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A Brief history of
Refractive Surgery:
Although refractive surgery has developed rapidly over the last few
years with the introduction of the LASIK procedure, surgical techniques
to correct refractive errors have been in use for many years.
 During
the mid 70’s Dr Fyodorov in Russia began treating myopia using radial
or bike spoke cuts through 90 to 95 % of the cornea. This was
technically referred to as Radial Keratotomy or RK. It worked by
weakening the peripheral cornea causing it to balloon in shape thereby
flattening the central cornea. Results, although not as accurate as
laser correction, were fairly good but have been shown to be
occasionally unstable, both visually and anatomically.
Arcuate Keratotomy (Arc T incisions) is a similar procedure, but is
used only to correct astigmatism. This involves the use of small
relaxing incisions around the mid periphery of the patients cornea. Arc
T incision’s are still commonly used for some patients with only
astigmatism or with high degrees of astigmatism.
Although lasers have been in use around the world since 1964 for various
scientific and medical purposes it was not until 1988 that an
ophthalmologist first used the laser for refractive purposes.
Photorefractive
Keratectomy (PRK) was born. The accuracy of the laser led to more
accurate results than previous techniques. PRK continues to be an
effective treatment for low refractive errors. Factors such as increased
corneal haze and regression have limited its effectiveness particularly
with higher amounts of myopia, hypermetropia and astigmatism.
The development of microkeratome technology led to the introduction
of the Laser In Situ Keratomileusis (LASIK)
technique, also in 1988, which is a combination of lamellar and laser
developments. This procedure has further increased the possibilities of
refractive surgery in terms of success and patient safety.
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WHAT IS LASIK or
‘Laser In-situ Keratomileusis’?
The LASIK procedure combines the experience of past surgical
techniques with current laser technology. LASIK allows the surgeon to
correct higher levels of
myopia,
hypermetropia
and
astigmatism.
The technique falls into two distinct steps, the creation of a
corneal flap and the subsequent lasering of the corneal bed.
The first step is performed using a device called a microkeratome which
creates a uniform cut across the patient’s cornea. The microkeratome
cuts a thin layer of corneal tissue, approximately 180 microns in depth.
The surgeon then hinges the newly created flap back across the cornea
exposing the corneal bed or stroma for the laser ablation. The surgeon
must be extremely careful at this time, as it is important to the
success of the procedure that a concise and full flap is created.
 With
the flap hinged the surgeon, using the laser machine, recontours the
corneal bed specifically to the patient’s refractive requirements.
After the laser is completed the flap is placed back in its original
position upon the cornea. The eye has a naturally occurring suction
capacity which holds the flap secure when the procedure is completed.
Because of this no sutures are necessary.
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What is PRK or
Photorefractive Keratectomy?
PRK is a similar refractive technique which recontours the shape of
the cornea using the laser. PRK differs from LASIK in that it involves
the removal of the surface layer of the cornea (epithelium) before the
laser correction begins.
The epithelium is removed either manually by the surgeon or with the
laser. Once the corneal tissue is exposed the refractive laser ablation
can begin. After the surgery a patch is placed over the eye while the
epithelium recovers. As the epithelium heals the patient may experience
pain. Medication and drops are provided to the patient over this time to
help with any discomfort and irritation.
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LASIK versus PRK
In most cases refractive surgeons now prefer to perform LASIK rather
than PRK. The LASIK procedure can provide several advantages over its
refractive counterpart.
These include :
- Faster visual recovery - as the epithelium is only minimally
disturbed during the procedure recovery is usually very fast with
the majority of patients returning to most activities the next day.
Useful vision in PRK occurs only when the epithelium has regrown,
this usually takes between 48 to 72 hours.
- Less postoperative discomfort - as the cornea is only slightly
disturbed it is rare for the LASIK patient to experience discomfort.
Minimal irritation is expected initially.
- Less haze involved with LASIK - corneal haze is a significant side
effect with PRK, particularly with higher refractive errors. Haze
can cause or exacerbate symptoms such as glare and haloes. Faster
visual recovery means that corneal haze has almost been eliminated
as a long term complication in conjunction with the LASIK technique.
Surgeons are now able to approach higher refractive errors with
greater confidence in relation to the end refractive result.
Treatment of corneal haze includes the use of topical steroids which
may also lead to an increase in the healing time.
- Faster stability - less fluctuation through the healing process (ie.
regression) and decreased corneal haze or scarring means a faster
and more stable correction with LASIK can be achieved.
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