A recent study by Hammond et al1 on outcomes of refractive surgery was large enough and sufficiently objective to begin comparing the risk of vision loss from surgery vs contact lenses. Previously, the public and ophthalmologists have assumed that refractive surgery, while attractive, constitutes the higher risk. This may not be correct.
This comparison has been slow in coming in part because the risks of refractive surgery vs contact lenses cannot be compared directly. Complications from contact lenses accumulate over years whereas those from surgery occur over a brief time. If one assumes that the risk from contact lenses accumulates steadily and that at least 5% of bacterial keratitis cases will result in vision loss to a visual acuity of 20/50 or worse, then the total risk may be estimated from the yearly rate. Surprisingly, the risk of bacterial keratitis from contact lenses has changed little over the years. If the risk does not accumulate steadily, then at least 1 subset may be at greater risk.
Mathers WD, Fraunfelder FW, Rich LF. Risk of Lasik Surgery vs Contact Lenses. Arch Ophthalmol. 2006;124(10):1510-1511. doi:10.1001/archopht.124.10.1510-b