Central corneal thickness and its relationship to myopia in Chinese adults

Abstract

Aim: To investigate the association between central corneal thickness (CCT) and the degree of myopia among Chinese. Methods: In this prospective observational study, 714 consecutive patients were recruited from a refractive surgery clinic. CCT was measured in both eyes of each patient using the Orbscan (Bausch and Lomb, Rochester, New York, USA), and data of the right eye were selected for analysis. CCT was correlated with the degree of myopia in dioptres (D) using Pearson's correlation coefficient and Dunnett's t test with multiple comparisons. Results: The age of the patients ranged from 15 to 59 years. The mean CCT was 534.5 mm, with a standard deviation (SD) of 38.1 (range 305-684) mm. M yopia is increasing in prevalence among the populations of East Asian origin. Estimates of the proportion of myopia in the young population of Singapore range from 30% to 65%, 1 2 and the prevalence was found to be greater among the Chinese, 3 4 and to increase with higher educational achievements.3 4 With increasing rates of myopia, refractive surgery such as laser in situ keratomileusis (LASIK) has become popular in Asia. When undertaking such surgery to correct myopia, central corneal thickness (CCT) is an important consideration to prevent the cornea from becoming too thin after treatment.Studies that have attempted to investigate the effect of refractive errors on CCT have reported conflicting results. One report showed no correlation between corneal thickness and the level of myopia, 5 whereas another study found the cornea to be thinner in more myopic eyes. 6 The two studies used different techniques of measuring CCT and there was some variability in the study population. The aim of this study was to prospectively investigate the relationship between CCT and the degree of myopia in a large sample of Asian adults with myopia who were being assessed for refractive surgery. METHODSPatients consisted of 714 consecutive ethnic Chinese refractive surgery candidates who presented at a refractive surgery clinic for LASIK assessment. The institutional review board provided approval for the protocol of this study and written informed consent was obtained from all patients. Exclusion criteria were previous ocular surgery, ocular pathology such as keratoconus or glaucoma, or recent contact lens wear in the previous 2 weeks.Manifest refraction and CCT measurements with the Orbscan II (Bausch and Lomb, Rochester, New York, USA) were carried out on both eyes of all the patients. Only data from the right eyes were used in the analysis. Pearson correlation analysis was carried out to examine the relationship between the degree of myopia and CCT. The Dunnett t test (two-sided) multiple comparisons were used to compare CCT among the classes of myopes, such as 0 to -4 D, 24 to -8 D and .-8 D, with the last group being used as the test group. A similar comparison was made of the degree of myopia among CCT groups, such as those ,500 mm, 500-550 mm, 550-600 mm and .600 mm. Data were analysed using SPSS V.11.0, and significance was assumed a...

Association between corneal biomechanical properties and myopia in Chinese subjects

“…Several studies have reported the associations between the refractive error and corneal properties, but are still under debate. 8,9 Chang et al 8 demonstrated an association between the refractive error and corneal dimensions and function in Chinese subjects using the ultrasonic pachymeter. In contrast, Fam et al 9 reported that CCT measured by the Orbscan II pachymeter had no correlation with myopia in Chinese adults.…”

Distribution and Trends in Corneal Thickness Parameters in a Large Population-Based Multicenter Study of Young Chinese Adults

“…may be the main cause of the difference in the biological parameters of the eyes in different regions. [27][28][29] A limitation of our study is that we did not study the corneal thickness of eyes with different diopters or compare eyes between male and female sexes; previous studies have shown that corneal thickness is independent of diopter and sex: there was no significant difference in central corneal thickness between emmetropic and ametropic eyes, 30 among eyes with different diopters, 31,32 or between men and women. 23 Based on these prior research results, we expect that our data should Possessing normal values for corneal thickness-related parameters in the Chinese population will aid in accurate diagnoses of early keratoconus, suspected keratoconus, and other diseases.…”

The relation between central corneal thickness, axial length and myopia among a sample of patients in Erbil

“…This finding agrees with the most of the earlier studies. [12][13][14][15][16][17][18][19][20][21][22] According to such findings, we consider that if the stretching process is actually active, the thinning is likely to be restricted only to the sclera and the cornea is not involved. The current study has the limitation that we measured CCT in the morning and there are studies that investigated the diurnal changes of corneal thickness with various techniques.…”

“…7 Others have found that CCT is thinner in myopic eyes, [8][9][10][11] while some studies have reported no association between central corneal thickness and degree of myopia. [12][13][14][15][16][17][18][19][20][21][22] The results of this study will help the refractive surgeons how to evaluate and choose the type of the refractive surgeries like the laser in situ keratomileusis and photorefractive keratectomy for myopic patients and to assess the risk of postoperative complications. The purpose of this study was to determine the correlation between central corneal thickness, axial length and myopia.…”