Short-Term Neural Adaptation to Simultaneous Bifocal Images

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.

VioBio lab adaptive optics: technology and applications by women vision scientists

“…Also, while habitually non‐corrected astigmats show strong bias towards oriented blur (coincident with the orientation of their retinal blur), the isotropic focus shifts rapidly after astigmatic correction wear, being significant only two hours after correction . In another study we also found rapid short‐term adaptation to simultaneous vision images …”

“…[30][31][32] In another study we also found rapid short-term adaptation to simultaneous vision images. 33 The strong bias towards the native blur suggests that the eye is adapted to its own aberrations. We also used AO to investigate whether the spatial coding in the visual system is matched to the native blur specific to an individual's HOAs in terms of amplitude 34 and pattern orientation.…”

Blur adaptation: clinical and refractive considerations

“…In the area of myopia management, the role of relative myopic retinal blur as a 'stop' signal for eye growth is building in the evidence base of clinical effectiveness. Radhakrishnan et al 55 examined the effect of simultaneous vision from a bifocal correction. Shifts in the perception of blur were observed with simultaneous vision bifocal designs, and the magnitude of the shifts in perception were related to the proportions of defocus.…”

Vision science and adaptive optics, the state of the field

“…In addition, the ability to perform measurements with and without the natural aberrations gives insight into the needs for the correction to be selected on an individual basis or alternatively whether the same correction works similarly across a larger population (Vinas et al 2015b, Vinas et al 2016). AO systems are able to predict both visual performance and short-term adaptation to new corrections before these are implanted in the eye or even manufactured (Radhakrishnan et al 2014)…”