‫د‪ /‬فاروق محمد صالح الباز ‪ --‬كليه العلوم‪-‬قسم البصريات الطبيه‬
‫علم تشريح جسم اإلنسان ‪opto2401‬‬‫يهدف إلى تفهيم الطالب على التركيب التشريحي العام لجسم اإلنسان مع التركيز الخاص على البطن و الصدر‬
‫و الرقبة والرأس مع فهم التركيب و وظائف األجهزة المختلفة في جسم اإلنسان و عالقتها بالعين ‪.‬‬
‫الساعات المعتمدة أربع ساعات نظري ‪.‬‬
‫عالج العين بالليزر ‪opto3208‬‬‫يهدف إلى إعطاء الطالب معرفة عن ماهية الليزر و كيفية استعماله في عالج أمراض العيون و كذلك تفهم‬
‫الطالب مبادئ الليزر و تطبيقاته الطبية في عالج أمراض العيون خاصة عيوب اإلبصار و عالج مضاعفات‬
‫السكري على الشبكية و كذلك عالج الجلوكوما بالليزر ‪.‬‬
‫الساعات المعتمدة ساعتين نظري‪.‬‬
‫‪1‬‬
Studying plan of general
Anatomy
First semester 2012-2013
Dr. Farouk El Baz
General anatomy of the human body
- First week:
cells and tissues of the body.
- Second week:
introduction to human anatomy.
- Third week: :
skeletal tissue.
-Fourth week:
skeletal system.
-Fifth week:
anatomy of muscular system.
-Sixth week:
-Seventh week:
anatomy of central nervous system.
peripheral nervous system.
-Eighth week:
special senses.
-Ninth week:
endocrine system.
-Tenth week:
The blood.
-Eleventh week:
anatomy of the cardiovascular system.
-Twelfth week:
anatomy of respiratory system.
- Thirteenth week:
anatomy of digestive system
- Fourteenth week:
anatomy of urinary system.
2
Studying plan of Laser in ophthalmology
First semester 2011 / 2012
Dr. Farouk El Baz
Laser in ophthalmology
- First week:
principles of laser, and laser therapy.
- Second week:
types of laser.
- Third week:
diagnostic use of laser.
- Fourth week:
laser indications on eye lids, cornea.
- Fifth week:
laser in glaucoma treatment..
Sixth week:
laser in treatment of retina and choroid.
- Seventh week:
laser photocoagulation and diabetic retinopathy.
- Eighth week:
pan retinal photocoagulation.
Ninth week:
-
Classification and pre-operative evaluation of
Refractive surgery.
- Tenth week:
photorefractive keratectomy and excimer laser.
- Eleventh week:
lasik indications.
- Twelfth week:
lasik techniques.
- Thirteenth week:
lasik complications.
- Fourteenth week:
lasek and laser thermal keratoplasty.
3
Refractive eye surgery is any eye surgery used to improve the refractive state of the
eye and decrease or eliminate dependency on glasses or contact lenses. This can
include various methods of surgical remodeling of the cornea or cataract surgery. The
most common methods today use excimer lasers to reshape curvature of the cornea.
Successful refractive eye surgery can reduce or cure common vision disorders such as
myopia, hyperopia and astigmatism.
According to surveys of members of the American Society of Cataract and Refractive
Surgery, approximately 948,266 refractive surgery procedures were performed in the
United States during 2004 and 928,737 in 2005.[1]
Contents
[hide]



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


1 History
2 Techniques
o 2.1 Flap procedures
o 2.2 Surface procedures
o 2.3 Corneal incision procedures
o 2.4 Other procedures
3 Expectations
4 Risks
5 See also
6 References
7 External links
[edit] History
The first experimental studies about refractive surgery were published in 1896 by
Lendeer Jans Lans, an ophthalmology teacher in Holland, where he developed a
theoretical work proposing penetrating corneal cuts to correct astigmatism. In 1930
the Japanese ophthalmologist Tsutomu Sato made the first practical attempt to
perform such surgery in military pilots. He practiced radial cuts in the cornea to
correct effects by up to 6 diopters, but this procedure was soon rejected by the
medical community because of the high rate of corneal degeneration.
In 1963, in the Barraquer ophthalmologic clinic (Bogotá,Colombia) Ignacio Barraquer
developed the first proficient refractive surgery technique called keratomileusis,
meaning corneal reshaping (from the Greek Kerato: cornea and Mileusis: to sculpt).
Keratomileusis allowed correction of not only myopia but also hyperopia. These early
surgeries removed a corneal layer, froze it so it could be manually sculpted in the
required shape, and finally reimplanted the layer (Keratomileusis with freezing).
While this form of surgery was later improved by Dr. Swinger in 1986
4
(keratomileusis without freezing)[citation needed], it was still a relatively imprecise
technique.
Meanwhile, experiments in 1970 using a xenon dimer and in 1975 using noble gas
halides resulted in the invention of a type of laser called an excimer laser. While
excimer lasers were initially used for industrial purposes, in 1980, R. Srinivasan, a
scientist of IBM who was using an excimer laser to make microscopic circuits in
microchips for informatics equipment, discovered that the excimer could also be used
to cut organic tissues with high accuracy without significant thermal damage. The
discovery of an effective biological cutting laser, along with the development of
computers to control it, allowed new refractive techniques which were previously
unavailable. In 1983, scientist Stephen Trokel of Columbia University in
collaboration with Srinivasan performed the first Photorefractive Keratectomy (PRK)
or keratomileusis in situ (without separation of corneal layer) in Germany. The first
patent for LASIK was granted by the US Patent Office to Gholam A. Peyman, MD on
June 20, 1989, US Patent #4,840,175, "METHOD FOR MODIFYING CORNEAL
CURVATURE", describing the surgical procedure in which a flap is cut in the cornea
and pulled back to expose the corneal bed. This exposed surface is then ablated to the
desired shape with an excimer laser, following which the flap is replaced. In 1991
Creta University and the Vardinoyannion Eye coined the name "LASIK".
[edit] Techniques
[edit] Flap procedures
Excimer laser ablation is done under a partial-thickness lamellar corneal flap.


Automated lamellar keratoplasty (ALK): The surgeon uses an instrument
called a microkeratome to cut a thin flap of the corneal tissue. The flap is lifted
like a hinged door, targeted tissue is removed from the corneal stroma, again
with the microkeratome, and then the flap is replaced.
Laser Assisted In-Situ Keratomileusis (LASIK): The surgeon uses a
microkeratome to cut a flap of the corneal tissue (usually with a thickness of
100-180 micrometres). The flap is lifted like a hinged door, but in contrast to
ALK, the targeted tissue is removed from the corneal stroma with an excimer
laser. The flap is subsequently replaced. Another method of creating this flap
is by using a procedure called IntraLasik, in which a femtosecond laser is used
to create the flap. Proponents of this method assert its superiority over
"traditional" LASIK, but there have been no conclusive independent studies to
prove that this is a true statement.[citation needed]
[edit] Surface procedures
The excimer laser is used to ablate the most anterior portion of the corneal stroma.
These procedures do not require a partial thickness cut into the stroma. Surface
ablation methods differ only in the way the epithelial layer is handled.
5



Photorefractive keratectomy (PRK) is an outpatient procedure generally
performed with local anesthetic eye drops (as with LASIK/LASEK) . It is a
type of refractive surgery which reshapes the cornea by removing microscopic
amounts of tissue from the corneal stroma, using a computer-controlled beam
of light (excimer laser). The difference from LASIK is that the top layer of the
epithelium is removed (and a bandage contact lens is used), so no flap is
created. Recovery time is longer with PRK than with LASIK, though the final
outcome (after 3 months) is about the same (very good). More recently,
customized ablation has been performed with LASIK, LASEK, and PRK.
Laser Assisted Sub-Epithelium Keratomileusis (LASEK) is a procedure that
also changes the shape of the cornea using an excimer laser to ablate the tissue
from the corneal stroma, under the corneal epithelium, which is kept mostly
intact to act as a natural bandage. The surgeon uses an alcohol solution to
loosen then lift a thin layer of the epithelium with a trephine blade (usually
with a thickness of 50 micrometres).[2] During the weeks following LASEK,
the epithelium heals, leaving no permanent flap in the cornea. This healing
process can involve discomfort comparable to that with PRK.
EPI-LASIK is a new technique similar to LASEK that uses an epi-keratome
(rather than a trephine blade and alcohol), to remove the top layer of the
epithelium (usually with thickness of 50 micrometres), which is subsequently
replaced. For some people it can provide better results than regular LASEK in
that it avoids the possibility of negative effects from the alcohol, and recovery
may involve less discomfort.
[edit] Corneal incision procedures

Radial keratotomy (RK) uses spoke-shaped incisions (usually made with a
diamond knife) to alter the shape of the cornea and reduce myopia or
astigmatism; this technique has now been largely replaced by the other
methods (that use excimer laser).

Arcuate keratotomy (AK) is similar to radial keratotomy, but the incisions on
the cornea are done at the periphery of the cornea. Arcuate keratotomy is used
to correct astigmatism. Although most incisional procedures are replaced
nowadays by Lasik, AK is still used in some special cases (correction of
residual astigmatism after a keratoplasty procedure or during cataract surgery).

Limbal relaxing incisions (LRI) are incisions near the outer edge of the iris,
used to correct minor astigmatism (typically less than 2 diopters). This is often
performed in conjunction with an Intraocular Lens implantation.
[edit] Other procedures


Thermal keratoplasty is used to correct hyperopia by putting a ring of 8 or 16
small burns surrounding the pupil, and steepen the cornea with a ring of
collagen constriction. It can also be used to treat selected types of astigmatism.
Laser thermal keratoplasty (LTK) is a non-touch thermal keratoplasty
performed with a Holmium laser, while conductive keratoplasty (CK) is
thermal keratoplasty performed with a high-frequency electric probe. Thermal
6



keratoplasty can also be used to improve presbyopia or reading vision after
age 40.
Intrastromal corneal ring segments (Intacs) are approved by FDA for treatment
of low degrees of myopia.
Lens implantation inside the eye can also be used to change refractive errors.
Generally refractive surgery can be broadly divided into : corneal surgery,
scleral surgery, lens realated surgery( including phakic IOL implantation, clear
lens extraction, photophacoreduction and photophacomodulation for
correction of pesbyopia)
[edit] Expectations
The Council for Refractive Surgery Quality Assurance - an independent, nonprofit,
patient/consumer health organization that provides information about refractive
surgery and certifies LASIK surgeons - considers surgeons to have met the US
national norms if 90% of their patients achieve 20/40 vision or better and 65% of their
patients achieve 20/20 vision or better, with less than approximately 3% of their
refractive surgery patients experiencing a surgery induced complication at six months
after surgery, and less than 0.5% being serious complications requiring extensive
maintenance or invasive treatment.[3]
Many people with myopia are able to read comfortably without eyeglasses. Myopes
considering refractive surgery are advised that this may be a disadvantage after the
age of 40 when the eyes become presbyopic and lose their ability to accommodate or
change focus.
[edit] Risks
While refractive surgery is becoming more affordable and safe, it may not be
recommended for everybody. Patients that have medical conditions such as glaucoma
or diabetes, uncontrolled vascular disease, autoimmune disease, pregnant women or
people with certain eye diseases involving the cornea or retina, are not good
candidates for refractive surgery. Keratoconus, a progressive thinning of the cornea, is
a common corneal disorder. It is believed that additional thinning of the cornea via
refractive surgery may contribute to advancement of the disease,[4] that may lead to
the need for a corneal transplant. Therefore, keratoconus is a contraindication to
refractive surgery. Corneal topography, pachymetry and, more recently, Pentacam
exams are used to screen for abnormal corneas. Furthermore, some people's eye shape
may not permit effective refractive surgery without removing excessive amounts of
corneal tissue. Those considering laser eye surgery should have a full eye
examination.
Although the risk of complications is decreasing compared to the early days of
refractive surgery,[5] there is still a small chance for serious problems. These include
vision problems such as ghosting, halos, starbursts, double-vision, and dry-eye
syndrome.[6] With procedures that create a permanent flap in the cornea (such as
LASIK), there is also the possibility of accidental traumatic flap displacement years
after the surgery,[7] with potentially disastrous results if not given prompt medical
attention.[8]
7
1.
^
See also: LASIK or Lasik (laser-assisted in situ keratomileusis) is a type of
refractive surgery for correcting myopia, hyperopia, and astigmatism. LASIK is
performed by ophthalmologists using a laser.[1] The procedure is generally preferred
to photorefractive keratectomy, PRK, (also called ASA, Advanced Surface Ablation)
because it requires less time for the patient's recovery, and the patient feels less pain
overall. However, there are special instances where a PRK/ASA procedure is
medically justified as being a better alternative to LASIK.[citation needed]
Many patients choose LASIK as an alternative to wearing corrective eyeglasses or
contact lenses.
Contents
[hide]










1 Technology
2 Procedure
o 2.1 Preoperative
o 2.2 Operation
 2.2.1 Flap creation
 2.2.2 Laser remodeling
 2.2.3 Repositioning of flap
o 2.3 Postoperative care
3 Higher-order aberrations
o 3.1 Wavefront-guided LASIK
o 3.2 Topography-guided Lasik
4 LASIK surgery results
5 Safety and efficacy
6 Patient dissatisfaction
7 Potential complications
o 7.1 Intraoperative complications
o 7.2 Early postoperative complications
o 7.3 Late postoperative complications
o 7.4 Other
o 7.5 Factors affecting surgery
o 7.6 Age considerations
8 References
9 See also
10 External links
[edit] Technology
The LASIK technique was made possible by the Colombia-based Spanish
ophthalmologist Jose Barraquer, who, around 1950 in his clinic in Bogotá, Colombia,
8
developed the first microkeratome, and developed the technique used to cut thin flaps
in the cornea and alter its shape, in a procedure he called keratomileusis. Barraquer
also researched the question of how much of the cornea had to be left unaltered to
provide stable long-term results.
Later technical and procedural developments included RK (radial keratotomy),
developed in Russia in the 1970s by Svyatoslav Fyodorov, and PRK (photorefractive
keratectomy), developed in 1983 at Columbia University by Dr. Steven Trokel, who
in addition published an article in the American Journal of Ophthalmology in 1983
outlining the potential benefits of using the Excimer laser patented in 1973 by Mani
Lal Bhaumik in refractive surgeries. (RK is a procedure in which radial corneal cuts
are made, typically using a micrometer diamond knife, and is completely different
from LASIK).
In 1968 at the Northrop Corporation Research and Technology Center of the
University of California, Mani Lal Bhaumik and a group of scientists were working
on the development of a carbon-dioxide laser. Their work evolved into what would
become the Excimer laser. This type of laser would become the cornerstone for
refractive eye surgery. Dr. Bhaumik announced his team's breakthrough in May 1973
at a meeting of the Denver Optical Society of America in Denver, Colorado. He
would later patent his discovery.[2]
The general term for changing a patient's optical measurements by means of an
operation is Refractive Surgery. The introduction of lasers in refractive surgeries
stemmed from Rangaswamy Srinivasan's work. In 1980, Srinivasan, working at IBM
Research Lab, discovered that an ultraviolet Excimer laser could etch living tissue in a
precise manner with no thermal damage to the surrounding area. He named the
phenomenon Ablative Photodecomposition (APD).[3]
The first patent for LASIK was granted by the U.S. Patent Office to Dr. Gholam A.
Peyman on June 20, 1989, U.S. Patent #4,840,175, "Method for modifying corneal
curvature," encompassing the surgical procedure in which a flap is cut in the cornea
and pulled back to expose the corneal bed. The exposed surface is then ablated to the
desired shape with an Excimer laser, after which the flap is replaced.[citation needed]
The LASIK technique was successfully applied in other countries before it arrived to
the United States. The first U.S. Food and Drug Administration (FDA) trial of the
Excimer laser was started in 1989. The first use of the laser was to change the surface
shape of the cornea, known as PRK. Dr. Joseph Dello Russo was one of the ten
original FDA researchers who tested and got approval for the Visx laser. The LASIK
concept was first introduced by Dr. Pallikaris in 1992 to the group of ten surgeons
who were selected by the FDA to test the Visx laser at 10 centers in the U.S.
Dr. Pallikaris theorized the benefits of performing PRK after the surface was raised in
a layer to be known as a flap performed by the Mikrokeratome developed by
Barraquer in 1950. The blending of a flap and PRK became known as LASIK, which
is an acronym. It quickly became very popular, since it provided immediate
improvements in vision and involved much less pain and discomfort than PRK.
9
Today, faster lasers, larger spot areas, bladeless flap incisions, intraoperative
pachymetry, and wavefront-optimized and -guided techniques have significantly
improved the reliability of the procedure compared to that of 1991. Nonetheless, the
fundamental limitations of Excimer lasers and undesirable destruction of the eye's
nerves have spawned research into many alternatives to "plain" LASIK, including
LASEK, Epi-LASIK, sub-Bowman’s Keratomileusis aka thin-flap LASIK,
wavefront-guided PRK and modern intraocular lenses.
LASIK may one day be replaced by intrastromal ablation[4] via all-femtosecond
correction (like Femtosecond Lenticule Extraction, FLIVC, or IntraCOR), or other
techniques that avoid weakening the cornea with large incisions and deliver less
energy to surrounding tissues. The 20/10 (now Technolas) FEMTEC laser has
recently been used for incision-less IntraCOR ablation on several hundred human
eyes and achieved very successful results for presbyopia,[5] with trials ongoing for
myopia and other disorders.[6]
[edit] Procedure
There are several necessary preparations in the preoperative period. The operation
itself involves creating a thin flap on the eye, folding it to enable remodeling of the
tissue beneath with a laser. The flap is repositioned and the eye is left to heal in the
postoperative period.
[edit] Preoperative
Patients wearing soft contact lenses are usually instructed to stop wearing them 5 to
21 days before surgery. One industry body recommends that patients wearing hard
contact lenses should stop wearing them for a minimum of six weeks plus another six
weeks for every three years the hard contacts have been worn.[7] Before the surgery,
the patient's corneas are examined with a pachymeter to determine their thickness, and
with a topographer to measure their surface contour. Using low-power lasers, a
topographer creates a topographic map of the cornea. This process also detects
astigmatism and other irregularities in the shape of the cornea. Using this information,
the surgeon calculates the amount and the locations of corneal tissue to be removed
during the operation. The patient typically is prescribed and self-administers an
antibiotic beforehand to minimize the risk of infection after the procedure.
[edit] Operation
The operation is performed with the patient awake and mobile; however, the patient is
sometimes given a mild sedative (such as Valium) and anesthetic eye drops.
LASIK is performed in three steps. The first step is to create a flap of corneal tissue.
The second step is remodeling of the cornea underneath the flap with the laser.
Finally, the flap is repositioned.
10
[edit] Flap creation
A corneal suction ring is applied to the eye, holding the eye in place. This step in the
procedure can sometimes cause small blood vessels to burst, resulting in bleeding or
subconjunctival hemorrhage into the white (sclera) of the eye, a harmless side effect
that resolves within several weeks. Increased suction typically causes a transient
dimming of vision in the treated eye. Once the eye is immobilized, the flap is created.
This process is achieved with a mechanical microkeratome using a metal blade, or a
femtosecond laser microkeratome (procedure known as IntraLASIK) that creates a
series of tiny closely arranged bubbles within the cornea.[8] A hinge is left at one end
of this flap. The flap is folded back, revealing the stroma, the middle section of the
cornea. The process of lifting and folding back the flap can sometimes be
uncomfortable.
[edit] Laser remodeling
The second step of the procedure is to use an Excimer laser (193 nm) to remodel the
corneal stroma. The laser vaporizes tissue in a finely controlled manner without
damaging the adjacent stroma. No burning with heat or actual cutting is required to
ablate the tissue. The layers of tissue removed are tens of micrometres thick.
Performing the laser ablation in the deeper corneal stroma typically provides for more
rapid visual recovery and less pain than the earlier technique, photorefractive
keratectomy (PRK).
During the second step, the patient's vision will become very blurry once the flap is
lifted. They will be able to see only white light surrounding the orange light of the
laser, which can lead to mild disorientation.
Currently, manufactured Excimer lasers use an eye tracking system that follows the
patient's eye position up to 4,000 times per second, redirecting laser pulses for precise
placement within the treatment zone. Typical pulses are around 1 millijoule (mJ) of
pulse energy in 10 to 20 nanoseconds.[9]
[edit] Repositioning of flap
After the laser has reshaped the stromal layer, the LASIK flap is carefully
repositioned over the treatment area by the surgeon and checked for the presence of
air bubbles, debris, and proper fit on the eye. The flap remains in position by natural
adhesion until healing is completed.
[edit] Postoperative care
Patients are usually given a course of antibiotic and anti-inflammatory eye drops.
These are continued in the weeks following surgery. Patients are usually told to sleep
much more and are also given a darkened pair of shields to protect their eyes from
bright lights and protective goggles to prevent rubbing of the eyes when asleep and to
reduce dry eyes. They also are required to moisturize the eyes with preservative-free
tears and follow directions for prescription drops. Patients should be adequately
11
informed by their surgeons of the importance of proper post-operative care to
minimize the risk of complications.
[edit] Higher-order aberrations
Higher-order aberrations are visual problems that cannot be diagnosed using a
traditional eye exam, which tests only for acuteness of vision. Severe aberrations can
cause significant vision impairment. These aberrations include starbursts, ghosting,
halos, double vision, and a number of other post-operative complications.
There have always been concerns about LASIK because of its tendency to induce
higher-order aberrations. The advancement of the LASIK technology has helped
reduce the risk of clinically significant visual impairment after surgery. There is a
correlation between pupil size and aberrations.[10] Effectively, the larger the pupil size,
the greater the risk of aberrations. This correlation is the result of the irregularity
between the untouched part of the cornea and the reshaped part. Daytime post-lasik
vision is optimal, since the pupil is smaller than the LASIK flap. But at night, the
pupil may expand such that light passes through the edge of the LASIK flap into the
pupil which gives rise to many aberrations, including the appearance of halos
surrounding sources of light. There are other currently unknown factors in addition to
pupil size that also may lead to higher order aberrations.
In extreme cases in which ideal procedures were not followed by ophthalmologists,
and before key advances, some people could suffer debilitating symptoms such as
serious loss of contrast sensitivity in poor lighting situations.
Over time, most attention has shifted from other aberrations and centered on spherical
aberration. LASIK and PRK tend to induce spherical aberration, because of the
tendency of the laser to undercorrect as it moves outward from the center of the
treatment zone. This is primarily an issue for major corrections. There are theories
that posit that if the lasers were simply programmed to adjust for this tendency, no
significant spherical aberration would occur. In eyes with few higher order
aberrations, wavefront-optimized LASIK (rather than wavefront-guided LASIK) may
well be the future.[citation needed]
Higher order aberrations are measured in micrometers (µm) on the wavescan taken
during the pre-op examination, while the smallest beam size of lasers approved by the
U.S. Food and Drug Administration lasers is about 1000 times larger, at 0.65 mm.
Thus imperfections are inherent in the procedure and a reason why patients
experience halo, glare, and starburst, even with small naturally-dilated pupils in dim
lighting.
[edit] Wavefront-guided LASIK
Wavefront-guided LASIK[11] is a variation of LASIK surgery in which, rather than
applying a simple correction of focusing power to the cornea (as in traditional
LASIK), an ophthalmologist applies a spatially varying correction, guiding the
computer-controlled Excimer laser with measurements from a wavefront sensor. The
goal is to achieve a more optically perfect eye, though the final result still depends on
12
the physician's success at predicting changes which occur during healing. In older
patients though, scattering from microscopic particles plays a major role and may
outweigh any benefit from wavefront correction. Therefore, patients expecting socalled "super vision" from such procedures may be disappointed. Still, surgeons claim
patients are generally more satisfied with this technique than with previous methods,
particularly regarding lowered incidence of "halos," the visual artifact caused by
spherical aberration induced in the eye by earlier methods. Currently, there is no
research in support of the surgeons' claims.
[edit] Topography-guided Lasik
Topography-guided Lasik[12] is a custom Lasik surgery. In many circumstances, high
order aberrations are due to corneal surface irregularities eg: corneal trauma, corneal
ulcers, and previous corneal surgeries etc...In these cases the ophthalmologist better
address the treatment to the source of aberration which is the irregular cornea; using a
special instrument he calculate a corneal Topography map showing elevations in
about 22000 different points and determine exactly any corneal surface anomaly.
These data are then transferred to the computer-controlled Excimer laser system to
produce a custom Lasik ablation profile correcting both the low and high corneal
aberrations. This corneal custom treatment is as good as wavefront-guided treatment
but with the major advantage to ablate less corneal tissue.
[edit] LASIK surgery results
The surveys determining patient satisfaction with LASIK have found most patients
satisfied, with satisfaction range being 92–98 percent.[13][14][15][16] A meta-analysis
dated March 2008 performed by the American Society of Cataract and Refractive
Surgery over 3,000 peer-reviewed articles published over the past 10 years in clinical
journals from around the world, including 19 studies comprising 2,200 patients that
looked directly at satisfaction, revealed a 95.4 percent patient satisfaction rate among
LASIK patients worldwide. [17]
[edit] Safety and efficacy
The reported figures for safety and efficacy are open to interpretation. In 2003, the
Medical Defence Union (MDU), the largest insurer for doctors in the United
Kingdom, reported a 166 percent increase in claims involving laser eye surgery;
however, the MDU averred that these claims resulted primarily from patients'
unrealistic expectations of LASIK rather than faulty surgery.[18] A 2003 study,
reported in the medical journal Ophthalmology, found that nearly 18 percent of
treated patients and 12 percent of treated eyes needed retreatment.[19] The authors
concluded that higher initial corrections, astigmatism, and older age are risk factors
for LASIK retreatment.
In 2004, the British National Health Service's National Institute for Health and
Clinical Excellence (NICE) considered a systematic review of four randomized
controlled trials[20][21] before issuing guidance for the use of LASIK within the
NHS.[22] Regarding the procedure's efficacy, NICE reported, "Current evidence on
LASIK for the treatment of refractive errors suggests that it is effective in selected
13
patients with mild or moderate short-sightedness," but that "evidence is weaker for its
effectiveness in severe short-sightedness and long-sightedness." Regarding the
procedure's safety, NICE reported that "there are concerns about the procedure's
safety in the long term and current evidence does not appear adequate to support its
use within the NHS without special arrangements for consent and for audit or
research."
Leading refractive surgeons in the United Kingdom and United States, including at
least one author of a study cited in the report, believe NICE relied on information that
is severely dated and weakly researched.[23][24]
On October 10, 2006, WebMD reported that statistical analysis revealed that contact
lens wear infection risk is greater than the infection risk from LASIK.[25] Daily
contact lens wearers have a 1-in-100 chance of developing a serious, contact lensrelated eye infection in 30 years of use, and a 1-in-2,000 chance of suffering
significant vision loss as a result of infection. The researchers calculated the risk of
significant vision loss consequence of LASIK surgery to be closer to 1-in-10,000
cases.
[edit] Patient dissatisfaction
Some patients with poor outcomes from LASIK surgical procedures report a
significantly reduced quality of life because of vision problems. Patients who have
suffered LASIK complications have created websites and discussion forums to
educate the public about the risks, where prospective and past patients can discuss the
surgery. In 1999, Surgical Eyes[26] was founded[27] in New York City[28] by RK patient
Ron Link[29] as a resource for patients with complications of LASIK and other
refractive surgeries. Most experienced and reputable clinics will do a full-dilation
medical eye exam prior to surgery and give adequate post-operative patient education
care to minimize the risk of a negative outcome.
For best results, Steven C. Schallhorn, an ophthalmologist who oversaw the US
Navy's refractive surgery program and whose research partly influenced the Navy's
decision to allow its aviators to get LASIK, recommends patients seek out what's
called "all-laser Lasik" combined with "wavefront-guided" software.[30][31]
The FDA website on LASIK clearly states: "Before undergoing a refractive
procedure, you should carefully weigh the risks and benefits based on your own
personal value system, and try to avoid being influenced by friends that have had the
procedure or doctors encouraging you to do so."[32] Consequently, prospective
patients still need to fully understand all the potential issues and complications, as
satisfaction is directly related to expectation.
The FDA received 140 "negative reports relating to LASIK" for the time period
1998–2006.[33]
[edit] Potential complications
14
A subconjunctival hemorrhage is a common and minor post-LASIK complication.
The most common complication from refractive surgery is the incidence of "dry
eyes." According to an American Journal of Ophthalmology study of March 2006, the
incidence rate of dry eyes from LASIK after the six month post operative healing
period was 36.36%.[34]. The FDA (Food and Drugs Administration) website states that
"dry eyes" may be permanent.[35]
The high incidence of dry eyes necessitates a proper preoperative and post operative
evaluation and treatment for dry eyes. There are a number of successful treatments for
dry eyes including artificial tears, prescription tears and punctal occlusion. Punctal
occlusion is accomplished by placing a collagen plug in the natural drain of the eye.
Dry eyes, if left untreated can compromise the visual outcome and result in regression
of the effect of LASIK or PRK, or in severe cases result in "chronic dry eye" where
permanent chronic pain and visual impairment is a possible outcome. It also must be
noted that some incidences of dry eye cannot be successfully mitigated using the
above mentioned techniques, so a potential lasik patient must consider that dry eye
can be permanent outcome and untreatable.
The risk for a patient of suffering from disturbing visual side effects such as halos,
double vision (ghosting), loss of contrast sensitivity (foggy vision) and glare after
LASIK depends on the degree of ametropia before the laser eye surgery and other risk
factors.[36] For this reason, it is important to take into account the individual risk
potential of a patient and not just the average probability for all patients.[37] The
following are some of the more frequently reported complications of LASIK[38][39]:
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Surgery induced dry eyes
Overcorrection[40] or undercorrection
Very Low level vitamin D - Sun sensitivity
Visual acuity fluctuation
Halos[41] or starbursts[42] around light sources at night
Light sensitivity
Ghost images[43] or double vision
Wrinkles in flap (striae)[44]
Decentered ablation
Debris or growth under flap
Thin or buttonhole flap [45]
Induced astigmatism
Corneal Ectasia
Floaters
Epithelium erosion
Posterior vitreous detachment[46]
15
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Macular hole[47]
Complications due to LASIK have been classified as those that occur due to
preoperative, intraoperative, early postoperative, or late postoperative sources:[48]
[edit] Intraoperative complications
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The incidence of flap complications has been estimated to be 0.244%.[49] Flap
complications (such as displaced flaps or folds in the flaps that necessitate
repositioning, diffuse lamellar keratitis, and epithelial ingrowth) are common
in lamellar corneal surgeries[50] but rarely lead to permanent visual acuity loss;
the incidence of these microkeratome-related complications decreases with
increased physician experience.[51][52] According to proponents of such
techniques, this risk is further reduced by the use of IntraLasik and other nonmicrokeratome related approaches, although this is not proven and carries its
own set of risks of complications from the IntraLasik procedure.
A slipped flap (a corneal flap that detaches from the rest of the cornea) is one
of the most common complications. The chances of this are greatest
immediately after surgery, so patients typically are advised to go home and
sleep to let the flap heal. Patients are usually given sleep goggles or eye
shields to wear for several nights to prevent them from dislodging the flap in
their sleep. A faster operation may decrease the chance of this complication, as
there is less time for the flap to dry.
Flap interface particles are another finding whose clinical significance is
undetermined.[53] A Finnish study found that particles of various sizes and
reflectivity were clinically visible in 38.7% of eyes examined via slit lamp
biomicroscopy, but apparent in 100% of eyes using confocal microscopy.[53]
[edit] Early postoperative complications
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The incidence of diffuse lamellar keratitis (DLK)[54], also known as the Sands
of Sahara syndrome, has been estimated at 2.3%.[55] DLK is an inflammatory
process that involves an accumulation of white blood cells at the interface
between the LASIK flap and the underlying corneal stroma. It is most
commonly treated with steroid eye drops, and sometimes it is necessary for the
eye surgeon to lift the flap and manually remove the accumulated cells.
The incidence of infection responsive to treatment has been estimated at
0.4%.[55] Infection under the corneal flap is possible. It is also possible that a
patient has the genetic condition keratoconus that causes the cornea to thin
after surgery. Although this condition is screened in the preoperative exam, it
is possible in rare cases (about 1 in 5,000)[citation needed] for the condition to
remain dormant until later in life (the mid-40s). If this occurs, the patient may
need rigid gas permeable contact lenses, Intrastromal Corneal Ring Segments
(Intacs),[56] Corneal Collagen Crosslinking with Riboflavin[57] or a corneal
transplant.
The incidence of persistent dry eye has been estimated to be as high as 28% in
Asian eyes and 5% in Caucasian eyes.[58] Nerve fibers in the cornea are
important for stimulating tear production. A year after LASIK, subbasal nerve
fiber bundles remain reduced by more than half.[59] Some patients experience
16

reactive tearing, in part to compensate for chronic decreased basal wetting tear
production.
The incidence of subconjunctival hemorrhage has been estimated at 10.5%
[55]
(according to a study undertaken in China; thus results may not be generally
applicable due to racial and geographic factors).
[edit] Late postoperative complications
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The incidence of epithelial ingrowth has been estimated at 0.1%.[55]
Glare is another commonly reported complication of those who have had
LASIK.[13]
Halos or starbursts around bright lights at night are caused by the irregularity
between the lasered part and the untouched part. It is not practical to perform
the surgery so that it covers the width of the pupil at full dilation at night, and
the pupil may expand so that light passes through the edge of the flap into the
pupil.[60] In daytime, the pupil is smaller than the edge. Modern equipment is
better suited to treat those with large pupils, and responsible physicians will
check for them during examination.
Late traumatic flap dislocations have been reported 1–7 years post-LASIK.[61]
Dry eye or in severe cases Chronic Dry eye. Due to nerves that are severed
during the Lasik operation (around 70% of corneal nerves are severed), the
lubrication system of the eye is affected and nerves may never recover to preoperative condition. This may leave the patient with potential permanent dry
eyes.
[edit] Other
Lasik and other forms of laser refractive surgery (i.e. PRK, LASEK and Epi-LASEK)
change the dynamics of the cornea. These changes make it difficult for your
optometrist and ophthalmologist to accurately measure your intraocular pressure,
essential in glaucoma screening and treatment. The changes also affect the
calculations used to select the correct intraocular lens implant when you have cataract
surgery. This is known to ophthalmologists as "refractive surprise." The correct
intraocular pressure and intraocular lens power can be calculated if you can provide
your eye care professional with your preoperative, operative and postoperative eye
measurements.
Although there have been improvements in LASIK technology[62][63][64], a large body
of conclusive evidence on the chances of long-term complications is not yet
established. Also, there is a small chance of complications, such as haziness, halo, or
glare, some of which may be irreversible because the LASIK eye surgery procedure is
irreversible.
The incidence of macular hole has been estimated at 0.2 percent[47] to 0.3 percent.[65]
The incidence of retinal detachment has been estimated at 0.36 percent.[65] The
incidence of choroidal neovascularization has been estimated at 0.33 percent.[65] The
incidence of uveitis has been estimated at 0.18 percent[66]
Although the cornea usually is thinner after LASIK, because of the removal of part of
the stroma, refractive surgeons strive to maintain the maximum thickness to avoid
17
structurally weakening the cornea. Decreased atmospheric pressure at higher altitudes
has not been demonstrated as extremely dangerous to the eyes of LASIK patients.
However, some mountain climbers have experienced a myopic shift at extreme
altitudes.[67][68]
In situ keratomileusis effected at a later age increases the incidence of corneal higherorder wavefront aberrations.[69][70] Conventional eyeglasses do not correct higher
order aberrations.
Microfolding has been reported as "an almost unavoidable complication of LASIK"
whose "clinical significance appears negligible."[53]
Blepharitis, or inflammation of the eyelids with crusting of the eyelashes, may
increase the risk of infection or inflammation of the cornea after LASIK.[citation needed]
Myopic (nearsighted) people who are close to the age (mid- to late-forties) when they
will require either reading glasses or bifocal eyeglasses may find that they still require
reading glasses despite having undergone refractive LASIK surgery. Myopic people
generally require reading glasses or bifocal eyeglasses at a later age than people who
are emmetropic (those who see without eyeglasses), but this benefit may be lost if
they undergo LASIK. This is not a complication but an expected result of the physical
laws of optics. Although there is currently no method to completely eradicate the need
for reading glasses in this group, it may be minimized by performing a variation of the
LASIK procedure called "slight monovision." In this procedure, which is performed
exactly like distance-vision-correction LASIK, the dominant eye is set for distance
vision, while the non-dominant eye is set to the prescription of the patient's reading
glasses. This allows the patient to achieve a similar effect as wearing bifocals. The
majority of patients tolerate this procedure very well and do not notice any shift
between near and distance viewing, although a small portion of the population has
trouble adjusting to the monovision effect. This can be tested for several days prior to
surgery by wearing contact lenses that mimic the monovision effect. Recently, a
variation of the laser ablation pattern called presbyLASIK, has been developed to
reduce or eliminate dependence on reading glasses while retaining distance vision
There are reports of decrease in the number of corneal keratocytes (fibroblasts) after
LASIK.[71]
[edit] Factors affecting surgery
Typically, the cornea is avascular because it must be transparent to function normally,
and its cells absorb oxygen from the tear film. Thus, low-oxygen-permeable contact
lenses reduce the cornea's oxygen absorption, sometimes resulting in corneal
neovascularization—the growth of blood vessels into the cornea. This causes a slight
lengthening of inflammation duration and healing time and some pain during surgery,
because of greater bleeding.
Although some contact lenses (notably modern RGP and soft silicone hydrogel
lenses) are made of materials with greater oxygen permeability that help reduce the
risk of corneal neovascularization, patients considering LASIK are warned to avoid
18
over-wearing their contact lenses. Usually, it is recommended that they discontinue
wearing contact lenses days or weeks before the LASIK eye surgery.
A 2004 Wake Forest University study established that heat and humidity affect
LASIK surgery results, both during the procedure and in the two weeks before the
surgery.[72]
[edit] Age considerations
New advances in eyesight corrective surgery are providing consumers greater choices.
Patients in their 40s or 50s who are considering LASIK surgery to improve their
vision might want to consider to be evaluated for implantable lenses as well. "Early
signs of a cataract might argue for surgery and implantation of multifocal lenses
instead." [73]
The FDA has approved LASIK for age 18 and over[74]. More importantly the person's
eye needs to be stable for two years prior to surgery.
2. NET.com
19