Comparison of Intraocular Lens Power Calculation between Standard Partial Coherence Interferometry-Based and
Sara Sardari1,2, Mehdi Khabazkhoob3, Ebrahim Jafarzadehpur4
1Research and Technology Deputy, Tehran University of Medical Sciences, Tehran, Iran.
Purpose:
To compare the intraocular lens (IOLs) power calculated with Haigis, Hoffer Q, Holladay 1, and SRK/T formulas between the IOLs Master 500 and Pentacam AXL according to the lens status.
Methods:
In this cross-sectional study, sampling was done in subjects above 60 years living in Tehran using multi-stage cluster sampling. All participants underwent optometric examinations including the measurement of visual acuity and refraction as well as slit-lamp biomicroscopy to determine the lens status. Biometric measurements and IOLs power calculation were done using the IOL Master 500 and Pentacam AXL. The order of imaging modalities was random in subjects. IOL power calculation was done according to optimized ULIB constants for the Alcon SA60AT lens. The IOL power was calculated according to a target refraction of emmetropia in all subjects.
Results:
After applying the exclusion criteria, 1865 right eyes were analyzed. The mean IOL difference between the two devices was -0.33 ± 0.35, -0.38 ± 0.39, -0.41 ± 0.43, and -0.51 ± 0.43 according to the SRK/T, Holladay, Hoffer Q, and Haigis formulas, respectively. The Pentacam calculated larger IOL power values in all cases. The 95% limits of agreement (LoA) between the two devices for the above formulas were -1.01 to 0.35, -1.14 to 0.39, -1.25 to 0.43, and -1.35 to 0.33, respectively. The best LoA were observed in normal lenses for all formulas. The difference in the calculated IOL power between the two devices using the four formulas had a significant correlation with axial length, mean keratometry reading, and anterior chamber depth. According to the results of the four formulas, mean keratometry reading had the highest standardized regression coefficient in all formulas.
Conclusion:
Although the difference in the calculated IOL power between IOL Master 500 and Pentacam AXL is not significant clinically, the results of these two devices are not interchangeable due to the wide LoA, especially for the Haigis formula; therefore, it is necessary to optimize lens constants for the Pentacam.
Related Concept Videos
01:16Focusing of Light in the Eye
01:18Imaging Biological Samples with Optical Microscopy
In optical microscopy, the specimen to be viewed is placed on a glass slide and clipped on the stage...
01:26Phase Contrast and Differential Interference Contrast Microscopy
In-phase-contrast microscopes, interference between light directly passing through a cell and light refracted by cellular components is used to create high-contrast, high-resolution images without staining. It is the oldest and simplest type of microscope that creates an image by altering the wavelengths of light rays passing through the specimen. Altered wavelength paths are created using an annular stop in the condenser. The annular stop produces a hollow cone of...