Chen Zhi, Zhou Jiaqi, Xue Feng, Zhou Xingtao, Qu Xiaomei
Department of Ophthalmology and Vision Science, Eye and ENT Hospital, Fudan University, Shanghai, China.
NHC Key Laboratory of Myopia, Fudan University, Shanghai, China.
J Ophthalmol. 2018 Oct 23;2018:7106028. doi: 10.1155/2018/7106028. eCollection 2018.
To investigate the change in corneal toricity and associated refractive astigmatism after discontinuation of long-term orthokeratology (ortho-k) lens wear.
This study investigated 136 subjects aged between 6 and 14 (9.1 ± 1.5) years old at the commencement of ortho-k treatment, who had been undergoing overnight ortho-k treatment for 24 to 72 (37.4 ± 11.9) months. Corneal refractive power and manifest refraction were measured and compared before ortho-k and 1 month after discontinuation of ortho-k lens wear. Changes in corneal curvature were analyzed. Corneal curvature data from a historical longitudinal study were used as control.
Compared to pre-ortho-k values, the corneal curvature became significantly flatter in the flatter meridian (-0.22 ± 0.27 D, < 0.001) and steeper in the steeper meridian (0.06 ± 0.34 D, =0.032) after cessation of ortho-k lens wear, resulting in a significant increase in corneal toricity (0.28 ± 0.43 D, < 0.001), which is associated with an increase in refractive astigmatism (0.57 ± 0.57 D, =0.465, < 0.001). The amount of residual corneal flattening in the flatter meridian is significantly affected by the length of ortho-k treatment (=-2.965, =0.004) and the baseline age of subject (=-2.841, =0.005), but not by the baseline spherical or cylindrical refractive error (both > 0.05). In the historical control group, there is no significant change in the corneal curvature over two years in children wearing spectacle lenses (both meridians, > 0.05). Change of corneal toricity was more significant in the ortho-k group than in the spectacle control group (=0.001).
Long-term ortho-k lens wear increases corneal toricity after discontinuation of the treatment, which is associated with an increase in refractive astigmatism. A more pronounced change in corneal toricity was found in subjects who were younger to start ortho-k and have been in a longer period of treatment. This trial is registered with http://www.chictr.org.cn (ChiCTR-TNRC-11001210).
研究长期角膜塑形术（ortho-k）停戴后角膜曲率及相关屈光性散光的变化。
本研究纳入了136名在角膜塑形术治疗开始时年龄在6至14岁（9.1±1.5岁）之间的受试者，他们接受过夜角膜塑形术治疗24至72个月（37.4±11.9个月）。测量并比较角膜塑形术前及停戴角膜塑形镜1个月后的角膜屈光力和显验光。分析角膜曲率的变化。将一项历史纵向研究中的角膜曲率数据作为对照。
与角膜塑形术前的值相比，停戴角膜塑形镜后，角膜曲率较平的子午线变平更为显著（-0.22±0.27D，P<0.001），较陡的子午线变陡（0.06±0.34D，P=0.032），导致角膜散光显著增加（0.28±0.43D，P<0.001），这与屈光性散光增加有关（0.57±0.57D，P=0.465，P<0.001）。较平子午线的残余角膜平坦量受角膜塑形术治疗时长（P=-2.965，P=0.004）和受试者基线年龄（P=-2.841，P=0.005）的显著影响，但不受基线球镜或柱镜屈光不正的影响（两者P>0.05）。在历史对照组中，佩戴框架眼镜的儿童两年内角膜曲率无显著变化（两个子午线，P>0.05）。角膜塑形镜组的角膜散光变化比框架眼镜对照组更显著（P=0.001）。
长期角膜塑形镜佩戴在停戴后会增加角膜散光，这与屈光性散光增加有关。在开始角膜塑形术时年龄较小且治疗时间较长的受试者中发现角膜散光变化更为明显。本试验已在http://www.chictr.org.cn注册（ChiCTR-TNRC-11001210）。
