Accuracy of intraocular lens power calculation formulas in eyes with an axial length greater than 27.0 mm

Session Details

Session Title: IOL Power Calculations

Session Date/Time: Sunday 11/09/2016 | 16:00-18:00

Paper Time: 16:54

Venue: Hall C2

First Author: : J.Zhou CHINA

Co Author(s): :                        

Abstract Details

Purpose:

To evaluate and compare the accuracy of formulas for calculating the intraocular lens (IOL) power using IOL Master for eyes with an axial length (AL) greater than 27.0 mm.

Setting:

Department of ophthalmology, Xijing hospital, Xi’an, China.

Methods:

This retrospective study reviewed 105 patients（148 eyes）with AL over 27.0 mm. The cases were divided into eight groups according to AL between 27.0 mm and 34mm with 1.0 mm difference. The actual postoperative diopters were spherical equivalent diopters (APSE), which were measured at about three months after surgery. The predicted postoperative spherical equivalence (PPSE) was calculated using standard formulas (SRK II, SRK-T, Holladay and Haigis). The predictive accuracy of formulas (Predictive Error, PE) was analyzed by comparing the differences between APSE and PPSE. The Student t, Dunnett T3 and Student-Newman-Keuls tests were used for statistical analysis.

Results:

PE calculating with SRK II, SRK-T, Holladay and Haigis formulas was 1.01±1.53, 0.76±0.96, 1.24±0.8, and 0.78±0.84, respectively. The differences between APSE and PPSE in these formulas were significant (P＜0.05). PE was the smallest using SRK-T and Haigis formulas, while it was the largest using Holladay. The AL groups were combined if PE had no significant difference among them. Four axial intervals were reformed: 27-30 mm, 30-32 mm，32-34 mm, and longer than 34mm. Calculating with SRK-T formulas in these axial intervals, mean PEs were 0.21±0.65, 0.58±0.56, 1.18±0.67, and 1.97±1.44, respectively.

Conclusions:

In eyes with AL of 27.0 mm or more, calculating with SRK-II, SRK-T, Holladay and Haigis formulas yield insufficient refractive results. The predictability of SRK-T formula appeared to be improved by adjusting PPSE -0.2～-2 D in different AL intervals.

Financial Disclosure:

NONE