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INTRODUCTION In 2011, a consensus report was produced on technology-enhanced assessment (TEA), its good practices, and future perspectives. Since then, technological advances have enabled innovative practices and tools that have revolutionised how learners are assessed. In this updated consensus, we bring together the potential of technology and the ultimate goals of assessment on learner attainment, faculty development, and improved healthcare practices. METHODS As a material for the report, we used the scholarly publications on TEA in both HPE and general higher education, feedback from 2020 Ottawa Conference workshops, and scholarly publications on assessment technology practices during the Covid-19 pandemic. RESULTS AND CONCLUSION The group identified areas of consensus that remained to be resolved and issues that arose in the evolution of TEA. We adopted a three-stage approach (readiness to adopt technology, application of assessment technology, and evaluation/dissemination). The application stage adopted an assessment ‘lifecycle’ approach and targeted five key foci: (1) Advancing authenticity of assessment, (2) Engaging learners with assessment, (3) Enhancing design and scheduling, (4) Optimising assessment delivery and recording learner achievement, and (5) Tracking learner progress and faculty activity and thereby supporting longitudinal learning and continuous assessment.

While debate about the use of-and alternatives to-human cadaveric dissection in medical training is robust, little attention has been paid to questions about timing. This study explores the perspectives of medical students and recent graduates with regard to two key questions: when in the degree program do students prefer dissection opportunities and what are the students getting out of participating in dissection? Self-report survey data from students in preclinical years (n = 105), clinical years (n = 57), and graduates (n = 13) were analyzed. Most (89%) preferred dissection during the preclinical years, with no effect by training year (χ

This chapter describes an innovative approach to the cross-disciplinary study of anatomy and art to facilitate visualization of the human body. We draw upon the literature, together with our own experience of designing, delivering and researching a cross-disciplinary art and anatomy course, to indicate the critical elements of the approach that foster students' visualization of the anatomy of the human body.Visual arts have been linked with anatomy for centuries, but typically biomedical science has existed in a utilitarian relationship with art only used as an aid. In this chapter, we discuss the rationale underpinning a cross-disciplinary anatomy and art course and describe our experience of devising activities and assessment that create a stimulating and mutually beneficial environment for visualizing the experience and physicality of the human body. We describe the structure of the course which integrates art and anatomy to train students in the language of anatomy and visual representation, by engaging them in a process of attempting their own visual communication. The cross-disciplinary nature of our approach creates a unique social environment that offers a supportive environment for exploration and experimentation without fear of failure. Students' personal growth in resilience, tolerance for uncertainty and creativity prepares them for the inclusion of these values in their career.

Teaching internal structures obscured from direct view is a major challenge of anatomy education. High-fidelity interactive three-dimensional (3D) micro-computed tomography (CT) models with virtual dissection present a possible solution. However, their utility for teaching complex internal structures of the human body is unclear. The purpose of this study was to investigate the use of a realistic 3D micro-CT interactive visualization computer model to teach paranasal sinus anatomy in a laboratory setting during pre-clinical medical training. Year 1 (n = 79) and Year 2 (n = 59) medical students undertook self-directed activities focused on paranasal sinus anatomy in one of two laboratories (traditional laboratory and 3D model). All participants completed pre and posttests before and after the laboratory session. Results of regression analyses predicting post-laboratory knowledge indicate that, when students were inexperienced with the 3D computer technology, use of the model was detrimental to learning for students with greater prior knowledge of the relevant anatomy (P < 0.05). For participants experienced with the 3D computer technology, however, the use of the model was detrimental for students with less prior knowledge of the relevant anatomy (P < 0.001). These results emphasize that several factors need to be considered in the design and effective implementation of such models in the classroom. Under the right conditions, the 3D model is equal to traditional laboratory resources when used as a learning tool. This paper discusses the importance of preparatory training for students and the technical consideration necessary to successfully integrate such models into medical anatomical curricula.

Australian and New Zealand universities commenced a new academic year in February/March 2020 largely with "business as usual." The subsequent Covid-19 pandemic imposed unexpected disruptions to anatomical educational practice. Rapid change occurred due to government-imposed physical distancing regulations from March 2020 that increasingly restricted anatomy laboratory teaching practices. Anatomy educators in both these countries were mobilized to adjust their teaching approaches. This study on anatomy education disruption at pandemic onset within Australia and New Zealand adopts a social constructivist lens. The research question was "What are the perceived disruptions and changes made to anatomy education in Australia and New Zealand during the initial period of the Covid-19 pandemic, as reflected on by anatomy educators?." Thematic analysis to elucidate "the what and why" of anatomy education was applied to these reflections. About 18 anatomy academics from ten institutions participated in this exercise. The analysis revealed loss of integrated "hands-on" experiences, and impacts on workload, traditional roles, students, pedagogy, and anatomists' personal educational philosophies. The key opportunities recognized for anatomy education included: enabling synchronous teaching across remote sites, expanding offerings into the remote learning space, and embracing new pedagogies. In managing anatomy education's transition in response to the pandemic, six critical elements were identified: community care, clear communications, clarified expectations, constructive alignment, community of practice, ability to compromise, and adapt and continuity planning. There is no doubt that anatomy education has stepped into a yet unknown future in the island countries of Australia and New Zealand.

Background Chemokine signalling is required for the homing of leukocytes during retinal inflammation, and is associated with pathogenesis of diseases such as age-related macular degeneration (AMD). Here, we explore the role of interleukin-1β (IL-1β) in modulating AMD-associated chemokines Ccl2, Cxcl1, and Cxcl10 during photo-oxidative retinal damage, and the effect on both the accumulation of outer-retinal macrophages, and death of photoreceptors. Methods Inhibition of retinal IL-1β expression was performed using either siRNA or antibody neutralisation, which was intravitreally injected in SD rats prior to photo-oxidative damage. Changes in the expression and localisation of Il-1β, Ccl2, Cxcl1 and Cxcl10 genes were assessed using qPCR and in situ hybridisation, while the recruitment of retinal macrophages was detected using immunohistochemistry for IBA1. Levels of photoreceptor cell death were determined using TUNEL. Results Photo-oxidative damage elevated the expression of Il-1β and inflammasome-related genes, and IL-1β protein was detected in microglia infiltrating the outer retina. This was associated with increased expression of Ccl2, Cxcl1, and Cxcl10. Intravitreal IL-1β inhibitors suppressed chemokine expression following damage and reduced macrophage accumulation and photoreceptor death. Moreover, in Müller and RPE cell cultures, and in vivo, Ccl2, Cxcl1 and Cxcl10 were variously upregulated when stimulated with IL-1β, with increased macrophage accumulation detected in vivo. Conclusions IL-1β is produced by retinal microglia and macrophages and promotes chemokine expression by Müller cells and RPE in retinal degeneration. Targeting IL-1β may prove efficacious in broadly suppressing chemokine-mediated inflammation in retinal dystrophies such as AMD.

A student's own body provides an often disregarded site of knowledge production and corporeal wisdom. Learning via cognitive processes anchored in physical movement and body awareness, known as embodied learning, may aid students to visualize structures and understand their functions and clinical relevance. Working from an embodied learning perspective, the current article evaluates the use of an offline physical learning tool (Anatomical Glove Learning System; AGLS) for teaching hand anatomy for clinical application in medical students. Two student samples (N1 = 105; N2 = 94) used the AGLS in two different ways. In the first sample, the AGLS was compared to a traditional approach using hand bones, models and prosected specimens. Secondly, the AGLS and traditional approach were combined. The evaluation consisted of three outcomes: short-term learning (post-test), medium-term applications (mock-objective structured clinical examination, MOSCE), and longer-term assessment (objective structured clinical examination, OSCE). Findings from the first sample indicated no significant differences between the AGLS and traditional laboratory groups on short- (F(1,78) = 0.036, P = 0.849), medium- (F(1,50) = 0.743, P = 0.393), or longer-term (F(1,82) = 0.997, P = 0.321) outcomes. In the second sample using the AGLS in combination with a traditional approach was associated with significantly better short-term post-test scores (F(2,174) = 5.98, P = 0.003) than using the AGLS alone, but demonstrated no effect for long-term OSCE scores. These results suggest an embodied learning experience alone does not appear to be advantageous to student learning, but when combined with other methods for studying anatomy there are learning gains.

Red-light treatment is emerging as a novel therapy for promoting tissue recovery but data on red-light penetration through human tissues are lacking. We aimed to: (1) determine the effect of light irradiance, tissue thickness, skin tone, sex and bone/muscle content on 660 nm light penetration through common sites of sports injuries, and (2) establish if cadaver tissues serve as a useful model for predicting red-light penetration in live tissues. Live and cadaver human tissues were exposed to 660 nm light at locations across the skull, spinal cord and upper and lower limbs. Red-light was produced by a light emitting diode array of various irradiances (15-500 mW/cm2 ) and measured by a light-probe positioned on the tissue surface opposite to the light emitting diodes. 100 mW/cm2 successfully penetrated tissue 50 mm. These results assist clinicians and researchers in determining red-light treatment intensities for penetrating human tissues.

Light-induced degeneration in rodent retinas is an established model for of retinal degeneration, including the roles of oxidative stress and neuroinflammatory activity. In these models, photoreceptor death is elicited via photo-oxidative stress, and is exacerbated by recruitment of subretinal macrophages and activation of immune pathways including complement propagation. Existing light damage models have relied heavily on albino rodents, and mostly using acute light stimuli. These albino models have proven valuable in uncovering the pathogenic mechanisms of such pathways in the context of retinal disease. However, their inherent albinism hinders comparability to normal retinal physiology, and also makes gene technology analysis time-consuming due to the predominance of the pigmented mouse strains in these applications. In this study, we characterise a new light damage model utilising C57BL/6J mice over a 7 day period of chronic light exposure. We use high-efficiency LED technology to deliver a sustained intensity of 100 k lux with negligible modulation of ambient temperature. We show that in the C57BL/6J mouse, chronic light exposure elicits the cardinal features of light damage including photoreceptor degeneration, atrophy of the choriocapillaris, decreased retinal function and increases in oxidative stress markers 4-HNE and 8-OHG, which emerge progressively over the 7 day period of exposure. These changes are accompanied by robust recruitment of IBA1+ and F4/80 + microglia/macrophages to the ONL and subretinal space, followed the strong up-regulation of monocyte-chemoattractants Ccl2, Ccl3, and Ccl12, as well as increases in expression of complement component C3. These findings are in agreement with prior damage models conducted in albino rodents such as Balb/c mice, and support the use of this new model in further investigating the causative features of oxidative stress and inflammation in retinal disease.

Purpose We sought to determine the role and retinal cellular location of microRNA-124 (miR-124) in a neuroinflammatory model of retinal degeneration. Further, we explored the anti-inflammatory relationship of miR-124 with a predicted messenger RNA (mRNA) binding partner, chemokine (C-C motif) ligand 2 (Ccl2), which is crucially involved in inflammatory cell recruitment in the damaged retina. Methods Human AMD donor eyes and photo-oxidative damaged (PD) mice were labeled for miR-124 expression using in situ hybridization. PDGFRa-cre RFP mice were used for Muller cell isolation from whole retinas. MIO-M1 immortalized cells and rat primary Muller cells were used for in vitro analysis of miR-124 expression and its relationship with Ccl2. Therapeutic efficacy was tested with intravitreal administration of miR-124 mimic in mice, with electroretinography used to determine retinal function. IBA1 immunohistochemistry and photoreceptor row counts were used for assessment of inflammation and cell death. Results MiR-124 expression was correlated with progressive retinal damage, inflammation, and cell death in human AMD and PD mice. In addition, miR-124 expression was inversely correlated to Ccl2 expression in mice following PD. MiR-124 was localized to both neuronal-like photoreceptors and glial (Muller) cells in the retina, with a redistribution from neurons to glia occurring as a consequence of PD. Finally, intravitreal administration of miR-124 mimics decreased retinal inflammation and photoreceptor cell death, and improved retinal function. Conclusions This study has provided an understanding of the mechanism behind miR-124 in the degenerating retina and demonstrates the usefulness of miR-124 mimics for the modulation of retinal degenerations.

The pathogenesis of many retinal degenerations, such as age-related macular degeneration (AMD), is punctuated by an ill-defined network of sterile inflammatory responses. The delineation of innate and adaptive immune milieu amongst the broad leukocyte infiltrate, and the gene networks which construct these responses, are poorly described in the eye. Using photo-oxidative damage in a rodent model of subretinal inflammation, we employed a novel RNA-sequencing framework to map the global gene network signature of retinal leukocytes. This revealed a previously uncharted interplay of adaptive immunity during subretinal inflammation, including prolonged enrichment of myeloid and lymphocyte migration, antigen presentation, and the alternative arm of the complement cascade involving Factor B. We demonstrate Factor B-deficient mice are protected against macrophage infiltration and subretinal inflammation. Suppressing the drivers of retinal leukocyte proliferation, or their capacity to elicit complement responses, may help preserve retinal structure and function during sterile inflammation in diseases such as AMD.

International audience; Purpose: Systemic increases in reactive oxygen species, and their association with inflammation, have been proposed as an underlying mechanism linking obesity and age-related macular degeneration (AMD). Studies have found increased levels of oxidative stress biomarkers and inflammatory cytokines in obese individuals; however, the correlation between obesity and retinal inflammation has yet to be assessed. We used the leptin-deficient (ob/ob) mouse to further our understanding of the contribution of obesity to retinal oxidative stress and inflammation.Methods: Retinas from ob/ob mice were compared to age-matched wild-type controls for retinal function (electroretinography) and gene expression analysis of retinal stress (), oxidative stress ( and ), and complement activation (, , , and ). Oxidative stress was further quantified using a reactive oxygen species and reactive nitrogen species (ROS and RNS) assay. Retinal microglia and macrophage migration to the outer retina and complement activation were determined using immunohistochemistry for IBA1 and C3, respectively. Retinas and sera were used for metabolomic analysis using QTRAP mass spectrometry.Results: Retinal function was reduced in ob/ob mice, which correlated to changes in markers of retinal stress, oxidative stress, and inflammation. An increase in C3-expressing microglia and macrophages was detected in the outer retinas of the ob/ob mice, while gene expression studies showed increases in the complement activators ( and ) and a decrease in a complement regulator (). The expression of several metabolites were altered in the ob/ob mice compared to the controls, with changes in polyunsaturated fatty acids (PUFAs) and branched-chain amino acids (BCAAs) detected.Conclusions: The results of this study indicate that oxidative stress, inflammation, complement activation, and lipid metabolites in the retinal environment are linked with obesity in ob/ob animals. Understanding the interplay between these components in the retina in obesity will help inform risk factor analysis for acquired retinal degenerations, including AMD.

The complement system is highly implicated in both the prevalence and progression of Age-Related Macular Degeneration (AMD). Complement system inhibitors therefore have potential therapeutic value in managing excessive activation of the complement pathways in retinal degenerations. The vaccinia virus complement control protein (VCP) has been shown to be effective as a complement inhibitor in neuroinflammatory models including traumatic brain injury and spinal cord injury. We aimed to investigate the potential of VCP as a therapeutic molecule for retinal degenerations. In this study, we investigated the effect, localisation and delivery of VCP to the rodent retina. Complement inhibition activity of VCP was tested using a hemolytic assay. Photoreceptor cell death, inflammation and retinal stress were assayed to determine if any retinal toxicity was induced by an intravitreal injection of VCP. The effect of VCP was investigated in a model of photo-oxidative retinal degeneration. Localisation of VCP after injection was determined using a fluorescein-tagged form of VCP, as well as immunohistochemistry. Finally, a copolymer resin (Elvax) was trialled for the slow-release delivery of VCP to the retina. We found that a dose equivalent to 20μg VCP when intravitreally injected into the rat eye did not cause any photoreceptor cell death or immune cell recruitment, but led to an increase in GFAP. In photo-oxidative damaged retinas, there were no differences in photoreceptor loss, retinal stress (Gfap) and inflammation (Ccl2 and C3) between VCP and saline-injected groups; however, Jun expression was reduced in VCP-treated retinas. After VCP was injected into the eye, it was taken up in all layers of the retina but was cleared within 1-3 hours of delivery. This study indicates that a method to sustain the delivery of VCP to the retina is necessary to further investigate the effect of VCP as a complement inhibitor for retinal degenerations.

The reduced use of dissection associated with the introduction of integrated systems problem-based learning curricula, graduate-entry programs and medical school expansion is a frequent topic of discussion and debate in modern medical training. The purpose of this study was to investigate the impact of these changes to the medical education landscape, by looking at the current utilization and integration of dissection in medical schools, in Australia and New Zealand. A survey and an invitation to participate in an interview were distributed to all Australian Medical Council-accredited medical schools. Sixteen schools (76%) responded to the survey and five interviews (24%) were conducted. Dissection was a component of the medical program in 12 of the 16 schools surveyed. The opportunity for medical students to dissect human cadavers was found to be related to whether the medical school was established pre- or post-2000 (P = 0.003) but was not significantly associated to undergraduate- or graduate-entry (P = 0.64), program length (P = 0.59) or the number of commencing students (P = 0.07). The methods used for the delivery and integration of dissection varied between schools. Despite substantial changes to the delivery of anatomy in Australian and New Zealand medical schools, a variety of approaches have been adopted to ensure dissection remains an integral component of medical student education. Based on our findings, a number of recommendations were formulated to encourage the integration of dissection, regardless of the didactics of the program, to enhance the anatomical knowledge of students. Anat Sci Educ. © 2015 American Association of Anatomists.

Retinopathy of prematurity (ROP) is a vasoproliferative disorder of the retina affecting extremely preterm or low birth weight infants The aim of this study was to assess the feasibility and safety of 670 nm red light use in a neonatal intensive care unit. Neonates

Anatomy students are typically provided with two-dimensional (2D) sections and images when studying cerebral ventricular anatomy and students find this challenging. Because the ventricles are negative spaces located deep within the brain, the only way to understand their anatomy is by appreciating their boundaries formed by related structures. Looking at a 2D representation of these spaces, in any of the cardinal planes, will not enable visualisation of all of the structures that form the boundaries of the ventricles. Thus, using 2D sections alone requires students to compute their own mental image of the 3D ventricular spaces. The aim of this study was to develop a reproducible method for dissecting the human brain to create an educational resource to enhance student understanding of the intricate relationships between the ventricles and periventricular structures. To achieve this, we created a video resource that features a step-by-step guide using a fiber dissection method to reveal the lateral and third ventricles together with the closely related limbic system and basal ganglia structures. One of the advantages of this method is that it enables delineation of the white matter tracts that are difficult to distinguish using other dissection techniques. This video is accompanied by a written protocol that provides a systematic description of the process to aid in the reproduction of the brain dissection. This package offers a valuable anatomy teaching resource for educators and students alike. By following these instructions educators can create teaching resources and students can be guided to produce their own brain dissection as a hands-on practical activity. We recommend that this video guide be incorporated into neuroanatomy teaching to enhance student understanding of the morphology and clinical relevance of the ventricles.

Photobiomodulation (PBM) with 670 nm light has been shown to accelerate wound healing in soft tissue injuries, and also to protect neuronal tissues. However, little data exist on its effects on the non-neuronal components of the retina, such as Muller cells (MCs), which are the principal macroglia of the retina that play a role in maintaining retinal homeostasis. The aim of this study was to explore the effects of 670 nm light on activated MCs using in vivo and in vitro stress models. Adult Sprague-Dawley rats were exposed to photo-oxidative damage (PD) for 24 h and treated with 670 nm light at 0, 3 and 14 days after PD. Tissue was collected at 30 days post-PD for analysis. Using the in vitro scratch model with a human MC line (MIO-M1), area coverage and cellular stress were analysed following treatment with 670 nm light. We showed that early treatment with 670 nm light after PD reduced MC activation, lowering the retinal expression of GFAP and FGF-2. 670 nm light treatment mitigated the production of MC-related pro-inflammatory cytokines (including IL-1β), and reduced microglia/macrophage (MG/MΦ) recruitment into the outer retina following PD. This subsequently decreased photoreceptor loss, slowing the progression of retinal degeneration. In vitro, we showed that 670 nm light directly modulated MC activation, reducing rates of area coverage by suppressing cellular proliferation and spreading. This study indicates that 670 nm light treatment post-injury may have therapeutic benefit when administered shortly after retinal damage, and could be useful for retinal degenerations where MC gliosis is a feature of disease progression.

Muller cells, the supporting cells of the retina, play a key role in responding to retinal stress by releasing chemokines, including CCL2, to recruit microglia and macrophages (MG/MΦ) into the damaged retina. Photobiomodulation (PBM) with 670 nm light has been shown to reduce inflammation in models of retinal degeneration. In this study, we aimed to investigate whether 670 nm light had an effect on Muller cell-initiated inflammation under retinal photo-oxidative damage (PD) in vivo and in vitro. Sprague-Dawley rats were pre-treated with 670 nm light (9J/cm2) once daily over 5 days prior to PD. The expression of inflammatory genes including CCL2 and IL-1β was analysed in retinas. In vitro, primary Muller cells dissociated from neonatal rat retinas were co-cultured with 661W photoreceptor cells. Co-cultures were exposed to PD, followed by 670 nm light treatment to the Muller cells only, and Muller cell stress and inflammation were assessed. Primary MG/MΦ were incubated with supernatant from the co-cultures, and collected for analysis of inflammatory activation. To further understand the mechanism of 670 nm light, the expression of COX5a and mitochondrial membrane potential (ΔΨm) were measured in Muller cells. Following PD, 670 nm light-treated Muller cells had a reduced inflammatory activation, with lower levels of CCL2, IL-1β and IL-6. Supernatant from 670 nm light-treated co-cultures reduced activation of primary MG/MΦ, and lowered the expression of pro-inflammatory cytokines, compared to untreated PD controls. Additionally, 670 nm light-treated Muller cells had an increased expression of COX5a and an elevated ΔΨm following PD, suggesting that retrograde signaling plays a role in the effects of 670 nm light on Muller cell gene expression. Our data indicates that 670 nm light reduces Muller cell-mediated retinal inflammation, and offers a potential cellular mechanism for 670 nm light therapy in regulating inflammation associated with retinal degenerations.

Introduction Light is the primary stimulus for vision, but may also cause damage to the retina. Pre-exposing the retina to sub-lethal amount of light (or preconditioning) improves chances for retinal cells to survive acute damaging light stress. Objectives This study aims at exploring the changes in retinal metabolome after mild light stress and identifying mechanisms that may be involved in preconditioning. Methods Retinas from 12 rats exposed to mild light stress (1000 lux × for 12 h) and 12 controls were collected one and seven days after light stress (LS). One retina was used for targeted metabolomics analysis using the Biocrates p180 kit while the fellow retina was used for histological and immunohistochemistry analysis. Results Immunohistochemistry confirmed that in this experiment, a mild LS with retinal immune response and minimal photoreceptor loss occurred. Compared to controls, LS induced an increased concentration in phosphatidylcholines. The concentration in some amino acids and biogenic amines, particularly those related to the nitric oxide pathway (like asymmetric dimethylarginine (ADMA), arginine and citrulline) also increased 1 day after LS. 7 days after LS, the concentration in two sphingomyelins and phenylethylamine was found to be higher. We further found that in controls, retina metabolome was different between males and females: male retinas had an increased concentration in tyrosine, acetyl-ornithine, phosphatidylcholines and (acyl)-carnitines. Conclusions Besides retinal sexual metabolic dimorphism, this study shows that preconditioning is mostly associated with re-organisation of lipid metabolism and changes in amino acid composition, likely reflecting the involvement of arginine-dependent NO signalling. Electronic supplementary material The online version of this article (doi:10.1007/s11306-016-1156-9) contains supplementary material, which is available to authorized users.

Marsupials are believed to be the only non-primate mammals with both trichromatic and dichromatic color vision. The diversity of color vision systems present in marsupials remains mostly unexplored. Marsupials occupy a diverse range of habitats, which may have led to considerable variation in the presence, density, distribution, and spectral sensitivity of retinal photoreceptors. In this study we analyzed the distribution of photoreceptors in the common brushtail possum (Trichosurus vulpecula). Immunohistochemistry in wholemounts revealed three cone subpopulations recognized within two spectrally distinct cone classes. Long-wavelength sensitive (LWS) single cones were the largest cone subgroup (67-86%), and formed a weak horizontal visual streak (peak density 2,106 ± 435/mm2) across the central retina. LWS double cones were strongly concentrated ventrally (569 ± 66/mm2), and created a "negative" visual streak (134 ± 45/mm2) in the central retina. The strong regionalization between LWS cone topographies suggests differing visual functions. Short-wavelength sensitive (SWS) cones were present in much lower densities (3-10%), mostly located ventrally (179 ± 101/mm2). A minority population of cones (0-2.4%) remained unlabeled by both SWS- and LWS-specific antibodies, and may represent another cone population. Microspectrophotometry of LWS cone and rod visual pigments shows peak spectral sensitivities at 544 nm and 500 nm, respectively. Cone to ganglion cell convergences remain low and constant across the retina, thereby maintaining good visual acuity, but poor contrast sensitivity during photopic vision. Given that brushtail possums are so strongly nocturnal, we hypothesize that their acuity is set by the scotopic visual system, and have minimized the number of cones necessary to serve the ganglion cells for photopic vision.

Light is a requirement for the function of photoreceptors in visual processing. However, prolonged light exposure can be toxic to photoreceptors, leading to increased reactive oxygen species (ROS), lipid peroxidation, and photoreceptor cell death. We used the 661W mouse cone photoreceptor-like cell line to study the effects of pyruvate in protecting these cells from light-induced toxicity.661W cells were exposed to 15,000 lux continuous bright light for 5 hours and incubated in Dulbecco's modified eagle medium (DMEM) with various concentrations of pyruvate. Following light damage, cells were assessed for changes in morphology, cell toxicity, viability, and ROS production. Mitochondrial respiration and anaerobic glycolysis were also assessed using a Seahorse Xfe96 extracellular flux analyzer.We found that cell death caused by light damage in 661W cells was dramatically reduced in the presence of pyruvate. Cells with pyruvate-supplemented media also showed attenuation of oxidative stress and maintained normal levels of ATP. We also found that alterations in the concentrations of pyruvate had no effect on mitochondrial respiration or glycolysis in light-damaged cells.Taken together, the results show that pyruvate is protective against light damage but does not alter the metabolic output of the cells, indicating an alternative role for pyruvate in reducing oxidative stress. Thus, sodium pyruvate is a possible candidate for the treatment against the oxidative stress component of retinal degenerations.

Photobiomodulation at a wavelength of 670 nm has been shown to be effective in preventing photoreceptor cell death in the retina. We treated Sprague-Dawley (SD) rats with varying doses of 670 nm light (9; 18; 36; 90 J/cm2) before exposing them to different intensities of damaging white light (750; 1000; 1500 lux). 670 nm light exhibited a biphasic response in its amelioration of cell death in light-induced degenerationin vivo. Lower light damage intensities required lower doses of 670 nm light to reduce TUNEL cell death. At higher damage intensities, the highest dose of 670 nm light showed protection.In vitro, the Seahorse XFe96 Extracellular Flux Analyzer revealed that 670 nm light directly influences mitochondrial metabolism by increasing the spare respiratory capacity of mitochondria in 661 W photoreceptor-like cells in light damaged conditions. Our findings further support the use of 670 nm light as an effective treatment against retinal degeneration as well as shedding light on the mechanism of protection through the increase of the mitochondrial spare respiratory capacity.

This study examined the impact of prolonged (up to 35 day) exposure to hyperoxia on the morphology and function of the retina, in the C57BL/6J mouse, as a basis for interpretation of gene expression changes. Mice of the C57BL/6J strain were raised from birth in dim cyclic illumination (12 h 5 lux, 12 h dark). Adult animals (90–110 days) were exposed to continuous hyperoxia (75% oxygen) for up to 35 d. Retinas were examined after 0 d (controls), 3 d, 7 d, 14 d and 35 d. Spatial and temporal patterns of photoreceptor death were mapped, using the TUNEL technique. Immunohistochemistry and a specific assay were used to assess the expression of a stress-related protein (GFAP) and the activity of key antioxidant enzymes (SOD). The dark-adapted flash electroretinogram was used to assess the function of rods and cones. RNA hybridized to Affymetrix Genechips was used to assess gene expression during the first 3 d of exposure. Photoreceptors were stable during the first 7 d exposure to hyperoxia, but thereafter showed progressive damage and degeneration, which began in a ‘hot-spot’ 0.5 mm inferior to the optic disc, then spread into surrounding retina. SOD activity was upregulated at 14 d, but not at earlier time points. GFAP expression was upregulated in Muller cells from 3 d. Rod and cone components of the ERG were supernormal at 3 d and 7 d, but then fell below control levels. Gene expression changes suggested possible mechanisms for this early supernormality of function. At 14 d exposure, damage to and death of photoreceptors were prominent and spreading, and function was correspondingly degraded. However at 3 d exposure, hyperoxia-induced supernormal functional responses in rods, while leaving their structure apparently undamaged. Variations in early (3 days) gene expression provide a partial insight into the mechanisms involved in this.

Purpose Glutathione-S-transferase omega 1-1 (GSTO1-1) is a cytosolic glutathione transferase enzyme, involved in glutathionylation, toll-like receptor signaling, and calcium channel regulation. GSTO1-1 dysregulation has been implicated in oxidative stress and inflammation, and contributes to the pathogenesis of several diseases and neurological disorders; however, its role in retinal degenerations is unknown. The aim of this study was to investigate the role of GSTO1-1 in modulating oxidative stress and consequent inflammation in the normal and degenerating retina. Methods The role of GSTO1-1 in retinal degenerations was explored by using Gsto1-/- mice in a model of retinal degeneration. The expression and localization of GSTO1-1 were investigated with immunohistochemistry and Western blot. Changes in the expression of inflammatory (Ccl2, Il-1β, and C3) and oxidative stress (Nox1, Sod2, Gpx3, Hmox1, Nrf2, and Nqo1) genes were investigated via quantitative real-time polymerase chain reaction. Retinal function in Gsto1-/- mice was investigated by using electroretinography. Results GSTO1-1 was localized to the inner segment of cone photoreceptors in the retina. Gsto1-/- photo-oxidative damage (PD) mice had decreased photoreceptor cell death as well as decreased expression of inflammatory (Ccl2, Il-1β, and C3) markers and oxidative stress marker Nqo1. Further, retinal function in the Gsto1-/- PD mice was increased as compared to wild-type PD mice. Conclusions These results indicate that GSTO1-1 is required for inflammatory-mediated photoreceptor death in retinal degenerations. Targeting GSTO1-1 may be a useful strategy to reduce oxidative stress and inflammation and ameliorate photoreceptor loss, slowing the progression of retinal degenerations.

PURPOSE: To characterize the long-term spatiotemporal features of light-mediated retinal degeneration. METHODS: Sprague-Dawley rats were exposed to 1000 lux for 24 h, then kept in dim light (5 lux), for up to 56 days. Animals were killed at 0, 3, 7, 28, and 56 days post-exposure, and retinas were prepared for immunohistochemistry. Outer nuclear layer (ONL) thickness and TUNEL labeling were used to quantify photoreceptor death. Antibodies to opsins, glial fibrillary acidic protein (GFAP), fibroblast growth factor-2 (FGF-2), and ED1 were used to assess the retina. RESULTS: At 0 days post-exposure, we detected photoreceptor death 2 mm superior to the optic disc (the "hotspot"), and ED1-positive macrophages in the retinal vasculature and underlying choroid. By 3 days, the ONL was thinner and there was gliosis in the outer retina, where ED1 positive macrophages were also present. Few ED1 positive cells remained at 28 days. At 56 days, there were TUNEL-positive nuclei in the penumbra, and increased FGF-2, and GFAP expression by Muller cells (MCs). In inferior retina, outer segment length was initially reduced, but recovered to near-normal by 28 days. CONCLUSIONS: Short exposure to damaging light destabilizes the retina adjacent to a hotspot of degeneration, so that the damaged region expands in size over time. Recruitment of macrophages is associated with the early phase of damage, but not with the longer term photoreceptor loss in the penumbra. Features of the focal and progressive retinal damage in this model are reminiscent of the progression of age-related macular degeneration (AMD).

Purpose To assess the effect of accelerated rod damage on the integrity of cones in the rat retina. Methods Rhodopsin-mutant P23H-3 and Sprague-Dawley (SD) rats were raised in scotopic ambient conditions (12 hours dark, 12 hours 5 lux) and then exposed to photopic conditions (12 hours dark, 12 hours 300 lux). Rods and cones were assessed for cell death, outer segment (OS) morphology, and electroretinogram (ERG) responses. Results Cones in the P23H-retina were affected rapidly by photopic exposure. Exposure for 2 days caused 50% reductions in LM- and S-cone OS length and cone ERG responses, associated with and preceded by reductions in rod OS length and ERG responses. Although 2 days' exposure increased the rate of rod death, outer nuclear layer thinning was minimal, and no evidence of cone death was detected. In the SD retina, the same photopic exposure had no measurable effects on death rates, OS length, or ERG responses in either rods or cones. Longer (7 days) photopic exposure reduced cone and rod OS length and ERG responses in SD, as well as P23H-3 retinas, but less severely than in the P23H-3 strain. Conclusions Cones are damaged rapidly in the P23H-3 retina when rod damage is accelerated by raised ambient illumination. This close dependence of cone integrity on rod integrity contrasts with the life-long persistence of cone function in the scotopic reared P23H-3 rat. In humans suffering comparable photoreceptor dystrophies, the maintenance of steady, low ambient light may, by minimizing acute rod damage, optimize the function of surviving cones.

Adult mammalian photoreceptors are elongated cells, and their mitochondria are sequestered to the ends of the cell, to the inner segments and (in some species) to axon terminals in the outer plexiform layer (OPL). We hypothesised that mitochondria migrate to these locations towards sources of oxygen, from the choroid and (in some species) from the deep capillaries of the retinal circulation. Six mammalian species were surveyed, using electron and light microscopy, including immunohistochemistry for the mitochondrial enzyme cytochrome oxidase (CO). In all 6 species, mitochondria were absent from photoreceptor somas and were numerous in inner segments. Mitochondria were prominent in axon terminals in 3 species (mouse, rat, human) with a retinal circulation and were absent from those terminals in 3 species (wallaby, rat, guinea pig) with avascular retinas. Further, in a human developmental series, it was evident that mitochondria migrate within rods and cones, towards and eventually past the outer limiting membrane (OLM), into the inner segment. In Müller and RPE cells also, mitochondria concentrated at the external surface of the cells. Neurones located in the inner layers of avascular retinas have mitochondria, but their expression of CO is low. Mitochondrial locations in photoreceptors, Müller and RPE cells are economically explained as the result of migration within the cell towards sources of oxygen. In photoreceptors, this migration results in a separation of mitochondria from the nuclear genome; this separation may be a factor in the vulnerability of photoreceptors to mutations, toxins and environmental stresses, which other retinal neurones survive.

Evidence is growing that exposure of tissue to low energy photon irradiation in the far-red (FR) to near-infrared (NIR) range of the spectrum, collectively termed "photobiomodulation" (PBM) can restore the function of damaged mitochondria, upregulate the production of cytoprotective factors and prevent apoptotic cell death. PBM has been applied clinically in the treatment of soft tissue injuries and acceleration of wound healing for more than 40 years. Recent studies have demonstrated that FR/NIR photons penetrate diseased tissues including the retina. The therapeutic effects of PBM have been hypothesized to result from intracellular signaling pathways triggered when FR/NIR photons are absorbed by the mitochondrial photoacceptor molecule, cytochrome c oxidase, culminating in improved mitochondrial energy metabolism, increased cytoprotective factor production and cell survival. Investigations in rodent models of methanol-induced ocular toxicity, light damage, retinitis pigmentosa and age-related macular degeneration have demonstrated the PBM attenuates photoreceptor cell death, protects retinal function and exerts anti-inflammatory actions.

Evidence is growing that exposure of tissue to low energy photon irradiation in the far-red (FR) to near-infrared (NIR) range of the spectrum, collectively termed "photobiomodulation" (PBM) can restore the function of damaged mitochondria, upregulate the production of cytoprotective factors and prevent apoptotic cell death. PBM has been applied clinically in the treatment of soft tissue injuries and acceleration of wound healing for more than 40 years. Recent studies have demonstrated that FR/NIR photons penetrate diseased tissues including the retina. The therapeutic effects of PBM have been hypothesized to result from intracellular signaling pathways triggered when FR/NIR photons are absorbed by the mitochondrial photoacceptor molecule, cytochrome c oxidase, culminating in improved mitochondrial energy metabolism, increased cytoprotective factor production and cell survival. Investigations in rodent models of methanol-induced ocular toxicity, light damage, retinitis pigmentosa and age-related macular degeneration have demonstrated the PBM attenuates photoreceptor cell death, protects retinal function and exerts anti-inflammatory actions.

Background The recruitment of macrophages accompanies almost every pathogenic state of the retina, and their excessive activation in the subretinal space is thought to contribute to the progression of diseases including age-related macular degeneration. Previously, we have shown that macrophages aggregate in the outer retina following damage elicited by photo-oxidative stress, and that inhibition of their recruitment reduces photoreceptor death. Here, we look for functional insight into macrophage activity in this model through the spatiotemporal interplay of macrophage polarisation over the course of degeneration. Methods Rats were exposed to 1000 lux light damage (LD) for 24hrs, with some left to recover for 3 and 7 days post-exposure. Expression and localisation of M1- and M2- macrophage markers was investigated in light-damaged retinas using qPCR, ELISA, flow cytometry, and immunohistochemistry. Results Expression of M1- (Ccl3, Il-6, Il-12, Il-1β, TNFα) and M2- (CD206, Arg1, Igf1, Lyve1, Clec7a) related markers followed discrete profiles following light damage; up-regulation of M1 genes peaked at the early phase of cell death, while M2 genes generally exhibited more prolonged increases during the chronic phase. Moreover, Il-1β and CD206 labelled accumulations of microglia/macrophages which differed in their morphological, temporal, and spatial characteristics following light damage. Conclusions The data illustrate a dynamic shift in macrophage polarisation following light damage through a broad swathe of M1 and M2 markers. Pro-inflammatory M1 activation appears to dominate the early phase of degeneration while M2 responses appear to more heavily mark the chronic post-exposure period. While M1/M2 polarisation represents two extremes amongst a spectrum of macrophage activity, knowledge of their predominance offers insight into functional consequences of macrophage activity over the course of damage, which may inform the spatiotemporal employment of therapeutics in retinal disease.

The present experiments were undertaken to test recovery of function in the retina of the rhodopsin-mutant P23H-3 rat, in response to the management of ambient light. Observations were made in transgenic P23H-3 and non-degenerative Sprague–Dawley albino (SD) rats raised to young adulthood in scotopic cyclic light (12 h 5 lx ’daylight’, 12 h dark). The brightness of the day part of the cycle was increased to 300 lx (low end of daylight range) for 1 week, and then reduced to 5 lx for up to 5 weeks. Retinas were assessed for the rate of photoreceptor death (using the TUNEL technique), photoreceptor survival (thickness of the outer nuclear layer), and structure and function of surviving photoreceptors (outer segment (OS) length, electroretinogram (ERG)). Exposure of dim-raised rats to 300 lx for 1 week accelerated photoreceptor death, shortened the OSs of surviving photoreceptors, and reduced the ERG a-wave, more severely in the P23H-3 transgenics. Returning 300 lx-exposed animals to 5 lx conditions decelerated photoreceptor death and allowed regrowth of OSs and recovery of the a-wave. Recovery was substantial in both strains, OS length in the P23H-3 retina increasing from 17% to 90%, and a-wave amplitude from 33% to 45% of control values. Thinning of the ONL over the 6 week period studied was minimal. The P23H-3 retina thus shows significant recovery of function and outer segment structure in response to a reduction in ambient light. Restriction of ambient light may benefit comparable human forms of retinal degeneration in two ways, by reducing the rate of photoreceptor death and by inducing functional recovery in surviving photoreceptors.

Ciliary neurotrophic factor (CNTF) is an important factor in the retina's mechanisms of self-protection. It is generated by retinal glial cells in response to stress, and has a significant protective effect on retinal neurones. In this study we have identified the location of the alpha component of the CNTF receptor complex (CNTFRalpha) in rat retina, using immunohistochemistry and high-resolution confocal microscopy. The major location of CNTFRalpha is on photoreceptor outer segments. More scattered, granular forms of CNTFRalpha were identified in association with Müller cell processes in other retinal layers. Colocalisation of CNTF with CNTFRalpha, suggestive of ligand-receptor binding, was detected on outer segments, and in both normal retinas and retinas stressed by light or oxygen. Results provide evidence that the principal site of CNTF action is the outer segments of photoreceptors. This confirms the known ability of CNTF to protect photoreceptors against stress, and suggest that it acts by modulating mechanisms specific to the outer segment, such as the phototransduction cascade or the membrane channels, which control dark current.

Complement system dysregulation is strongly linked to the progression of age-related macular degeneration (AMD). Deposition of complement including C3 within the lesions in atrophic AMD is thought to contribute to lesion growth, although the contribution of local cellular sources remains unclear. We investigated the role of retinal microglia and macrophages in complement activation within atrophic lesions, in AMD and in models of focal retinal degeneration.Human AMD donor retinas were labeled for C3 expression via in situ hybridization. Rats were subject to photo-oxidative damage, and lesion expansion was tracked over a 2-month period using optical coherence tomography (OCT). Three strategies were used to determine the contribution of local and systemic C3 in mice: total C3 genetic ablation, local C3 inhibition using intravitreally injected small interfering RNA (siRNA), and depletion of serum C3 using cobra venom factor.Retinal C3 was expressed by microglia/macrophages located in the outer retina in AMD eyes. In rodent photo-oxidative damage, C3-expressing microglia/macrophages and complement activation were located in regions of lesion expansion in the outer retina over 2 months. Total genetic ablation of C3 ameliorated degeneration and complement activation in retinas following damage, although systemic depletion of serum complement had no effect. In contrast, local suppression of C3 expression using siRNA inhibited complement activation and deposition, and reduced cell death.These findings implicate C3, produced locally by retinal microglia/macrophages, as contributing causally to retinal degeneration. Consequently, this suggests that C3-targeted gene therapy may prove valuable in slowing the progression of AMD.

The reduced use of dissection associated with the introduction of integrated systems problem-based learning curricula, graduate-entry programs and medical school expansion is a frequent topic of discussion and debate in modern medical training. The purpose of this study was to investigate the impact of these changes to the medical education landscape, by looking at the current utilization and integration of dissection in medical schools, in Australia and New Zealand. A survey and an invitation to participate in an interview were distributed to all Australian Medical Council-accredited medical schools. Sixteen schools (76%) responded to the survey and five interviews (24%) were conducted. Dissection was a component of the medical program in 12 of the 16 schools surveyed. The opportunity for medical students to dissect human cadavers was found to be related to whether the medical school was established pre- or post-2000 (P = 0.003) but was not significantly associated to undergraduate- or graduate-entry (P = 0.64), program length (P = 0.59) or the number of commencing students (P = 0.07). The methods used for the delivery and integration of dissection varied between schools. Despite substantial changes to the delivery of anatomy in Australian and New Zealand medical schools, a variety of approaches have been adopted to ensure dissection remains an integral component of medical student education. Based on our findings, a number of recommendations were formulated to encourage the integration of dissection, regardless of the didactics of the program, to enhance the anatomical knowledge of students.

Diseases of the retina are difficult to treat as the retina lies deep within the eye. Invasive methods of drug delivery are often needed to treat these diseases. Chronic retinal diseases such as retinal oedema or neovascularization usually require multiple intraocular injections to effectively treat the condition. However, the risks associated with these injections increase with repeated delivery of the drug. Therefore, alternative delivery methods need to be established in order to minimize the risks of reinjection. Several other investigations have developed methods to deliver drugs over extended time, through materials capable of releasing chemicals slowly into the eye. In this investigation, we outline the use of Elvax 40W, a copolymer resin, to act as a vehicle for drug delivery to the adult rat retina. The resin is made and loaded with the drug. The drug-resin complex is then implanted into the vitreous cavity, where it will slowly release the drug over time. This method was tested using 2-amino-4-phosphonobutyrate (APB), a glutamate analogue that blocks the light response of the retina. It was demonstrated that the APB was slowly released from the resin, and was able to block the retinal response by 7 days after implantation. This indicates that slow-release drug delivery using this copolymer resin is effective for treating the retina, and could be used therapeutically with further testing.

Purpose Aquaporin-4 (AQP4) and potassium channel Kir4.1 are normally expressed in retinal Muller glia, and play a major role in controlling retinal fluid and maintaining retinal integrity and function. We examined AQP4 and Kir4.1 distribution and expression in human eyes with late age-related macular degeneration (AMD) or long-term serous retinal detachment secondary to choroidal melanoma. Methods Paraffin sections of central and peripheral choroid/retina from young ( 70 years, n=4) and AMD (>70 years, n=5) human post-mortem eyes, and whole human eyes with choroidal melanoma (n=5), were co-immunolabelled with antibodies to AQP4, Kir4.1 and GFAP, and visualised using immunofluoresence and confocal microscopy. Results We found differential expression of AQP4 and Kir4.1 in detached retina of melanoma eyes, with upregulation of AQP4 and downregulation of Kir4.1 compared to unaffected eyes. This was most obvious in the retina overlying melanomas and in detached retina separated from underlying choroid. GFAP immunoreactitvity was upregulated in areas of serous retinal detachment, and retinal thinning; Muller cell processes extended along the anterior surface of melanomas. No apparent difference in distribution or expression of AQP4 or Kir4.1 was observed for retinas with late stage AMD compared to controls. Conclusion Decreased Kir4.1 expression in long term serous retinal detachment may be associated with Muller cell proliferative gliosis, as suggested in earlier animal studies. Increased AQP4 expression suggests efforts to restore retinal fluid balance in areas with photoreceptor degeneration and compromised outer blood-retinal barrier. Support: NFMRI (MCM), Lions NSW Eye Eyebank

Aging is a major risk factor for the development of diseases related to the central nervous system (CNS), such as Alzheimer's disease (AD) and age-related macular degeneration (AMD). In both cases, linkage studies and genome-wide association studies found strong links with complement regulatory genes and disease risk. In AD, both CLU and CR1 genes were implicated in the late-onset form of the disease. In AMD, polymorphisms in CFH, CFB and C2 were similarly implicated. The cost of caring for patients with AD or AMD is approaching billions of dollars, and with the baby boomers reaching their 60's, this amount is likely to increase further. Intervention using complement inhibitors for individuals in their early 50s who are at a higher risk of disease development, (testing positive for genetic risk factors), could slow the progression of AD or AMD and possibly prevent the severity of late stage symptoms. Although we have used the vaccinia virus complement control protein (VCP) to elucidate the role of complement in CNS diseases, it has merely been an investigational tool but not the only possible potential therapeutic agent.

PURPOSE: To assess the role of hypoxia in inducing the proliferation, hypertrophy, and dysfunction of Muller cells in detached retina and the effectiveness of supplemental oxygen in limiting these reactions. METHODS: Retinal detachments were produced in the right eye of each of 13 cats; the cats survived surgery for 3 days, during which six were kept in normoxia (room air, 21%) and seven in hyperoxia (70% oxygen). Retinas were labeled for proliferation with an antibody (MIB-1) to a cell cycle protein (Ki-67), for evidence of hypertrophy employing antibodies to the intermediate filament protein glial fibrillary acidic protein (GFAP) and to β-tubulin and for disturbance of glutamate neurochemistry employing antibodies to glutamate to a glutamate receptor (GluR-2) and to glutamine synthetase. RESULTS: Results from the two animals kept in normoxia after retinal detachment confirmed previous reports that detachment caused the proliferation of Muller cells, the hypertrophy of Muller cell processes, and the disruption of glutamate recycling by Muller cells. Oxygen supplementation during detachment reduced Muller cell proliferation and hypertrophy and reduced the abnormalities in the distributions of glutamate, GluR-2, and glutamine synthetase. CONCLUSIONS: Oxygen supplementation reduced the reaction of retinal Muller cells to retinal detachment, limiting their proliferation and helping to maintain their normal structure and function. In the clinical setting, oxygen supplementation between diagnosis and reattachment surgery may reduce the incidence and severity of glial-based complications, such as proliferative vitreoretinopathy.

Marsupials are believed to be the only non-primate mammals with both trichromatic and dichromatic color vision. The diversity of color vision systems present in marsupials remains mostly unexplored. Marsupials occupy a diverse range of habitats, which may have led to considerable variation in the presence, density, distribution, and spectral sensitivity of retinal photoreceptors. In this study we analyzed the distribution of photoreceptors in the common brushtail possum (Trichosurus vulpecula). Immunohistochemistry in wholemounts revealed three cone subpopulations recognized within two spectrally distinct cone classes. Long-wavelength sensitive (LWS) single cones were the largest cone subgroup (67-86%), and formed a weak horizontal visual streak (peak density 2,106 ± 435/mm2) across the central retina. LWS double cones were strongly concentrated ventrally (569 ± 66/mm2), and created a "negative" visual streak (134 ± 45/mm2) in the central retina. The strong regionalization between LWS cone topographies suggests differing visual functions. Short-wavelength sensitive (SWS) cones were present in much lower densities (3-10%), mostly located ventrally (179 ± 101/mm2). A minority population of cones (0-2.4%) remained unlabeled by both SWS- and LWS-specific antibodies, and may represent another cone population. Microspectrophotometry of LWS cone and rod visual pigments shows peak spectral sensitivities at 544 nm and 500 nm, respectively. Cone to ganglion cell convergences remain low and constant across the retina, thereby maintaining good visual acuity, but poor contrast sensitivity during photopic vision. Given that brushtail possums are so strongly nocturnal, we hypothesize that their acuity is set by the scotopic visual system, and have minimized the number of cones necessary to serve the ganglion cells for photopic vision.

Background Irradiation with light wavelengths from the far red (FR) to the near infrared (NIR) spectrum (600 nm -1000 nm) has been shown to have beneficial effects in several disease models. In this study, we aim to examine whether 670 nm red light pretreatment can provide protection against hyperoxia-induced damage in the C57BL/6J mouse retina. Adult mice (90–110 days) were pretreated with 9 J/cm2 of 670 nm light once daily for 5 consecutive days prior to being placed in hyperoxic environment (75% oxygen). Control groups were exposed to hyperoxia, but received no 670 nm light pretreatment. Retinas were collected after 0, 3, 7, 10 or 14 days of hyperoxia exposure (n = 12/group) and prepared either for histological analysis, or RNA extraction and quantitative polymerase chain reaction (qPCR). Photoreceptor damage and loss were quantified by counting photoreceptors undergoing cell death and measuring photoreceptor layer thickness. Localization of acrolein, and cytochrome c oxidase subunit Va (Cox Va) were identified through immunohistochemistry. Expression of heme oxygenase-1 (Hmox-1), complement component 3 (C3) and fibroblast growth factor 2 (Fgf-2) genes were quantified using qPCR. Results The hyperoxia-induced photoreceptor loss was accompanied by reduction of metabolic marker, Cox Va, and increased expression of oxidative stress indicator, acrolein and Hmox-1. Pretreatment with 670 nm red light reduced expression of markers of oxidative stress and C3, and slowed, but did not prevent, photoreceptor loss over the time course of hyperoxia exposure. Conclusion The damaging effects of hyperoxia on photoreceptors were ameliorated following pretreatment with 670 nm light in hyperoxic mouse retinas. These results suggest that pretreatment with 670 nm light may provide stability to photoreceptors in conditions of oxidative stress.

Irradiation by light in the far-red to near-infrared (NIR) region of the spectrum (photobiomodulation, PBM) has been demonstrated to attenuate the severity of neurodegenerative disease in experimental and clinical studies. The purpose of this study was to test the hypothesis that 670 nm PBM would protect against the loss of retinal function and improve photoreceptor survival in a rodent model of retinitis pigmentosa, the P23H transgenic rat. P23H rat pups were treated once per day with a 670 nm LED array (180 sec treatments at 50 mW/cm 2 ; fluence 9 joules/cm 2 ) (Quantum Devices Inc., Barneveld WI) from postnatal day (p) 16-20 or from p10-20. Sham-treated rats were restrained, but not exposed to NIR light. The status of the retina was determined at p22 by assessment of mitochondrial function, oxidative stress and cell death. In a second series of studies, retinal status was assessed at p30 by measuring photoreceptor function by ERG and retinal morphology by Spectral Domain Optical Coherence Tomography (SD-OCT). 670 nm PBM increased retinal mitochondrial cytochrome oxidase activity and upregulated the retina’s production of the key mitochondrial antioxidant enzyme, MnSOD. PBM also attenuated photoreceptor cell loss and improved photoreceptor function. PBM protects photoreceptors in the developing P23H retina, by augmenting mitochondrial function and stimulating antioxidant protective pathways. Photobiomodulation may have therapeutic potential, where mitochondrial damage is a step in the death of photoreceptors.

IntroductionTo investigate the validity of using 670nm red light as a preventative treatment for Retinopathy of Prematurity in two animal models of oxygen-induced retinopathy (OIR).Materials and methodsDuring and post exposure to hyperoxia, C57BL/6J mice or Sprague-Dawley rats were exposed to 670 nm light for 3 minutes a day (9J/cm²). Whole mounted retinas were investigated for evidence of vascular abnormalities, while sections of neural retina were used to quantify levels of cell death using the TUNEL technique. Organs were removed, weighed and independent histopathology examination performed.Results670 nm light reduced neovascularisation, vaso-obliteration and abnormal peripheral branching patterns of retinal vessels in OIR. The neural retina was also protected against OIR by 670 nm light exposure. OIR-exposed animals had severe lung pathology, including haemorrhage and oedema, that was significantly reduced in 670 nm+OIR light-exposed animals. There were no significance differences in the organ weights of animals in the 670 nm light-exposed animals, and no adverse effects of exposure to 670 nm light were detected.DiscussionLow levels of exposure to 670 nm light protects against OIR and lung damage associated with exposure to high levels of oxygen, and may prove to be a non-invasive and inexpensive preventative treatment for ROP and chronic lung disease associated with prematurity.

Aim Complement activation is associated with the pathogenesis of age-related macular degeneration (AMD). We aimed to investigate whether 670-nm light treatment reduces the propagation of complement in a light-induced model of atrophic AMD. Methods Sprague–Dawley (SD) rats were pretreated with 9 J/cm2 670-nm light for 3 minutes daily over 5 days; other animals were sham treated. Animals were exposed to white light (1,000 lux) for 24 h, after which animals were kept in dim light (5 lux) for 7 days. Expression of complement genes was assessed by quantitative polymerase chain reaction (qPCR), and immunohistochemistry. Counts were made of C3-expressing monocytes/microglia using in situ hybridization. Photoreceptor death was also assessed using outer nuclear layer (ONL) thickness measurements, and oxidative stress using immunohistochemistry for 4-hydroxynonenal (4-HNE). Results Following light damage, retinas pretreated with 670-nm light had reduced immunoreactivity for the oxidative damage maker 4-HNE in the ONL and outer segments, compared to controls. In conjunction, there was significant reduction in retinal expression of complement genes C1s, C2, C3, C4b, C3aR1, and C5r1 following 670 nm treatment. In situ hybridization, coupled with immunoreactivity for the marker ionized calcium binding adaptor molecule 1 (IBA1), revealed that C3 is expressed by infiltrating microglia/monocytes in subretinal space following light damage, which were significantly reduced in number after 670 nm treatment. Additionally, immunohistochemistry for C3 revealed a decrease in C3 deposition in the ONL following 670 nm treatment. Conclusions Our data indicate that 670-nm light pretreatment reduces lipid peroxidation and complement propagation in the degenerating retina. These findings have relevance to the cellular events of complement activation underling the pathogenesis of AMD, and highlight the potential of 670-nm light as a non-invasive anti-inflammatory therapy.