Central corneal thickness measurements in patients with normal tension glaucoma, primary open angle glaucoma, pseudoexfoliation glaucoma, or ocular hypertension

Abstract

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 important not only for individual patient care, in permitting more precise estimations of IOP, but also for clinical studies, in assuring a more reliable classification of subjects. (Br J Ophthalmol 2001;85:792-795)

Evaluation of anterior segment parameters in patients with pseudoexfoliation syndrome using Scheimpflug imaging

“…Detorakis et al (11) reported that differences in CCT between PXS eyes and age-and sex-matched controls were not statistically significant. Ventura et al (12) and Yagci et al (13) reported that there were no significant differences in CCT among normal-tension glaucoma, primary open-angle glaucoma, pseudoexfoliative glaucoma, and healthy control groups. However, Gorezis et al (14) found that the CCT was significantly thinner in patients with pseudoexfoliative glaucoma.…”

“…However, there are conflicting studies about central corneal thickness (CCT) in patients with PXS or pseudoexfoliative glaucoma. Most studies have reported similar CCT in PXS and normal eyes (9)(10)(11)(12)(13) , but some authors have reported a thinner (14,15) or thicker (16,17) CCT in PXS eyes than in normal eyes.…”

The relationship between central corneal thickness and the optic disc in an elderly population: the Bridlington Eye Assessment Project

“…Thus, true IOP, and therefore glaucoma risk, may be underestimated in these eyes. This may explain the findings that mean CCT is thinner in patients with normal tension glaucoma compared with those having POAG, 6,7 and thicker in patients with OHT. 8,9 These findings are replicated among different racial groups.…”

Central Corneal Thickness – A Must In Management of Glaucoma

“…Optical low coherence reflectometry represents the most precise pachymetric method available, with its measurements reproducible to 1 µm. 12 In the future, appropriate refinement of the correction formula may need to be undertaken, depending on the corneal pachymetric method adopted.…”