Agreement and Reproducibility of Contact and Immersion Techniques for Axial Length Measurement and Intraocular Lens Power Calculation
Kitthisak Kitthaweesin MD*, Warataporn Mungsing MD*
Affiliation : * Department of Ophthalmology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
Objective : To investigate the agreement and reproducibility of contact and immersion ultrasound biometry in
an axial length measurement and intraocular lens power calculation.
Study design: Prospective cross-sectional study
Material and Method: Axial length was measured in 198 cataract patients using both contact and immersion
techniques, randomly assigned to two measurers, one with more experience than the other. Both techniques
were repeated by each measurer. The mean difference of both techniques was calculated for the difference of
the intraocular lens power.
Results : The respective mean differences of both techniques for the first and the second measurers were 0.03
and 0.07 mm. The repeatability coefficient was two-fold for the contact but was similar for the immersion
technique. The respective difference of the intraocular lens power of both measurers was 1.15 and 1.65
diopters (D). A statistically significant agreement was noted between both techniques. The reproducibility of
both techniques was similar when performed by an experienced measurer however, the less experienced
measurer had greater reproducibility with the immersion technique.
Conclusion : The difference in the intraocular lens power from both techniques may have clinical significance;
hence, the immersion technique should be considered, particularly for less-experienced measurer.
Keywords : A-scan biometry, Axial length, Contact technique, Immersion technique, Intraocular lens power
