Pupillary Response to Chromatic Light Stimuli as a Biomarker at the Early Stage of Glaucoma

Glaucoma is a multifactorial neurodegenerative disease of the optic nerve currently considered a severe health problem because of its high prevalence, being the primary cause of irreversible blindness worldwide. The most common type corresponds to Primary Open-Angle Glaucoma (POAG). Glaucoma produces, among other alterations, a progressive loss of Retinal Ganglion Cells (RGC) and its axons, key to generate the action potential that reaches the visual cortex to create the visual image. It indicates a Visual Field (VF) loss whose main feature is to be painless, and this makes early detection difficult, causing a late diagnosis and delaying a timely treatment indication that slows down its progression. Intrinsically photosensitive Retinal Ganglion Cells (ipRGCs), which represent a subgroup of RGCs being sensitive to damage, are characterized by reacting to short-wave light stimulation close to 480 nm and among their non-visual function, the role in the generation of the pupillary reflex stands out. Currently, the sensitivity of clinical trials correlates to RGC damage, however the need for an early damage biomarker is still relevant. It is an urgent task to create new diagnostic approaches to detect an early stage of glaucoma in a prompt, quick, and economical manner. We suggest evaluating the pupillary response to chromatic light as a potential biomarker of disease, its diagnostic benefit, and its cost-effectiveness in clinical practice to reduce irreversible damage caused by glaucoma.

Tertiary Cataract- A Rare Postoperative Complication after Cataract Surgery: A Case Study

Introduction: IOL opacification is a rare and serious complication of post operative diminution of vision with the only effective treatment being lens explantation and replacement, preferably involving lens of different material1. Following cataract surgery, it can occur anytime varying from months to years after the surgery. Case Report: A 57-years-old male presented with chief complaints of left eye diminution of vision since 2 years which was painless and progressive. Patient had undergone both eyes cataract surgery 4 years back elsewhere. He was a known case of Ischemic Heart Disease on treatment. On examination, his best corrected visual acuity (BCVA) was 6/9 in right eye and 6/36 in left eye. On slit light examination, there was presence of white pupillary reflex in left eye giving appearance of white cataract. On dilated examination, both eyes were found to be pseudophakic with left eye having posterior chamber opacified foldable Intra Ocular Lens and posterior segment details in left eye were not visible. B Scan was done and noted to be normal.He was posted for Left eye IOL (Intra Ocular Lens) exchange with rigid IOL Implantation with surgical capsulotomy after which his vision improved. Conclusion: Cases of opacified Intraocular lenses if visually significant require IOL exchange procedure for treatment which is associated with good visual prognosis. Key words: Pseudophakia, Intra Ocular Lens (IOL), Opacified IOL, Acrylic, Hydrophilic, Hydrophobic.

Atypical presentation of subdural block resulting in Horner’s syndrome and loss of consciousness

Horner’s syndrome is a rare side effect for patients receiving epidural anaesthesia. Studies described Horner’s syndrome due to cephalic spread of injected anaesthetics, a high spinal anaesthesia, or a sign of an inadvertent subdural block. A 31-year-old woman (Gravida 1 Para 0) at 40 weeks and 2 days had a caesarean section secondary to second stage arrest. Fourteen minutes after she received the lidocaine bolus, she became unresponsive with nystagmus, unequal pupils and no pupillary reflex. Head CT and MRI showed no intracranial haemorrhage and 2 hours later, she had spontaneous resolution of neurological symptoms with no further sequelae. Although Horner’s syndrome is a benign, transient process, clinicians should be mindful regarding epidural catheter placement causing subdural blocks resulting in spontaneous, reversible neurological deficits.

Refractive Error in Juvenile Patients Presenting with Nystagmus at Tertiary Care Hospital of Karachi

Objective: To evaluate the types of refractive errors in nystagmus patients among the age (5-15 years) patients. Study Design and Setting: An observational cross-sectional study was conducted at Pediatric department of Al-Ibrahim Eye Hospital, Karachi from June 2018 to March 2019. Methodology: A total of 55 patients (110 eyes) were selected from study setting. The protocol for examination for all patients were evaluated at the special clinic of Orthoptics includes the demographic data, educational status, history of onset, type of nystagmus. The anterior segment was examined with a slit-lamp to exclude any other ocular disease. Orthoptic assessment includes cover uncover test, Hirschberg, ocular motility, prism cover test and pupillary reflex test, to observe any associated deviation. All the patients were examined after obtaining a fully informed consent. After the proper diagnosis of nystagmus patient was recruited as per inclusion and exclusion criteria with no restrictions of gender. All the observations were noted on a Proforma, Data analysis was done by using SPSS version 20. P-value <0.05 was considered as statistically significant. RESULTS: A total of 55 patients, 29 male (52.7%) and 26 female (47.3%) were selected. This study shows out of 55 patients (110 eyes), 46 (42%) eyes had myopic astigmatism, while 33 (30%) eyes were found hyperopic astigmatism, 20 (18%) eyes were observed hyperopic and 11 (10%) eyes were observed myopic. CONCLUSION: Most common type of refractive error in nystagmus was myopic astigmatism. The refractive correction should be encouraged in children with nystagmus; improvement in visual function is likely to occur

The essential neurological examination in telemedicine consultations in the context of COVID 19/ O exame neurológico essencial nas consultas de telemedicina no contexto da COVID 19

Introduction: In clinical evaluation, the neurological area is one of the most complex and extensive to be analyzed, besides that, when added with Neurophobia it becomes even more difficult. With the COVID-19 Pandemic, there was an accelerated process of migration from outpatient clinics to digital platforms, requiring doctors to update their way of examining patients. The essential neurological examination, the tool that collaborates in this updated assessment, demonstrates greater objectivity in confirming the normality of the neurological system. The practice of checklists is a tool that helps these doctors to better evaluate their patients, optimizing their time and exams, contributing to its clinical diagnosis. Methodology: Review study integrative process that culminated in the elaboration and adaptation of new measures for essential neurological therapy in patients in the context of COVID-19 through Telemedicine. Results and Discussion: When comparing the essential neurological exam with the knowledge experienced by the authors of this article and the global pandemic context, were recommendations on the application of telemedicine were made. In addition to the need for doctor-patient communication to be audible and visible, without external interference so as not to impair the exams, the participation of a patient's companion is important to assist the doctor in exams. With that done, we identified that some of the exams essential neurological conditions become difficult to perform digitally, being: Indirect fundoscopy and reflexes (Biceps, Brachioradialis, Triceps, Patellar, Aquileu). However, exams such as direct fundoscopy, pupillary reflex, eye chase, mimic facial, gait, and plantar reflex can be examined via digital platforms as long as always the patient is accompanied. Conclusion: It is concluded that, amid pandemic, essential neurological examination becomes outdated, but useful in several areas, helping the doctor to take more informed measures.

Comparative Neurology of Circadian Photoreception: The Retinohypothalamic Tract (RHT) in Sighted and Naturally Blind Mammals

The mammalian eye contains two systems for light perception: an image detecting system constituted primarily of the classical photoreceptors, rods and cones, and a non-image forming system (NIF) constituted of a small group of intrinsically photosensitive retinal ganglion cells driven by melanopsin (mRGCs). The mRGCs receive input from the outer retina and NIF mediates light entrainment of circadian rhythms, masking behavior, light induced inhibition of nocturnal melatonin secretion, pupillary reflex (PLR), and affect the sleep/wake cycle. This review focuses on the mammalian NIF and its anatomy in the eye as well as its neuronal projection to the brain. This pathway is known as the retinohypothalamic tract (RHT). The development and functions of the NIF as well as the knowledge gained from studying gene modified mice is highlighted. Furthermore, the similarities of the NIF between sighted (nocturnal and diurnal rodent species, monkeys, humans) and naturally blind mammals (blind mole rats Spalax ehrenbergi and the Iberian mole, Talpa occidentalis) are discussed in relation to a changing world where increasing exposure to artificial light at night (ALAN) is becoming a challenge for humans and animals in the modern society.

Leber Congenital Amaurosis

Leber Congenital Amaurosis (LCA) is one of the most severe forms of hereditary retinal dystrophies described approximately 150 years ago and is a cause of vision loss early in childhood. Although LCA is characterized by wandering nystagmus, poor pupillary reflex (amaurotic pupils), and undetectable or severely abnormal ERG responses in infancy, there is a milder form called Severe Early Childhood Onset Retinal Dystrophy (SECORD) presenting after infancy usually before the age of five. LCA and SECORD describe a clinically and genetically diverse group of diseases. To date, there are 30 different genes determined to cause LCA/SECORD, and these genes are thought to account for approximately 70-80% of the disease spectrum. In recent years, with the initial successful results reported in treatment with gene therapy, LCA/SECORD has become the focus of new researches. This review summarizes the genetic and pathophysiological basis, different genetic types, and their clinical findings, diagnosis, differential diagnosis, and current developments in the treatment of LCA/SECORD.

Pupillary reflex and behavioral masking responses to light as functional measures of retinal degeneration in mice

Background Pre-clinical testing of retinal pathology and treatment efficacy depends on reliable and valid measures of retinal function. The electroretinogram (ERG) and tests of visual acuity are the ideal standard, but can be unmeasurable while useful vision remains. Non-image-forming responses to light such as the pupillary light reflex (PLR) are attractive surrogates. However, it is not clear how accurately such responses reflect changes in visual capability in specific disease models. The purpose of this study was to test whether measures of non-visual responses to light correlate with previously determined visual function in two photoreceptor degenerations. Methods The sensitivity of masking behavior (light induced changes in running wheel activity) and the PLR were measured in 3-month-old wild-type mice (WT) with intact inner retinal circuitry, Pde6b-rd1/rd1 mice (rd1) with early and rapid loss of rods and cones, and Prph2-Rd2/Rd2 mice (Rd2) with a slower progressive loss of rods and cones. Results In rd1 mice, negative masking had increased sensitivity, positive masking was absent, and the sensitivity of the PLR was severely reduced. In Rd2 mice, positive masking identified useful vision at higher light levels, but there was a limited decrease in the irradiance sensitivity of negative masking and the PLR, and the amplitude of change for both underestimated the reduction in irradiance sensitivity of image-forming vision. Conclusions Together these data show that in a given disease, two responses to light can be affected in opposite ways, and that for a given response to light, the change in the response does not accurately represent the degree of pathology. However, the extent of the deficit in the PLR means that even a limited rescue of rod/cone function might be measured by increased PLR amplitude. In addition, positive masking has the potential to measure effective treatment in both models by restoring responses or shifting thresholds to lower irradiances.

Evaluation of Nociception Using Quantitative Pupillometry and Skin Conductance in Critically Ill Unconscious Patients: A Pilot Study

Background: Pain assessment is a challenge in critically ill patients, in particular those who are unable to express movements in reaction to noxious stimuli. The purpose of the study was to compare the pupillary response and skin conductance to pain stimulation in critically ill unconscious patients. Methods: This observational study included adult patients admitted to the intensive care unit (ICU) with acute brain injury (Glasgow Coma Scale < 9 with a motor response < 5) and/or requirements for deep level of sedation. Automated pupillometry (Algiscan, ID-MED, Marseille, France) was used to determine pupillary reflex dilation during tetanic stimulation. The maximum intensity of the stimulation value allowed the determination of a pupillary pain index score ranging from 1 (no nociception) to 9 (high nociception): a pupillary pain index (PPI) score of ≤4 was used to reflect adequate pain control. For skin conductance (SC), the number of SC peaks per second (NSCF) was collected concomitantly to tetanic stimulation. An NSCF of ≤0.07 peak/second was used to reflect adequate pain control. Results: Of the 51 included patients, there were 32 with brain injury and 19 receiving deep sedation. Mean PPI score was 5 (Interquartile Range= 2–7); a total of 28 (55%) patients showed inadequate control of the nociceptive stimulation according to the PPI assessment. Only 15 (29%) patients showed a detectable skin conductance, with NSCF values from 0.07 to 0.47/s. No correlation was found between skin conductance algesimeter (SCA)-derived variables and PPI score or pupillary dilation to pain. Conclusions: Detection of inadequate pain control might vary according to the method used to assess nociception in ICU patients. A poor agreement between quantitative pupillometry and skin conductance was observed.