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Hang My Tran, Jessica Taibl, Samir I Sayegh, Not Applicable; Adjusting axial length between ultrasound and partial coherence interferometry to minimize differences in postoperative spectacle power following cataract refractive surgery. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):1958.
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© ARVO (1962-2015); The Authors (2016-present)
To demonstrate the effect of adjusting axial length measurements of cataractous eyes on change in spectacle power and provide a simple method to perform the adjustment.
We performed a retrospective review of axial lengths of cataractous eyes prior to cataract surgery. A-scan ultrasound (ASU) device, DGH 5100E, and a partial coherence interferometry (PCI) device, IOLMaster500, measured axial lengths on the same day on the same cataractous eye(s) of the same patient, Axial lengths based on the PCI measurements were categorized into 3 groups: short (<22.5mm), medium (22.5mm to < 25.0mm), and long (>=25.0mm). Uncorrected axial length was an ASU value and corrected axial length was an ASU value adjusted by the mean difference within each group. Within each axial length group, the mean difference and standard deviation (SD) between PCI and ASU were reported. Additionally, predicted spectacle power difference between PCI and ASU within 0.5 diopters was reported for uncorrected and corrected axial length.
The sample consisted of 126 cataractous eyes in 71 subjects ranging from 43 to 92 years old with the average age of 68. There were 11 short, 86 medium, and 29 long axial length eyes. The mean difference between PCI and ASU was 0.16mm (P<0.01). The mean difference for short axial length was 0.24mm (SD=0.071mm), medium axial length was 0.15mm (SD= 0.22mm), and long axial length was 0.16mm (SD=0.22mm). In the short axial length group, uncorrected axial length showed 72.73% and corrected axial length showed 100% spectacle power concordance within 0.5 diopters. In the medium axial length group, uncorrected axial length showed 81.40% and corrected axial length showed 93.02% concordance. Finally, in the long axial length group, the uncorrected axial length showed 65.52% and corrected axial length showed 86.21% concordance.
In a clinical context and with the devices used, axial length differences between ASU and PCI appear to vary as a function of axial length. This suggests the need for a variable adjustment factor to complement the different A constant recommendations for ASU and PCI made by manufacturers.
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