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Beatrice Cochener, Charly Maindron, Marzieh Kohandani Tafreshi, Matthieu Le Loir, Mathieu Lamard; Contribution Of 3-d Anterior Segment Reconstruction By Rotative Ubm To The Sizing Of Posterior Phakic Iol. Invest. Ophthalmol. Vis. Sci. 2012;53(14):3627.
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© ARVO (1962-2015); The Authors (2016-present)
Posterior phakic implantation is the recommended procedure for high ametropia correction. The limitation of its popularity seems to be due to the inaccuracy of the future location of the lens, induced by the present reference sizing method. We designed a 3D rotative UBM prototype in order to take into account the volume of the posterior chamber which is the implantation site.
12 myopic eyes (mean MRSE: -10.8 D) of 6 patients underwent a posterior phakic implantation by one surgeon using ICL V4 (STAAR Surgical®) with a "white to white"-based sizing method. During the 3rd postoperative month, we evaluated the rotative stability of the phakic lens in addition to usual refractive efficacy parameters. In particular, we focused on ICL vaulting - which represents the main safety parameter - that we assessed by anterior segment OCT (in 2-D) and by our UBM prototype (in 3-D). This system, designed by the Laboratoire de Traitement de l’Information Médicale (LaTIM - Inserm U1101) in association with Quantel Medical®, contains a linear scanning probe of 50 MHz with a rotative motor. It allows the acquisition of 30 coaxial slides in a 180° angle interval with an accuracy of 0.08 +/- 0.03 mm.
The analysis of 8 out of 12 implanted eyes revealed a excellent rotative stability, and the vaulting measured in 2-D between 0.29 and 0.39 mm is significantly correlated to the 3-D size of the posterior chamber. On the other hand, 4 of them presented a noncompliant implantation: there was one case of 60° ICL rotation, and 3 cases of incorrect vaulting, according to the 3-D anatomical data of the sulcus. In 2 cases, vaulting was significantly less than 0.35 mm, indicating an undersized implant; in the other case, excessive vaulting increased the irido-corneal angle closing (-50%).
Our UBM prototype allowed the first 3-D reconstruction of the anterior segment of the eye and, in particular, the access to measurable data necessary to qualify the posterior chamber as a volume. New sectional drawings and real-time 3-D sulcus reconstruction may offer customized ICL sizing, accurate visualization of the anatomical connections of the ICL within the anterior segment, and preoperative simulation possibilities.
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