Nonsurgical correction of presbyopia

This study aimed to describe the basic optical properties for presbyopia correction, including eyeglasses and contact lenses. Conventional eyeglasses are the most established technology for presbyopia correction, and contact lenses have been recognized to have a huge potential in presbyopia correction. However, successful treatment using contact lenses is dependent on age-related factors, such as upper and lower eyelid movements, palpebral aperture, and decreased lacrimal secretion and tear stability. Monovision and multifocality are optical properties of the lens that form the basis of presbyopia correction. The monovision method is based on the principle of neuro-adaptation, wherein one eye automatically selects a clear image and suppresses an unclear image for processing in the brain when there is a difference in the clarity of the images obtained from both the eyes because of anisopia, which is characterized by unequal visual power between the two eyes. Simultaneous views of near and far objects cannot be achieved using eyeglasses, but these can be realized using contact lenses or intraocular lenses. Alternative views of near and far objects can be achieved using a variety of bifocal contact lenses, which function similar to bifocal eyeglasses. Traditional strategies for presbyopia correction, including the use of monovision, bi/tri/multifocal, and progressive eyeglasses and the use of contact lenses, are being challenged by novel strategies involving pharmacotherapy and electrostimulation. Although the immediate prospect of any newly developed innovation remains slim, improved lens profiles would lead to a better match between the lens and the needs of individuals with presbyopia.