Effect of Different Corneal Curvature on Corrected Power of Conductive Keratoplasty
Introduction Conductive Keratoplasty (CK) induce refractive change of cornea by peripheral deformation1. The predictability of CK is still unsatisfactory, partly due to wound-healing response and refractive regression2. Because the same surgery operation was performed on corneas of different curvature3,4,5,6, we infer that different curvature of cornea may be one of the reasons for diverse surgery results. In this paper, the effect of different curvature of cornea on corrected power of conductive keratoplasty was evaluated.Methods Mathematical analysis was done on the assumption that front surface of deformation zone of cornea is spherical before and after surgery, back surface of cornea is stable before and after surgery. Results After surgical deformation, relative change of refractive power of front surface of cornea △φ/φ=(R-r)/r=△R/h, where R is curvature radius of front surface of cornea before surgery, r is that after surgery,R is the deformation of cornea at location of surgical operation, h is the difference of height between apex of cornea and location of surgical operation. Absolute change of refractive power of cornea △φ≈-2(n-1)△R/L2, where n is refractive index of cornea, L is the distance from the location of surgical operation to the axis of cornea. Calculation by the above formula with operation values of actual surgery shows that the absolute theoretical errors will be less than 0.1 diopter. Thus, refractive power change of cornea induced by peripheral deformation has linearity relationship with deformation and change rapidly with surgery location, but it is almost stable with different curvature of cornea.Conclusion Both deformation and surgery location are parameters related to surgery response, surgery regression and surgery operation. Hence, different surgery response, surgery regression and unsatisfactory precision of surgery operation are main causes for unsatisfactory predictability of such surgery.New work to be presented Theoretical analysis shows that different curvature of cornea has little effect on corrected power of conductive keratoplasty.
conductive keratoplasty curvature refractive power cornea
Xiaobing WANG Jing ZHANG Aizhen LIU Yanjun ZENG Yuhua Peng
Beijing Tongren Hospital, Capital University of Medical Sciences Beijing 100730,China School of Biomedical Engineering, Capital University of Medical Sciences, Beijing 100069, China Beijing University of Technology, Beijing 100022,China Department of Biomedical Engineering, Beijing Institute of Technology, Beijing 100081, China
国际会议
北京
英文
1170-1173
2007-05-23（万方平台首次上网日期，不代表论文的发表时间）