Results in application of the Fyodorov’s IOL power formula for posterior chamber lenses calculation

Results in application of the Fyodorov’s IOL power formula for posterior chamber lenses calculation

L.I. Balashevich, E.V. Danilenko

The S. Fyodorov Eye Microsurgery Federal State Institution, St.-Petersburg


Purpose

To estimate results in application of the Fyodorov’s IOL power formula for posterior chamber lenses calculation and to determine retrospectively an optimum level of preliminary correction factors actually performed by surgeons for this formula.


Material and methods

The data of 701 patients (944 eyes) who have undergone cataract phacoemulsification with in-the-bag IOL implantation, provided by one of two surgeons, were included in the study. All the patients were divided into 3 groups with different AL: group I — AL < 22.0 mm, group II — AL 22.0-24.5 mm, group III — AL > 24.5 mm. For each group target refraction was determined.


Results

In each group the percent of target refraction achievement was counted within ±0.50 D and ±1.00 D deviation of spherical component of subjective refraction (BCVA) and autorefractometry. Correction factors for the Fyodorov’s IOL calculation formula for each AL group were calculated from the results of subjective refraction with ±0.50 D deviation from target refraction. For the first group correction factor was equal to 2.11±0.33 D, for the second group — 1.73±0.09 D, for the third group — 1.42±0.33 and 3.29±0.39 D in correspondence with target refraction. Correction factors for common types of IOLs also were calculated.

Conclusions

As a result of retrospective calculation an optimum level of preliminary correction factors actually performed by surgeons for the Fyodorov’s IOL power formula is determined to achieve the target refraction. The obtained result can be a basis for a further development of calculation method for posterior chamber IOL power which prototype will be the Fyodorov’s IOL power calculation formula.


Key words

Fyodorov’s IOL power calculation formula, correction factor, target refraction, cataract phacoemulsification.