Background: All neurons of the visual system exhibit response to differences in luminance. This neural response to visual contrast, also known as the contrast response function (CRF), follows a characteristic sigmoid shape that can be fitted with the Naka-Rushton equation. Four parameters define the CRF, and they are often used in different visual research disciplines, since they describe selective variations of neural responses. As novel technologies have grown, the capacity to record thousands of neurons simultaneously brings new challenges: processing and robustly analyzing larger amounts of data to maximize the outcomes of our experimental measurements. Nevertheless, current guidelines to fit neural activity based on the Naka-Rushton equation have been poorly discussed in depth. In this study, we explore several methods of boundary-setting and least-square curve-fitting for the CRF in order to avoid the pitfalls of blind curve-fitting. Furthermore, we intend to provide recommendations for experimenters to better prepare a solid quantification of CRF parameters that also minimize the time of the data acquisition. For this purpose, we have created a simplified theoretical model of spike-response dynamics, in which the firing rate of neurons is generated by a Poisson process. The spike trains generated by the theoretical model depending on visual contrast intensities were then fitted with the Naka-Rushton equation. This allowed us to identify combinations of parameters that were more important to adjust before performing experiments, to optimize the precision and efficiency of curve fitting (e.g., boundaries of CRF parameters, number of trials, number of contrast tested, metric of contrast used and the effect of including multi-unit spikes into a single CRF, among others). Several goodness-of-fit methods were also examined in order to achieve ideal fits. With this approach, it is possible to anticipate the minimal requirements to gather and analyze data in a more efficient way in order to build stronger functional models.

Methods: Spike-trains were randomly generated following a Poisson distribution in order to draw both an underlying theoretical curve and an empirical one. Random noise was added to the fit to simulate empirical conditions. The correlation function was recreated on the simulated data and re-fit using the Naka-Rushton equation. The two curves were compared: the idea being to determine the most advantageous boundaries and conditions for the curve-fit to be optimal. Statistical analysis was performed on the data to determine those conditions for experiments. Experiments were then conducted to acquire data from mice and cats to verify the model.

Results: Results were obtained successfully and a model was proposed to assess the goodness of the fit of the contrast response function. Various parametres and their influence of the model were tested. Other similar models were proposed and their performance was assessed and compared to the previous ones. The fit was optimized to give semi-strict guidelines for scientists to follow in order to maximize their efficiency while obtaining the contrast tuning of a neuron.

Conclusions: The aim of the study was to assess the optimal testing parametres of the neuronal response to visual gratings with various luminance, also called the CRF. As technology gets more powerful and potent, one must make choices when experimenting. With a strong model, robust boundaries, and strong experimental conditioning, the best fit to a function can lead to more efficient analysis and stronger cognitive models.

Abstract: Successful management of a case of aggressive posterior retinopathy of prematurity (APROP) poorly responsive to laser therapy with intravitreal bevacizumab (IVB) is discussed. IVB is useful as rescue therapy in such cases, if given within the correct window period post laser therapy.

Abstract: Retinopathy of prematurity (ROP) is an emerging cause of childhood blindness in the developing countries. The low and middle-income countries are facing common challenges in the midst of the ‘third epidemic’ of ROP. Improvement in neonatal care facilities has increased survival of preterm babies. Lack of awareness and non-uniform standards of care in the ever-increasing number of neonatal intensive care units (NICUs) and special newborn care units (SNCUs) has resulted in this surge of ROP. Apart from low birth weight and the degree of prematurity, use of unblended supplemental oxygen, sepsis, anemia and blood transfusion are important risk factors associated with ROP in developing countries. Atypical forms of aggressive posterior ROP (APROP) are seen in heavier birth weight babies in the developing countries. Prevention of ROP by good quality neonatal care, timely diagnosis by mandatory ROP screening in NICUs and training manpower for laser treatment of ROP requires close collaboration between the neonatologists, ophthalmologists and the policy makers. Team approach and inter-disciplinary co-ordination are keys in a nation’s drive to fight this preventable cause of blindness.

Abstract: To describe the current aging population in China and globally, especially as it applies to age-related macular degeneration (AMD). To review the current standards of care for treating both wet (exudative) eAMD and dry (atrophic) aAMD. And to introduce a model for experimentation that is based on the Age-Related Eye Disease Study (AREDS) using eye bank tissue. A literature search that outlines current aging populations, standards of clinical treatment as defined by large, multicenter, randomized clinical trials that present level-I data with a low risk for bias. An experimental model system of AMD is presented that enables scientific analysis of AMD pathogenesis by applying grading criteria from the AREDS to human eye bank eyes. Analysis includes proteomic, cellular, and functional genomics. The standard of care for the treatment of eAMD is currently defined by the use of several anti-vascular endothelial growth (anti-VEGF) agents alone or in combination with photodynamic therapy. Monotherapy treatment intervals may be monthly, as needed, or by using a treat-and-extend (TAE) protocol. There are no proven therapies for aAMD. AMD that is phenotypically defined at AREDS level 3, should be managed with the use of anti-oxidant vitamins, lutein/zeaxanthin and zinc (AREDS-2 formulation). By understanding the multiple etiologies in the pathogenesis of AMD (i.e., oxidative stress, inflammation, and genetics), the use of human eye bank tissues graded according to the Minnesota Grading System (MGS) will enable future insights into the pathogenesis of AMD. Initial AMD management is with lifestyle modification such as avoiding smoking, eating a healthy diet and using appropriate vitamin supplements (AREDS-2). For eAMD, anti-VEGF therapies using either pro re nata (PRN) or TAE protocols are recommended, with photodynamic therapy in appropriate cases. New cellular information will direct future, potential therapies and these will originate from experimental models, such as the proposed eye bank model using the MGS, that leverages the prospective AREDS database.

Abstract: Timely and widely available, social media (SM) platforms and tools offer new and exciting learning opportunities in medical education. Despite scarce, we sought for a body of consistent evidence allowing us to substantially approach the concept of SM and how physicians as learners and medical educators can use SM based-education to benefit their clinical practice and their patients’ outcomes. We correlate education theories with the progression of world-wide web phases and how this influences the process of teaching and learning. We mention some examples of SM tools already in use in healthcare education. Potential advantages and effectiveness SM in medical education, as well as limitations of SM and pre-requisites for its use are discussed. Our concluding remarks underline the good practices in effectively utilizing SM in healthcare education.

Abstract: Training in residency programs is highly competitive, it requires the formation of competent physicians that achieve the performance standards that were declared for their technical skills, attitudes and interpersonal abilities. The use of simulation and technology on the medical education has increased considerably. Particularly in ophthalmology the simulators used are: live models from animal or cadavers, mannequins, wet laboratories, simulated patients, part-task moles, laser or surgical models, and more recently, virtual reality (VR). VR places a person in a simulated environment that has a specific sense of self-location, where the participant interacts with the objects within the setting. Teaching with VR refers to the use of the available resources in technology and visualization of structures to improve the educational experience of medical students, residents and physicians in professional continuous development programs. Several authors highlight the benefits of assessing trainees with the tools, they argue that the key contribution of this model is in the formative assessment. Rather than evaluating and putting a score on student’s grades, VR provides a powerful experience for the acquisition of skills. A conclusion is the need to develop studies to document the effects that it has on knowledge, skills and behaviors, and to patient related outcomes.

Abstract: The outcomes of modern ophthalmic surgery, especially cataract surgery, continue to improve and patients now realistically expect an excellent and speedy outcome with good vision and few complications. Social and regulatory demands for greater transparency and accountability in medicine have increased, highlighting a fundamental ethical tension in medical education—balancing the needs of trainees (who have not yet mastered the technique) to gain experience by performing surgery, with patient safety and the needs of the public to be protected from risk. Patient safety and well-being are the paramount considerations in any training program and must be the first consideration in program design. A variety of different educational strategies, each implemented with the aim of improving operative skills assessment and teaching, has recently been described in the literature. Effective use of these educational tools, combined with a structured approach to teaching and providing meaningful feedback, could improve outcomes, decrease complications and improve the quality and efficiency of surgical training in ophthalmology. Supervisors must assess their teaching style and communication, as being a good surgeon does not necessarily make a good trainer. Open disclosure must be given to patients about who will be performing the surgery, and communication during surgery between supervisors and trainees must be clear, respectful and appropriate.

Abstract: Optical coherence tomography (OCT) is a widely used non-invasive medical imaging technology that has revolutionized clinical care in ophthalmology. New developments, such as OCT angiography (OCTA) are expected to contribute even further to the widespread use of OCT-based imaging devices in the diagnosis and monitoring of patients with ophthalmic diseases. In recent years, many of the disadvantages such as limited field of view and imaging artefacts have been substantially reduced. Similar to the progress achieved in the assessment of retinal disorders, OCT is expected to change the approach to patients seen in the neuro-ophthalmology clinic. In this article, we review the technical features of OCT and OCT-based imaging techniques, highlighting the specific factors that should be taken into account when interpreting OCT in the field of neuro-ophthalmology.