The crucial role of patient age when calculating IOL power
Refractive prediction error changes with a patient's age, according to results from a prospective, cohort study. The researchers suggest patient age should be taken into account when determining intraocular lens (IOL) power for cataract surgery.
In addition to age, the authors also found that preoperative axial length (AL), anterior chamber depth (ACD; effective lens position), and average keratometry readings (K values) were significant independent predictors of PE.
On the basis of these findings, lead author Ken Hayashi, MD, and coauthors recommend that "the A-constants for the SRK/T formula should be slightly modified according to a patient's age at the time of surgery," in an article published in the October issue of the American Journal of Ophthalmology.
PE is the most common complication of cataract extraction and IOL insertion, Dr Hayashi, from the Hayashi Eye Hospital, Fukuoka, Japan, and colleagues note. Because ocular biometry measurements, including AL, corneal curvature, and estimated postoperative ACD, all increase with age, they hypothesize that age may influence PE as well.
Recent efforts to diminish PE include adjusting the standard formulas and use of developments such as the Holladay 2 or Haigis-L formulas in IOL power calculations, the authors write. "Although these efforts have improved refractive outcomes in modern cataract surgery, patient age should also be taken into consideration to determine the precise IOL power." Specifically, they recommend modifying the A-constants for the SRK/T formula to reflect the patient's age.
However, they warn, it is uncertain "whether the age-related difference in PE holds true in eyes for which the IOL power was calculated using other formulas."
Article source: http://www.medscape.com/viewarticle/870276