Accommodating intraocular lenses a critical review Free kenyan sex dates

Posted by / 08-Dec-2019 22:16

Accommodating intraocular lenses a critical review

In numerous studies different models of both refractive [9, 10] and diffractive [9, 14] multifocal IOLs have been shown to result in high levels of uncorrected distance and near visual acuity: both mean uncorrected near and distance visual are 20/25 or better in most studies, resulting in complete spectacle independence in around 75% of patients [9, 12].

Uncorrected near visual acuity is generally slightly better for diffractive IOLs compared to refractive IOLs, and uncorrected distance visual acuity is comparable for the two types of IOLs [9, 10].

Patients with a monofocal IOL can have both good uncorrected distance and near visual acuity as well as the result of favorable corneal astigmatism [15, 16], favorable corneal wavefront aberrations [17, 18] or myopic undercorrection in one eye, resulting in “pseudophakic monovision” [19, 20].

Despite large differences in the percentages of patients with a monofocal IOL being able to read [3] print size, a meta-analysis concluded that uncorrected near vision is improved by implantation of a multifocal IOL compared to implantation of a monofocal IOL [21].

Similarly, an IOL of more rigid material which could (partially) change its position within the eye would allow patients to regain accommodation.

the difference between the smallest and largest distance where visual acuity is sufficient for the execution of visual tasks) is to give them two or more fixed optical powers. In multifocal spectacles there is only one retinal image at a time, which is the result of the focal point of the part of the spectacle glass best-suited for the distance of the object viewed.

Refractive multifocal IOLs appear to be associated with more photic phenomena compared to diffractive multifocal IOLs [10].

Photic phenomena are among the most frequent reasons for patients’ dissatisfaction following implantation of multifocal IOLs [24, 25].

Von Helmholtz pioneered the theory that accommodation is the result of changes in optical power of the crystalline lens, as a result of changes in shape and position of the crystalline lens due to changes in tensile strength of the zonular fibers after relaxation or contraction of the ciliary muscle [1].

After the age of 40, the ability to accommodate decreases to such an extent that visual tasks at a normal near distance (e.g.

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Although these IOLs are pseudo-accommodative rather than truly accommodative (since they have several fixed rather than one adapting focal point) they have been the most widely used IOLs in cases where replacing the natural crystalline lens is used to overcome presbyopia following cataract surgery of refractive lens exchange.