Theoretical influence of segmented axial length on intraocular lens power calculation in short eyes.

PURPOSE: To compare the segmented axial length (AL) provided by the Argos with the traditional AL provided by the IOLMaster 700 in short eyes and assess their impact on intraocular lens (IOL) power calculation.

SETTING

IRCCS Bietti Foundation, Rome, Italy.

DESIGN

Retrospective case series.

METHODS

Patients undergoing cataract or refractive surgery preoperative examinations were enrolled if their AL was <22.0 mm with the IOLMaster 700. The ALs given by the 2 biometers were compared. Using the formulas included in the ESCRS IOL calculator, the IOL power for a schematic eye was calculated with both AL measurements.

RESULTS

In 78 eyes, the traditional mean AL (21.22 ± 0.54 mm) was shorter than the segmented AL (21.29 ± 0.51 mm, P < .0001) with a proportional bias (r2 = 0.3312, P < .0001). The difference decreased with thicker lenses (r2 = 0.4941, P < .0001). Based on the IOL power calculated when the traditional AL was entered and the first negative refractive value was aimed at, the predicted refraction was more myopic with the Argos AL (P < .0001). The difference ranged from -0.18 ± 0.13 D (Cooke K6) to -0.24 ± 0.18 D (Barrett Universal II). The same IOL power would have been recommended by the ESCRS IOL calculator in only 40% to 50% of eyes, irrespective of formula used. The difference was minimized when the sum-of-segments option was used.

CONCLUSIONS

AL measurements provided by the Argos and IOLMaster 700 are not interchangeable for IOL power calculation in short eyes <22.0 mm.