11/4/2022 0 Comments Beyond contact lenses![]() ![]() A potential advantage with the aspheric design is an increased depth of focus, providing greater tolerance for small focus errors. Concentric rings and aspheric designs are the two types of simultaneous vision lenses that are presently available in both soft and rigid gas-permeable (RGP) materials. The distant and near images are viewed simultaneously requiring the patient to discern between the focused and unfocused images (figure 2). Simultaneous designs contain regions of the lens designated for near and distant viewing. ![]() Presently, multifocal contact lenses can be categorized into two lens designs: simultaneous and alternating designs. ![]() A simultaneous bifocal contact lens design includes smaller zones for near vision. 3 Let’s review what is currently known about the effectiveness of commercially available multifocal contact lenses on the management of aphakia/pseudophakia, accommodative dysfunction, binocular disorders and retardation of myopia progression.Ģ. Multifocal contact lenses can address the limitations of multifocal spectacle lenses and have been recommended for therapeutic purposes outside of the management of presbyopia. In many cases, pre-presbyopic patients who wear multifocal spectacle lenses are interested in eliminating the use of their spectacles for improved cosmesis and convenience. 2 Off-axis viewing through a spectacle lens may also induce an unwanted prismatic demand that can exacerbate a binocular disorder. One study found that school children often adopted insufficient downward viewing with a progressive addition lens, reducing its therapeutic effect for near addition. For example, the downward viewing angle required for a bifocal spectacle add power is misaligned to the often straight ahead viewing gaze of a computer. #BEYOND CONTACT LENSES PLUS#The prescribing of plus lenses requires an understanding of the patient’s visual demands and knowledge of the lens options that fit within the context of those demands. Thus, small amounts of add power may significantly reduce a patient’s eso-deviation. 1 For example, a patient with an AC/A of 10 would increase accommodative convergence by 10r for every 1.00D of accommodation exerted. Plus lenses may also be considered in the management for symptomatic relief of intermittent blur, eyestrain and headaches due to an over-taxed accommodative system or for binocular disorders when patients yield a high accommodative convergence to accommodation (AC/A) ratio (figure 1). The use of plus lenses to reduce the demands on the accommodative system is routine in the management of presbyopia. ![]()
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