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Refractive Errors, Myopia, and Presbyopia
Published in Ching-Yu Cheng, Tien Yin Wong, Ophthalmic Epidemiology, 2022
Ka Wai Kam, Chi Pui Pang, Jason C. S. Yam
Presbyopia affects quality of life by imposing difficulties in near-vision tasks regardless of living environment, geographic location, or socioeconomic condition. In developed regions, there may be more intensive near work in reading and writing. A study conducted in the USA showed the association of presbyopia with substantial negative effects on health-related quality of life.177 In developing areas reading and writing may be replaced by winnowing grain, sorting rice, weeding, and sewing.170 A study in Tanzania showed that almost 80% of people were having difficulties in handling near-vision jobs and 71% of them were dissatisfied with their ability at work.178 However, the global unmet need for presbyopia correction was estimated to be 45% in 2015, indicating a great need for improvement in awareness and treatment worldwide, particularly in the rural areas of low-resource regions.190 While treatments for presbyopia, such as bifocal or progressive lenses, are easily accessible in affluent places, they are much less available in lower-income regions, where the rate of presbyopia correction can be as low as 10%.179
Optics and refractive errors
Published in Mostafa Khalil, Omar Kouli, The Duke Elder Exam of Ophthalmology, 2019
Nemat Ahmed, Omar Kouli, Mostafa Khalil, Obaid Kousha
Methods that may be helpful in slowing myopic progression but there is no strong evidence for any strategy: Use of atropine (lower doses of atropine were more effective with fewer side effects than higher doses [1]) and pirenzepine drops.Outdoor activity: It is thought that too much near work may contribute in myopic progression (2).Bifocals and progressive lenses.
Vitreoretinal surgery for idiopathic epiretinal membranes
Published in A Peyman MD Gholam, A Meffert MD Stephen, D Conway MD FACS Mandi, Chiasson Trisha, Vitreoretinal Surgical Techniques, 2019
H Richard McDonald, Robert N Johnson, Robert N Johnson, Everett Ai, J Michael Jumper, Arthur D Fu
The most common complication of vitrectomy and ERM stripping surgery is cataract formation. Indeed, increasing nuclear sclerosis is considered a guaranteed side-effect of surgery in older individuals. It has been described in 12–68% of postoperative phakic eyes:20,22,41,42,49,83,84 the longer the follow-up period, the greater the incidence of progressive lens opacity. In many eyes, vision improves for 6–9 months and then slowly begins to decline as progressive lens opacity begins. Usually, patients will not experience their best postoperative vision until cataract surgery has been performed.
Double vision in adults
Published in Journal of Binocular Vision and Ocular Motility, 2018
Management of patients is primarily with prisms. Correction of diplopia in patients with divergence insufficiency begins with correcting full distance ET. Most patients with divergence insufficiency ET can fuse the full distance BO prism at near. However, some patients cannot tolerate BO prism at near without developing a near XT. In those patients, the bifocal can be nasally displaced to induce some BI prism at near, although this displacement is not possible with progressive lenses. Separate reading glasses with less or no prism may be helpful in patients using progressive lenses. A BI Fresnel prism over one bifocal or occlusion of a bifocal lens may be necessary.
Modern spectacle lens design
Published in Clinical and Experimental Optometry, 2020
In 1995 a patent was taken out by Kelch et al.17 describing a progressive lens which had a convex progressive power surface and an aspherical (for spherical prescriptions) or atoroidal (for astigmatic prescriptions) concave surface. This strategy optimised the design for the required prescription in that the design criterion is restored to the lens, no matter what prescription or cylinder axis direction is prescribed.
Non-surgical treatment options for presbyopia
Published in Expert Review of Ophthalmology, 2018
Although the concept is now many centuries old, spectacle correction remains the method of choice for the majority of those who need assistance with near vision. A wide range of single-vision, multifocal, and progressive lens types is available to meet the needs of the individual presbyope. What has so far been disappointing is the relative failure of spectacles with full-aperture lenses of controllable variable power to become an established form of presbyopic correction. While in part this may, as discussed earlier, be due to technical difficulties with current designs, a significant further problem is that, unlike CL or other nonsurgical or surgical treatments for presbyopia, spectacles involve placing some form of frame on the face and hence have a powerful effect on the cosmetic appearance of their wearer. For many wearers, this cosmetic effect is comparable in importance to the clarity of the retinal mages that the correction provides. The valuable features of conventional spectacle lenses are that not only do they provide the appropriate sphero-cylindrical correction but that they are relatively easy to edge, center, and fit them to almost any design of frame at the appropriate inter-pupillary distance and to incorporate any necessary prism. In contrast, most of the variable-power spectacle lenses that have been produced so far have to be incorporated into one of, at best, a limited set of frames. Often these are of chunky appearance, due to the need to incorporate liquid reservoirs, batteries, or mechanisms to move lens components, etc. Thus, even if the optical performance and the quality of vision at different distances given were excellent, many presbyopes might reject this type of spectacle on the grounds of their appearance. Again, the necessity of using manual adjustment each time the viewing distance is changed is likely to constitute a serious disincentive to may potential wearers. In the longer term, with advances in miniaturization of electro-optical components, it should be possible to overcome the latter problem by introducing automatic adjustment of lens power to suit the distance of the object of regard. This might favor devices based on liquid crystal technology, rather than technology involving movement of, e.g., lens components or liquid fillings.