Relationship between Spectralis optical coherence tomography with Nsite axonal analytics system, automated perimetry and pattern-reversal or multifocal visual evoked potential in compressive and inflammatory diseases of the anterior visual pathway

Abstract

Measuring the neural integrity of the retina and the optic nerve are important elements when studying anterior optic pathway diseases. A number of different thecnologies have been developed for such purpose including optical coherence tomography (OCT), pattern electroretinogram (PERG), multifocal PERG (mf-PERG), pattern-reversal visual evoked potential (pr-VEP) and multifocal VEP (mf-VEP). The ability of OCT, PERG and mf-PERG to quantify the neural integrity of the anterior visual pathway has already been verified in some of our previous studies, investigating the neural loss in patients with temporal hemianopia from chiasmal compression and band atrophy (BA) of the optic nerve and with inflammatory optic neuropathies from multiple sclerosis (MS) or neuromyelitis optica (NMO). However, recent advances in technology allowed the development of spectral domain OCT (SD-OCT), with extremelly high resolution compared to previous devices, and high acquisition velocity allowing increased resolution of the images. An eye tracking devide exists to reduce artifacts from ocular movement, and the software now allos for segmenting different retinal layers and measuring choroidal thickness (CT). Obtainig such measurements is utmost importance, to correlate such measurements with VF and electrophysiological tests.uctural abnormalities. Furthermore, the development of the Nsite Axonal Analytics system a software for the Spectralis HRA equipment (Heildelberg Engeneering), developed to improve acuracy of the retinal nerve fiber layer (RNLF) particularly in the papilomacular bundles. Such equipment is available in our service because, it was acquired through the Project number FAPESP, number 2011/50936-7). The only support we need now from FAPESP is to obtain the appropriate softwares to update the equipment to our projects. Purpose: To compare peripapillary RNFL measurements obtained using the software Nsite Axonal Analytics system, macular thickness measurements (full thickness and segmented) and also of the CT using extremely high-resolution OCT in patients with chiasmal compression, MS, NMO, longitudinal extensive transverse myelitis (LETM) and controls. To investigate the relationship between such measurements and those from VF, pr-VEP and mf-VEP. Methods: Transversal, cohort study with 30 patients with BA of the optic nerve, 30 with MS, 30 with NMO, 30 with LETM and 30 controls. Subjects will be submitted to a complete ophthalmic evaluation includind computerized perimetry, pr-VEP, mf-VEP and SD-OCT including peripapillary retinal nerve fiber layer (RNFL) and macular as well as choroid thickness evaluation of the posterior pole of the eye (30 degree). Peripapillary RNFL, full-thickness as well as segmented retinal layers including macular RNFL, ganglion cell layer (GCL), internal plexiform layer, the inner nuclear layer (INL) and outer plexiform layer will be assessed. Mf-VEP and perimetry results will be analysed in different sectors of the VF. SD-OCT results will be analysed in different areas of the optic disc and macula in order to enable evaluating the relationship between SD-OCT, perimetry and mf-VEP. Results in different groups of subjects will be compared and the relationship between measurements will be assessed. The occurrence of microcystic INL degeneration will be evaluated and its incidence in different groups compared. Expected results: We expect to be able to define the diagnostic ability of the equipment with the new software for detecting abnormalities in RNFL, different layers of the retina as well as the choroid in eyes with BA of the optic nerve, MS, NMO spectrum as compared to normals. To determine the relationship between SD-OCT and findings on pr-VEP, mf-VEP as well as with VF defects. To investigate the CT measurements and the incidence of mycrocistic degeneration of the INL in such patients. (AU)