Ophthalmology & Vision Sciences, University of Arizona, Tucson, Ariz 85711, USA.
J Refract Surg. 2010 Jan;26(1):66-70. doi: 10.3928/1081597X-20101215-11.
To predict the potential clinical visual acuity of different presbyopia treatments.
The defocus transfer function (DTF) is a mathematical technique for simultaneously illustrating the optical transfer function for all levels of defocus. Through-focus clinical visual acuity measurements were superimposed onto the DTF to determine the corresponding retinal contrast and map out a modulation threshold curve. The process is performed for an apodized diffractive and a zonal refractive intraocular lens, as well as an opaque annular ring implant that extends depth of focus.
Clinical visual acuity measurements appear to track contours on the DTF. The elevation of these contours changes as a function of spatial frequency, with the general trend being that for higher spatial frequencies, more retinal contrast is needed to achieve a given level of visual acuity. The presence of these contours suggests a minimum level of retinal contrast is needed to achieve a given visual acuity, and if this threshold is exceeded, the presbyopia treatment can provide the corresponding acuity clinically.
The DTF provides a global view of ocular performance for all object distances. The disparate technologies investigated all gave similar modulation threshold curves. These results suggest that the modulation threshold curve can be used to predict potential visual acuity of other multifocal lens designs and methods for treating presbyopia.
预测不同老视治疗方法的潜在临床视力。
离焦传递函数（DTF）是一种同时说明所有离焦水平的光学传递函数的数学技术。通过将焦点临床视力测量值叠加到 DTF 上，确定相应的视网膜对比度并绘制调制阈值曲线。该过程针对渐变分散衍射和区域折射眼内透镜以及扩展景深的不透明环形植入物进行。
临床视力测量值似乎与 DTF 上的轮廓相吻合。这些轮廓的升高随空间频率而变化，一般趋势是对于较高的空间频率，需要更高的视网膜对比度才能达到给定的视力水平。这些轮廓的存在表明，达到给定的视力需要最低限度的视网膜对比度，如果超过这个阈值，老视治疗就可以在临床上提供相应的视力。
DTF 为所有目标距离的眼部性能提供了全局视图。所研究的不同技术都给出了相似的调制阈值曲线。这些结果表明，调制阈值曲线可用于预测其他多焦点透镜设计和治疗老视的方法的潜在视力。
