Visual performance and adaptation to light disturbances in pseudophakic patients implanted with multifocal intraocular devices for presbyopia correction

Resumo

Background and Purpose: Cataract surgery has evolved tremendously in the last 20 years motivated by significant advances in the instrumentation assisting the procedure and more recently the advances in intraocular devices to compensate the lack of accommodation of the human eye after crystalline lens removal. It is particularly relevant to highlight the advances in multifocal devices comprising complex optical designs based on refractive and/or diffractive designs. Despite these devices provide a certain independency of other optical compensation to provide functional vision at different distances, there are significant drawbacks in terms of symptoms of loss of contrast and increased light distortions under dim illumination. Indeed, such symptoms are the main cause of explantation which is an undesirable outcome. Having a significant clinical and socioeconomic impact, there is a vast literature in peerreview journals and book chapters on the topic, but most of this information has been gathered using different methodologies what limits the ability to compare study outcomes. Standardization of procedures is even more necessary now that devices with novel optical designs are delivered to the market every year. Therefore, the main goals of this project were 1) to develop a comprehensive routine to evaluate visual performance and to quantify objectively and subjectively the complaints of light disturbances in pseudophakic patients implanted with different devices and 2) to quantify the potential adaptation process that occurs in the short- to medium-term after surgery in clear lens and cataract patients. Subjects, Materials and Methods: The clinical measures were obtained at Hospital da Luz in Lisbon, between April 2015 to September 2016, with the collaboration of the Clinical and Experimental Optometry Research Laboratory (CEORLab) at University of Minho in Braga, both institutions in Portugal. In agreement with the Declaration of Helsinki, the protocol of the study was reviewed and approved by the Ethics Committee of the Hospital da Luz (Lisbon, Portugal). Though other monofocal IOLs will be covered in the thesis, the main focus of the project was the evaluation of the following multifocal devices: The lenses were FineVision® Pod F (PhysIOL, Liège, BE), AcrySof® IQ PanOptixTM (TFNT00) (Alcon Laboratories, Fort Worth, Texas, USA) and EDoF TECNIS® Symfony model ZXR00 (Abbott Medical Optics, Santa Ana, USA). In retrospective studies, measures were obtained after 3 to 8 months after surgery while in the prospective studies pre-operative (only in the case of clear lens) and after surgery at 1, 3 and 6 months were obtained. After uneventful surgery conducted by the same experienced surgeon and comprehensive ophthalmic examination, the main outcomes considered in this study were obtained with the following procedures: binocular high contrast visual acuity (VA) for different levels of defocus from +1.00 to -3.00 in 0.50 steps, contrast sensitivity function (CSF) for 1.5, 3.0, 6.0, 12.0 and 18.0 cycles per degree (cpd) without and with glare at 28 lux, subjective quality of vision (QoV) questionnaire (McAlinden et al, 2010) and light distortion (LD) analysis for size, shape and regularity of the positive dysphotopsia surrounding a source of glare (Light Distortion Analyzer - CEORLab, University of Minho, Portugal). Statistical analysis was conducted using SPSS for Windows software (version 22, SPSS, Inc.). Normality of data distribution was assessed using the Shapiro-Wilk test. Paired sample comparisons, analysis of variance and correlation analysis were used in most of the studies conducted. For all statistical analyses the level of significance was a P value less than 0.05 and samples were estimated to ensure a minimum power of 80%. Results: A total of 119 cataract patients (mean age: 64.39 ± 9.56 years) participated in the retrospective studies, 57 (mean age: 61.53 ± 8.92 years) cataract patients participated in the prospective longitudinal study and 17 clear lens presbyopes (mean age: 55.73 ± 5.78 years) participated in another prospective study. A significant increase in light disturbances has been observed in pseudo phakic patients implanted with multifocal and extended depth of focus devices compared to monofocal devices. The simultaneous compensation of astigmatism and presbyopia was satisfactory, reaching levels compatible with non-astigmatic corrections. Clear lens extraction and implantation of trifocal and extended depth of focus devices increase light disturbances symptoms in a similar fashion as in older cataract patients implanted with the same devices. In both groups, there has been a reduction in the bothersome of symptoms (potential psychological effect) and an improvement in contrast sensitivity (potential neural effect), though the light disturbances (directly related with the optics of the IOLs) remain present. Conclusions: the present thesis shows that it is possible to include a comprehensive examination in clinical routine to investigate specifically the objective measures and subjective symptoms of light disturbances under night vision conditions in pseudophakic patients of younger and older ages (at least up to 80 years of age). Trifocal and extended depth of focus devices increase the light disturbance compared to monofocal IOLs in a similar way. There is an adaptation process that reduces the bothersome of light disturbances that remain present even after 3 and 6 months after surgery suggesting that this process involves more psychological than neural effects.