白癜风治疗最好医院 http://m.39.net/pf/a_5291113.htmlAlongheldbeliefisthatmyopiamaydevelopduetotheeye’semmetropizationresponsetoinherentocularaberrationsthatdegraderetinalimagequalityandtriggeraxialelongation.Sincethereisminimalvariationinlongitudinalchromaticaberrationbetweenindividualsorrefractiveerrorgroupsinhumans,mostinvestigationshavefocusedonmonochromatichigherorderaberrations(HOAs)asapotentialmyopigenicstimulus.EvidenceconcerningtherelationshipbetweenHOAsduringdistanceviewingandrefractiveerrorfromcross-sectionalstudiesisconflicting.However,duringorfollowingnearworktasks,adultmyopiceyestendtodisplayatransientincreaseincornealandtotalocularHOAs(Figs.4.8and4.9),suggestingapotentialrolefornearworkinducedretinalimagedegrada-tioninmyopiadevelopment.Longitudinalstudiesofmyopicchildrenalsoindicatethateyeswithgreaterpositivesphericalaberrationdemonstrateslowereyegrowth.长期以来，人们一直认为近视可能是由于眼睛对眼固有像差进行正视反应而引起的，因为这种眼内像差会降低视网膜图像质量并触发轴向伸长。由于人类个体或屈光不正组之间的纵向色差变化很小，因此大多数研究把单色高阶像差（HOA）作为潜在的近视成因刺激因素进行研究。横截面研究中关于视觉距离的HOAs和屈光不正之间关系的证据是相互矛盾的，但是，在近距离工作过程中或之后，成人近视眼往往会表现出短暂的角膜和全眼HOA增高（图4.8和4.9），提示近距离工作引起的视网膜图像质量下降在近视发展中具有潜在的作用。对近视儿童的纵向研究也表明，具有较大正球差的眼睛显示眼球生长较慢。Fig.4.8Cornealrefractivepowerdifferencemapfollowinga10minreadingtaskat25°downwardgaze.Theblackcircledenotesthepupiloutlinedetectedbythevideokeratoscope.Ahorizon-talbandofcornealflatteningisobservedinthesuperioraspectofthepupilcorrespondingtothepositionoftheuppereyelidduringdownwardgaze.Thisrefractivechangeisequivalenttoa0.20Dhyperopicshiftoverthecentral4mm图4.8在向下25度注视进行10分钟阅读任务后，角膜屈光力差异图。黑色圆圈表示由视频角膜镜检测到的瞳孔轮廓。在向下注视期间，在瞳孔的上方观察到了角膜平坦的水平带，对应于上眼睑的位置。该屈光度变化相当于在中心4mm处发生0.20D远视位移Fig.4.9Refractivepowermaps,agraphicalrepresentationoftotalocularhigherorderaberra-tions,during(a)distancefixation(0Dac
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