Refractive enhancements: making the patient happy second time round

July 1, 2007

The quest for safe, effective surgery, which produces optimal results, has prompted much debate among experts on what the best procedure is for performing laser enhancements. For wavefront-guided enhancements, lamellar and surface procedures are both popular methods and I would like to discuss my experience and share my thoughts on their future in refractive surgery.

The quest for safe, effective surgery, which produces optimal results, has prompted much debate among experts on what the best procedure is for performing laser enhancements. For wavefront-guided enhancements, lamellar and surface procedures are both popular methods and I would like to discuss my experience and share my thoughts on their future in refractive surgery.

Why is an enhancement needed?

When you are going to perform an enhancement on a patient, it is critical to evaluate why the patient did not achieve the intended correction the first time around. There are a number of factors to discuss with patients. In particular, it is important to examine the ocular surface.

Finally, I tend to look closely at the patient's underlying systemic conditions and other medications they may be taking that could be contributing to poor results. Addressing these pathologies prior to surgery I find is always beneficial.

The value of wavefront-guided treatments

The value of wavefront-guided treatments has already been proven in primary refractive surgery. It is known that a higher percentage of eyes achieve 20/20 vision or better, with less induction of higher order aberrations (HOAs), with wavefront-guided treatments in comparison to standard treatments. One aspect that I find particularly valuable is cylinder correction when the cylinder component is very large. In these cases, iris registration becomes beneficial because it compensates for cyclotorsional movement and pupil centroid shift. I also opt for wavefront-guided treatments if the patient's HOAs are relatively large or greatly increased over baseline.

In addition, I find the point spread function of wavefront-guided enhancement particularly useful. If a patient is shown the point spread function and they confirm that the point spread function accurately depicts their visual complaints, surgeons can proceed with greater confidence.

Lamellar versus surface

In my opinion, surface enhancements offer a number of advantages over lamellar enhancement. When treating another surgeon's patient, there is sometimes limited, or no data available regarding the residual stromal bed or flap thickness and, in such cases, it could be rather embarrassing to lift the flap, perform pachymetry and, only then discover that there is not enough residual stromal bed to proceed. As such, I find that considering a surface treatment in these types of cases is very important.

If a surgeon is concerned that lifting and replacing the flap will induce HOAs, I again recommend surface enhancements. In addition, if the flap is irregular or was a cause for concern during primary surgery, I would suggest opting for surface enhancements. Of course, there are also great concerns about epithelial in-growth; as LASIK enhancements occur, the chance of epithelial in-growth increases. Finally, if the cornea is too thin to lift and treat, I highly recommend the use of surface enhancements.

LASIK versus PRK wavefront-guided enhancements