Presbyopia Rehabilitation Through Vision Training: From Laboratory Efficacy Testing to Home-Training Evaluation.

Abstract

Our visual Presbyopia is a common age-related visual condition that typically develops after the age of 40, caused by a gradual loss of lens elasticity that reduces accommodative ability. As the lens becomes less flexible, light from near objects focuses behind the retina, leading to blurred near vision and difficulty performing tasks such as reading. High spatial-frequency sensitivity—critical for recognizing fine details—is especially impaired in presbyopia. Presbyopia treatment remains a greater challenge. Optical corrections like bifocals, or multifocal lenses can help, but they are often inconvenient for daily activities, especially tasks that require quick shifts between near and far vision. Surgical options—such as LASIK conductive keratoplasty (CK) can reshape the cornea, but none can fully restore natural accommodation across all focal distances, also have side effects and are usually effective only for mild-to-moderate cases. Thus, no existing treatment can truly restore the dynamic focusing ability of the eye. Despite its prevalence, effective rehabilitation for presbyopia remains limited. Optical corrections such as bifocal or multifocal lenses provide temporary assistance but are often inconvenient for tasks requiring rapid shifts between near and far vision. Surgical interventions, including LASIK or conductive keratoplasty, can modify corneal shape but fail to restore natural accommodation and may involve side effects. Parallel to presbyopia, myopia (nearsightedness) represents another major refractive condition in which the eye elongates or possesses excessive optical power, causing distant objects to appear blurred. Myopia often begins in childhood and typically progresses with age. Although optical and surgical interventions can correct refractive errors, they do not halt the underlying progression of myopia. Understanding both presbyopia and myopia provides valuable insight into how vision training can serve as a general, non-invasive rehabilitation approach for both younger and older adults. Consequently, there is an increasing demand for non-invasive strategies that can enhance visual function without surgical risk. Vision training has therefore been proposed as a potential solution for both presbyopia and myopia. Vision training generally includes two main approaches: eye exercises and visual perceptual learning. Eye exercises aim to improve eye coordination and focusing ability, whereas perceptual learning involves repetitive visual tasks that enhance the brain’s capacity to process fine visual details. This thesis therefore begins with a meta-analysis of 84 studies encompassing both presbyopia and myopia to establish the broad efficacy of vision training as a non-invasive visual rehabilitation strategy. Building on this foundation, Chapters 2 and 3 focus exclusively on presbyopia. Chapter 2 compares two training paradigms—alternating-distance versus fixed- distance visual tasks—and reveals that fixed-distance training yields comparable or even superior improvements in visual performance. Chapter 3 extends these findings by translating the laboratory-based paradigm into a smartphone-based home training program, demonstrating equivalent efficacy and greater accessibility for older adults. Overall, this thesis challenges the prevailing assumption that frequent accommodative alternation is essential for improving presbyopic vision. Instead, it shows that fixed-distance perceptual training can produce significant functional gains. The smartphone-based implementation offers a practical, scalable, and non-invasive rehabilitation tool for presbyopic individuals, potentially improving quality of life and reducing the socioeconomic burden of age- related visual decline.