Laser in situ keratomileusis (ie, L...

Laser in situ keratomileusis (ie, LASIK) is a surgical action designed to reshape the surface of the cornea with laser to focus visual images directly onto the retina, which improves visual acuity. The word keratomileusis is derived from the native of greece root words keras (ie, hornlike cornea) and mileusis (ie, carving).(1) It is the general denomination for surgical procedures that can improve or correct the eye's focus by dint of permanently changing the shape of the cornea to bend light rays onto the retina and enhance the optical power of the eye(2) Refractive lamellar corneal surgery attempts to either destroy add, or modify the corneal stroma or composition so the anterior corneal curvature is altered as desired.(3)

The cornea is the main refracting proper state of the optical system of the human estimate and small changes in the anterior curvature will make relatively large changes in the patient's overall refraction.(4) The mete keratomileusis refers to refractive keratoplasty techniques that combine a lamellar (ie, horizontal, platelike) resection of the cornea performed to change the corneal radius of curvature with a microkeratome (ie, a knife that is used for incising the cornea) or other instrument and cryolathe, microkeratome excision, or excimer laser ablation.(5) Refractive corneal surgery is a cornerstone for invasive vision correction from which succeeding surgical techniques and innovations are evolving.

The LASIK conduct uses the excimer laser for photoablation of the corneal stromal bed to alter the corneal curvature, bending admitted light onto the retina and generating a refractive change. The reported benefits of the measure are rapidly improved visual acuity and minimal postoperative recruiting The LASIK procedure leaves the corneal surface nearly intact, resulting in minimal healing from the excimer laser light sculpting of the cornea.(6) The LASIK management is an effective outpatient operation that is suitable not solitary for patients with strong len prescriptions however also for patients with moderate to weaker prescriptions.

Approximately 62 million nation in the United States are myopic (ie, nearsighted) and require eyeglasses or contact lense for vision correction.(7) There is a greater number of the population who are farsighted, have astigmatism, or have a combination of astigmatism with either farsightedness or nearsightednes.(8) In 1998 approximately 420000 LASIK measures were performed in the United States. This number was almost double the number of LASIK deeds performed in 1997.(9) Two million tribe throughout the world have benefited from the LASIK procedure(10)

An elective surgical conduct the LASIK procedure often is performed at the patient's cost as many insurers will not reimburse the charges for an elective procedure. Consumer demand, generated by the agency of timely, satisfactory postoperative results, has made this process one of the fastest growing elective surgical measures in the United States. As as it was perioperative nurses should be familiar with LASIK and the implications of this innovative ophthalmic surgical procedure

ANATOMY

A review of the refractive apparatus of the view (Figure 1) is necessary to better understand LASIK surgery The estimate is located within the orbital cavity of the brain-pan between the cranium and the facial skeleton. This orbit is a bony depression where the eyeball, a bulbous, fluid-filled sac, eases within a cushion of adipose tissue. The orbit is a socket for the eyeball, muscles, fortitudes and vessels that are necessary for accurate functioning of the eye.(11)

[Figure 1 ILLUSTRATION OMITTED]

The observation is composed of three layers of tissue surrounding a fluid-filled center and occupies les than one-third of the orbit.(12) The external corneal-scleral layer of the inspection is fibrous and protects the other couple layers, which are the middle and internal layers. The middle layer is a vascular, pigmented layer consisting of the iris, ciliary material part and choroid. The internal layer is called the sensory retina.(13) The serous fluid satisfaction of the anterior chamber is called the aqueous humor, and the thicker, viscous fluid within the posterior chamber is the vitreous humor.(14)

The observation consists of two spheres. The cornea invents the anterior one-sixth and has a radius curvature of approximately 8 mm The posterior five-sixths, the sclera, has a radius curvature of approximately 12 mm The limbus is the area where the cornea intersects with the sclera.(15) The central portion of the bulbar conjunctiva is continuous at the limbus with the anterior epithelium of the cornea.(16) The adult globe has an internal bulk of 5.5 [cm.sup.3] and weighs approximately 75 g(17)

The sclera consists of densely packed collagen fibers that course in bundle ups and are arranged in a lamellar fashion (ie, layered). The randomness of the orientation of the collagen fibers and the hydration of the sclera contribute to its white appearance. The support for the posterior portion of the organ of sight is provided by the sclera. At the external border between the cornea and the sclera is the external scleral sulcus depression.(18)