Abstract
Simultaneous vision is an increasingly used solution for the correction of presbyopia (the age-related loss of ability to focus near images). Simultaneous Vision corrections, normally delivered in the form of contact or intraocular lenses, project on the patient's retina a focused image for near vision superimposed with a degraded image for far vision, or a focused image for far vision superimposed with the defocused image of the near scene. It is expected that patients with these corrections are able to adapt to the complex Simultaneous Vision retinal images, although the mechanisms or the extent to which this happens is not known. We studied the neural adaptation to simultaneous vision by studying changes in the Natural Perceived Focus and in the Perceptual Score of image quality in subjects after exposure to Simultaneous Vision. We show that Natural Perceived Focus shifts after a brief period of adaptation to a Simultaneous Vision blur, similar to adaptation to Pure Defocus. This shift strongly correlates with the magnitude and proportion of defocus in the adapting image. The magnitude of defocus affects perceived quality of Simultaneous Vision images, with 0.5 D defocus scored lowest and beyond 1.5 D scored “sharp”. Adaptation to Simultaneous Vision shifts the Perceptual Score of these images towards higher rankings. Larger improvements occurred when testing simultaneous images with the same magnitude of defocus as the adapting images, indicating that wearing a particular bifocal correction improves the perception of images provided by that correction.
Highlights
Presbyopia is the physiological inability to focus near objects that occurs with aging, as the crystalline lens stiffens and loses the ability to reshape upon the accommodative force produced by the ciliary muscle in response to an accommodative stimulus [1]
Natural Perceived Focus and Its Shift with Adaptation Natural perceived focus was tested by a single stimulus detection task by using Pure Defocus test images after adaptation to a neutral gray field, sharp image (0 D defocus), and after adaptation to Pure Defocus image series (PD) and Simultaneous Vision (SV) images
For PD images this corresponds to the amount of defocus, for SV it is equivalent to the power of addition for near vision in a bifocal correction in SV images
Summary
Presbyopia is the physiological inability to focus near objects that occurs with aging, as the crystalline lens stiffens and loses the ability to reshape upon the accommodative force produced by the ciliary muscle in response to an accommodative stimulus [1]. Multifocal optical corrections such as multifocal contact lenses or intraocular lenses have become an increasingly used solution to restore near vision [2,3], where certain pupillary regions are corrected for far vision, and other regions have a relative positive power, which allows correction for near. How the visual system gets adapted to SV has never been tested
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