Lentes de contacto hidrofílicas tintadas a mano y filtros oftálmicos de absorción selectivacaracterización y análisis de su función visual

Abstract

Population ageing represents a global challenge at an economic, social, public health and technological level. Much of the impact of aging falls on health and on diseases that in¬crease in prevalence with age. Visual health also perceives the impact of the aging of the population and affects the quali¬ty of life of older people due to vision-related problems. Ocular diseases or conditions such as cataracts, age-related macular degeneration (AMD) or diabetic retinopathy, among oth¬ers, can cause a worsening of visual function to different degrees, or also with an increase in processes such as photophobia and glare. This greatly limits the life and daily activities of these patients, so it is necessary to find devices with which to restore or improve their visual function. Selective cut-off filters in ophthalmic lenses have demonstrated their usefulness in improv-ing visual function in patients with ocular pathologies or conditions that worsen contrast sensitivity, especially in dim lighting conditions or in which glare represents a significant limitation. These filters are mounted on the glasses as classic ophthalmic lenses or are also used as supplements (clip-on) on the glasses so that they can be removed and used on certain occasions. Although its use is widespread, the use of ophthalmic lenses in glasses is not exempt from limitations. In this sense, contact lenses have a refractive function like ophthalmic lenses, however, they present notable optical and physical differences that can make a difference in the final approach of patients. Analyzing the differentiating aspects of contact lenses with respect to ophthalmic lenses and their use in spectacles, it is of clinical interest to analyze whether contact lenses with hand-tinted selective cut-off filters can offer a visual function similar to classic filters mount¬ed on glasses. In the same way, and in order to complement their use, it is interesting to analyze the subjective aspects in which these contact lenses offer better or worse vision compared to classic ophthalmic filters. To analyze these aspects, in this Doctoral Thesis three experiments were carried out. Ex-periment 1 consisted of the characterization, through spectrophotometric analysis, of hand-tinted contact lenses with 4 selective cut filters common in clinical practice. These filters were 450, 511, 527 and 550 nm. In the same way, classic filters in ophthalmic lenses were characterized with the same selective cuts. The results obtained in experiment 1 showed similar transmissibility values throughout the entire spectrum for both devices in the four selective cuts studied. Therefore, with the re-sults of the experiment, a second experiment was designed to analyze whether, in addition to obtaining similar light transmissibility values, visual function with both devices was also similar in healthy patients. To that end, experiment 2 evaluated different parameters of visual function in patients without pathologies who used both devices in their four selective cuts. The results showed that, indeed, visual function with both contact lenses and ophthalmic filters was similar. However, since selective cut filters are often used in patients with age-related complica¬tions, a third experiment was designed. In this experiment visual function was analyzed in cataract patients with hand-tinted contact lenses and with a filter mounted on glasses, both of 450 nm. In this experiment 3, apart from visual function, subjective issues of the use of both meth¬ods were analyzed. The results showed that the visual function was similar, but there were positive and negative aspects of one device with respect to another. As a conclusion to the results of all the experiments of this Doctoral Thesis, it can be said that hand-tinted contact lenses are a device that can complement and, in some cases, improve the visual results and comfort obtained with selective cut-off filters mounted on glasses, for patients with pathologies or eye conditions related to age.