Abstract
Abstract: :
Purpose: Effects of ocular accommodation on the measuring accuracy of axial length in optical coherence biometry were analyzed. Methods: Axial length measurements with and without accommodation were carried out with an optical coherence biometry, IOLMasterTM (Zeiss, Germany). Ten eyes of five normal subjects (mean age: 23.5+/-1.5 years) who had no ocular diseases except for refractive errors were participated in this study. For accommodative stimulus, we used an external fixation target coaxially with the measuring axis. Accommodative response was confirmed using pupillary size and ACD (anterior chamber depth) with the IOLMasterTM. We also evaluated the effect of accommodation on the optical path length and the final accuracy of axial length with IOLMasterTM. Results: Average axial length before and during accommodation was 25.09+/-0.76mm and 25.15+/-0.77mm, respectively. Axial length was significantly elongated during accommodation with a mean 0.06+/-0.01mm (p<0.005). Estimated maximum error in axial length due to accommodation (10D) was approximately 20mm derived from the optical path length changes in ACD and lens thickness using standard indices of refraction. Conclusions: Small elongation of the axial length during accommodation can be detected with an optical coherence biometry, IOLMasterTM with an accuracy of 0.020mm or less in clinical usage.
Keywords: accommodation • imaging methods (CT, FA, ICG, MRI, OCT, RTA, S • refractive surgery