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Comparison of Central Corneal Thickness using Anterior Segment Optical Coherence Tomography Versus Ultrasound Pachymetry
摘要： Introduction: Corneal thickness is an important and sensitive indicator of corneal health. It is useful in monitoring corneal diseases such as corneal oedema and keratoconus, and selecting patients for refractive surgery. Central Corneal Thickness (CCT) is a risk factor for Primary Open-Angle Glaucoma (POAG). Aim: To compare CCT using ultrasound pachymetry and Anterior Segment Optical Coherence Tomography (AS-OCT), and also to find out the reproducibility of AS–OCT readings for both central and pericentral corneal areas. Materials and Methods: This prospective cross-sectional study was conducted on 120 patients above 40 years of age, and with clinically normal corneas, who underwent CCT measurements by both ultrasound and AS-OCT. Both the eyes were analysed. Two measurements by AS-OCT and 25 measurements by ultrasound pachymetry were taken. The readings were averaged and compared by paired t-test. Repeatability of the OCT pachymetry map sector averages, was assessed by pooled standard deviation, obtained from the two measurements taken from each eye. Results: The CCT in right eye by OCT and ultrasound was 516.28±29.76 μm and 532.42±29.71 μm, respectively. The CCT in left eye by OCT and ultrasound was 515.82±29.88 μm and 532.36±29.83 μm, respectively. The difference in CCT measurement by AS-OCT and ultrasound was statistically significant (p<0.001); mean ultrasound CCT being 16.14 μm and 16.54 μm greater than the mean AS-OCT, CCT in right eye and left eye respectively. For AS-OCT, intra-session repeatability was measured. Repeatability of the OCT mapping was 0.01 μm to 1.6 μm and 0.01 μm to 1.9 μm in the right eye and left eye respectively. Conclusion: The CCT measurement by ultrasound pachymetry gives higher values compared to AS-OCT measurement. Hence, they cannot be interchangeably used in clinical practice. The AS- OCT provides highly repeatable pachymetry map measurements both centrally and pericentrally.
关键词： Primary open-angle glaucoma,Reproducibility,2-mm pachymetry map
更新于2025-09-09 09:28:46
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Optic disc topography in Malay patients with normal-tension glaucoma and primary open-angle glaucoma
摘要： Background: There are limited data concerning the optic disc topography in normal-tension glaucoma (NTG) and primary open-angle glaucoma (POAG) patients living in Southeast Asian countries. This study aims to compare optic disc parameters in patients with NTG and POAG in Malaysia and to discuss the results in comparison with studies of NTG and POAG in other Asian countries. Methods: This prospective cross-sectional study was performed in two hospitals with glaucoma service in Malaysia from 2010 to 2012. Seventy-seven patients of Malay ethnicity were enrolled in this study, including 32 NTG patients and 45 POAG patients. Using the Heidelberg Retinal Tomograph III, we measured optic disc area, cup area, rim area, cup volume, rim volume, cup-to-disc area ratio, mean cup depth, maximum cup depth, cup shape measure, height variation contour, mean retinal nerve fiber layer thickness, and retinal nerve fiber layer cross-sectional area. Results: The eyes for NTG patients had significantly larger optic disc areas (2.65 [standard deviation, 0.41] vs 2.40 [standard deviation, 0.36] mm2, respectively; P=0.006) and cup areas (1.54 [standard deviation, 0.43] vs 1.32 [standard deviation, 0.40] mm2, respectively; P=0.027) compared with the eyes of POAG patients. Comparison of the other parameters between the two groups revealed no significant difference (P0.050). The moderate and severe NTG patients showed significantly deeper cups and larger disc and cup areas when compared with the moderate and severe POAG patients (P0.050). Conclusion: The NTG patients in this study have notably larger optic disc and cup areas than the POAG patients. Our observations are consistent with those reported in studies of NTG and POAG patients in Korea. The deeper cups and larger disc and cup areas may serve as indicators of severity when comparing NTG with POAG. However, these findings require verification with IOP and visual field results.
关键词： optic disc topography,primary open-angle glaucoma,Heidelberg Retina Topography III,Malay ethnicity,normal-tension glaucoma
更新于2025-09-04 15:30:14