[Presbyopia in tropical countries].
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For 100 persons of different age the visual charge for the accommodation was examined by an objective procedure. Already at the age of 40 the dynamic range of accommodation decreases. This decrease could be a reason for the loss of mobility during work at VDUs, as it has been observed in a group of persons aged 40 to 55 years.
Modern cataract surgery has advanced tremendously over the past 20 years. Improved surgical techniques, as well as improved implant materials and designs, have enlarged patient profiles and indications not only for cataract surgery, but also for refractive lens exchange surgery. This has also created much higher patient expectations. The loss of accommodation is a loss of quality of life for presbyopic and especially young pseudophakic patients. Multifocal intraocular lenses (MIOL) have been implanted since 1986, starting with 2-3 zone refractive and diffractive designs. Due to the surgical techniques available at that time, MIOL decentration and surgically induced astigmatism were possible complications. In addition, reduced contrast perception and increased glare were common problems of MIOL because of their optical principles. New developments in this field in recent years such as the folding, multizonal, progressive refractive MIOL and aspheric diffractive MIOL in combination with improved surgical techniques have overcome those initial problems. Therefore, modern MIOL (and in the future also accommodative IOL) can be considered not only for the correction of aphakia but also for refractive purposes.
Contact lens fitting for presbyotic patients needs more than simple fitting shill; patients need additional psychological support. The wearer has to accept optical quality reduction due to the multifocality of the lens design. In general, the technical fitting of presbyotic contact lenses is comparable to monofocal systems. They work with the same rules of performance. The difference lies in the principles of correction by the lens itself. Simple presbyotic systems use uncorrected optical aberration to widen depth perception. These lenses are suitable for young presbyopes, up to a need of 1 diopter plus power for near vision. Uncorrected aspherical designs have a multifocal effect which can be used for presbyotic lenses. There are contact lenses on the market with simultaneous imaging, which is based on concentric rings around the near or distance centre. Another principles are based on segmented reading portions in the lower part of the lens, also called alternating systems. These very few design variations are the basis for the various specific models which are sold on the market today. The results of the fitting can never be foreseen as subjective and psychological aspects of the wearer overlay the objective results. Thus, the fitter needs experience and patient understanding, combined with fundamental knowledge of the specific lens type used.
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A contentious middle-age patient inadvertently obstructs the management of a simple presbyopic problem related to asymmetric accommodative loss.
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