Study On The Design And The Performance Of Intraocular Lenses Based On Individual Eye Models

Intraocular lens (IOL) implantation is the most effective treatment for cataract patient at present. With the improvement of surgical technique and the application of the advanced instruments, postoperative visual quality is expected to be better, such as excellent vision and extended depth of focus (DOF). Consequently, it is important to design new IOLs to obtain better optical quality. Moreover, with the traditional methods, the IOL power calculated for the eye undergoing corneal refractive surgery is notoriously inaccurate. Therefore, it is important to design IOL accurately for the eye after corneal refractive surgery in Optometry.Phakic intraocular lens (PIOL) implantation becomes an interesting technology of vision correction recently for the advantages, such as accommodation retained, minor injury, excellent accuracy and reversibility. However, there are only PIOLs for lower order aberration correction in clinic, and so it is necessary to design new PIOLs to correct other aberrations.Based on individual pseudophakic eye model and the technology of ocular wavefront aberrations, some new IOLs and PIOLs are designed in this research, and the main contents are as following:(1) An achromatic free-form IOL is designed firstly to correct monochromatic aberrations and chromatic aberration. The individual pseudophakic eye model is constructed with the measured corneal topography data and the eye's axial lengths, and some individual IOLs are designed based on the constructed eye model, including a biconvex IOL, a spherocylindrical IOL, an aspherical IOL, a free-form IOL and a chromatic free-form IOL. It is shown that the free-form IOL can offer better optical performance than aspherical IOL, and the more the corneal higher order aberrations (HOAs) are, the more the improvement. The achromatic free-form IOL provides a much better optical performance under photopic condition than the free-form IOL. If the HOAs are uncorrected, the correction of the chromatic aberration plays a little role in the improvement of the optical quality in white light, because the HOAs are relatively large for general pseudophakic eyes.(2) An achromatic spherocylindrical PIOL is designed firstly. The optical structure of nature crystalline lens is obtained by Zemax with the measured corneal topography data, the eye's axial lengths and ocular wavefront aberrations, and then the individual eye model is constructed. Based on this eye model, a spherocylindrical PIOL and an achromatic spherocylindrical PIOL are designed. It is shown that for the eye with little ocular HOAs, compared with spherocylindrical PIOL, the achromatic spherocylindrical PIOL can improve the white light modulation transfer function significantly.(3) The IOL power for the eye after corneal refractive surgery is calculated firstly with the individual eye model. The individual eye model is constructed with the individual eye model before the surgery and the ocular wavefront aberrations after the surgery, and then the spherical IOL is designed with the established eye model. It is shown that the IOL power acquired with this method is more accurate.(4) Eye model is firstly used to design an aspherical IOL with extended DOF, a refractive multifocal IOL and a diffractive multifocal IOL, and then based on the multi-configuration in Zemax, the optical performance of the eye with multifocal IOL is assessed by analyzing the optical performance at distant and near focus respectively. It is shown that the pseudophakic eye with aspherical IOL achieves larger DOF and reasonable visual acuity, when appropriate spherical aberration is introduced. In photopic condition, the pseudophakic eye with refractive or diffractive multifocal IOL achieves good near and distant vision, but a worse intermediate vision. For the refractive multifocal IOL, the light proportion going to each of the focal points differs over the pupil size. For the diffractive multifocal IOL, the light proportion is relatively constant, but 19% of the input light wastes.