Axial Length and Anterior Chamber Depth by IOL-Master, A-scan according to Viscosity of Silicone Oil

ABSTRACT

PURPOSE: To evaluate differences between partial coherence laser interferometry (IOL-Master, Zeiss) and A-scan measurement of axial length and anterior chamber depth in silicone oil-filled eyes according to viscosity. METHODS: Using IOL-Master and A-scan, axial length and anterior chamber depth in silicone oil-filled eyes (n=54) and normal eyes (control, n=54) were measured and analyzed. In silicone oil-filled eyes, calculated axial lengths by A-scan using conversion factors, axial length multiplied by 0.71, and vitreous cavity multiplied by 0.64 (classic method) were compared with those calculated by IOL-Master. Anterior chamber depths were also analyzed., and axial lengths and anterior chamber depths were compared according to the viscosities of silicone oil for measurement by A-scan. RESULTS: Axial length and anterior chamber depth using IOL-Master were shorter than those using A-scan by 9.45+/-1.81 mm (p<0.05) and 0.11+/-1.29 mm, respectively. In normal eyes, axial length and anterior chamber depth using IOL-Master and A-scan were not significantly different. In silicone oil-filled eyes, axial length using IOL-Master and conversion factor was also not significantly different. At the highest silicone oil viscosity the difference in measured axial length was greatest (p<0.05) while the difference in anterior chamber depths was smallest. CONCLUSIONS: In silicone oil-filled eyes, axial length by IOL-Master was more accurate than that by A-scan, regardless of silicone oil viscosity. Thus, IOL-Master is more useful than A-scan when measuring axial length in silicone oil-filled eyes.