Background: To compare objective electrophysiological contrast sensitivity function (CSF) in patients implanted with either multifocal intraocular lenses (MIOLs) or monofocal intraocular lenses (IOLs) by pattern reversal visual evoked potentials (prVEP) measurements.
Methods: Fourty-five cataract patients were randomly allocated to receive bilaterally: apodized diffractive-refractive Alcon Acrysof MIOL (A), full diffractive AMO Tecnis MIOL (B) or monofocal Alcon Acrysof IOL (C). Primary outcomes: 1-year differences in objective binocular CSF measured by prVEP with sinusoid grating stimuli of 6 decreasing contrast levels at 6 spatial frequencies. Secondary outcomes: psychophysical CSF measured with VCTS-6500, photopic uncorrected distance (UDVA), and mesopic and photopic uncorrected near and intermediate visual acuities (UNVA and UIVA respectively).
Results: Electrophysiological CSF curve had an inverted U-shaped morphology in all groups, with a biphasic pattern in Group B. Group A showed a lower CSF than group B at 4 and 8 cpd, and a lower value than group C at 8 cpd. Psychophysical CSF in group A exhibited a lower value at 12 cpd than group B. Mean photopic and mesopic UNVA and UIVA were worse in monofocal group compared to the multifocal groups. Mesopic UNVA and UIVA were better in group B.
Conclusions: Electrophysiological CSF behaves differently depending on the types of multifocal or monofocal IOLs. This may be related to the visual acuity under certain conditions or to IOL characteristics. This objective method might be a potential new tool to investigate on MIOL differences and on subjective device-related quality of vision.
Abstract: The article discusses the early abandonment of mechanical theories about eye enlargement in degenerative myopia at the turn of the 20th century. At that time, the number of theories about myopia grew unrestricted, but with scant support from the experimental field. The mechanical theories vanished as a new wave of metabolism-based theories appeared, propelled by the huge advances in molecular biology. Modern techniques allow reconsidering those theories and to put them to test with higher confidence.
Background: With a large portion of older adults living longer, the number of individuals diagnosed with low vision is increasing. The use of optical coherence tomography/scanning laser ophthalmoscope (OCT/SLO) to diagnose retinal disease has become common place in the last 10 years, yet currently there are no OCT/SLO databases for pathological vision. Our aim is to develop a clinical database of individuals who have drusen (i.e., lipid deposits found under the retina), or have been diagnosed with age-related macular degeneration (AMD), with information as to how the structure of the diseased retina changes over time, as well as measures of visual and cognitive functional performance.
Methods: Fundus photographs and retinal scans will be taken using the same model of optos OCT/SLO located in three test sites (MAB-Mackay Rehabilitation Centre, School of Optometry Clinic at the University of Montreal, and the Lighthouse Institute, New York, USA). For each individual entry in the database, demographic and diagnosis information will be available. All OCT/SLO images will be graded according to the Age-related Eye Disease Study standard, in addition to number and size of drusen, severity of geographic atrophy, severity of pigment mottling and presence of choroidal neovascularization. Retinal topography and Raster scans from the OCT/SLO will provide a cross-sectional look at affected retinas. Fixation stability will be recorded using the SLO function, and present four different tasks that are designed to reproduce typical tasks of daily vision, with each task lasting for 10 seconds. The tasks are cross fixation, face recognition, visual search, and reading. These tasks in addition to the retinal scans will be used to determine the eccentricity of a preferred retinal locus from the anatomical fovea, and can be used as an outcome measure for clinical interventions in visually impaired patients.
Results: The database will be available to professors training eye-care practitioners and rehabilitation specialists as a teaching tool. Students will be able to familiarize themselves with the retina and a variety of AMD-related pathologies before they start working with patients. The database will also be accessible by researchers interested in studying AMD from basic science to epidemiology, to investigate how drusen and AMD impact visual and cognitive functional performance.
Conclusions: The common infrastructure is easily accessible to all VHRN members on request. The database will also be accessible online in 2018 (see http://cvl.concordia.ca for more information).
Background: The purpose of this infrastructure is to provide to the Network researchers a database and diverse related tools for the anatomical and functional analysis of the normal, pathological and surgical cornea.
Methods: This database is composed of normal and pathological individuals, totaling more than 36,000 patients. It includes anatomical and functional imaging data, physiological optics data, psychometric and clinical data (medical history, surgical parameters, acuteness, etc.). Various corneal topography tools were added, giving the database a unique character: tools for analyzing individual maps, average map tools for the study and comparison of populations, 3D modeling and visualization tools, statistical tools, etc. There are also screening tools for detecting various corneal conditions (LASIK, PRK, RK, keratoconus) and for secure data exchange between colleagues.
Results: Several studies were made in recent years thanks to this common infrastructure. For example, this database has provided important information regarding the evolution of the 3D shape of the normal cornea with age and ametropia and has confirmed the mirror symmetry of corneas for the right and the left eyes (enantiomorphism). The different stages of Fuchs’ dystrophy were also characterized to provide essential knowledge for surgery of the posterior layer of the cornea. Our database also allowed studying the anatomy of the wounds and the shape of the cornea before and after a transfixing transplant or an endothelial transplant (DSAEK and DSEK). The data on the characterization of experimentally transplanted corneas with corneal equivalents generated by tissue engineering and the recent addition of clinical data on the replacement of a diseased cornea with a synthetic corneal equivalent (keratoprosthesis) also resulted in several publications. More recently, the database has allowed to develop innovative algorithms to determine the optimal shape of an implant according to the clinical parameters of the recipient. On the other hand, we also demonstrated that the 3D shape of the cornea can be used as a biometric characteristic (such as fingerprints) for identification of individuals for various applications ranging from forensics to secure border crossings. Consequently, a new multimodal database (cornea + iris + eventually retina) was created for the purpose of biometric identifications. This database provides a unique set of anatomical and functional tools for the analysis of the cornea. It is characterized by the scientific quality and large quantity of accumulated information on the cornea and the high-level tools to exploit its content.
Conclusions: The common infrastructure is easily accessible to all VHRN members on request. The database will also be accessible online in 2018 (see http://cvl.concordia.ca for more information).
Abstract: Optical coherence tomography (OCT) angiography is a new non-invasive imaging modality which is providing clinicians with an alternative to traditional dye-based angiography. The images are obtained using the concept of motion contrast and provide a quicker safer way to image the retinal and choroidal circulation. Not only are there practical aspects to support its integration but new insights are being made into the path; hysiology of various retinal choroidal diseases due to its ability to provide a 3-dimensional view of the vasculature which can be segmented in many ways to focus in on the circulation of a given anatomic region of the retina. We are currently in the phase of integration of this new technology into our practices.
Background: The expression, localization, and function of the endocannabinoid system has been well characterized in recent years in the monkey retina and in the primary thalamic relay, the lateral geniculate nucleus (dLGN). Few data are available on cortical recipients’ structures of the dLGN, namely the primary visual cortex (V1). The goal of this study is to characterize the expression and localization of the metabotropic cannabinoid receptor type 1 (CB1R), the synthesizing enzyme N-acyl phosphatidyl-ethanolamine phospholipase D (NAPE-PLD), and the degradation enzyme fatty acid amide hydrolase (FAAH) in the vervet monkey area V1.
Methods: Using Western blots and immunohistochemistry, we investigated the expression patterns of CB1R, NAPE-PLD, and FAAH in the vervet monkey primary visual cortex.
Results: CB1R, NAPE-PLD, and FAAH were expressed in the primary visual cortex throughout the rostro-caudal axis. CB1R showed very low levels of staining in cortical layer 4, with higher expressions in all other cortical layers, especially layer 1. NAPE-PLD and FAAH expressions were highest in layers 1, 2 and 3, and lowest in layer 4.
Conclusions: Interestingly enough, CB1R was very low in layer 4 of V1 in comparison to the other cortical layers. The visual information coming from the dLGN and entering layer 4Calpha (magno cells) and 4Cbeta (parvo cells) may be therefore modulated by the higher expression levels of CB1R in cortical layers 2 and 3 on the way to the dorsal and ventral visual streams. This is further supported by the higher expression of NAPE-PLD and FAAH in the outer cortical layers. These data indicate that CB1R system can influence the network of activity patterns in the visual stream after the visual information has reached area V1. These novel results provide insights for understanding the role of the endocannabinoids in the modulation of cortical visual inputs, and hence, visual perception.
Background: Exposure to ethanol in utero leads to several brain development disorders including retinal abnormalities whose underlying cellular pathogenesis remains elusive. We have previously reported changes in electroretinogram recordings in moderate fetal alcohol exposure (MFAE) vervet monkeys. The goal of this study is to characterize the anatomical effects of moderate MFAE during the third trimester in the vervet monkey retina.
Methods: Using immunohistochemistry and Western blots, we analyzed changes in the expression of cell-type specific proteins that may occur in the MFAE retina compared to the normal retina. We also compared the basic retinal anatomy across groups by examining retinal layering and thickness.
Results: Our main result indicates that GFAP (a potent marker of astrocytes) immunoreactivity was increased in the MFAE retina indicating strong astrogliosis. There was no obvious change in the overall anatomy in the MFAE retina and no significant differences in the mean thickness of each retinal layer. Furthermore, no significant changes in the morphology of the photoreceptors, horizontal cells, bipolar cells, and amacrines cells was observed.
Conclusions: These data indicate that astrogliosis is a consequence of prenatal alcohol exposure and might explain the reported changes in the electroretinographic responses.
Background: Our national collaborative research initiative is proposing to develop a common infrastructure for Rb research. We are proposing a novel in vivo Rb model using human Rb cells line.
Methods: The rabbit model has advantages over the mouse models: (I) the larger eye size of rabbits, similar to the human infant eye, permits a more accurate injection of the drugs and evaluation of methods of targeted intraocular drug delivery; (II) the rabbit model demonstrated similar fundus appearance and pathologic features to human Rb, including vitreous seeds of viable tumor when the retinal tumor is mid-sized, which are usually found in the late stage in mouse models. The lack of ability to eliminate vitreous seeds is a major reason of current treatment failures in Group C and D tumors; therefore, the rabbit model of Rb may be used as a model to evaluate the effectiveness and various routes of drug delivery.
Results: This is an implementation of an infrastructure for evaluating therapeutic targets. In addition, this finding enables a variety of pharmacokinetic studies, pharmacodynamic and toxicology studies for new therapeutic agents.
Conclusions: This infrastructure meets the growing concern of practitioners and researchers in the field. The common facility is easily accessible to all VHRN members on request, including requests from other sectors.
