Corneal thickness and curvature in normal-tension glaucoma (original) (raw)
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American Journal of Ophthalmology
PURPOSE: To evaluate corneal biomechanical properties across the glaucoma spectrum and study the relationship between these measurements and intraocular pressure measured by Goldmann applanation tonometry (GAT-IOP) and central corneal thickness (CCT). • DESIGN: Prospective cross-sectional study. • METHODS: SETTING: Tertiary-care teaching institute. STUDY POPULATION: A total of 323 eyes of 323 participants (71 normal, 101 glaucoma suspect [GS], 38 ocular hypertension [OHT], 59 primary angle-closure disease [PACD], 36 primary open-angle glaucoma [POAG], and 18 normal-tension glaucoma [NTG]) who had received no ophthalmic treatment. OBSERVATION PROCEDURES: Corneal hysteresis (CH), corneal resistance factor (CRF), corneal-compensated IOP (IOPcc), and Goldmann-correlated IOP (IOPg) measured by the Ocular Response Analyzer (ORA). GAT-IOP and CCT recorded in all subjects. MAIN OUTCOME MEASURES: Regression analysis used to determine the relationship between GAT-IOP, CCT, age, CRF, and CH. Bland-Altman plots used to assess agreement between IOP measured by GAT and the ORA (IOPg).
British Journal of Ophthalmology, 2001
Background/aims-Recent studies have revealed patients with ocular hypertension to have thicker than normal central corneas and those with normal tension glaucoma to have thinner than normal ones, as determined by ultrasonic pachymetry. Since corneal thickness measurements and applanation tonometric estimates of intraocular pressure (IOP) correlate positively, monitoring of the former parameter have served as the basis for adjusting readings pertaining to the latter, with the consequence that many patients have had to be reclassified. With a view to validating these pachymetric studies, the central corneal thickness was determined in patients with normal tension glaucoma, primary open angle glaucoma, pseudoexfoliation glaucoma, or ocular hypertension, as well as that of normal subjects, using optical low coherence reflectometry, which is a new and more precise method than ultrasonic pachymetry. Methods-34 patients with normal tension glaucoma, 20 with primary open angle glaucoma, 13 with pseudoexfoliation glaucoma, and 12 with ocular hypertension, together with 21 control subjects, were included in this observational, concurrent case-control study. One eye per individual was randomly selected for investigation. IOP was measured by Goldmann applanation tonometry and central corneal thickness by optical low coherence reflectometry. Results-Central corneal thickness was significantly higher (p <0.001) in patients with ocular hypertension than in normal individuals or in subjects with either normal tension glaucoma, primary open angle glaucoma, or pseudoexfoliation glaucoma, there being no significant differences between the latter four groups. Patients with ocular hypertension were also significantly younger (p <0.003) than those within any of the three glaucomatous groups. Conclusion-This study confirms that a significant number of patients with ocular hypertension have normal IOPs after the appropriate adjustments have been made for deviations from normal in their central corneal thickness. The accurate measurement of this latter parameter is
Investigative ophthalmology & visual science, 2016
To analyze the diagnostic efficacy of normalization of corneal deformation variables by the IOP in healthy, primary-angle closure (PACG), and primary open angle glaucoma (POAG) patients. Fifty-nine healthy, 83 POAG, and 57 PACG eyes, matched for age and pachymetry, were included in a prospective, observational, cross-sectional study. Goldmann applanation tonometry (GAT-IOP), Corvis-ST IOP, IOPg (Goldmann correlated), and IOPcc (cornea compensated) from the ocular response analyzer were acquired. Corneal hysteresis (CH) and corneal resistance factor (CRF) from the ORA, and deformation amplitude (DA) from Corvis-ST were analyzed. Further, ratios of CH, CRF, and DA to IOP were assessed among the groups and defined as new variables (e.g., ratio [CH, IOPcc] was the ratio of CH to IOPcc). Goldmann applanation tonometry-IOP, IOPcc, and IOPg of PACG and POAG eyes were significantly higher than normal (P < 0.05). Corvis-ST IOP of healthy eyes was similar to POAG (P > 0.05) but lower th...
Central Corneal Thickness – A Must In Management of Glaucoma
IOSR Journal of Dental and Medical Sciences, 2017
Purpose: To determine the correlation of central corneal thickness (CCT) with intraocular pressure measurement (IOP) & to reclassify the patients of Primary Open Angle Glaucoma (POAG), Normal Tension Glaucoma (NTG) & Ocular Hypertension (OHT) based on their corrected IOP. Design: Retrospective analysis. Material & Methods: It was a retrospective noninterventional, observational study. 100 cases & 20 controls were inducted in the study. Central corneal thickness was measured by ultrasonic pachymeter. Corrected IOP was calculated based on CCT value (correction factor of 3.0mm Hg for every 50μm of difference from 550μm) using a linear formula Corrected IOP = Measured IOP – (CCT – 550)/50 x 3.0mm Hg. Results: Total of 100 cases (POAG -54, NTG26 & OHT20) & 20 controls were included in the study. There was no significant difference in CCT between controls and patients with POAG but the CCT in the group with NTG was significantly lower than that in the control group or the group with POAG ...
Purpose: To investigate the correlation between central corneal thickness (CCT) and intraocular pressure (IOP) measured by Schiotz and Goldmann tonometers. Methods: CCT and IOP were determined by ultrasonic pachymetry and with the Goldmann and Schiotz tonometers, respectively. The correlation between IOP measured by Goldmann and Schiotz tonometers on one hand and CCT on the other, was determined by regression analysis. Results: Overall, 168 eyes of 168 glaucoma patients including 85 male (50.6%) and 83 female (49.4%) subjects with mean age of 54.6±19.8 (range 7-85) years were evaluated. Mean CCT was 547.6±53.02 (range: 446-848) μm without any significant difference between men and women (P=0.811). IOP was correlated with CCT with both types of tonometry: every 20 μm change in CCT was associated with 1.9±1.4 mmHg and 1.54±0.95 mmHg change in IOP as measured by the Goldmann and Schiotz tonometers respectively with no statistically significant difference between the two devices (P=0.6). Conclusion: IOP measurement by Schiotz tonometry is affected by CCT to the same extent as Goldmann applanation tonometry.
Journal of Clinical Medicine, 2021
Purpose: To evaluate and compare corneal hysteresis (CH), corneal resistance factor (CRF), and central corneal thickness (CCT), measurements were taken between a healthy population (controls), patients diagnosed with glaucoma (DG), and glaucoma suspect patients due to ocular hypertension (OHT), family history of glaucoma (FHG), or glaucoma-like optic discs (GLD). Additionally, Goldmann-correlated intraocular pressure (IOPg) and corneal-compensated IOP (IOPcc) were compared between the different groups of patients. Methods: In this prospective analytical-observational study, a total of 1065 patients (one eye of each) were recruited to undergo Ocular Response Analyzer (ORA) testing, ultrasound pachymetry, and clinical examination. Corneal biomechanical parameters (CH, CRF), CCT, IOPg, and IOPcc were measured in the control group (n = 574) and the other groups: DG (n = 147), FHG (n = 78), GLD (n = 90), and OHT (n = 176). We performed a variance analysis (ANOVA) for all the dependent va...
Central Corneal Thickness, Tonometry, and Ocular Dimensions in Glaucoma and Ocular Hypertension
Journal of Glaucoma, 2001
Purpose: To assess possible correlations between central corneal thickness, tonometry, and ocular dimensions. Patients and Methods: One hundred seventeen eyes of 117 patients who were not taking any intraocular pressure-lowering medications were studied prospectively. Forty-one patients had ocular hypertension; 13 patients had primary open-angle glaucoma; and 10 patients had normal-pressure glaucoma. Twenty-three healthy eyes were included. Thirty glaucoma suspects (10 patients monitored for possible normalpressure glaucoma and 20 patients with intermittent ocular hypertension) were included for correlation analysis. Tonometry was performed with Goldmann applanation and pneumotonometry, and central corneal thickness, anterior chamber depth, lens thickness, and axial length were measured ultrasonically. Results: Central corneal thickness was lowest in eyes with normal-pressure glaucoma (538 ± 51 m), highest in eyes with ocular hypertension (570 ± 32 m), and intermediate and similar in eyes with primary open-angle glaucoma and healthy eyes (547 ± 34 m and 554 ± 32 m, respectively). These differences were significant (P ס 0.028). Goldmann applanation tonometry and central corneal thickness were weakly correlated (r ס 0.12, P ס 0.205), with a 0.2-mm Hg change per 10-m variation in central corneal thickness. Pneumotonometry measurements were more strongly correlated with central corneal thickness (r ס 0.21, P < 0.05). Lens thickness was strongly correlated with age (r ס 0.57, P < 0.001). Anterior chamber depth was negatively correlated with lens thickness and age (r ס −0.29, P < 0.005 and r ס −0.25, P < 0.01). Axial length was correlated with anterior chamber depth and age (r ס 0.5, P <.001 and r ס −0.19, P < 0.05). Conclusion: Eyes diagnosed as having ocular hypertension have thicker corneas and eyes labeled as having normal-pressure glaucoma have thinner corneas, when compared with healthy eyes or eyes with primary open-angle glaucoma. The effect of central corneal thickness on Goldmann applanation tonometry accuracy appears to be small and usually not clinically relevant. When corneal thickness is markedly different from normal, the clinician may need to factor this into diagnosis and management.
Journal of the Medical Sciences, 2017
Background: Glaucoma is an optic neuropathy characterized by a typical appearance of optic nerve head and characteristic visual field loss. The diagnosis of primary glaucoma, normal tension glaucoma and ocular hypertension is made on the basis of an IOP cut-off point of 21 mmHg. Thus, any factor that alters the value of the IOP can lead to a misclassification of the patient. There is a growing consensus that assessment of Central Corneal Thickness (CCT) has become an important element of the clinical evaluation of the glaucoma patient. This study intends to analyse the CCT trends amongst three study groups: Normal subjects; Primary Open Angle Glaucoma subjects; and Ocular Hypertension subjects. It also intends to explore the relationship between CCT and GAT IOP amongst the three study groups. Lastly, this study aims to evaluate if CCT can be used as a useful tool for prognostication of disease progression in ocular hypertensives, and for glaucoma diagnosis. Aims and Objective: 1. To...
2020
Background The aim of this study was to determine whether Central Corneal Thickness (CCT) is associated with intraocular pressure measurement (IOP) with a Non-contact tonometer and the Goldmann applanation tonometer in glaucoma patients. Materials and Methods The study involved two hundred and thirty-two eyes of clinically diagnosed glaucoma patients receiving care at a referral facility. IOP measurements were obtained using both the Non-Contact Tonometer (NCT) and Goldmann Applanation Tonometer (GAT). The association between age, ethnicity, and CCT, as well as CCT on the measures of NCT and GAT, were analyzed. Results There were 64(55.2%) males and 52 (44.8%) females and their ages ranged from 18 to 85 years (mean age = 47.72; SD ± 15.75 years). There was a weak positive correlation between the CCT and NCT findings in the right eye (r = 0.19, n = 116, p < 0.05) and in the left eye (r = 0.25, n = 116, p < 0.05). However, there was no correlation between CCT and GAT measurement...