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J. L. Eikenberry, D. WuDunn, C. W. Yung; Accuracy of Manual Keratometry, IOL Master, and Immersion A-Scan by Inexperienced Users. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5437.
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© ARVO (1962-2015); The Authors (2016-present)
To compare the accuracy of manual keratometry (K) versus IOL Master K for first time users. To compare the accuracy of immersion A-scan measurements with IOL Master axial length measurements for first time users. To compare the IOL choice accuracy when manual K and immersion A-scan are used versus IOL Master for first time users.
A 30 minute tutorial was given to five first year ophthalmology residents on the IOL Master, manual K, and immersion A-scan. No further instruction was provided unless necessary to complete the task; exemptions were recorded. Residents performed IOL Master, manual K, and immersion A-scan measurements on both eyes of their partner or a volunteer. The head technician took measurements on the same eyes. An identical workshop was held with the following year's first year residents. This time, residents measured one of their partner’s eyes. In total, measurements were taken by 10 beginning residents on 15 eyes. Results by residents were compared to those of the lead technician (standard) who was qualified based on eight years of IOL Master experience and more than 20 years of immersion and manual K experience.
For manual K, the absolute delta between resident measurements and the standard was 0.16 diopters (D) versus 0.10 D for IOL Master K (p=0.229, Wilcoxon). Considering axial length, residents differed from the standard on immersion A-scan with an absolute delta of 0.11 mm. For IOL Master, the absolute delta was 0.02 mm (p=0.017, Wilcoxon). For IOL choice, when using resident manual K and immersion data vs. the standard, the absolute delta was 0.43 D. With the IOL Master, the absolute delta was 0.17 D (p=0.301, Wilcoxon). Five of 10 residents required one re-instruct to complete the task of obtaining an IOL approximating emmetropia with immersion A-scan. No re-instruct was required with IOL Master or manual K.
There was no statistical difference in the accuracy of keratometry by inexperienced users for manual technique vs. IOL Master. The IOL Master was statistically more accurate than immersion A-scan for axial length measurements in inexperienced hands. However, this did not translate into a statistical difference for IOL choice accuracy. Our data suggest that inexperienced users are able to obtain IOL results with manual keratometry and immersion A-scan that are statistically as accurate as with IOL Master when an experienced user is available to re-instruct. The IOL Master may be a great asset in a busy clinic where different technicians of various experience levels are performing axial length measurements and re-instruction by an experienced user is not available.
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