Influence of intraocular lens haptic design on refractive error

To assess the influence of intraocular (IOL) haptic design on the refraction prediction error in patients having cataract surgery.

Private practice.

Comparative case series.

Corneal power and axial length were measured with the same devices in eyes with a 3-piece Acrysof IOL and eyes with a 1-piece Acrysof IOL and were entered into the Haigis, Hoffer Q, Holladay 1, and SRK/T formulas. The median absolute error and mean absolute error in refraction prediction (ie, difference between expected refraction and actual refraction) were assessed 1 month postoperatively.

The study evaluated 110 eyes with the 3-piece IOL and 84 eyes with the 1-piece IOL. With all formulas, the median absolute error was lower with the 3-piece IOL. It ranged between 0.15 diopter (D) (Haigis and Holladay 1) and 0.19 D (SRK/T) with the 3-piece IOL and between 0.23 D (Haigis) and 0.30 D (SRK/T) with the 1-piece IOL. With all formulas, a higher percentage of eyes with the 3-piece IOL were within ±0.25 D and ±0.50 D of the target refraction.

Three-piece IOLs may yield better refractive outcomes than 1-piece IOLs. A possible reason is that once the early forward IOL shift previously observed with the 3-piece design occurs because of the haptic-compression force decay typical of these IOLs, the rigid haptics of 3-piece IOLs still exert more pressure against the capsular bag than the haptics of 1-piece IOLs. Therefore, 3-piece IOLs may better resist subsequent capsule contraction and provide a more predictable effective lens position.

Dr. Hoffer receives royalties for his book IOL Power, Slack, Inc., and formula royalties from all manufacturers using the Hoffer Q formula. No other author has a financial or proprietary interest in any material or method mentioned.