الفهرس 
PresbyopiaOnly 14 pages are availabe for public view
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Abstract
Scleral expansion surgery; Corneal laser surgery with
multifocal patterns or monovision approaches; Conductive
keratoplasty (CK); and Clear lens extraction or cataract
surgery using multifocal, accommodating, or monovision
monofocal IOLs are among the techniques that have been
used for the treatment of presbyopia. Although Corneal laser
surgery and CK are minimally invasive methods, they
provoke irreversible changes in corneal anatomy, whereas
scleral surgery and clear lens extraction are even more
invasive techniques.
Presbyopic patients with emmetropia who are between
the ages of 45 and 60 years are a particular target group for
corneal inlays because they have healthy eyes, usually with
excellent distance visual acuity. Many surgeons consider
these individuals too old for corneal laser surgery and too
young for cataract surgery. Furthermore, these patients are
dissatisfied with procedures that leave even minimal damage
to their far binocular visual acuity and quality of vision.
The corneal inlay being removable, allows the patient to
take advantage of future technologies for correcting
presbyopia or cataract if needed. If the patient doesn’t like
them, they can be easily removed and no further procedure
is required to restore them back to their original refractive
status. The inlays may enhance near vision, with only a
marginal loss of distance acuity depending on the inlay
utilised. Because it is a monocular procedure, quality
distance vision in the other eye is always maintained, and
the patients seem to appreciate that .
The inlays were tested and found that there was only a
very slight reduction in the mean deviation visual field of 2dB
after five years’ follow-up – a time frame that seems quite
reasonable to postulate that they are very safe .
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Another potential problem is that not all patients adapt
quickly to their post-inlay vision. For instance, a LASIK
procedure followed by Kamra implantation in the nondominant
eye of a myopic patient could be performed but
after several days the patient may still not be very
comfortable with it. However, patients are urged to give it
time because there is a process of neuro-adaptation with the
inlay. It is a little bit like the IntraCor procedure in this
respect – some patients have immediate results after the
surgery, but sometimes it takes a few weeks for other
patients to adapt to their new vision .
Centration is another potential issue with inlays, and
some concerns have also been raised about longterm biocompatibility.
An electronic alignment system such as that
recently introduced for the Kamra inlay, effectively deals
with the centration issue and will become the norm for
optimal placement of these types of implant.
There can be some mild interface reaction that occurs
between the implant and the cornea. Some earlier
generation hydrogel inlays have been seen 20 years after
implantation and they look good with no visually significant
scarring. But after removal of the inlay the site where the
implant was placed can be seen. That occurs with the Kamra
inlay as well, although it does not cause visually significant
light scatter or other symptoms.
The use of the latest-generation femtosecond laser
technology helps to reduce variations in wound healing.
Creating the femtosecond pocket or flap atraumatically using
the latest laser models resulted in faster visual rehabilitation.
The key is to use modern equipment for a smooth ablation
and then there is less variability in the wound healing.
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For optimal outcomes with the Presbylens/Vue+ inlay, it is
advised to deliver the inlay in the centre of the pupil, and
keep the flap hydrated to avoid microstriae. The importance
of aggressive management of dry eye pre- and
postoperatively has also been highlighted, as this population
tends to have drier eyes.
Implantation of corneal inlays is differentiated from simple
monovision procedures with laser correction or cataract
surgery not just in the procedure’s reversibility but also in its
dependence on pupil size. The maximal inlay effect occurs
during near vision when the pupil becomes smaller, and it
decreases during far vision when the pupil is larger. The
phenomenon of “smart monovision” is a unique mechanism
of action of the Flexivue Micro-Lens; other inlays have
different mechanisms of action, including increasing depth of
focus (AcuFocus), and reshaping of corneal curvature
(PresbyLens).
Even the best technology has its downsides and corneal
inlays are no exception. The main disadvantage is that the
inlay is a reasonable but not a perfect solution for
presbyopia, as only one eye is corrected. With this approach,
binocularity is disturbed, at least at near, and patients
become independent but not completely free of glasses for
near vision. In most doctor’s view, the best candidates for
inlays are emmetropic presbyopes with a clear lens, 20/20
uncorrected distance vision and a near add of about+2.00 D.
Inlays may also be unsuitable for patients with very high
expectations. As with all bifocal or multifocal corrections,
retinal image contrast may be reduced in eyes implanted
with the Flexivue and Vue+ devices and retinal illuminance
may be markedly reduced with the Kamra implant.
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Corneal inlay technology moved in the direction of
hydrogels more than 20 years ago, but problems with
corneal biocompatibility and surgical difficulty caused earlier
efforts to be unsuccessful. Corneal reaction to the ReVision
Optics Vue+ inlay is either absent or mild. About 10% of
patients develop a light haze over the inlay about 6 months
after implantation. In some cases, this effect gradually
disappears by itself, but in others a second round of steroids
quickly clears the cornea, and the haze rarely returns.
Emmetropic presbyopes are certainly candidates but the
largest number of patients who seem to ask for the surgery
are presbyopes who are also myopic or hyperopic and may
also have astigmatism. Understandably they don’t want to
trade far glasses for near glasses. For these patients, the
best solution is usually what is called SIM-LASIK (LASIK first
to correct their ametropia and then the inlay to deal with
their presbyopia). While the demand for presbyopic
treatments worldwide is on the increase, patients today are
much better informed about the options open to them. There
has been a definite shift in the age profile of the typical
refractive surgery patient in recent years, from around 35
years about a decade ago to around 45 or 50 years-of-age
today. There is no steep learning curve for the surgeon and
the surgery can be performed without changing or adding
new equipment or software in a modern refractive surgery
theatre equipped with a femtosecond laser .
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To summarize the features & benefits of corneal inlays
include Improved Vision (Sharp and clear near vision, Minor
or no distance visual acuity change & Quick visual recovery
typically within a few days ), Safety (Reversible, safely
remove lens for surgeon and patient, Flexibility to remove
lens if prescription upgrade is needed or new technology
appears, No permanent loss of tissue, Biocompatible with the
cornea & Allows for corneal metabolism) as well as
Satisfaction(Improves lifestyle, ending the need for reading
glasses for daily activities & Cosmetically appealing, lens is
invisible to the eye) .
Table 4: Summary of corneal inlays for presbyopia