The changing face of refractive surgery

Several promising techniques are already available

Ametropia, when the eye needs corrective lenses to bring an image into focus, is common—and has been so for centuries. The Roman emperor Nero observed gladiator fights through an emerald to correct his ametropia. The presence of 1 dioptre (D) of refractive error reduces Snellen visual acuity to less than 6/12—that is, below the level needed to drive. More than half of all eyes have a refractive error of greater than 1D and 15% have an error greater than 2D.1 Although the vast majority of patients will continue to wear spectacles or contact lenses, the popularity of refractive surgery to correct ametropia continues to grow. So too does the variety of surgical techniques available to correct ametropia.

The factors exerting the greatest influence on refractive power are corneal curvature, the power of the lens, and axial length. The surgeon can thus act on the cornea or the natural lens with or without introducing artificial lenses. Assessing the best procedure for a particular refractive error is difficult because of the speed of change within this field. Most data come only from case series, and individual surgeons may also be limited by lack of experience in particular refractive techniques or by …