Abstract
Abstract: :
Purpose: We used M–mode ultrasound biometery modified with A–mode biometry to assess the dynamic movement of the implanted intraocular lens (IOL). Effects of accommodative stimulus on the measurement of anterior chamber depth (ACD) and axial length (AL) in psudophakic eyes were analyzed. Methods: M–mode ultrasound biometry device was used for measurement of the axial movement of IOL. A–mode waveforms were continuously recorded before and after accommodation. In pseudophakic eyes, ACD and AL were measured 3 times, respectively. For comparison, ACD and AL were measured with the IOLMasterTM (Zeiss, Gemany). We enrolled two eyes of the pseudophakia and ten eyes of normal volunteers (college students) for the subjects. Results: Average changes due to accommodative stimulus were 0.05+/–0.04mm (AL), –0.27+/–0.13mm (ACD) in pseudophakia. In phakic eyes, –0.01+/–0.12mm (AL), –0.39+/–0.22mm (ACD) and 0.40+/–0.21mm (lens thickness change). Real–time recording of the dynamic movement of the implanted IOL and axial length changes can be obatained in all subjects. ACD was significantly reduced with accommodative stimulus (forward movement). Axial length was slitely elongated during accommodation with a mean 50mm (p<0.05). Estimated dioptric power change due to ACD change was approximately 0.7D and that due to AL elongation was 0.1D. Conclusions: Small elongation of the axial length and significant forward movement of the implanted IOL due to accommodative stimulus can be dynamically detected with M–mode ultrasound biometry. This device can be applied to continuous measurement of axial movement of IOLs, especially accommodating IOLs.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • clinical research methodology • cataract