The comparison of immersion B-scan guided with respective sonic velocity and Lenstar LS900 onmeasurement of axial length in silicone oil-filled eyes / 中华眼底病杂志

ABSTRACT

Objective To evaluate the accuracy of the biometry using immersion B scan and partial coherence interferometry (Lenstar LS900) for the axial length (AL) of silicone oil-filled eyes respectively.Methods Thirty-five silicone oil-filled eyes (38 patients) were included in the study.All of these eyes underwent silicone oil removal,cataract extraction and intraocular lenses implantation.The AL of all the silicone oil-filled eyes was measured with A/B-scan ultrasound and Lenstar LS900 before operation and with Lenstar LS900 after operation.The measured distance was compared respectively.The method of immersion B-scan guided with respective sonic velocity.AL was the sum of corneal thickness,anterior chamber depth,lens thickness,the apparent length of oil bubble (velocity values 996 m/s),the depth of the water layer beneath the oil bubble.Results Thirty-one eyes were measured with Lenstar LS900 before silicone oil removal,and the mean AL was (24.12± 1.70) mm,7 eyes failed to get the results before the operation;36 eyes were measured with Lenstar LS900 after silicone oil removal,and the mean AL was (24.45±1.89) mm.All eyes were measured with B-scan before silicone oil removal,and the mean AL was (24.87±2.52) mm.The difference (31 eyes) of AL measurement before silicone oil removal by two methods was (-0.00±0.09) mm;the difference (31 eyes) between pre-and post-surgical AL measurement with Lenstar LS900 was (0.02±0.07) mm;the difference (36 eyes) between pre-surgical AL measured with B-scan and post-surgical AL measured with Lenstar LS900 was (-0.02±0.11) mm.All the differences were not statistically significant (t=-0.205,1.752,-1.280;P＞ 0.05).The consistency of the results measured by two methods was well in Bland-Ahamn analysis.Conclusions Measurement results of AL between immersion B-scan guided with respective sonic velocity and Lenstar LS900 are high repeatability on silicone oil-filled eyes.The AL of silicone oil-filled eyes can be measured reliably by immersion B-scan guided with respective sonic velocity.