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Accuracy of IOL power calculation in long eyes using the C-constant

Session Details

Session Title: Biometry

Session Date/Time: Tuesday 08/10/2013 | 08:00-10:30

Paper Time: 08:00

Venue: Elicium 2 (First Floor)

First Author: : T.Olsen DENMARK

Co Author(s): :                  

Abstract Details


To evaluate the accuracy of IOL power calculation in eyes more than 26 mm using the newly developed C-constant for the prediction of IOL position


University Eye Clinic


A total of 235 eyes with a minimum axial length of 26 mm were investigated. They comprised a consecutive series of patients submitted for cataract or refractive lens surgery. Preoperatively all eyes were measured with the Lenstar biometer recording the anterior chamber depth, the lens thickness as well as the axial length by laser interferometry. Cases with previous refractive surgery or other abnormalities in the anterior segment were excluded from the study. The IOL powers ranged from - 5.0 D to + 20.5 D. The IOL power calculation was performed with the Olsen formula using the C-constant and compared with the Hoffer Q, Holladay 1 and the SRK/T formulas on optimized datasets. The error of the prediction was expressed as the error between the observed and the predicted refraction on the optimized dataset


The mean / median absolute prediction error with the Olsen formula using the C-constant was found to be 0.35 D / 0.25 D, respectively. For the Hoffer Q, the Holladay 1 and the SRK/T formuas the corresponding errors were 0.48 D / 0.38 D, 0.46 D / 0.37 D and 0.44 D / 0.36 D, respectively (p < 0.001). Contrary to the Olsen formula the error of the Hoffer Q, the Holladay 1 and the SRK/T formuas was found to be linearly correlated with the axial length giving a significant hyperopic in the very long eyes


Accurate IOL power calculation can be performed without bias in the long eyes using the C-constant approach with the Olsen formula

Financial Interest:

... has significant investment interest in a company producing, developing or supplying product or procedure presented

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