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V. Pierre–Kahn, E. Bui Quoc, G. Renard, D. Chavaud; Late Results Confirm High Accuracy of Axial Length Measurements in Silicone Oil–Filled Eyes With Optical Biometry . Invest. Ophthalmol. Vis. Sci. 2006;47(13):2628.
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© ARVO (1962-2015); The Authors (2016-present)
Laser Doppler Interferometry (LDI) is a non contact optical method that uses partial coherent interferometry to measure axial length (AL). It had been shown (Poster 5543, ARVO 2005) that optical biometry gave longer measurements in silicone oil (SO)–filled eyes than in SO–removed eyes when the postoperative biometry was performed at day 1 following the SO removal. The average deviation was small but statistically significant (0.25±0.51 mm). The aim of this study is to assess the accuracy of LDI in measuring axial length in SO–filled eyes by comparing LDI AL–measurements before and 6 months to one year after SO removal.
Optical Biometry (IOL Master®, Carl Zeiss Meditec) was performed in 34 eyes scheduled for silicone oil removal, both before and after 6 months following the surgical procedure. Eyes with recurrent retinal detachment at the time of the postoperative biometry were excluded. Optical biometries with a Signal to Noise Ratio (SNR) < 2 were also excluded.
Results and Discussion: :
Axial length was measured in 32 eyes using LDI. The mean AL ±SD of the silicone oil–filled eyes and silicone oil–removed eyes were respectively 24.99±2.71mm and 24.93 ±2.55mm. These values were highly correlated (r=0.99, p<0.0001). The average deviation was 0.062±0.22mm and was not statistically significant (p=0.166). Optical biometry performed on the post operative day gives shorter measurements than if performed after 6 months following the SO removal. Transient low postoperative intraocular pressure due to leakage at the sclerotomy sites or transient choroïdal thickening may explain this discrepancy. After 6 month post–operatively, optical biometry gives similar measurements than pre operatively.
Laser Doppler Interferometry can be used to measure axial length in silicone oil–filled eyes with a high accuracy level which is particularly usefull in phakic eyes were removal of the silicone oil can be combined with phacoemulsification and intraocular lens implantation.
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