Optical, morphological and visual implications of posterior chamber phakic refractive lens (prl) implantation for the correction of moderate to high myopia

Abstract

Phakic Refractive Lens (PRL) is one of many options for correcting moderate to high myopia. However, little has been reported on the optical and visual performance after implantation of this lens, or its impact in patients¿ quality of life. This Thesis aimed to shed some light into these aspects of lens performance. Particularly, the specific aims were: 1- To analyze the safety and efficacy indexes, in terms of visual acuity and refractive change, and the rate of complications in a long-term follow-up in patients operated of moderate to high myopia with the posterior chamber phakic refractive lens PRL. 2- To evaluate the PRL performance in terms of contrast sensitivity function (CSF) under different lighting conditions as well as with two levels of glare. 3- To study the change in higher-order aberrations after the implantation of PRL. 4- To assess the impact of PRL correction in quality of life metrics and their relationship with visual performance and optical quality. 5- To analyze the intraocular behavior of the PRL and its relationship with adjacent anatomical structures. 6- To explore the outcomes resulting from combining PRL implantation and other surgical procedures. 7- To determine the consequences of PRL decentration in terms of visual performance. Ray tracing aberrometry, contrast sensitivity function measured with the Functional Acuity Contrast Test (FACT), anterior segment optical coherence tomography (AS-OCT), ultrasound biomicroscopy (UBM) and a validated quality of life (QoL) questionnaire were used to obtain the following findings: 1- Good refractive outcomes in a medium-term follow-up, yielding high efficacy and safety index values. The complication rate was very low and there was no change in intraocular pressure (IOP) 2- Optical performance after PRL implantation under low-mesopic conditions was not as good as desirable, with a significant influence of glare on CSF, particularly for lower and medium spatial frequencies. 3- A significant increase in HOAs after PRL implantation was found for 3 and 5-mm pupil diameters, possibly resulting from the spherical design and the small optical zone diameter of the lens. 4- Optical and visual performance outcomes resulting from PRL implantation minimally affected quality of life measures. 5- Vault of the PRL was lower compared to other models of posterior chamber phakic intraocular lenses (PC-pIOLs). Difference on the horizontal vault represents the tilting of the lens which was not correlated to induction of coma-like aberration for 3-mm pupil diameter in this sample. Also, the ideal position of the haptics was obtained in a high percentage of eyes. 6- Laser in situ keratomileusis (LASIK) was an option to correct associated astigmatic errors, either before or after the implantation of a PRL. 7- Spontaneous PRL decentration was not necessarily associated with a visual quality loss and an uncorrect selection of the lens size.