Central corneal thickness of Caucasians, Chinese, Hispanics, Filipinos, African Americans, and Japanese in a glaucoma clinic
ABSTRACT To characterize the central corneal thickness (CCT) of Asian (Chinese, Japanese, and Filipino), Caucasian, Hispanic, and African American patients in a multiethnic glaucoma practice.
Retrospective study (chart review).
Glaucomatous (n = 600) and nonglaucomatous (n = 201) eyes of 801 patients examined in a San Francisco glaucoma clinic from June 2002 to April 2004 who met inclusion criteria were included in the study. The 6 racial (ethnic) groups represented in the study were Caucasian (n = 186, 23.2%), Chinese (n = 157, 19.6%), Japanese (n = 121, 15.1%), Hispanic (n = 116, 14.5%), Filipino (n = 114, 14.2%), and African American (n = 107, 13.4%).
Central corneal thickness was measured by means of ultrasound pachymetry in Asian (Chinese, Japanese, and Filipino), Caucasian, Hispanic, and African American participants with glaucomatous and normal eyes. The relationship between CCT and race was investigated using multivariate regression analyses, controlling for confounders. One eye of each of 801 participants was included for analysis.
Correlation of mean CCT with race, glaucoma diagnosis, age, spherical equivalent, gender, and history of ocular surgery.
The mean CCT of all participants was 542.9 mum. Central corneal thicknesses of Chinese (555.6 microm), Caucasian (550.4 microm), Filipino (550.6 microm), and Hispanic (548.1 microm) participants did not significantly differ. The CCT of Japanese participants (531.7 microm) was significantly less than that of Caucasians, Chinese, Filipinos, and Hispanics (all, P< or =0.001) and greater than that of African Americans (P = 0.03). African Americans had a CCT (521.0.0 microm) less than that of all races (P< or =0.05). Glaucoma suspects and patients with normal tension glaucoma (NTG), primary open-angle glaucoma (POAG), pseudoexfoliation glaucoma (PEX), and chronic angle-closure glaucoma (CACG) had corneas significantly thinner than those of normal participants (P< or =0.004), whereas ocular hypertensives had significantly thicker corneas (P<0.0001). Among all participants, decreasing values of CCT were significantly related to older age (P<0.01). Less negative or more positive refractive errors, gender, and history of ocular surgery were not associated with changes in CCT (P = 0.38, P = 0.50, and P = 0.97, respectively).
Studies examining individual Asian subpopulations in isolation suggest that differences in CCT may exist among different Asian groups. The results of this study indicate that CCT does, in fact, vary among Asian subpopulations; Japanese have thinner corneas than Chinese and Filipinos. Caucasians, Chinese, Hispanics, and Filipinos have comparable CCT measurements, whereas the corneas of African Americans are significantly thinner. Additionally, older individuals; glaucoma suspects; and participants with NTG, POAG, PEX, and CACG have thinner corneas. Ocular hypertensives, however, have thicker corneas.
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ABSTRACT: An experimental study has been conducted to determine the stress-strain behaviour of human corneal tissue and how the behaviour varies with age. Fifty-seven well-preserved ex vivo donor corneas aged between 30 and 99 years were subjected to cycles of posterior pressure up to 60 mm Hg while monitoring their behaviour. The corneas were mechanically clamped along their ring of scleral tissue and kept in physiological conditions of temperature and hydration. The tissue demonstrated hyper-elastic pressure-deformation and stress-strain behaviour that closely matched an exponential trend. Clear stiffening (increased resistance to deformation) with age was observed in all loading cycles, and the rate of stiffness growth was nonlinear with bias towards older specimens. With a strong statistical association between stiffness and age (p < 0.05), it was possible to develop generic stress-strain equations that were suitable for all ages between 30 and 99 years. These equations, which closely matched the experimental results, depicted corneal stiffening with age in a form suitable for implementation in numerical simulations of ocular biomechanical behaviour.Journal of The Royal Society Interface 04/2010; 7(51):1475-85. DOI:10.1098/rsif.2010.0108 · 3.86 Impact Factor
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ABSTRACT: To determine the relationship between central corneal thickness (CCT) and myopia among Saudi adults. In a prospective study, the CCT of 982 myopic eyes and 158 emmetropic eyes as a control group was measured using ultrasound pachymetry at the Eye Consultants Center, Riyadh, Saudi Arabia. The mean myopic spherical equivalent (SE) was -3.7 +/- 2.12 D, range -0.25 to -15.0 D.The mean CCT of the myopic group was 543.8 +/- 35.40 microm, while for the emmetropic group it was 545.7 +/- 27.6 microm. The difference in mean CCT between the two groups was statistically insignificant (P = 0.5). There was no correlation between CCT and the degree of myopic spherical equivalent (r = -0.014, P = 0.939). This clinical study showed that there was no difference in CCT between emmetropic and myopic eyes. CCT did not correlate with the degree of myopia. It seems that the central cornea is not significantly involved in the process of myopic progression.International Ophthalmology 07/2008; 29(5):373-8. DOI:10.1007/s10792-008-9249-8 · 0.55 Impact Factor
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ABSTRACT: From the results of the Ocular Hypertension Treatment Study emerged the conclusion that ocular hypertensive subjects with thinner central corneal thickness (CCT) are at increased risk of developing glaucoma. Although possible underlying biases that could have led to this conclusion are still under investigation, there is an increasing interest in the scientific community to understand the potential mechanisms of this increased risk profile. It has been proposed that interindividual differences in CCT might be purely responsible for inaccuracies of the tonometric readings with potential underestimation of the true IOP in subjects with thinner CCT although it is becoming progressively clearer that the true IOP is unpredictable with linear correction formulas for CCT, and it is likely that other material properties of the cornea contribute, together with CCT, to the tonometric artifact. Recently, it has become possible to measure the biomechanical properties of the cornea in vivo and it has been suggested that differences in corneal biomechanics may be the expression of interindividual structural differences of the ocular tissues (including lamina cribrosa), with potential consequences on the interindividual susceptibility to the glaucomatous damage under the same IOP level. A possible underlying biological risk related to thinner CCTs, independent of the influence on tonometric reading, has been proposed and largely studied after the results of the OHTS were published. Besides the understanding of the mechanism underlying the role of CCT as a risk factor for the development of glaucoma, it is important to understand how the information about CCT should be integrated in the clinical management of both ocular hypertension (OHT) and glaucoma and whether other ocular properties should be measured to better understand the individual risk profile.Progress in brain research 02/2008; 173:25-30. DOI:10.1016/S0079-6123(08)01103-5 · 5.10 Impact Factor