A lens fragmentation device can help to maintain zonular integrity, which can improve refractive outcomes, explain Kenneth J. Hoffer, MD, FACS, and Gerald J. Roper, MD.
Exacting IOL power calculations are required to provide optimal refractive results to patients following cataract surgery. One of the most common sources of error in these calculations remains the effective lens position (ELP). It is difficult to determine this exact healed postoperative axial position from preoperative biometric data.
The ELP may be reasonably estimated by the vector physics and mathematics of the latest IOL calculation formulas, though validating this specific parameter for error is limited by challenges in determining the postoperative axial IOL final lens position (FLP). Going forward, swept-source ocular coherence tomography images on newer biometers may be able to help assess the accuracy of the ELP calculation parameter in the various formulas.
The FLP will be compared with the ELP estimates of the IOL axial position, presuming that surgical technique will not significantly influence zonular support. We realize, however, that the surgery may well have an effect. In eyes that have had previous corneal surgery, it is also challenging to determine the exact power of the cornea.1
Formulas such as the Barrett Universal II, Haigis, Hoffer H-5, Holladay 2, Olsen, and others address more variables than in the past.2
Kenneth J. Hoffer, MD
E: [email protected]
Dr. Hoffer is a clinical professor of ophthalmology at Jules Stein Eye Institute, University of California, Los Angeles. He did not indicate any proprietary interest in the subject matter.
Gerald R. Roper, MD
E: [email protected]
Dr. Roper is in private practice at Advanced Eye Care, Batesville, IN. Dr. Roper is a consultant to IanTECH.
1. Savini G, Hoffer KJ. Intraocular lens power calculation in eyes with previous corneal refractive surgery. Eye Vis (Lond). 2018;5:18. doi: 10.1186/s40662-018-0110-5. eCollection 2018.
2. Hoffer KJ, Savini G. Clinical results of the Hoffer H-5 formula in 2707 eyes: First 5th-generation formula based on gender and race. Intl Ophthalmol Clin. 2017;57:213-219. doi: 10.1097/ IIO.0000000000000183.
3. Norrby S. Sources of error in intraocular lens power calculation. J Cataract Refract Surg. 2008;34:368- 376.