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Ajay Pillai, Dustin Morley, Richard Olmstead; Evaluation of an Intraoperative Anterior Segment Biometric System. Invest. Ophthalmol. Vis. Sci. 2013;54(15):812. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To quantify the correlation between the anterior segment biometry derived from the LENSAR Augmented Reality (AR) imaging system and preoperative ultrasound biometry. To objectively quantify the correlation between cataract severity metrics derived from the LENSAR AR system and ultrasound energy required for cataract removal.
Between January 2012 and March 2012, 52 patients underwent Refractive Laser-assisted Cataract Surgery at the Asian Eye Institute (Makati City, Philippines). Each patient’s medical chart was retrospectively reviewed for preoperative LOCS III cataract grade and average keratometry values. Preoperative A-scan ultrasound biometry values for corneal thickness (CT), anterior chamber depth (ACD), lens thickness (LT), and axial length (AL) were recorded. AR images of the anterior segment acquired immediately prior to laser treatment were analyzed for CT, ACD, LT, corneal anterior and posterior radius of curvature (ROC), and lens anterior and posterior ROC. Lens backscatter metrics were extracted as previously described by our research team and used to issue a lens scatter cataract grade (LSCG). Cumulative dissipated energy (CDE) during cataract extraction was recorded from the Alcon Infiniti phacoemulsification platform.
Average (SD) measurements for AR derived CT, Anterior Cornea ROC, ACD, and LT were 572.04 (46.90) µm, 7.6 (0.3) mm, 3.28 (0.50) mm, and 4.70 (0.41) mm respectively. Average (SD) measurements for ultrasound biometry derived CT, ACD, and LT were 544.88 (40.03) µm, 3.39 (0.44) mm, and 4.45 (0.60) mm. Average (SD) preoperative keratometry was 44.24 (1.70) D. Absolute deviation (SD) of AR derived CT, corneal keratometry, ACD, and LT from preoperative counterparts were 33.0 (25.2) µm, 0.73 (0.62) D, 0.24 (0.41) mm, and 0.29 (0.45) mm. AR measurements for CT (p<0.001), corneal keratometry (p<0.001), ACD (p=0.002), and LT (p<0.001) correlated highly with preoperative ultrasound biometry. LSCG correlated directly with CDE (p<0.05).
Initial results demonstrate that intraoperative anterior segment biometry shows direct correlation to preoperative ultrasound biometry and to preoperative keratometry. LSCG based on AR image analysis of the cataractous lens shows a direct correlation to the ultrasound energy required for successful phacoemulsification.
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