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Saturday, November 26, 2011

LASIK SURGERY

DOC I HAVE LASIK SURGERY

LASIK (an acronym for laser-assisted in situ keratomileusis) is a type of refractive surgery done by ophthalmologists for correcting myopia, hyperopia, and astigmatism using excimer laser.

The LASIK technique use of the laser was to change the surface shape of the cornea first done in 1991.

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.

Preoperative:
Patients who are wearing soft contact lenses are instructed to stop wearing them 5 to 21 days before operation.

The patient's corneas are examined with a pachymeter to determine their thickness and to measure their surface contour.

This process also discover astigmatism and other irregularities in the shape of the cornea.

With this information the eye surgeon calculates the amount and the locations of corneal tissue to be removed during the operation.

The patient typically is given a course of antibiotic beforehand to minimize the risk of infection.

Operation:
The operation is performed when the patient is awake and mobile although he/she is sometimes given a mild sedative (such as Valium) and anesthetic eye drops.

LASIK is performed in three steps.
A corneal suction ring is applied to the eye, holding the eye in place.
1.create a flap of corneal tissue.

Once the eye is immobilized, the flap is created with a mechanical microkeratome using a metal blade, or a femtosecond laser microkeratome that creates a series of tiny closely arranged bubbles within the cornea.
A hinge is left at one end of this flap.
The flap is folded back, revealing the stroma, the middle section of the cornea.

2.remodeling of the cornea underneath the flap with the laser.
An excimer laser (193 nm) is used to remodel the corneal stroma.
The laser vaporizes tissue in a finely controlled manner without damaging the adjacent stroma.

3.the flap is repositioned.
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.
This flap stays in position by natural adhesion until healing is completed.

Postoperative care:
Patients are usually given a course of antibiotic and anti-inflammatory eye drops.
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.
Proper post-operative care is important to prevent the risk of complications.

LASIK surgery results:
The surveys determining patient satisfaction with LASIK have found most patients satisfied, with satisfaction range being 92–98 percent.

Complications:
Intraoperative complications
1.flap complications
2.slipped flap (a corneal flap that detaches from the rest of the cornea) is one of the most common complications.
3.Flap interface particles

Early postoperative complications
1.dry eye symptoms at 6 months period post surgery.
2.diffuse lamellar keratitis (DLK),
3.infection responsive to treatment.Infection under the corneal flap is possible.

Late postoperative complications
1.A subconjunctival hemorrhage
2.Surgery induced dry eyes or in severe cases chronic dry eye.Due to 70% of corneal nerves that are severed during the Lasik operation , the lubrication system of the eye is affected and nerves may never recover to pre-operative condition.
3.Overcorrection or undercorrection
4.Vitamin D deficiency from Sun sensitivity
5.Visual acuity fluctuation
6.Halos or starbursts around light sources at night
7.Light sensitivity
8.Ghost images or double vision
9.Wrinkles in flap (striae)
10.Decentered ablation
11.Debris or growth under flap
12.Thin or buttonhole flap
13.Induced astigmatism
14.Corneal Ectasia -decrease in the number of corneal keratocytes (fibroblasts) after LASIK.
15.Floaters
16.Epithelium erosion
17.Posterior vitreous detachment
18.Macular hole.
19.flap dislocations have been reported 1–7 years post-LASIK.
20.intraocular pressure, essential in glaucoma screening and treatment.
21.retinal detachment
22.choroidal neovascularization
23.uveitis
24.keratomileusis effected at a later age increases the incidence of corneal higher-order wavefront aberrations.
25.Microfolding -an almost unavoidable complication of LASIK usually negligible
26.Blepharitis,  with crusting of the eyelashes can lead to infection or inflammation of the cornea after LASIK.

Newer methods like Femtosecond laser intrastromal vision correction via all-femtosecond correction (like Femtosecond Lenticule Extraction, FLIVC, or IntraCOR), or other techniques that avoid permanently weakening the cornea with incisions and deliver less energy to surrounding tissues will replace LASIK Surgery.

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