This very popular form of refractive surgery is primarily undertaken to correct myopia and/or astigmatism, thereby removing or reducing the need for eye-glasses and contact lenses.
A thin flap of the surface of the cornea is removed, a precisely calculated underlying slice is vaporised by laser, and the surface flap is replaced.
If postoperatively the cornea is too thin, it may bulge, causing poor uncorrected vision. Depending on severity, correction may require contact lenses or even corneal transplant.
Keratoconus is recognised as a risk factor for iatrogenic corneal ectasia1 and should be looked for pre-operatively1a. Forme fruste keratoconus, in which there is a congenital weakness of the cornea but thinning of the cornea has not yet occurred, is also recognised to be a contra-indication to the procedure2. The complication may take many months to become evident or reach its worst2a.
This complication is relatively common, and is largely avoidable by intentionally erring on the side of under-correction because the latter can be corrected by a further procedure3.
After LASIK, dry eye is common4 and must be disclosed pre-operatively as a possible complication. It usually lasts for a few weeks up to a year but worsening of pre-existing dry eye may be permanent. This complication was first recognised and documented in the clinical research literature in 19994a.
LASIK has largely superseded PRK, which laser-sculpts the cornea without a surgical flap, and which may correct mild to moderate myopia. Because the surface of the cornea is disrupted, a contact lens must be worn for some days postoperative until healing has taken place.
Up to 1 in 5 patients will suffer under-correction, over-correction, or some loss of corrected vision5. 3% of procedures may result in permanent scarring of the cornea6.