HEALINGphase. PRK is particularly effective for
people who have large pupils or thin corneas,
because it does not create a corneal flap, which
reduces the likelihood of postoperative glare
and halos at night.- Automated lamellar keratoplasty (ALK) is simi-
lar in concept to LASIK, though the surgeon
uses a microkeratome, a specialized surgical
blade. The eye surgeon makes a flap in the
cornea and removes minute segments of
corneal tissue, then replaces the flap. As with
LASIK, there is little discomfort during healing
and results are apparent immediately. ALK is
particularly successful for severe myopia.
•LENS replacement uses techniques perfected
through 60 years of CATARACT EXTRACTION AND
LENS REPLACEMENT surgery. The eye surgeon
removes the natural lens and replaces it with
one curved to accommodate for severe hyper-
opia or myopia. Multifocal lens implants allow
the eye to adjust between close and distant
vision.
- Phakic intraocular contact lens implantation
places a permanent contact lens in front of or
behind the natural lens to supplement its focus-
ing ability. This approach preserves the focusing
ability of the natural lens.
The eye surgeon may choose other methods,
depending on an individual’s refractive situation,
age, and general health status. Not everyone with
refractive errors is a good candidate for refractive
surgery. It is important to consult with a qualified
and experienced eye surgeon and to understand
the potential risks and benefits of the different
operations. Refractive surgery permanently alters
the eye’s structure, although subsequent opera-
tions can often refine the effects when they are
not as expected. Severe refractive errors may
require multiple procedures.
Risks and ComplicationsAs with any surgery, a potential complication of
refractive surgery is postoperative INFECTION that
can range from mild discomfort to significant
damage to the eye with resulting VISION
IMPAIRMENT. Prompt treatment prevents further
complications. Most eye surgeons have stringent
follow-up procedures intended to detect operative
complications before they cause eye problems; it is
important to maintain the recommended follow-
up procedures. Other common complications
include dry eyes and seeing halos around lights at
night. Procedures involving lens replacement
carry the additional risks of excessive bleeding and
RETINAL DETACHMENT, which can compromise vision.
Complications particular to LASIK include irregu-
larity in the corneal surface after the corneal flap
heals and overgrowth of corneal tissue that
requires subsequent surgery to remove.
Occasionally the outcome is not as desired or
expected, perhaps as a consequence of complica-
tions during the operation or during the healing
process. It is important for the eye surgeon to
appropriately match the person with the proce-
dure, which takes into consideration the nature
and severity of the refractive error, the person’s
age and general health status, and the person’s
expectations. Despite the precision of computer-
guided procedures, there remains an element of
unpredictability that influences outcome. Some
people may find their vision undercorrected and
others overcorrected as a consequence of individ-
ual variation in eye structure, refractive error, and
healing process.
Though the changes of refractive surgery are
permanent, the effects on vision are not. Everyone
eventually acquires PRESBYOPIA, a decrease in the
ability to focus on near objects that is a function of
change that occurs with aging. People who have
had refractive surgery to correct astigmatism,
hyperopia, or myopia will still need corrective
measures for close vision as presbyopia develops.
Nonsurgical solutions for presbyopia include con-
tact lenses or reading glasses. Surgical solutions for
presbyopia currently employ an approach called
monovision, in which the eye surgeon undercor-
rects the vision in one eye for near focus. The
refractive correction for the other eye is full,
allowing for distant focus. The BRAIN does the
work of switching between the eyes according to
the vision needs.Outlook and Lifestyle Modifications
Refractive surgery dramatically improves visual
acuity for nearly everyone who has a successful
surgical experience—that is, was properly112 The Eyes