Dr. Boothe Treatments
Over time, most of the attention has been focused on spherical aberration. LASIK and PRK tend to induce spherical aberration, because of the tendency of the laser to undercorrect as it moves outward from the center of the treatment zone. This is really a significant issue for only large corrections. There is some thought if the lasers were simply programmed to adjust for this tendency, no significant spherical aberration would be induced. Hence, in eyes with little existing higher order aberrations, "wavefront optimized" LASIK rather than wavefront guided LASIK may well be the future.[citation needed]
In any case, higher order aberrations are measured in µm (micrometers) on the wavescan taken during the pre-op examination, while the smallest beam size of FDA approved lasers is about 1000 times larger, at 0.65 mm. Thus imperfections are inherent in the procedure and a reason why patients experience halo, glare, and starburst even with small naturally dilated pupils in dim lighting.