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| Correlation between Differences of Central and Peripheral Corneal Thickness and Corneal Biomechanics |
| Jing Li 1, Ying Xiong 1, Jianying Liu 1, Xiuhua Wan 1, Ningli Wang 2 |
| 1Beijing Tongren Eye Center, Beijing Tongren Hospital of Capital Medical University, Beijing 100730, China 2Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital of Capital Medical University, Beijing 100005, China |
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Abstract Objective: To investigate the effect of the thickness difference between central and peripheral cornea on the biomechanical properties of cornea. Methods: In this retrospective case series study, population ata measured in Handan Eye Hospital in Handan Eye Study from October 2006 to October 2007 were reviewed, 336 eyes were included. Orbscan II was used to measure the central corneal thickness (CCT), the thinnest point of cornea (TCP) and the corneal thickness of temporal, upper, nasal and lower parts at 3, 4, 5, 6, 7 mm; the corneal thickness index (CTI), which reflects the difference between the central and peripheral thicknesses of the cornea, was obtained by calculating the ratio of the corneal thickness to the central thickness in the average 3, 4, 5, 6, 7 mm area. Corneal hysteresis (CH) and corneal resistance factor (CRF) were measured by ocular response analyzer (ORA); Pearson or Spearman correlation were used to analyze the correlation between CH、CRF and corneal thickness and age. Independent sample t-test was used to determine the difference of CH and CRF between the two groups of which the 7 mm CTI is located at the maximum 5% and minimum 5% at both ends of the overall distribution. Results: There was a negative correlation between 4, 5, 6, 7 mm corneal thickness and age (r=-0.15, P=0.003; r=-0.23, P<0.001; r=-0.33, P<0.001; r=-0.41, P<0.001) and the correlation increases gradually; the thinnest point, central corneal thickness and corneal thickness at 3 mm were not correlated with age. Five, 6, 7 mm CTI was negatively correlated with age (r=-0.18, P=0.001; r=-0.27, P<0.001; r=-0.27, P<0.001); There was no correlation between 3, 4 mm CTI and age. There was no significant correlation between CH and age and CRF was negatively correlated with age (r=-0.15, P=0.006). CH was negatively correlated with 3, 4, 5, 6 mm CTI (r=-0.13, P=0.023; r=-0.14, P=0.010; r=-0.15, P=0.008; r=-0.13, P=0.019), CRF was negatively correlated with 3, 4, 5, 6 mm CTI (r=-0.21, P<0.001; r=-0.24, P<0.001; r=-0.26, P<0.001; r=-0.16, P=0.005). There was significant difference in CH and CRF between the two groups of which the 7 mm CTI was located at the maximum 5% and minimum 5% at both ends of the overall distribution (t=2.93, P=0.006; t=2.78, P=0.009). Conclusion: With the increase of age, the central corneal thickness remains unchanged while the peripheral corneal thickness decreases significantly in healthy people. The cornea with great difference between central and peripheral thickness may have the risk of the decreased ability to resist intraocular pressure and external force.
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Received: 05 March 2022
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Corresponding Authors:
Xiuhua Wan, Beijing Tongren Eye Center, Beijing Tongren Hospital of Capital Medical University, Beijing 100730, China (Email: wanxh@ccmu.edu.cn)
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