SAN FRANCISCO — Secondary or piggyback IOLs are a viable alternative to other methods of managing refractive error after cataract surgery in eyes that have had previous laser refractive surgery, a speaker said here.
Warren E. Hill, MD, shared pearls on refractive assessment and lens choice during Cornea Day preceding the American Society of Cataract and Refractive Surgery meeting.
Warren E. Hill
"[Piggyback IOLs] are sort of your get-out-of-jail-free card when you have a refractive surprise. We’re all going to have them," Hill said.
Piggyback IOL power is independent from axial length, Hill said.
"The good news is that it’s an axial length-independent exercise," he said. "The same problems that got you a refractive surprise would do it again if you used a formula."
Manifest refraction, keratometry, target refraction, the refractive vergence formula and Holladay R formula are most useful in determining the appropriate power for a piggyback IOL, Hill said.
For hyperopic errors, the spherical equivalent should be multiplied by 1.5, up to +7 D. For myopic errors, the spherical equivalent should be multiplied by 1.3, down to –7 D, Hill said.
To accurately place a piggyback IOL, the primary IOL must be in the capsular bag with 360° of capsular overlap, there must be sufficient space between the iris and the IOL, and the primary IOL cannot have a steep radius.
Acrylic lenses are not ideal for piggyback use because the material may interact with the posterior iris, causing iris transillumination defects, pigment dispersion, secondary glaucoma or intermittent uveitis, Hill said.
A three-piece large-diameter silicone IOL should be used in cases with adequate space between the iris and the primary IOL, he said.
Disclosure: Hill is a consultant for Alcon, Bausch + Lomb, Elenza, LenSx, Haag-Streit and Oculus.