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José F. Costa, Andreia C Rosa, Ângela Miranda, Conceicao F Lobo, Fátima Silva, Miguel Castelo-Branco, Joaquim N Murta; RETINOTOPIC MAPPING AFTER BILATERAL IMPLANTATION OF A MULTIFOCAL DIFFRACTIVE IOL. Invest. Ophthalmol. Vis. Sci. 2016;57(12):3753. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Multifocal intraocular lenses (mIOLs) are thought to induce changes in patient’s capability of processing visual stimuli. Yet, the organization of the visual cortex in these patients has never been studied before. We conducted a prospective case-control study in order to delineate and describe different areas of the visual cortex after bilateral implantation of a diffractive mIOL using a new method for retinotopic mapping with functional magnetic resonance imaging (MRI).
We included consecutive patients with presbiopia and cataract that underwent sequential bilateral implantation of a diffractive mIOL (ReSTOR SN6AD1, Alcon), along with a nonintervention control group. Exclusion criteria included high ametropia (>-6D or +6D), corneal astigmatism >1D and ocular comorbitities. On the 4th postoperative week, structural and functional MRI was performed. All patients underwent 2 structural acquisition sessions to obtain high-resolution tridimensional anatomical images (MPRAGE), followed by 3 functional sessions to map retinotopic areas. A new method, based on the “3h/4v Simultaneous Bars” technique (Dumoulin & Wandell, 2008), was used to measure the cortical response to a variety of visual stimuli. The anatomic and functional images were then processed with the BrainVoyager QX software, and the functional data was projected on a tridimensional reconstruction of the cerebral cortex in order to delineate the visual areas.
Thirty patients (mean age 61.5±5.8 years) and 15 controls (mean age 62.8±6.2 years) were included. Average follow-up was 23.6±4.1 days. There were no intra- or postoperative complications. High-resolution retinotopic maps were successfully acquired in the two groups. On the posteromedial region of the occipital lobe, V1 (primary visual cortex), V2 and V3 (extraestriate cortex) were found. Furthermore, our methods allowed the identification of more peripheral and complex areas, such as V3A/B, LO-1/2 and VO-1/hV4. Data analysis showed no significant differences between the two groups (patients and controls).
For the first time, we prove that it is possible to acquire high-resolution retinotopic maps in patients with bilateral mIOL. In the early postoperative period, no significant changes were found between patients and controls. We believe that this study is the first step towards the research of the long-term effect of non-conventional optics on cortical processing.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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