الفهرس 
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Abstract
The surgical solutions to correct refractive errors include: corneal
refractive surgery, clear lens extraction, and phakic intraocular lens
implantation.
A phakic intraocular lens (PIOL) is a supplementary IOL implanted
between the cornea and the crystalline lens; fixated in the angle, enclavated
to the mid-peripheral iris with a claw or placed in the posterior chamber,
giving rise to a condition called duophakia or artiphakia. Phakic intraocular lenses (PIOLs) offer a number of potential
advantages over competing refractive surgical techniques and spectacles or
contact lenses. For high ammetropes spectacles cause significant optical
aberrations. Minification in high myopes wearing spectacles may be a
significant cause of reduced acuity. In addition, the cosmetic appearance of
high power spectacles is psychologically unaccepted by many patients.
Contact lenses have problems associated with over-wear, infection, giant
papillary conjunctivitis, war-page, and occasionally vascularization of the
cornea. Kerato-refractive procedures, being based on modification of corneal
curvature, face many limitations including aggressive alteration of corneal
architecture ( aspherical corneal curvature), induction of higher order optical
aberrations, and lack of predictability. In addition, corneal refractive surgery
carries risks as ecstasies, haze, diffuse lamellar keratitis, or regression. Clear
lens extraction with or without intraocular lens implantation differs from
phakic intraocular lens insertion in that the vitreous body is more likely to be
disturbed with increased risk of retinal detachment, and the frequent need for
YAG capsulotomy. Furthermore accommodation is lost. For the above mentioned potential problems, there has been a
growing interest in the use of phakic intraocular lenses (IOL) to correct
refractive errors.
In comparison to lamellar refractive corneal surgery, which requires
technically complex and expensive lasers and micro-keratomes , phakic IOLs
require minimal investment for the advantage of preserving the architecture
of the cornea (which is arguably the healthiest part of a highly myopic eye),
and no interface is formed in the optical axis of the corneal stroma. In
addition, it may provide more predictable and potentially reversible
refractive results than surgical technique that manipulate the corneal
curvature. Compared with clear lens extraction, myopic implantation is
reversible, preserves accommodation, and reduces the risk of retinal
complications.
The reversible nature of the procedure is important, because if there
are any signs of implant intolerance or if there is a refractive error, it is easy
to remove or exchange the lens for a more suitable one.
The surgical technique of phakic IOL implantation is within the reach
of any anterior segment surgeon.
Contrary to an aphakic IOL which can fit in the space created by the
removed cataract, phakic IOLs must fit within the space available in the
anatomically normal anterior ocular segment. This increases the challenge
for phakic IOL design to avoid damage to the corneal endothelium, anterior
chamber angle, iris and crystalline lens.