Impacto sobre la visión de la exposición a filtros de difusiónanálisis morfológico de la retina y la coroides en sujetos miopes

Resumen

Introduction: The human visual system is capable of adapting and changing its response based on vision conditions. Bangerter filters are optical filters that generate different degrees of diffusion, producing a gradual decrease in visual acuity, which allows their use in clinical practice for the treatment of amblyopia. Although the impact of blur on the human visual system has been extensively studied, It is not the case of the impact of induced optical diffusion, particularly with Bangerter filters. Objectives: To analyze possible changes in the visual system associated with controlled diffusion exposure through Bangerter filters of density 0.6. To investigate the possible impact of visión through diffusion vision for a period of 40 minutes on retinal and choroidal morphology in a population of stable myopic subjects with normal vision. To evaluate the visual response in this group of subjects by measuring visual acuity, exploring possible adaptation phenomena associated with exposure to diffusion. Characterize possible alterations of other biometric parameters of the eye associated with visión thorough diffusion. Material and methods: 64 subjects participated in the measurements of this work. Out of these, a total of 42 subjects, myopic without any other type of ocular pathology and with normal vision, constituted the measurement group. Another group compounded by of 22 subjects with similar characteristics formed the control group. Measurements included obtaining visual acuity, keratometry, intraocular pressure, refraction, retinal and choroidal morphology using low coherence light optical tomography, OCT, under different viewing conditions, with and without diffusion filter, as well as those after a period of continuous exposure to it. Results: The morphological study of the retina showed that there are no changes in the foveal thickness in relation to the degree of myopia when it is low or moderate, appearing significant differences in thickness only for high myopia. In contrast, subfoveal choroidal thickness showed a linear correlation with refraction. After exposure to controlled diffusion, neither morphological changes were measured in the retina and choroid, nor in any other biometric parameter of the eye. On the other hand, exposure to diffusion did generate a significant adaptation effect, measured in terms of visual acuity. This showed an improvement of 15% after an adaptation period of 40 minutes with respect to the initial measurement with diffusion. Conclusions: The foveal thickness remained stable in relation to the degree of myopia, while the subfoveal choroidal thickness changed with the degree of myopia. The effect of vision through low diffusion, such as the one induced in this work, and for relatively short exposure times of 40 minutes, produced an improvement in visual acuity that may correspond to a purely neuronal adaptation phenomenon, since no other studied morphological parameter of the eye presented associated changes. The results are of practical interest in the use, even for short times, of diffusion filters for the eye, such as in amblyopia treatments. They are also relevant to understanding the visual degradation produced by the initial stages of cataracts.