LASIK

LASIK
Name	LASIK
Caption	A patient undergoing the procedure.
Specialty	Ophthalmology
MeshID	D020731
MedlinePlus	007018
EMedicine	1190332

LASIK. It is a type of refractive surgery performed by ophthalmologists to correct myopia, hyperopia, and astigmatism. The procedure permanently reshapes the cornea using an excimer laser to improve the eye's refractive error and reduce dependency on eyeglasses or contact lenses. First approved in the United States in the 1990s, it has become one of the most common elective surgeries worldwide.

Procedure

The surgery is typically performed under topical anesthesia using eye drops. The surgeon creates a thin, hinged flap in the corneal epithelium using a mechanical microkeratome blade or a femtosecond laser. This flap is folded back to expose the underlying corneal stroma. An excimer laser, guided by sophisticated wavefront or topography-guided aberrometry systems, then precisely ablates a predetermined amount of stromal tissue. The Food and Drug Administration has approved specific laser platforms, such as those from Johnson & Johnson (VISX) and Alcon. After the laser application, the flap is repositioned, where it adheres without sutures, and a bandage contact lens may be applied.

Indications and contraindications

Candidates typically have a stable refractive error for at least one year and are over the age of 18. Ideal patients have moderate myopia, hyperopia, or astigmatism within the treatable ranges approved by the Food and Drug Administration. Significant contraindications include keratoconus, autoimmune diseases like rheumatoid arthritis, pregnancy, severe dry eye syndrome, and corneal dystrophy. A comprehensive preoperative evaluation is essential, involving tests such as corneal pachymetry, corneal topography, and pupillometry to assess corneal thickness and rule out ectasia.

Risks and complications

While generally safe, potential complications exist. These include diffuse lamellar keratitis (also known as "Sands of the Sahara"), epithelial ingrowth, corneal flap dislocation, and infectious keratitis. Some patients experience dry eyes, halos, glare, or starburst vision, particularly in low-light conditions. Rare but serious risks involve corneal ectasia, a progressive thinning and bulging of the cornea, and retinal detachment. The American Academy of Ophthalmology provides extensive guidelines on managing these adverse events.

Outcomes and effectiveness

The vast majority of patients achieve uncorrected visual acuity of 20/20 or better, with high rates of patient satisfaction reported in studies from institutions like the Mayo Clinic. Long-term studies, including those published in the Journal of Cataract and Refractive Surgery, show stable refractive results over decades. Effectiveness can be enhanced with advanced technology such as wavefront-guided treatments, which aim to reduce higher-order optical aberrations and improve contrast sensitivity. However, some individuals may require an enhancement surgery or eventually need reading glasses due to presbyopia.

History and development

The foundational concept was developed in the 1970s by Svyatoslav Fyodorov in the Soviet Union with radial keratotomy. The modern procedure evolved from the work of Gholam A. Peyman, who patented the concept of creating a corneal flap, and Ioannis Pallikaris in Greece, who combined flap creation with excimer laser ablation in 1990. The Food and Drug Administration granted its first approval for a laser system to Summit Technology in 1995. Subsequent technological milestones include the introduction of the femtosecond laser for flap creation, pioneered by companies like IntraLase, and the development of all-laser LASIK.

Alternatives

Other surgical options for vision correction include photorefractive keratectomy, which does not involve creating a corneal flap, and small incision lenticule extraction, a flapless procedure. For patients with presbyopia, options include refractive lens exchange and the implantation of multifocal intraocular lenses. Non-surgical alternatives remain the use of eyeglasses, contact lenses, and orthokeratology. Newer technologies under investigation include corneal inlays and advanced phakic intraocular lens designs from companies like STAAR Surgical.

Category:Ophthalmology Category:Surgical procedures Category:Eye surgery