There has been a lot of publicity in the UK about complications associated with laser in-situ keratomileusis (LASIK) eye surgery. The publicity has concentrated mainly on complications after surgery undertaken at laser eye clinics on the high street rather than in hospitals.
The real safety issues of laser eye surgery have not, however, been addressed. Refractive surgeons have two major concerns—namely, loss of contrast sensitivity (which can be permanent and untreatable) and the potential for corneal weakening or ectasia.
In 1996, researchers from Tubingen University, Germany,(1) reported that three quarters of their patients in 10 years who had photorefractive keratectomy for myopia, that is surface ablation of the cornea, had sufficient loss of contrast sensitivity (the inability to distinguish objects in poor light) as to fail the federal German night vision standards. In view of this information, we at the London Centre for Refractive Surgery recalled all patients treated with an Excimer laser, and noted that 56% (36 of 54) had greatly reduced contrast sensitivity. Further reports from Germany(2) and Ottawa(3) have confirmed these findings, and the Federal Canadian Government in Ottawa has since advised all provincial governments that night vision tests should be done after laser treatment, before a driving licence is issued.
At a symposium in London, UK, in March, 2001,(4) researchers from Moorfield’s Eye Hospital reported that 30% of patients treated with photorefractive keratectomy and 50% of those treated with LASIK had lost contrast sensitivity within 2 years and 1 year of surgery, respectively. The association between loss of contrast sensitivity and Excimer laser treatment for myopia was finally published in a peer-reviewed journal in June, 2002.(5)
This effect on night vision seems to be permanent and untreatable by glasses or contact lenses. Damage might be reduced by the new technique of wavefront technology, which does not, however, repair the underlying damage.
LASIK eye surgery involves cutting a corneal flap to about a third the thickness of the cornea. Excimer laser treatment, which vapourises cornea to a precise depth, is then undertaken on the deep surface, before the flap is repositioned. After surgery, the corneal flap no longer contributes to the strength of the cornea. Thus, in every case of LASIK, the cornea is weakened on average by 40%. In some individuals the weakened cornea resumes its original curvature, and myopia returns. Furthermore, some corneae, even after minor surgery is done and the cornea healthy before surgery, become conical (a condition called keratoconus), which if sufficiently progressive can be repaired only by corneal transplantation.
No one knows the rate of risk or the timescale of this serious complication. No warnings are carried in advertisements and almost all treatments are bilateral, so patients are unable to assess the effect of surgery on one eye, before surgery on the second is undertaken.
*A 2007 review of data from FDA clinical trials for LASIK devices, including newer custom wavefront technology, demonstrates that approximately 20% of patients report dry eyes and night vision problems persisting beyond six months after surgery.