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Laser Assisted In Situ Keratomileusis
(LASIK "flap & zap" ALK-E)
There
has been a dramatic move towards
LASIK,
which offers fresh hope to the millions of
people with poor eye sight who need to wear glasses or contact lenses.
Successful LASIK provides rapid
improvement in unaided vision with little pain or discomfort and minimal use of
drops following surgery.
The advantages of LASIK in
providing a rapid recovery of vision allows many professional people to undertake laser refractive surgery with
little break from their lifestyle. After LASIK if the refractive target has not
been achieved further laser pulses can be applied after 12 weeks from the
original treatment.
If there is a significant
residual refractive error
after the first
treatment,
then a flap-lift procedure can be performed to correct
the remainder.
LASIK is now often
performed for all myopic and hyperopic treatment but some still prefer PRK for
the lower refractive changes as it has a low complication rate. However LASIK
is now the procedure of choice for much refractive surgery.
Non-Corneal Refractive Surgery
Benefits of LASIK over PRK
-
Usually minimal
discomfort with LASIK. The corneal epithelium is removed with PRK but is left
almost intact with LASIK
-
Post surgery vision
returns within hours with LASIK, rather than weeks or months with PRK
-
Reduced incidence of
corneal haze (scarring) in the long term for LASIK than PRK for high myopia
-
Less change due to
healing (regression) and thus greater predictability of the correction with
LASIK for high myopia or astigmatism
-
Treatment to the second
eye is normally performed simultaneously with LASIK
-
Often
fewer follow-up
visits required
Disadvantages of LASIK
-
Failure of the
microkeratome leading to problems with the corneal flap
-
Loss or damage to the
corneal flap during or after the treatment or slipping of the flap and healing
off centre causing distortion and wrinkling of the cornea
-
Invasion of the surface
tissue under the flap, known as "epithelial in-growth”
-
Infection of the cornea
“corneal abscess” which may extend inside the eye
-
Loss of visual acuity -
from scarring, wrinkling or from decentration of the LASIK flap
-
The excimer laser application is
deep within the cornea and shock waves may potentially damage
the cells on the inner
surface of the cornea
-
Failure of the suction device to
maintain suction with consequent damage to the cornea and
possible aborting
of the procedure mid way across the cornea
-
Retinal haemorrhage
(bleeding), macular oedema, retinal tear, central retinal artery occlusion
from the pressure change
The frequency of
re-treatment is 1% to 2% for lower myopic treatments and 6- 20 % for high
myopia. Re-treatment after LASIK is generally successful but has a small risk
of flap dislocation or wrinkling.
There may be
contraindications
for corneal refractive surgery
if
certain
conditions
are present,
since there may be additional risk or a poor outcome may be involved:
-
Non-Corneal Refractive Surgery
Extreme degrees of myopia and hyperopia cannot be
successfully treated by corneal surgery and treatment requires other
techniques.
These include implantation of an intra-ocular "phakic" lens
implant. Such lenses may have a long-term risk to the cornea or lens of the
eye and there may be problems with night glare and glaucoma in some cases.
Alternatives to the use of the
excimer laser have been investigated for many years including the use of
infrared laser systems and implantation of rigid rings into the clear cornea
of the eye. There will be a continuing debate in refractive surgery regarding
the place of this technology against modern laser refractive surgery.
The LASIK procedure
explained
 The
excimer laser is used to reshape the surface of the cornea
next >>>The
Procedure
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Page last updated on
Saturday, 25 June 2005 12:36:28
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