Refractive and visual outcome of hyperopic cataract cases operated on before and after implementation of the Holladay II formula

Abstract

Objective: The primary objective was to evaluate the refractive and visual outcomes in a series of hyperopic cataract cases in which the Holladay II intraocular lens (IOL) power formula was used in conjunction with added eye measurements (measured anterior chamber depth [ACD], lens thickness, and corneal diameter) to improve predictability of refractive outcome. In addition, the impact of use of a double ("piggyback") IOL on refractive outcome was evaluated.

Design: Prospective, nonrandomized comparative clinical trial.

Participants: A total of 136 consecutive hyperopic primary cataract-IOL cases operated on at in an outpatient eye surgery center were evaluated. The main inclusion criterion was the requirement of at least 30 D of emmetropia power.

Intervention: Implantation of a total implanted power calculated using a newly developed (Holladay II) formula, which uses additional eye measurements (measured ACD, lens thickness, corneal diameter) in addition to the axial length and keratometry normally used, was performed. In the first series, IOL powers were chosen using the Lloyd-Gills formula with modifiers; in the second series, powers were chosen using the Holladay II formula option in the Holladay IOL Consultant software. Selection criteria for both series were the same (requiring at least 30 diopters [D] of power for emmetropia). Keratometry and axial length measurements (by immersion) were taken using the same instrumentation and methodology in both series. Predicted postoperative refraction based on the IOL implanted and the method of power calculation used were computed for each case in both groups and compared to the actual achieved refraction.

Main outcomes measurements: Main clinical outcome parameters evaluated were the postoperative spherical equivalent (compared with the predicted spherical equivalent) and the best-corrected vision. These outcome parameters were evaluated within each surgical series, in the total group of cases (regardless of power calculation method). Further stratification according to the use of single or double implants also was done.

Results: In the group using an older formula system, mean preoperative spherical equivalent of 4.79 D was reduced to -0.67 D. Similarly, in the Holladay II group, the preoperative mean of 5.60 D was reduced to -0.58 D. However, there were fewer large deviations between predicted and achieved spherical equivalent in the Holladay II group as indicated by a smaller standard deviation of the absolute deviation (0.47 vs. 0.59), and the range of postoperative refractions was smaller with fewer large overcorrections or undercorrections. However, almost 90% of both groups were within a diopter of the predicted refraction. Visual results were comparable in the two groups.

Conclusion: Both IOL calculation systems showed good predictability in these extremely short eyes. The Holladay II formula was simpler because it is incorporated into a user-friendly software package (Holladay IOL Consultant) and required only the input of IOL constants and preoperative measurements with no "fudge factor" modifiers. Results within the series using this formula had a tendency toward a smaller standard deviation with fewer outliers.