Central corneal thickness, radius of the corneal curvature and intraocular pressure in normal subjects using non‐contact techniques: Reykjavik Eye Study

Eysteinsson, Þór; Jónasson, Friðbert; Sekiya, Hiroshi; Arnarsson, Ársæll; Sverrisson, Thordur; Sasaki, Kohsuke; Stefánsson, Einar

doi:10.1034/j.1600-0420.2002.800103.x

Cited by 172 publications

(148 citation statements)

References 25 publications

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“…21 Our study found that CCT was positively correlated with IOP in elderly white subjects without visual field defect. A similar relationship has been found in various populations, [21][22][23][24] although it was not present in the black participants of the Barbados Eye Study. 25 IOP measured by Goldmann applanation tonometry should ideally be adjusted for CCT, although a simple nomogram is unlikely to be accurate in all cases due to the influence of other factors such as corneal rigidity.…”

Section: Discussionsupporting

confidence: 86%

“…8,10,19,20 Two studies which also only recruited older participants, failed to detect a significant relationship. [21][22][23][24] The changes in structural corneal biomechanics with subject age adds further complexity to the relationship between CCT and Goldmann IOP. 26 The diabetic patients in our study had significantly greater CCTs than the non-diabetic patients, although only by a mean of 9 mm.…”

Section: Discussionmentioning

confidence: 99%

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

Hawker

Edmunds

Vernon

et al. 2007

Eye

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Purpose To determine population-based normative CCT data for elderly white subjects, with and without diabetes, and to explore the relationship between CCT and IOP and HRT2 measurements in such subjects with normal visual fields. Methods All eligible subjects were consecutive in a population screened for eye disease. CCT was measured by ultrasound pachymetry, and the optic disc was morphometrically defined using Heidelberg retinal tomography (HRT2). Inclusion criteria were: (1) normal visual field on suprathreshold testing and (2) corrected logMAR acuity of at least 0.3 in both eyes. Subjects with significant corneal pathology, previous corneal surgery, or known history of glaucoma or treatment for raised intraocular pressure were excluded. One eye was randomly selected from each subject for analysis. Results In all, 983 eyes of 983 subjects were included with 690 HRT images deemed acceptable for the analysis. The mean age (414 men and 569 women) was 73.3 years (minimum 65 years). Mean (SD) CCT was 544.1 (36.5) lm, with a normally distributed range of 429-633 lm. There was no significant difference in CCT between men and women (mean CCT 546.1 and 542.7 lm, respectively, P ¼ 0.15, Student's t-test), though CCT was correlated weakly and negatively with age (Pearson's r ¼ À0.063, P ¼ 0.047). Diabetic patients (n ¼ 103) had a greater mean CCT than non-diabetic patients (551.9 and 543.0 lm respectively, P ¼ 0.02). No significant correlation was found between any global optic disc parameter and CCT in the 690 eyes analysed. Conclusion Elderly white eyes with normal fields have CCTs that are normally distributed, with those from diabetic persons having greater CCTs. No clear evidence of a relationship between CCT and HRT2 optic disc parameters used in glaucoma diagnosis was found.

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Section: Discussionsupporting

confidence: 86%

Section: Discussionmentioning

confidence: 99%

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

Hawker

Edmunds

Vernon

et al. 2007

Eye

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“…We did not consider the corneal curvature because the effect of it on applanation tonometer readings remains uncertain. Using 925 randomly sampled right eyes, Eysteinsson et al 15 could not establish any relationship between the radius of corneal curvature and the NCT measurements. Paranhos et al 23 also found no significant influence of corneal curvature on IOP readings obtained with the GAT and NCT in 404 eyes with keratometric readings between 8.6 and 6.39 mm.…”

Section: Discussionmentioning

confidence: 97%

“…In a population study on subjects aged 50 years or older, Eysteinsson et al 15 found that every 10 mm increase in CCT is associated with a rise of 0.22-0.28 mmHg in NCT (Nidek NT 2000) readings. However, their study did not take into account individual variation in true intraocular hydrostatic pressure while estimating the influence of CCT on IOP readings.…”

Section: Discussionmentioning

confidence: 99%

Varying Effects of Corneal Thickness on Intraocular Pressure Measurements with Different Tonometers

Liu

Hsu

2004

Eye

109

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Aims To compare the intraocular pressure (IOP) measurements using the Goldmann applanation tonometer (GAT), noncontact tonometer (NCT), and ocular blood flow tonometer (OBFT), and to evaluate the effects of varying central corneal thickness (CCT) on the readings. Methods Ultrasound pachymetry and tonometry were performed on 170 eyes. Using the corrected GAT values that took CCT into account as the standard, we calculated the NCT and OBFT measurement errors related to the CCT variable by a linear regression model. Group comparisons were performed with the v 2 test and one-way ANOVA test. The correlation between the various tonometer measurements was analysed by Pearson's correlation method. Results Both the NCT (r ¼ 0.872, Po0.001) and OBFT measurements (r ¼ 0.861, Po0.001) were highly correlated with the GAT measurements. IOP measurements using the three tonometers were all correlated with CCT (all Po0.001), with the NCT measurements showing the greatest regression coefficient (b ¼ 0.063, r ¼ 0.650) and the GAT measurements the least (b ¼ 0.037, r ¼ 0.496). A linear regression model indicated that a 10 lm change in CCT resulted in a NCT measurement deviation of 0.47-0.98 mmHg and an OBFT measurement deviation of 0.29-0.81 mmHg.Conclusion Pressure readings with the GAT, NCT, and OBFT are all affected by CCT, with the NCT being the one most affected and the GAT the least. Our findings suggest CCT an essential variable to consider in interpreting IOP readings, especially for the NCT measurements.

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“…2,3 In vivo, it is measured either by ultrasonography or by partial coherence interferometry. The AL of the eye at birth is approximately 17 mm and reaches approximately 24 mm in adulthood.…”

Section: Introductionmentioning

confidence: 99%

The relation between central corneal thickness and axial length in a sample of Erbil population

Muhammad¹,

Joma

Abdulgani

2015

ZJMS

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IntroductionThe axial length (AL) of the eye is the distance between the anterior and posterior poles of the eye, 1 and it is typically defined as the distance from the anterior corneal surface to the anterior surface of the retina. 2,3 In vivo, it is measured either by ultrasonography or by partial coherence interferometry. The AL of the eye at birth is approximately 17 mm and reaches approximately 24 mm in adulthood. It is typically longer than 24 mm in myopes and shorter than 24 mm in hyperopes. Each one millimeter of change in AL of the eye corresponds to approximately 2.5 diopters (D) change in refractive power of the eye. 4 From birth to age six years, the AL of the eye grows by approximately 5 mm, and one might expect from this a high prevalence of myopia in infants. However, most children are actually emmetropic, with only a 2% incidence of myopia at six years. This phenomenon is due to a still undetermined mechanism called emmetropization. During that first six years of life, a compensatory loss of 4 D of corneal power and 2 D of lens power keeps most eyes close to emmetropia. It appears that the immature human eye develops so as to reduce refractive errors. The cornea is a transparent, avascular tissue that measures 11-12 mm horizontally and 10-11 mm vertically. Its refractive index is 1.376, although, in calibrating a keratometer, a refractive index of 1.3375 is used to account for the combined optical power of the anterior and posterior curvatures of the cornea. The average radius of curvature of the central cornea is 7.8 mm. The cornea thus contributes 74%, or 43.25 D, of the total 58.60 dioptric power of a normal human eye.5 Normal central Background and objective:A thin central corneal thickness has been reported to be a risk factor for developing primary open-angle glaucoma. This has led to a hypothesis that thinning of the cornea may be an indication of generalized weakness of the ocular integument. This study was conducted to explore the relationship between central corneal thickness and axial length in a sample of Erbil population. Methods: This is an observational cross sectional prospective study that was conducted from October 2012 to March 2013 and included 260 eyes of 130 patients. The mean age (± SD) was 37.8 ± 17.7 years for males and 35.4 ± 15.5 years for females. Axial length was measured with A-scan ultrasound biometry and central corneal thickness with ultrasonic Pachymeter. Results:The mean central corneal thickness (± SD) was 542.8 ± 36 µm in male eyes and 530.1 ± 32.5 µm in female eyes. The mean axial length (± SD) was 23.38 ± 1.1 mm in male eyes, 23.15 ± 1.2 mm in female eyes. Central corneal thickness was not correlated with axial length (Pearson correlation coefficient r = 0.037, P = 0.558). Conclusion:Central corneal thickness and axial length of the eye are two independent measurements. Thin corneas are not related to longer eye.

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Central corneal thickness, radius of the corneal curvature and intraocular pressure in normal subjects using non‐contact techniques: Reykjavik Eye Study

Cited by 172 publications

References 25 publications

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

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

Varying Effects of Corneal Thickness on Intraocular Pressure Measurements with Different Tonometers

The relation between central corneal thickness and axial length in a sample of Erbil population

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