衍射多焦点人工晶体的设计

Design of Diffraction Multifocal Intraocular Lens

运用ZEMAX光学设计软件构建Liou-Brennan (L-B)眼模型,设计了前表面为衍射面,后表面为非球面的三焦点人工晶体,并用球差和光学调制传递函数(MTF)分析了所设计的人工晶体的光学质量。对于所设计的人工晶体,首先介绍了非球面基底的详细设计步骤以及优化操作,随后介绍了三焦点人工晶体的设计方法,采用的设计为附加光焦度为3.32D,即三个焦点分别对应20D,21.66D,23.32D,衍射级次为0、+1、+2三个衍射级次,当物在不同位置时,使不同衍射级次发挥作用。设计结果表明,三个焦点的光学调制传递函数(MTF)在50lp/mm处均大于0.35,满足多焦点人工晶体国标设计要求。衍射光学元件的加入使人工晶体满足白内障患者视远、视中、视近的需求,非球面的设计实现了对人眼存在的正球差的校正,降低了术后眼的总球差,以获得更好的视觉效果。

The Liou-Brennan(L-B) eye model is constructed by using the optical design software Zemax. The trifocal intraocular lens with diffractive surface on the anterior surface and aspheric surface on the anterior surface are included in the design; and the optical quality of the designed intraocular lens is analyzed by spherical aberration and optical modulation transfer function(MTF). For the design of the intraocular lens,firstly,the detailed design steps and optimization of aspheric substrates are introduced,and then the design method of the trifocal intraocular lens is introduced.The light can be distributed as evenly as possible in the three focuses under light conditions through the design of trifocal intraocular lens. In this paper,the additional optical power of the design is 3.32 D,the three focal points correspond to 20 D,21.66 D,23.32 D respectively,diffractive order is 0,+1,+2 respectively. So when the object is in different positions,the different diffraction orders play a different role. The design results show that the optical modulation transfer function(MTF) for all three focuses is over 0.35 at 50 lp/mm and meet the multi-focus IOL design requirements.The addition of diffractive optics allows the intraocular lens to meet the needs of patients with cataract,and the design of aspheric is to achieve the existence of the correction of the spherical aberration in human eyes. This design can reduce the total spherical aberration after surgery and obtain better visual effects.