Visual quality through different monofocal intraocular lenses in patients with different corneal profiles using adaptive opticsimpact of tilt and decentration

Resumen

The available intraocular lenses (IOLs) in the market present classical spherical and aspheric designs. These aspheric models are designed to compensate the averaged spherical aberration (SA) of the cornea of the population and then improving visual quality of patients. However, corneal refractive surgery has become a common procedure among surgeons and the public and it is well documented that corneal refractive surgeries provoke changes in corneal shape and then in the amount of corneal SA. Then, if one takes in consideration the available designs of IOLs and the changes that corneal refractive surgery provokes, it should be interesting to know which are the current designs of IOLs good enough to provide an optimal visual quality in patients with different corneal profile (that is, virgin corneas, and corneas with prior corneal refractive surgery for both myopia and hyperopia correction). To properly assess the benefits of one design of IOL over the others in patients with different corneal profiles, it would be interesting to analyze the visual performance provided by each one of the different designs in the same patient under the same conditions. Considering that, it is not possible to submit one patient to different surgeries, an adaptive optics (AO) visual simulator can be used to simulate the wavefront pattern of different IOLs designs and different corneal profiles to analyse visual quality differences among IOLs in the same patient without the need of surgery. The lens design is an important issue for patients to achieve good visual quality after cataract surgery, but some aspects as centration or tilt of the IOL are also important. However, there are no previous studies that have assessed the impact of tilt and decentration of different designs of IOLs on the visual quality on the same patient. Therefore, three studies of visual quality through different IOLs with different corneal profiles using AO visual simulation are described in this Thesis. The aim of the first study (chapter 2) was to analyse visual quality differences among four IOLs through VA and depth-of-focus measurement in patients with virgin corneas (without any corneal refractive surgery). Different degrees of decentration and tilt were induced to properly assess their effect on visual quality. The results of this study showed that for averaged corneas when the IOLs are centered, the aberration-correcting and spherical IOLs studied provided a comparable visual quality when they are centered. At the same time, tilt and decentration of the IOL have an impact on visual quality of the patients, being higher the impact with the aberrations-correcting IOLs than with the aberrations-free and the spherical IOLs. Chapter 3 analysed the visual quality differences among different IOLs through VA and depth-of-focus measurements in patients with prior myopic laser ablation for low and high myopia correction. At the same time, different degrees of decentration and tilt were induced to properly assess their effect on visual quality. In this chapter, it is shown that for this profile of patients the aberration-correcting IOLs provided better results than the other IOLs studied (aberration-free and spherical designs) when they were centered and when they were misaligned, this lens provided a visual quality comparable to the other designs. Chapter 4 analysed the same parameters than those studied in chapter 3 with two spherical designs of different amount of SA and one aberration-correcting aspheric design, but low and high hyperopic ablations were considered. In this chapter, it is shown that for this profile of patients all the lenses studied provided comparable visual quality results when they were centered. However, the results were better for low hyperopic ablations than for high hyperopic ablations. Within the IOLs studied and for this profile of patients, the spherical design with the higher amount of positive SA seems to be more robust to misalignments than the other designs. The depth-of-focus results obtained through the different chapters suggest that some residual SA may help for obtaining a higher depth-of-focus, however, over a certain amount of SA the visual quality decreases considerably and then, the depth-of-focus decreases too. All these results are reviewed in chapters 5 and 6 and future studies are proposed.