Purpose: To compare the achieved refractive outcomes of patients undergoing cataract surgery with intraocular lens (IOL) power calculation performed by conventional immersion ultrasound (US) or partial coherence interferometry (PCI).
Methods: Prospective, comparative case series. Patients undergoing cataract surgery were randomly divided in two groups with regard to the IOL power calculation method. Group 1 had calculations performed by PCI (IOL Master; Carl Zeiss Meditec), while US was used in Group 2 (Ultrascan; Alcon), using the Holladay 1 formula. Differences between target and achieved refractions were then compared.
Results: The study comprised 120 eyes from 79 patients. Biometry with PCI was used in 50 eyes of 33 patients, and US was used in 70 eyes of 46 patients. Mean age of patients in the PCI Group was 69.8 ± 13.1 years (range 11 - 85) and 70.0 ± 9.3 (45 - 86) in the US Group (P=0.7165). Mean axial length measured by PCI was 23.22 ± 1.00 mm (range 21.01 - 25.45) and that by US was 23.22 ± 1.06 mm (20.05 - 25.78) (P=0.9110). Mean absolute error in the PCI group was 0.15 ± 0.33 D (range -0.65 - 0.9) and that in the US group was 0.26 ± 0.48 D (-1.05 - 1.76). All eyes in the PCI group and 94.3% of those in the US group were within 1.00 D of the planned refraction.
Conclusion: Although both PCI and US yielded good prediction in IOL power calculation, the PCI group tended to show better accuracy and improved refractive outcome.