瞳孔扩张过程中不同解剖和生理因素对虹膜轮廓和前房角变化的影响：理论分析。
Contribution of different anatomical and physiologic factors to iris contour and anterior chamber angle changes during pupil dilation: theoretical analysis.
机构信息
Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455, USA.
出版信息
Invest Ophthalmol Vis Sci. 2013 Apr 26;54(4):2977-84. doi: 10.1167/iovs.12-10748.
PURPOSE
To investigate the contribution of three anatomical and physiologic factors (dilator thickness, dynamic pupillary block, and iris compressibility) to changes in iris configuration and anterior chamber angle during pupil dilation.
METHODS
A MATHEMATICAL MODEL OF THE ANTERIOR SEGMENT BASED ON THE AVERAGE VALUES OF OCULAR DIMENSIONS WAS DEVELOPED TO SIMULATE PUPIL DILATION. TO CHANGE THE PUPIL DIAMETER FROM 3.0 TO 5.4 MM IN 10 SECONDS, ACTIVE DILATOR CONTRACTION WAS APPLIED BY IMPOSING STRESS IN THE DILATOR REGION. THREE SETS OF PARAMETERS WERE VARIED IN THE SIMULATIONS: (1) a thin (4 μm, 1% of full thickness) versus a thick dilator (covering the full thickness iris) to quantify the effects of dilator anatomy, (2) in the presence (+PB) versus absence of pupillary block (-PB) to quantify the effect of dynamic motion of aqueous humor from the posterior to the anterior chamber, and (3) a compressible versus an incompressible iris to quantify the effects of iris volume change. Changes in the apparent iris-lens contact and angle open distance (AOD500) were calculated for each case.
RESULTS
The thin case predicted a significant increase (average 700%) in iris curvature compared with the thick case (average 70%), showing that the anatomy of dilator plays an important role in iris deformation during dilation. In the presence of pupillary block (+PB), AOD500 decreased 25% and 36% for the compressible and incompressible iris, respectively.
CONCLUSIONS
Iris bowing during dilation was driven primarily by posterior location of the dilator muscle and by dynamic pupillary block, but the effect of pupillary block was not as large as that of the dilator anatomy according to the quantified values of AOD500. Incompressibility of the iris, in contrast, had a relatively small effect on iris curvature but a large effect on AOD500; thus, we conclude that all three effects are important.
目的
研究三个解剖学和生理学因素（扩瞳器厚度、动态瞳孔阻滞和虹膜可压缩性）对瞳孔扩张过程中虹膜形态和前房角变化的影响。
方法
建立了基于眼尺寸平均值的前节数学模型，以模拟瞳孔扩张。为了在 10 秒内将瞳孔直径从 3.0 毫米增加到 5.4 毫米，在扩瞳器区域施加应力以实现主动扩瞳器收缩。在模拟中改变了三组参数：（1）薄（4μm，占整个扩瞳器厚度的 1%）与厚扩瞳器（覆盖整个虹膜厚度），以量化扩瞳器解剖结构的影响；（2）存在（+PB）与不存在瞳孔阻滞（-PB），以量化房水从后房向眼前房的动态运动的影响；（3）可压缩与不可压缩虹膜，以量化虹膜容积变化的影响。计算了每种情况下的可见虹膜-晶状体接触和角度开放距离（AOD500）的变化。
结果
薄的情况下预测虹膜曲率显著增加（平均 700%），与厚的情况下（平均 70%）相比，表明扩瞳器的解剖结构在扩张过程中对虹膜变形起着重要作用。存在瞳孔阻滞（+PB）时，可压缩和不可压缩虹膜的 AOD500 分别减少了 25%和 36%。
结论
瞳孔扩张时的虹膜弯曲主要由扩瞳器肌肉的后位和动态瞳孔阻滞驱动，但根据 AOD500 的量化值，瞳孔阻滞的影响不如扩瞳器解剖结构的影响大。相比之下，虹膜的不可压缩性对虹膜曲率的影响相对较小，但对 AOD500 的影响较大；因此，我们得出结论，这三个因素都很重要。
Zotero 插件