Conjunctival flaps have previously proven to be effective in preserving the globe for individuals with severe ocular surface disease. Infectious keratitis, neurotrophic keratitis, nontraumatic corneal melts, descemetoceles, perforations, and corneal burns are all indications for this procedure. The flaps promote nutrition, metabolism, structure, and vascularity, as well as reduce pain, irritation, inflammation, and infection. Furthermore, patients avoid the emotional and psychological repercussions of enucleation or evisceration, while requiring fewer postoperative medications and office visits. Currently, fewer flaps are performed due to the emergence of additional therapeutic techniques, such as serum tears, bandage lenses, corneal grafting, Oxervate, amniotic membrane, and umbilical cord grafting. However, despite newer conservative medical methods, conjunctival flaps have been demonstrated to be useful and advantageous. Moreover, future technologies and approaches for globe preservation and sight restoration after prior conjunctival flaps are anticipated. Herein, we review the history, advantages, and disadvantages of various surgical techniques: Gundersen’s bipedicle flap, partial limbal advancement flap, selective pedunculated conjunctival flap with or without Tenon’s capsule, and Mekonnen’s modified inferior palpebral-bulbar conjunctival flap. The surgical pearls and recommendations offered by the innovators are also reviewed, including restrictions and potential complications. Procedures for visual rehabilitation in selective cases after conjunctival flap are reviewed as well.
Abstract: The highly competitive offer of medical training programs and schools, globalization and constant mobility of physicians and medical students (MS), and the commitment to society to deliver competent physicians, demands the definition of performance standards. This would allow to make their performances comparable no matter where they studied or which textbook did they used as reference, to have evaluation mechanisms that guarantee mastery of the integral evaluation of the performance. Assessment has been the key in the teaching-learning process as this obtains a formative and summative element, at different moments, from the extent to which the students have acquired knowledge, skills and attitudes. The progress of the learner must be enhanced with effective feedback on their performance and self-direction of the results obtained in each of the mechanisms established. If, traditionally, this has been considered as the accreditation of compliance with a standard, the evaluation also functions in an integral way as a formative process that identifies advances and deficiencies in the training of residents that allows the definition of actions and strategies for improving the operation of the programs. Different assessment mechanisms are associated with the areas of competence domain, some of the most common tools are: theoretical exams, checklists and rubrics, portfolio, projects and challenges. However, the importance of defining standards which are perceived as fair and designed according to the learning objectives remains a priority to guarantee the credibility of the evaluation agencies and institutions. Some strategies to assure credibility include the involvement of expert and trained evaluators, allowing the process to be carried out with transparency and diligence, and the principles employed should be supported by educational research.
Abstract: Blinding diseases such as photoreceptor degenerations are debilitating conditions that severely impair daily lives of affected patients. This group of diseases are amenable to photoreceptor replacement therapies and recent transplantation studies provided proof-of-principle for functional recovery at the retinal and behavioral level, though the actual mechanism of repair still needs further investigations. The immune system responds in several ways upon photoreceptor engraftment, resulting in T-cell and macrophage infiltrations and, consequently, decrease in graft survival. Most studies on the role of the immune system suggest a detrimental effect in a therapeutic setting. Conversely, the opposite idea wherein the immune system can be activated towards a protective state was also explored in other experimental paradigms. Here, Neves and colleagues explored the potential of cross-species studies and, to a certain extent, the concept of a protective immune system in retinal degeneration and therapy. Mesencephalic astrocyte-derived neurotrophic factor (MANF) was identified in this study as a novel factor that, by modulating the immune system, can slow down photoreceptor degeneration and improve transplantation outcome.
Abstract: This article reviews the history of the femtosecond laser in ophthalmology and its subsequent introduction into the field of cataract surgery. It discusses the innovations that this technology has brought to the field. The article also describes the current system of teaching cataract surgery to ophthalmology residents in the United States and then examines how femtosecond laser-assisted cataract surgery (FLACS) can be a beneficial part of residency education.
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 ability to track objects as they move is critical for successful interaction with objects in the world. The multiple object tracking (MOT) paradigm has demonstrated that, within limits, our visual attention capacity allows us to track multiple moving objects among distracters. Very little is known about dynamic auditory attention and the role of multisensory binding in attentional tracking. Here, we examined whether dynamic sounds congruent with visual targets could facilitate tracking in a 3D-MOT task.
Methods: Participants tracked one or multiple target-spheres among identical distractor-spheres during 8 seconds of movement in a virtual cube. In the visual condition, targets were identified with a brief colour change, but were then indistinguishable from the distractors during the movement. In the audio-visual condition, the target-spheres were accompanied by a sound, which moved congruently with the change in the target’s position. Sound amplitude varied with distance from the observer and inter-aural amplitude difference varied with azimuth.
Results: Results with one target showed that performance was better in the audiovisual condition, which suggests that congruent sounds can facilitate attentional visual tracking. However, with multiple targets, the sounds did not facilitate tracking.
Conclusions: This suggests that audiovisual binding may not be possible when attention is divided between multiple targets.
Background: For years, studies using several animal models have highlighted the predominant role of the primary visual area in visual information processing. Its six cortical layers have morphological, hodological and physiological differences, although their roles regarding the integration of visual contrast and the messages sent by the layers to other brain regions have been poorly explored. Given that cortical layers have distinct properties, this study aims to understand these differences and how they are affected by a changing visual contrast.
Methods: A linear multi-channel electrode was placed in the primary visual cortex (V1) of the anesthetized mouse to record neuronal activity across the different cortical layers. The laminar position of the electrode was verified in real time by measuring the current source density (CSD) and the multi-unit activity (MUA), and confirmed post-mortem by histological analysis. Drifting gratings varying in contrast enabled the measurement of the firing rate of neurons throughout layers. We fitted this data to the Naka-Rushton equations, which generated the contrast response function (CRF) of neurons.
Results: The analysis revealed that the baseline activity as well as the rate of change of neural discharges (the slope of the CRF) had a positive correlation across the cortical layers. In addition, we found a trend between the cortical position and the contrast evoking the semi-saturation of the activity. A significant difference in the maximum discharge rate was also found between layers II/III and IV, as well as between layers II/III and V.
Conclusions: Since layers II/III and V process visual contrast differently, our results suggest that higher cortical visual areas, as well subcortical regions, receive different information regarding a change in visual contrast. Thus, a contrast may be processed differently throughout the different areas of the visual cortex.
