Evaluation of the optical design and performance of translating-optics accommodating intraocular lenses

Implantation of an intraocular lens (IOL) has become a standard procedure for vision correction following cataract surgery. Continually rising demand for perfect long-term post-operative vision has led to a proliferation of novel IOL designs. Though a standard monofocal or single-vision IOL affords near perfect vision for a fixed viewing distance, a patient may yet require supplementary optical devices for comfortable near vision.The quest for restoration of accommodative ability in pseudophakic eyes have led to number of advancement in the technology including the development of accommodating intraocular lenses. Translating-optics accommodating intraocular lenses is a rapidly emerging class of implant devices which has debatably gained increasing popularity among scientists and practitioners within a short period of time. A large variety of accommodating intraocular lenses, prominently represented by single-element and two-element designs, has been proposed. These devices work under the principle of changing effective power by shifting axial position of the optical element within the eye which is brought about by complex opto-mechanical arrangements.Earlier studies on accommodating intraocular lenses are primarily focused on their accommodative capacity. A comprehensive theoretical design analysis and evaluation of their performance is lacking. Virtually no report exists investigating other important aspects of their optical performance such as magnification, aberrations and optimization of retinal image quality. This thesis, using paraxial optical principles, undertakes a systematic development of the optical principles involved in the evaluation of design and performance of translating optics accommodating intraocular lenses and applies the results to seek superior performance.In the thesis, it is demonstrated that an appropriate design of accommodating intraocular lens may enhance performance overcoming a long-standing unmet visual need of pseudophakic presbyopia. A two-element accommodating intraocular lens has been found to afford greater accommodative amplitude compared to a single element accommodating intraocular lens. It is also shown that a wide range of accommodating intraocular lens designs may effectively eliminate or control several on and off-axis aberrations and optimize the retinal image quality. Dynamic magnification induced due to pseudophakic accommodation is one of the important issues identified. The power combination of lens elements in two-element accommodating intraocular lens designs requires special attention prior to implantation to avoid potential dynamic anisometropia and dynamic aniseikonia.Finally, while two-element accommodating intraocular lenses offer a potentially promising answer to post-cataract surgical presbyopia, further work is recommended particularly in understanding the mechanics of accommodation, the causes of presbyopia and to develop improved optical materials and mechanical designs to maximize translation and provide robust peripheral structures that may withstand mechanical strain arising from the numerous continuous accommodative cycle and also to resist long-term biological changes