渐变多焦镜与非渐变镜配戴者阅读前后脑血流速度的比较

<TITLE>THE EFFECT OF PALS ON CELEBRAL BLOOD SUPPLY OF PRESBYOPES DURING READING

目的利用经颅多普勒超声技术,测定老视人群脑血流动力学指标,探讨配戴渐变多焦镜阅读时老视者脑血供的可能变化。方法测定有两年以上渐变多焦镜配戴史的老视者(渐变镜组)阅读前及阅读后1小时的脑血流速度(包括颈内动脉系和椎基底动脉系的收缩峰及舒张峰血流速度),并与无渐变多焦镜配戴史的老视者(非渐变镜组)做对照,比较两组阅读前后的血流速度差值,是否存在差异,从而探讨不同的镜片设计对配戴者阅读时脑血流量的影响。结果比较两组在阅读前脑血流速度值(包括颈内动脉系和椎基底动脉系的收缩峰及舒张峰血流速度)无统计学意义(P>0.05);经阅读1小时后,两组的椎基底动脉系阅读前后血流速度差值有统计学意义(P<0.01)。结论非渐变镜配戴者由于阅读时保持了头部过屈的相对固定体位,长时间阅读可导致椎基底动脉系的收缩期血流速度降低。随着年龄的增加,脑自身调节功能下降,将可能造成椎基底动脉供血不足。而对于配戴渐变镜的老视者,由于镜片视近区的存在,改变了阅读体位,去除了造成椎基底动脉血流速度降低的危险因素,从而可在一定程度上改善老视者脑血供。

Objective To monitor the cerebral hemodynamic index of presbyopia people using the Transcranial Doppler （TCD） and to explore the possible changes in cerebral blood supply of presbyopia people as a result of wearing Progressive Addition Lenses （PALs）, Methods Measured the cerebral bloodstream velocity of subjects （PALs group）who have worn PALs for more than two years, one hour prior to and after the reading task respectively. Compared the results randomly with that of subjects （non-PALs group） who have worn single vision lenses for presbyobia, in order to study the effect of these two types of lenses on the amount of cerebral bloodstream, Results Difference between two groups in bloodstream velocity（including the internal carotid arteries system and the verterbral-basilar arteries system） prior to the reading task was insignificant（/） 〉 0.05）, There was significant difference in the verterbral-basilar arteries system between results measured prior to and after the reading task. Conclusions Due to the declining self adjustment function of the brain as a result of the aging process, over hending the head resulted from reading using the single vision lenses for presbyopia may lead to insufficient blood supply in the vertebral-basillar artery. Wearing PALs during the reading task, which have the near zone, helps improve the cerehral blood supply of preshyopia people by altering the body position and avoiding the risk of reducing the bloodstream velocity of the verterbral-basilar arteries system.