价高眼压症患者中央角膜厚度(CCT)与眼压(IOP)的关系,并探讨CCT在判断高眼压症患者是否给予降眼压药物干预治疗中的临床意义.方法 对54例(108只眼)高眼压症患者进行非接触眼压计检测和超声角膜厚度测量,并对校正眼压＜21 mmHg的患者31例62只眼(占57.4%)不予降眼压治疗,追踪观察其眼压、视野、视乳头以及视网膜神经纤维层的情况.结果 IOP随CCT增加而增高,并呈正相关(CCT每增加100μm,IOP将随之增加2.1mmHg).对校正眼压＜21mmHg的患者不予降眼压治疗,随访24～36个月,平均30个月,其中1例2只眼出现视野改变,发生率为1.85%.结论 中央角膜厚度测量可以作为高眼压症与青光眼进行鉴别诊断,以及判断高眼压症能否发展为青光眼的重要依据,常规测量高眼压症患者的CCT并校正其眼压,对高眼压症患者的合理处置非常重要,对校正眼压＜21mmHg的患者可以不需降压药物干预治疗,仅需密切随访.     

Central corneal thickness in Latinos

PURPOSE: To characterize central corneal thickness (CCT) in Latinos aged 40 or more years. METHODS: A population-based cohort of Latinos from two census tracts in La Puente, California, underwent measurements of CCT and intraocular pressure (IOP). CCT was measured with an ultrasonic pachymeter, and IOP was measured by applanation tonometry. One eye of each of 1699 participants was included in the analyses. RESULTS: The mean (+/-SD) CCT was 546.9 +/- 33.5 micro m. Older participants (>or=70 years) had significantly thinner CCs compared with participants 40 to 49 years of age (P < 0.05). Eyes with ocular hypertension had thicker CCs than did normal and glaucomatous eyes (P < 0.05). Multivariate adaptive regression spline analyses and analysis of variance contrasting IOP subgroups revealed that eyes with thinner CCs had lower IOP than did eyes with thicker CCs (P < 0.001). The absolute range of interocular differences in CCT in the same subject was as high as 24 micro m. CONCLUSIONS: On average, CCT in Latinos was less than that previously reported in whites but greater than that reported in African Americans and Asians. Older Latinos had thinner corneas compared with younger Latinos. Asymmetry in CCT of 25 micro m or more should be evaluated for potential corneal disease. Spline analyses suggest that although the relationship between IOP and CCT is best explained by a nonlinear equation, when measuring IOP with the Goldmann tonometer, it is likely that IOP is underestimated in eyes with thinner CCs and overestimated in eyes with thicker CCs.     

正常人中央角膜厚度与Goldmann压平眼压的关系

目的:了解正常人中央角膜厚度(central corneal thickness,CCT)的分布特点并探讨其与压平眼压测量值的关系。方法:采用光学角膜测厚仪及Goldmann压平眼压计检测169名正常人CCT和压平眼压。结果:169名受检者右眼平均CCT为0.547mm(95%可信区间0.443~0.651mm),左眼0.551mm(95%可信区间0.453~0·649)。压平眼压右眼平均15.8mmHg,左眼15.5mmHg。CCT与年龄无相关关系,但与压平眼压测量值显著相关。线性回归分析表明,CCT每增加0.018mm,压平眼压增加1mmHg。结论:CCT变异是眼压测量误差的主要来源。CCT较厚的正常个体可表现"眼压增高"被误诊为高眼压症,而CCT偏薄的原发性开角型青光眼患者则可能因眼压测量"正常"被误诊为正常眼压性青光眼。在诊断青光眼或高眼压症时,特别是在眼压值与其他临床表现不符时,应考虑CCT有无变异。     

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     

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.     

Cambios morfométricos de las células del endotelio corneal en el síndrome pseudoexfoliativo y glaucoma pseudoexfoliativo

ObjetiveTo evaluate the corneal endothelial morphometry and central corneal thickness (CCT) in pseudoexfoliative (PEX) eyes with and without glaucoma and to compare with normal eyes and eyes with primary open-angle glaucoma (POAG).MethodA total of 166 patients were included in this study: 36 eyes with pseudoexfoliation syndrome (PXS), 30 eyes with pseudoexfoliation glaucoma (PXG), 40 eyes with POAG, and 60 normal eyes. Corneal endothelial cell density (ECD), coefficient of variation (CV) in cell size, and percentage of hexagonal cells, were measured using a non-contact specular microscope, whereas CCT was measured with an ultrasonic pachymeter.ResultsECD and percentage of hexagonal cells were lower in PEX groups and in the POAG group compared with normal eyes, while the CV in cell size was greater. There was a tendency for greater cell loss and morphological abnormalities of the corneal endothelial cells in PXG eyes compared to PXS eyes, when all pseudoexfoliative eyes were analyzed together. Changes in endothelial cells increased with age. There were no significant differences in mean CCT between the four groups.ConclusionEndothelial cell density is significantly decreased, and pleomorphism and polymegathism of cells are increased in PEX eyes, particularly when intraocular pressure is high.     

Effects of brinzolamide on aqueous humor dynamics in monkeys and rabbits.

This study examines the mechanisms by which brinzolamide reduces intraocular pressure (IOP) in healthy rabbits and in monkeys with unilateral ocular hypertension. Intraocular pressures were measured by pneumatonometry and aqueous flow was determined by fluorophotometry before and after three twice-daily drops of 1% brinzolamide to both eyes per monkey and after similar treatment to one eye per rabbit. In monkeys, outflow facility was determined by fluorophotometry and uveoscleral outflow was calculated. In rabbits, outflow facility was determined by two-level constant pressure infusion and uveoscleral outflow was measured by an intracameral tracer technique. Compared with contralateral vehicle-treated rabbit eyes, IOP was reduced in brinzolamide-treated eyes by 2.5 +/- 1.9 mmHg (mean +/- standard deviation; p =.006) at four hours after the second dose. Aqueous flow was reduced by 0.50 +/- 0.65 microl/min (p =.02). This effect was found in rabbits previously treated with brinzolamide but not in naive rabbits. Treated hypertensive eyes of monkeys had a reduction in IOP of 7.3 +/- 8.8 mmHg (p = 0.01) and aqueous flow of 0.69 +/- 1.10 microL/min (p = 0.05) when compared with baseline. Brinzolamide did not affect outflow facility or uveoscleral outflow in either rabbits or monkeys. It is concluded that, in normotensive eyes of rabbits and hypertensive eyes of monkeys, brinzolamide reduces IOP by reducing aqueous flow and not by affecting aqueous humor drainage.     

Central corneal thickness in normal eyes, patients with ocular hypertension, normal-pressure and open-angle glaucomas--a clinical study

BACKGROUND: The relation between Goldmann applanation tonometry and central corneal thickness (CCT) was investigated in several studies during the last thirty years. It was the aim of the present study to evaluate CCT in normals, patients with ocular hypertension, low-tension, and open-angle glaucomas. PATIENTS AND METHODS: CCT was measured in 135 normal eyes, 137 with ocular hypertension, 65 with low-tension, and 94 with primary and secondary open-angle glaucomas using the AL-11000-pachymeter (Tomey). The results were compared using the unpaired t-test. RESULTS: CCT was significantly higher in the patients with ocular hypertension (586 +/- 43 microns) than in the normal group (566 +/- 37 microns, p < 0.0001), in low-tension glaucomas (555 +/- 46 microns, p < 0.0001), and in open-angle glaucomas (558 +/- 31 microns, p < 0.0001). The latter three groups did not differ significantly. There was no significant correlation between CCT and age, the actually measured IOP, the highest IOP in the patient's history, or the spherical equivalent. CONCLUSIONS: Only patients with ocular hypertension showed a significant difference in CCT compared with normals. Pachymetry thus should be conducted in those patients to avoid overestimation of the IOP by applanation tonometry. In most of the patients with low-tension and open-angle glaucomas however, CCT regarded without other parameters (e.g. corneal or scleral rigidity) plays a minor role in detection of elevated IOP according to the results of this study.     

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   

Changes in corneal thickness in patients with treated and untreated ocular hypertension

PURPOSE: The elevated intraocular pressure (IOP) in eyes with ocular hypertension is often accompanied by increased corneal thickness. We tested the hypotheses that chronically elevated IOP causes a slow increase in corneal thickness and that lowering the IOP reverses this slow increase. METHODS: Fifty patients with ocular hypertension were randomized to medication and observation groups in the Mayo Clinic site of the Ocular Hypertension Treatment Study. Central corneal thickness was measured using an optical pachymeter at baseline and annually for 6 years. The rates of change of corneal thickness was compared between the groups. Epithelial thickness was measured by confocal microscopy 8 years after the baseline examination. RESULTS: Corneal thickness increased 1.5 +/- 3.3 microm/yr in the observation group (n = 23) and decreased -1.3 +/- 2.8 microm/yr in the medication group (n = 27, P = 0.002). Both rates were significantly different from zero (P = 0.04 and P = 0.02, respectively). Epithelial thickness was 46.4 +/- 4.9 microm in the observation group and 41.3 +/- 4.4 microm in the medication group (P = 0.008). CONCLUSION: Results of this single-center series imply that corneal thickness increases slowly in eyes with ocular hypertension and decreases slowly if the IOP is lowered by topical medications. These phenomena could be explained by a causal relationship between elevated IOP and a slow increase in corneal thickness. A decrease in epithelial thickness accounts for a portion of the thinning that occurs with treatment. If confirmed in a larger series, these findings indicate that the effects of previous treatment on thickness should be considered if corneal thickness is to be used as a discriminant factor in the management of patients with ocular hypertension.     

A retrospective pilot study to assess the impact of strabismus surgery on the corneal endothelium in children

PURPOSE: To investigate if strabismus surgery has an impact on the corneal endothelium in children. METHODS: Fourteen children who had undergone uncomplicated strabismus surgery an average of 41 months previously (range 24-73 months) were compared with a group of age-matched (range 5-12 years) and refractive error (RE)-matched (range -4.74 to +4.25 D) children. Following noncontact specular microscopy, areas of at least 100 cells were measured, the number of sides for each cell recorded, and endothelial cell density (ECD) calculated from the area measures. Corneal diameter was measured with a clinical rule, corneal curvature with a manual keratometer, central corneal thickness (CCT) by ultrasound pachometry, and IOP by non-contact tonometry. RESULTS: The average ECD (+/-S.D.) in the post-surgery group was 4467+/-627 cells mm(-2), which was significantly higher (p < 0.02) than in the control group (3781+/-452 cells mm(-2)). This was because the average endothelial cell area in the surgery group was significantly smaller than in the control group (p < 0.005; 252+/-25 microm2 vs 296+/-29 microm2). Differences in cell areas were slightly greater for smaller cells (-15.7% for five-sided cells, -15.6% for six-sided cells, -14.3% for seven-sided cells and -13.8% for eight-sided cells). The cell differences appear to be related to both a slightly smaller corneal diameter (11.00+/-0.52 mm vs. 11.21+/-0.58 mm) and a slightly higher CCT (0.528+/-0.033 mm vs. 0.515+/-0.032 mm) in the post-operative group. CONCLUSION: The endothelial mosaic in children after strabismus surgery can show a higher than expected ECD value and slight cell pleomorphism. These signs indicate that there might be differences in eye growth and endothelial inflammatory stress associated with uneventful strabismus 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.     

Corneal endothelial cell density and pachymetry measured by contact and noncontact specular microscopy

PURPOSE: To determine the endothelial cell density and thickness of normal human and postkeratoplasty corneas with contact specular microscopy and to compare these measurements with those obtained by noncontact specular microscopy. SETTING: Department of Ophthalmology, University of Erlangen-Nürnberg, Erlangen, Germany.METHODS: The central corneal endothelial cell density and thickness were determined in 65 healthy eyes of 39 patients with a mean age of 71 years +/- 12 (SD) and in 50 corneal grafts of 41 patients with a mean age 53 +/- 17 years using noncontact (Topcon SP-2000P, Topcon Corp.) and contact (EM-1000, Tomey) specular microscopes. Appropriate conversion factors were used for accurate cell count comparison. RESULTS: The mean cell count of the normal corneas was 2445 +/- 425 cells/mm(2) measured by noncontact specular microscopy and 2471 +/- 393 cells/mm(2) measured by contact specular microscopy (P =.70). After penetrating keratoplasty, the mean cell density was 1610 +/- 499 cells/mm(2) and 1584 +/- 469 cells/mm(2), respectively (P =.88). Significantly lower thickness was measured with the noncontact specular microscope than by contact pachymetry in normal eyes (543 +/- 46 micro m and 642 +/- 42 micro m, respectively) and postkeratoplasty eyes (538 +/- 61 micro m and 627 +/- 48 micro m, respectively) (P <.0001). CONCLUSION: To determine endothelial cell density, contact and noncontact specular microscopy may be used interchangeably. However, for the combined measurement of endothelial cell density and pachymetry, the use of the same specular microscope is recommended for long-term patient follow-up.     

The effect of corneal thickness on intraocular pressure measurement in patients with corneal pathology

BACKGROUND/AIM: To compare intraocular pressure (IOP) measurements taken by the Goldmann applanation tonometer, the Tono-Pen and the ocular blood flow pneumotonometer in eyes with varying central corneal thickness (CCT) due to penetrating keratoplasty (PK), keratoconus (KC), and Fuchs' endothelial dystrophy (FED). METHODS: IOP was measured with the Goldmann applanation tonometer, Tono-Pen XL, and OBF pneumotonometer in 127 eyes with the following corneal abnormalities. There were 56 eyes that had undergone PK, 37 eyes with KC, and 34 eyes with FED. CCT was measured using an ultrasound pachymeter after IOP determinations had been made. RESULTS: Mean IOP measurements in all three patient groups were significantly higher when measured by OBF pneumotonometer. Linear regression analysis showed that patients with FED had a significant increase in IOP with increasing CCT of 0.18 mm Hg/10 microm using the Goldmann tonometer, 0.15 mm Hg/10 microm with the Tono-Pen, and 0.26 mm Hg/10 microm with the OBF pneumotonometer. In patients with KC and after PK, linear regression analysis did not show a significant effect of CCT on IOP. A multivariate linear regression model controlling for age, sex, graft size, and patient group, showed that the effect of CCT on IOP for Tono-Pen (0.13 mm Hg/10 microm CCT) and Goldmann (0.14 mm Hg/10 microm CCT) were significantly lower than for the OBF pneumotonometer (0.26 mm Hg/10 microm CCT). CONCLUSIONS: This study found that mean IOP measurements using the OBF pneumotonometer were significantly higher than those made using the Goldmann applanation tonometer or Tono-Pen in eyes with a variety of cornel pathologies. The OBF pneumotonometer was found to be most affected by variation in CCT. For all three instruments, the relation between IOP and CCT depended on the corneal pathology and was greatest for FED.     

Corneal thickness measurements with contact and noncontact specular microscopic and ultrasonic pachymetry

PURPOSE: To evaluate the central corneal thickness values in normal and postkeratoplasty corneas with the new Topcon SP-2000P noncontact specular microscopic, contact specular microscopic, and the "common standard" ultrasonic pachymetry. METHODS: Central corneal thickness was determined in 119 eyes of 81 patients (73 normal eyes of 44 patients and 46 eyes after penetrating keratoplasty) first with a noncontact specular microscopic (Topcon SP-2000P; Topcon Corporation, Tokyo, Japan), then an ultrasonic (AL-1000; Tomey, Erlangen, Germany), and finally with a contact specular microscopic (EM-1000; Tomey, Erlangen, Germany) pachymetry two times each by the same investigator. RESULTS: Reliability of the central corneal measurements was equally high both in normal and in postkeratoplasty corneas with all of the instruments (Cronbach alpha = 0.99). Noncontact specular microscopic corneal thickness determination correlated significantly both with ultrasonic (r =.86, P <.0001) and contact specular microscopic pachymetry (r =.62, P <.0001). The ultrasonic pachymetry correlated well with the Tomey pachymetry (r =.69, P <.0001). The Topcon normal mean central corneal thickness value (542 +/- 46 microm) was 28 +/- 4 microm lower (P <.0001) compared with the ultrasonic data (570 +/- 42 microm), which was 68 +/- 1 microm lower (P <.0001) compared with Tomey thickness (638 +/- 43 microm). CONCLUSIONS: Central corneal thickness measurements with noncontact specular microscopic, contact specular microscopic, and ultrasonic pachymetry demonstrate that each of the instruments is reliable but cannot be simply used interchangeably.     

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.