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Published on: September 16, 2025
Comparison of Horizontal Corneal Diameter Measurements Using Orbscan IIz, OPD Scan III, and IOLMaster 700
Sebastian Cruz1, Felipe Valenzuela, Juan Stoppel
1Fundación Oftalmológica Los Andes (S.C., F.V., J.S., E.M.), Department of Ophthalmology, Universidad de los Andes, Santiago, Chile ; Department of Ophthalmology (F.V.), Clinica Universidad de Los Andes, Santiago, Chile; and Bascom Palmer Eye Institute (A.G.), University of Miami, Miller School of Medicine, Miami, FL.
Purpose:
To compare three automated devices for measuring the horizontal corneal diameter (white to white [WTW]).
Methods:
In 65 eyes of 38 patients, the WTW distance was measured independently by three examiners using the following techniques: Orbscan IIz tomography system (Bausch & Lomb), IOLMaster 700 (Carl Zeiss Meditec), and OPD Scan III (NIDEK). We tested for systematic differences in measurements and estimated the limits of agreement (LoA) using linear mixed-effects models.
Results:
The mean WTW distance was 11.8±0.40 mm with Orbscan IIz, 12.1±0.5 mm with IOLMaster 700 and 12.0±0.4 mm with OPD Scan III. The mean difference between IOLMaster 700 and Orbscan IIz was 0.33 (95% CI, 0.28 to 0.38; P<0.001), between OPD Scan III and Orbscan IIz was 0.24 mm (95% CI, 0.21 to 0.28; P<0.001), and between IOL Master 700 and OPD Scan III was 0.09 (95% CI, 0.05 to 0.12; P<0.001). The 95% LoA for Orbscan IIz versus IOLMaster 700 was -0.69 to 0.03 mm, Orbscan IIz versus OPD Scan III was -0.52 to -0.03 mm, and OPD versus IOLMaster 700 was -0.39 to 0.22 mm.
Conclusions:
The data suggest that these devices are not interchangeable for usual clinical practice. Adjustments based on mean differences were not enough to compensate for interinstrument discrepancy in WTW measurements.
