Background: Pericytes are contractile cells that wrap along the walls of capillaries. In the brain, pericytes play a crucial role in the regulation of capillary diameter and vascular blood flow in response to metabolic demand. During ischemia, it has been suggested that pericytes may constrict capillaries, and that pericytes remain constricted after reperfusion thus resulting in impaired blood flow.

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.

Background: The purpose of this study is to develop a screening questionnaire for the Charles Bonnet syndrome (CBS) that is valid, particularly in terms of specificity and sensitivity, and that allows to examine certain dimensions of these hallucinatory manifestations, to better assess the needs of people who live with the CBS. Methods: Interviews with clients of the Institut Nazareth et Louis-Braille who experienced visual hallucinations, supported by scientific literature and expert experience, guided the development of the questionnaire. Its content was first validated by six experts who assessed the questions developed, organized in seven subscales: (I) unusual perceptions; (II) contact with reality; (III) discriminatory screening; (IV) adaptation strategies; (V) psychological impact; (VI) description of the context of occurrence and (VII) characteristics. In a second step, a clinical study involving 76 people with visual impairment made it possible to determine the sensitivity and specificity of the instrument according to a criterion validity methodology, namely the clinical impression of a psychologist and/or an optometrist specialized in visual impairment, based on specific examinations and clinical tests. Subjects who appeared to have a CBS following the scouting done by subscale 1 (Unusual Perceptions) completed the rest of the questionnaire. Results: (I) The analyzes revealed a sensitivity of 1.00 and a specificity that varies from of 0.42 to 0.77 for the identification of CBS with the “Unusual Perceptions” subscale; (II) the administration of the questionnaire to the 76 study participants revealed that the wording of some questions needs to be improved; (III) the responses to the other 6 subscales of the questionnaire given by the 21 participants with SCB, show among others that most have simple rather than complex hallucinations and that these occur daily for 50% of them. Hallucinations do not negatively affect their mood, although they are experienced as disturbing by half of the participants with CBS. Only 11 participants with CBS have already talked about their hallucinations to a relative or a health professional, and only 5 have heard about CBS before. Conclusions: The CBS screening questionnaire has an excellent sensitivity, and an acceptable specificity. The CBS “Unusual Perceptions” subscale should include additional items. Further studies are needed for this purpose. In addition, the rest of the questionnaire reveals clinically important information about various aspects of these individuals’ hallucinations, such as the fact that many are disturbed by their hallucinations and have never heard of CBS. This questionnaire will help to better assess their needs and better plan interventions.

Background: Saccades are rapid and abrupt eye movements that allow us to change the point of fixation very quickly. Saccades are generally made to visual points of interest, but we can also saccade to non-visual objects that attract our attention. While there is a plethora of studies investigating saccadic eye movements to visual targets, there is very little evidence of how eye movement planning occurs when individuals are performing eye movements to non-visual targets across different sensory modalities.

Background: To review the trends in adult strabismus procedures in Ontario from 2000–2014. Methods: A population based, retrospective data analysis was conducted. Ontario Health Insurance Plan billing claims for strabismus procedures were collected and subdivided by number of muscles repaired, the use of adjustable sutures and repeat procedures, adjusted by the total adult population. The number of Ophthalmologists performing adult strabismus surgery was also analyzed, subdivided by high volume and low volume surgeons. Results: From 2000–2014, per 100,000 adult population, the number of total strabismus surgeries in Ontario increased 29.1%; single muscle surgery increased 25.0%, two muscle surgery increased 46.3%, and three or more muscle surgeries increased 8.3%. During the study period, strabismus procedures using adjustable sutures increased 26.1% and repeat procedures increased 65.1%. The number of surgeons performing adult strabismus surgery decreased 21.7% from 2000–2014. In 2014, 88.4% of surgeries were performed by 29.8% of all of surgeons who performed adult strabismus surgery. Conclusions: From 2000–2014, more strabismus surgery was performed in adults by fewer surgeons from 2000–2014. The number of adult strabismus surgeries in Ontario increased since 2000, including procedures using adjustable sutures and repeat procedures. These changes may be due to increases in healthcare funding and an increased awareness of the functional and psychosocial benefits of strabismus surgery.

The results from the tube versus trabeculectomy (TVT) study provided the evidence to support the use of aqueous shunt surgery and its increasing popularity in the world. The Ahmed versus Baerveldt (AVB) study, a randomized controlled study, compared the efficacy and safety between two of the most commonly used glaucoma drainage implants. A significant proportion of the participants had failed trabeculectomy, neovascular or uveitic glaucoma. The 5-year results showed that the cumulative probability for failure is significantly lower for Baerveldt compared to Ahmed group (52.3% vs . 40.0%, P=0.039). The most common reason for failure was high intraocular pressure (IOP) but 4% of the Baerveldt group has refractory hypotony. Both surgeries were also effective in reducing dependency on intra-ocular pressure lowering medications but the Baerveldt group is superior in this aspect (median of 1 medication compared to 2 medications for Ahmed group). Both surgeries experienced 60–70% rate of complications but most were self-limiting. The most common long-term complication was corneal decompensation (10%). Overall, the results of the AVB study mirrored the results from the Ahmed Baerveldt Comparison (ABC) study. In conclusion, the 5-year report from the AVB study suggested that the Baerveldt tube is more appropriate for eyes which require much lower IOP such as eyes with advanced glaucoma or in young patients. The Ahmed tube would be more suitable for patients who are at risk of hypotony (such as uveitic and neovascular glaucoma) and those who require immediate IOP lowering after surgery.

Abstract: Neuromyelitis optica (NMO) refers to an antibody mediated, inflammatory disorder of the central nervous system (CNS) characterized by recurrent or monophasic attacks of optic neuritis and myelitis. Most patients with NMO possess a specific serum immunoglobin, NMO-IgG, which can serve as a biomarker for NMO. The autoantibodies target aquaporin-4 (AQP4), the main water channel protein found in the CNS including the brain, spinal cord, and optic nerve. The remaining 10–25% of patients are seronegative for NMO-IgG despite meeting the diagnostic criteria for NMO. Recent studies have shown that a subset of these patients is seropositive for antibodies against myelin oligodendrocyte glycoprotein (MOG). This paper will provide an overview of the current English scientific literature published regarding the history, epidemiology, AQP4 biomarker, MOG biomarker, diagnosis, clinical features, related diseases in NMO spectrum disorder (NMOSD), and treatments of NMO.

You have worked hard in school over many years to excel in academic and extracurricular activities. You submitted a strong application for successful entry into medical school during which time you doubled up on your academic productivity and soaked in everything that you could possibly learn about medicine. You feel that your academic productivity paid off since you were able to obtain a residency in your favorite field: ophthalmology.

Recent innovations and technological advances have ushered in a new era of surgical approaches to glaucoma management. Our options have expanded beyond traditional incisional glaucoma surgery (i.e., trabeculectomy and tube shunts) to include newer procedures that can be implemented earlier in patients with milder disease. Many of these recently introduced operations can be classified as micro-invasive glaucoma surgery (MIGS), for which five defining criteria have been proposed: an ab interno approach; minimal tissue trauma; at least modest efficacy; high safety; and rapid recovery (1). Candidates for currently available MIGS are generally those with early glaucoma whose disease does not require very low intraocular pressure (IOP) to retard progression and/or who may benefit from reduction in medical therapy.

Pediatric cataract is a major cause of treatable blindness worldwide (1,2). The prevalence of cataract in children has been estimated between 1–15/10,000 children (3). There are 200,000 children blind from cataract worldwide, and 20,000 to 40,000 children with developmental bilateral cataract are born each year (3). Pediatric cataracts are responsible for more than 1 million childhood blindness in Asia alone (3). Pediatric cataract blindness presents an enormous problem in terms of human morbidity, economic loss, and social burden. Despite the availability of meticulous surgery, cataract is still the leading cause of blindness worldwide in children (4). There is no “ideal” lens to date that can replace the natural lens and at the same time preserving all the properties of the natural lens and devoid of complications. We are in an era where stem cells have revolutionized the treatment of many human diseases to the extent of changing blood groups as well. It is high time that we focus on this major cause of treatable blindness with treatments that would bring about a paradigm shift in the outcome of surgery.