Femtosecond thin-flap LASIK effective in eyes with thin corneas, normal topography

J. Bradley Randleman, MD

The authors report good news, that LASIK appeared stable in their population of patients with “thin” corneas (below 500 μm) for at least 3 years postoperatively. This provides further evidence that no absolute cut-offs likely exist for screening parameters, but rather that risk exists on a continuum depending on a variety of factors. The authors also reinforce the need for in-depth screening of corneal parameters, including topographic and tomographic findings. These findings support previous work demonstrating that a variety of potential individual risk factors should be taken into account when assessing risk for postoperative ectasia.
It is difficult to draw more detailed conclusions than these because the patient variables are reported as aggregate averages and ranges rather than as individual metrics that could be more thoroughly evaluated for each patient. While these variables follow generally conservative ranges, there appears to be some outliers in thickness, residual bed and topographic patterns that warrant further investigation.
Recent research has addressed the percentage of tissue altered at the time of LASIK (flap thickness and tissue ablated); this may prove to be a more sensitive metric than central corneal thickness or residual stromal bed thickness as it more directly accounts for the probably biomechanical alteration for an individual cornea at the time of LASIK in eyes with normal topographic evaluations. This paper would seem to at least indirectly support that concept.