Laboratory of Vision Sciences and Applications, University of Granada, Spain. aixaalarcon.ugr.es
J Refract Surg. 2011 Nov;27(11):833-6. doi: 10.3928/1081597X-20111005-02.
To evaluate the visual quality of two theoretical multifocal corneal models designed to correct presbyopia by corneal photoablation.
Two theoretical multifocal corneal surfaces were analyzed by ray tracing: a central model (with a central zone for near vision and a peripheral zone for distance vision), and a peripheral model (with a central zone for distance vision and a peripheral zone for near vision). For both models, the effect of the size of the central zone and transition zone as well as the size of the pupil was evaluated.
Our results show that a smaller transition zone favors total visual quality in both models. The optimal size of the central zone depends both on the size of the transition zone used as well as the model. However, both models responded similarly with respect to the variations in pupil size, providing the same visual quality although in an opposite way.
This work shows that the optimal diameter of the central zone is smaller for the central model than for the peripheral model. Also, pupil size plays a fundamental role in achieving multifocality, showing that patient's pupil size should be thoroughly evaluated prior to multifocal refractive surgery.
评估两种通过角膜光蚀矫正老视的理论性多焦点角膜模型的视觉质量。
通过光线追踪分析了两种理论性多焦点角膜表面：中央模型（用于近视力的中央区和用于远视力的周边区）和周边模型（用于远视力的中央区和用于近视力的周边区）。对于这两种模型，评估了中央区和过渡区的大小以及瞳孔大小的影响。
我们的结果表明，较小的过渡区有利于两种模型的总视觉质量。中央区的最佳尺寸既取决于所用过渡区的尺寸，也取决于模型。然而，两种模型对瞳孔大小的变化反应相似，尽管以相反的方式提供相同的视觉质量。
这项工作表明，中央模型的中央区最佳直径小于周边模型。此外，瞳孔大小在实现多焦点方面起着至关重要的作用，表明在进行多焦点屈光手术之前，应彻底评估患者的瞳孔大小。
