[Relationship between central corneal thickness, intraocular pressure and severity of glaucomatous visual field loss].
ABSTRACT to determine central corneal thickness in normal subjects, glaucomatous patients and ocular hypertension patients, to evaluate if the central corneal thickness is related to the presence of glaucoma or ocular hypertension. Furthermore, we aim to verify the relationship between central corneal thickness and severity of glaucomatous visual field loss.
comparative study including 150 eyes of 150 subjects, separated into three groups: normal (47 eyes), ocular hypertension (35) and glaucomatous (68). This last group was subdividided in three subgroups depending on the Hodapp-Parrish-Anderson criteria for scoring Humphrey visual field defects (initial, moderate and advanced). We evaluated the visual field, the central corneal thickness measured by pachymetry and the intraocular pressure measured by Goldmann tonometry. Results were analysed using the Student's t-test for normally distributed independent samples.
the central corneal thickness was 526+/-25 microns (mean +/-standard deviation (SD)) in glaucomatous patients, 560+/-27 microns in ocular hypertension patients, and 556+/-27 microns in the normal group. Statistical significance could be found between the glaucomatous group of patients and the other groups (p< 0.01), but not between the ocular hypertension group and normal subjects (p= 0.4). The comparison between central corneal thickness of the subgroup with advanced damage of the visual field and the two other subgroups was also statistically significant (p< 0.01), but not between the subgroups of initial damage and moderate damage (p= 0.7).
the central corneal thickness in glaucomatous patients is lower than in normal subjects and in ocular hypertension patients. Patients classified as having advanced damage in their visual field have significantly lower central corneal thickness measurements than patients classified as having initial or moderate damage.
Article: Intraocular pressure adjusted for central corneal thickness as a screening tool for open-angle glaucoma in an at-risk population.[show abstract] [hide abstract]
ABSTRACT: Evaluation of intraocular pressure (IOP) adjusted for central corneal thickness (CCT) screening for open-angle glaucoma (OAG) in an at-risk population. Community-based screening clinic. Three hundred and forty-nine persons of black race, or >50 years of age, or with a positive family history of glaucoma. Ophthalmological examination including Goldmann applanation tonometry, ultrasonographic corneal pachymetry, and visual field testing. Glaucomatous optic nerve damage with visual field loss was the gold standard. IOP was adjusted for CCT based on 3 nomograms. Results were compared with screening using unadjusted IOP. Outcome measures included sensitivity, specificity, areas under the receiver operating characteristic (ROC) curves, positive and negative predictive values (PPVs and NPVs), as well as positive and negative likelihood ratios. No significant difference in CCT was found between those with glaucoma (560 [SD 37] microm, n = 31) and those without (557 [SD 35] microm, n = 233). Screening adjusted IOPs for glaucoma with an IOP > 21 mm Hg resulted in PPVs of 23.8% to 25% and NPVs of 89.3% to 89.6%, similar to preadjustment values. Areas under the ROC curves varied from 0.544 to 0.571 post adjustment from the initial value of 0.574. IOP adjusted for CCT is unlikely to improve tonometry as a screening tool for OAG in an at-risk population.Canadian Journal of Ophthalmology 10/2009; 44(5):571-5. · 1.47 Impact Factor
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ABSTRACT: To evaluate if using the Ehlers correction factor on the intraocular pressure (IOP) measured using the Goldmann applanation tonometer (GAT) improves its agreement with the PASCAL dynamic contour tonometer (DCT). A total of 120 eyes of 120 individuals were examined. Participants underwent IOP measurement with both the DCT and the GAT and central corneal thickness measurement. The Ehlers correction factor was applied on the GAT IOP measurements to calculate Ehlers-corrected GAT IOP. The agreement between the DCT and GAT, and DCT and Ehlers-corrected GAT IOP was analyzed. The analyses were repeated by stratifying the data by race. The mean IOP of the GAT, DCT, and the Ehlers-corrected GAT was 15.30, 16.78, and 14.68 mmHg, respectively. The agreement as assessed by Bland-Altman plot for the GAT with the DCT and DCT and Ehlers-corrected GAT IOP was +4.1 to -6.9 and +4.15 to -8.25 mmHg, respectively. The results were similar even when stratifying the data by race. Using Ehlers correction factor to account for the effect of corneal parameters on the IOP measured by the GAT worsens the agreement with the DCT. This effect remains even when stratifying the data by race.Clinical Ophthalmology 01/2010; 4:611-6.