Visual snow syndrome: recent advances in understanding the pathophysiology and potential treatment approaches.

PURPOSE OF REVIEW: Visual snow syndrome (VSS) is a disorder characterized by persistent visual disturbances, including the visual snow phenomenon, palinopsia, heightened perception of entoptic phenomena, impaired night vision, and photophobia. The purpose of this review is to provide an update on recent findings over the past 18 months in VSS research and to summarize the current state of treatment approaches. RECENT FINDINGS: Electrophysiological studies have revealed cortical hyperresponsivity in visual brain areas, imaging studies demonstrated microstructural and functional connectivity alterations in multiple cortical and thalamic regions and investigated glutamatergic and serotoninergic neurotransmission. These findings suggest that VSS might be a network disorder.Only few treatment studies are currently available demonstrating limited response to medication and even worsening or triggering of visual symptoms by certain antidepressants. Promising nonpharmacological treatments include mindfulness-based cognitive therapy, the use of chromatic filters, and research on visual noise adaption and neuro-optometric visual rehabilitation therapy (NORT). However, the level of evidence is still low and further research is needed including larger trials and involving objective measures of individual dysfunction. SUMMARY: Although there has been recent progress, we still have not fully understood the nature of VSS. Further research is needed on a clinical and pathophysiological level to successfully treat the condition.

Effect of vision impairment on match-related performance and technical variation in attacking moves in Paralympic judo.

In Paralympic judo for athletes with vision impairment (VI judo) all eligible athletes (i.e. B1, B2 and B3 classes) compete against each other in the same competition. Evidence suggests that athletes with more impairment may be disadvantaged, but that more sensitive measures of performance are necessary to understand the impact of impairment on performance. The aim of this study was to investigate the relationship between Para sport class and technical variation, time-motion variables, and performance in Paralympic judo. All 175 judo matches from the Rio 2016 Paralympic Games were analysed across 129 competitors (82 male and 47 female). The main results indicated that athletes who demonstrated less technical variation also experienced less competitive success, with the functionally blind athletes (class B1) demonstrating less technical variation than partially sighted (class B2 and B3) athletes (p < 0.05). There was no difference in the time-motion variables between sport classes (p > 0.05). We conclude that measures of technical variation are sensitive to differences in impairment and are suitable for studies that investigate the impairment-performance relationship in VI judo. Results further confirm that some athletes with impairment are disadvantaged under the current rules of VI judo.

The role of clinical examination of the optic nerve head in glaucoma today.

PURPOSE OF REVIEW: The study was undertaken to assess the current importance of clinical examination of the optic nerve head (ONH) in glaucoma management. RECENT FINDINGS: ONH changes in glaucoma are easily assessed with good specificity on examination, whereas imaging has not been able to identify pallor of the neuroretinal rim (NRR), disc hemorrhages, or vascular signs of acquired cupping. Glaucomatous neuropathy in primary open angle glaucoma (POAG) has extensive databases on imaging machines, however, other glaucomas such as primary angle closure glaucoma (PACG), juvenile open angle glaucoma (JOAG), congenital, and secondary glaucomas have been reported to have a significantly different ONH morphology. Clinical evaluation with knowledge of the underlying cause of glaucoma allows easy diagnosis of any abnormality, whereas the absence of an imaging database in such eyes makes diagnosis difficult on optical coherence tomography (OCT) and so forth. In eyes with congenital anomalies and dysplastic discs, clinical examination and history provide better identification of glaucomatous damage. Staging of glaucoma on ONH examination when perimetry is unreliable provides a means of determining the amount of damage and appropriate reduction of intraocular pressure (IOP). SUMMARY: Clinical examination of the ONH is very relevant for screening, diagnosis, staging, and management of all glaucomas, and is irreplaceable in detecting nonglaucomatous causes of ONH cupping and visual field defects similar to those in glaucoma.

May the best-sighted win? The relationship between visual function and performance in Para judo.

This study aimed to establish the optimal cut-off point(s) between classes in a new, evidence-based classification system for VI judo. We collected results from international VI judo competitions held between 2012 and 2018. Data on visual acuity (VA) and visual field (VF) measured during classification were obtained. Performance was determined by calculating a win ratio for each athlete. VA was significantly associated with judo performance (r = -.33, p <.001), VF was not (r =.30, p =.15). Decision tree analysis suggested to split the data into two groups with a VA cut-off of 2.5 logMAR units. Stability assessment using bootstrap sampling suggested a split into two groups, but showed considerable variability in the cut-off point between 2.0 and 3.5 logMAR. We conclude that to minimise the impact of impairment on the outcome of competition, VI judo should be split into two sport classes to separate partially sighted from functionally blind athletes. To establish an exact cut-off point and to decide if other measures of visual function need to be included, we argue for continued research efforts together with careful evaluation of research results from a multidisciplinary perspective.

Efficacy of biofeedback rehabilitation based on visual evoked potentials analysis in patients with advanced age-related macular degeneration.

Age-related macular degeneration (AMD) is a progressive and degenerative disorder of the macula. In advanced stages, it is characterized by the formation of areas of geographic atrophy or fibrous scars in the central macula, which determines irreversible loss of central vision. These patients can benefit from visual rehabilitation programmes with acoustic "biofeedback" mechanisms that can instruct the patient to move fixation from the central degenerated macular area to an adjacent healthy area, with a reorganization of the primary visual cortex. In this prospective, comparative, non-randomized study we evaluated the efficacy of visual rehabilitation with an innovative acoustic biofeedback training system based on visual evoked potentials (VEP) real-time examination (Retimax Vision Trainer, CSO, Florence), in a series of patients with advanced AMD compared to a control group. Patients undergoing training were subjected to ten consecutive visual training sessions of 10 min each, performed twice a week. Patients in the control group did not receive any training. VEP biofeedback rehabilitation seems to improve visual acuity, reading performances, contrast sensitivity, retinal fixation and sensitivity and quality of life in AMD patients.

Visual-to-auditory sensory substitution alters language asymmetry in both sighted novices and experienced visually impaired users.

Visual-to-auditory sensory substitution devices (SSDs) provide improved access to the visual environment for the visually impaired by converting images into auditory information. Research is lacking on the mechanisms involved in processing data that is perceived through one sensory modality, but directly associated with a source in a different sensory modality. This is important because SSDs that use auditory displays could involve binaural presentation requiring both ear canals, or monaural presentation requiring only one - but which ear would be ideal? SSDs may be similar to reading, as an image (printed word) is converted into sound (when read aloud). Reading, and language more generally, are typically lateralised to the left cerebral hemisphere. Yet, unlike symbolic written language, SSDs convert images to sound based on visuospatial properties, with the right cerebral hemisphere potentially having a role in processing such visuospatial data. Here we investigated whether there is a hemispheric bias in the processing of visual-to-auditory sensory substitution information and whether that varies as a function of experience and visual ability. We assessed the lateralization of auditory processing with two tests: a standard dichotic listening test and a novel dichotic listening test created using the auditory information produced by an SSD, The vOICe. Participants were tested either in the lab or online with the same stimuli. We did not find a hemispheric bias in the processing of visual-to-auditory information in visually impaired, experienced vOICe users. Further, we did not find any difference between visually impaired, experienced vOICe users and sighted novices in the hemispheric lateralization of visual-to-auditory information processing. Although standard dichotic listening is lateralised to the left hemisphere, the auditory processing of images in SSDs is bilateral, possibly due to the increased influence of right hemisphere processing. Auditory SSDs might therefore be equally effective with presentation to either ear if a monaural, rather than binaural, presentation were necessary.

Physical activity interventions for adults who are visually impaired: a systematic review and meta-analysis.

OBJECTIVES: Compared with sighted individuals, people with visual impairment have a higher prevalence of chronic conditions and lower levels of physical activity. This review aims to systematically review physical activity interventions for those with a visual impairment and to assess their effectiveness. DESIGN: A systematic review of articles reporting physical activity interventions in visually impaired individuals was conducted. Medline, EMBASE, The Cochrane Library, Cumulative Index to Nursing and Allied Health Literature, SPORTDiscus and the Physiotherapy Evidence Database were searched in August 2018. Meta-analyses were conducted on randomised controlled trials with the same outcome measure. SETTING: Most interventions were conducted in a group setting, with some including an at-home, self-directed component. PARTICIPANTS: Following identification of a recent systematic review of physical activity interventions in children, our review focused on adults aged 18 years and older with a visual impairment. PRIMARY AND SECONDARY OUTCOME MEASURES: Outcomes included measures of balance, mobility, mental well-being (eg, quality of life), number of falls, muscle strength, flexibility and gait. RESULTS: Eighteen papers from 17 studies met inclusion criteria. Physical activity components include falls prevention and/or balance-based activities, walking, tai chi, Alexander Technique, Yoga, dance, aerobics and core stability training. Significant results in favour of the intervention were reported most commonly in measures of functional capacity (9/17 studies) and in falls/balance-related outcomes (7/13 studies). The studies identified were generally small and diverse in study design, and risk of bias was high across several categories for most studies. Meta-analyses indicated non-significant effects of the included interventions on the Timed Up and Go, Chair Sit Test and Berg Balance Scale. CONCLUSIONS: Physical activity interventions in individuals with visual impairment incorporating activities such as tai chi, Yoga and dance can have positive results, particularly in physical measures such as mobility and balance. However, when performing a meta-analysis of randomised controlled trials, the evidence for effectiveness is less clear. More studies with larger sample sizes, stronger designs and longer follow-up periods are needed. PROSPERO REGISTRATION NUMBER: CRD42018103638.

Branch retinal artery occlusion in a patient undergoing Methotrexate therapy for ectopic pregnancy: A case report.

Methotrexate is a commonly used agent in the treatment of an un-ruptured ectopic pregnancy. Thromboembolic events are rarely seen side effects of such a medicine. We report the case of the 22-year-old woman who underwent Methotrexate therapy for an un-ruptured ectopic pregnancy without any history of thromboembolic risk factors. A second dose (50 mg/m2) was administered to the patient showing a nondecreasing pattern of ß-HCG levels after an initial standard dosage of Methotrexate (50 mg/m2). On the 12th day of the treatment, a sudden onset of painless vision loss was seen in the right eye. Fundal imaging and fluorescein angiography revealed an occlusion of the superior temporal branch of the right retinal artery. After a month of hyperbaric oxygen therapy, complete recovery without loss of vision was achieved.

Non-invasive current stimulation in vision recovery: a review of the literature.

BACKGROUND: Around 253 million people worldwide suffer from irreversible visual damage. Numerous studies have been carried out in order to unveil the effects of electrical stimulation (ES) as a useful tool for rehabilitation for different visual conditions and pathologies. OBJECTIVE: This systematic review aimed to 1) examine the current evidence of ES efficacy for the treatment of visual pathologies and 2) define the corresponding degree of the recommendation of different ES techniques. METHODS: A systematic review was conducted in MEDLINE and Cochrane Library database to collect documents published between 2000 and 2018. For each study, Level of Evidence of Effectiveness of ES as well as the Class of Quality for the treatment of different visual pathologies were determined. RESULTS: Thirty-eight articles were included. Studies were grouped according to the pathology treated and the type of stimulation administered. The first group included studies treating pre-chiasmatic pathologies (age-related macular degeneration, macular dystrophy, retinal artery occlusion, retinitis pigmentosa, glaucoma, optic nerve damage, and optic neuropathy) using pre-chiasmatic stimulation; the second group included studies treating both pre-chiasmatic pathologies (amblyopia, myopia) and post-chiasmatic pathologies or brain conditions (hemianopsia, brain trauma) by means of post-chiasmatic stimulation. In the first group, repetitive transorbital alternating current stimulation (rtACS) reached level A recommendation, and transcorneal electrical stimulation (tcES) reached level B. In the second group, both high-frequency random noise stimulation (hf-RNS) and transcranial direct current stimulation (tDCS) reached level C recommendation. CONCLUSIONS: Study's findings suggest conclusive evidence for rtACS treatment. For other protocols results are promising but not conclusive since the examined studies assessed different stimulation parameters and endpoints. A comparison of the effects of different combinations of these variables still lacks in the literature. Further studies are needed to optimize existing protocols and determine if different protocols are needed for different diseases.

Clinical analysis of severe visual loss caused by inhalational methanol poisoning in a chronic process with acute onset:a retrospective clinical analysis.

BACKGROUND: To analyze the clinical features and prognosis of the visual loss resulted from inhalational methanol poisoning in 8 Chinese patients. METHODS: Eight consecutive patients seen at the Beijing Tongren Hospital of Capital Medical University, Beijing, China between January 2003 to August 2017, with complains of vision loss in both eyes, identified as inhalational methanol poisoning. Detailed medical history was extracted. All patients underwent optic nerve and brain magnetic resonance imaging (MRI) scan, laboratory tests, and visual function analysis. Treatment protocols were large dosage of methylprednisolone and B vitamins over 3 months. Patients were seen at 3-month intervals until a year. RESULTS: Eight patients with optic neuropathy caused by inhalation toxicity of methanol were under observation, whose methanol-contact time spans were form 4 days to 5 years for occupational exposure. All the patients had acute onset, transient systemic symptoms on early stage, both eyes involved with severe visual impairment (visual acuity 0.1 or even worse). Retrobulbar optic nerves (ONs) were the major sites involved. Optic nerve MRI scan showed increased signal of bilateral ONs in the orbit and the canal parts, with enhancement. After treatment, the visual function of these patients got improved in different degree in a year follow-up, but not satisfactorily. CONCLUSIONS: Inhalational methanol toxicity may lead to serious damage to ON in a process of chronic intoxication with acute attack, and with poor prognosis.

Corneal melt secondary to eosinophilic granulomatosis with polyangiitis.

Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare antineutrophil cytoplasmic antibody-associated vasculitis that can affect any organ system. It is most often characterised by chronic airway inflammation along with prominent peripheral blood eosinophilia, although the disease can affect the cardiovascular, gastrointestinal, renal or central nervous systems. Ocular manifestations are uncommon and when they do occur, are varied in their clinical presentations. To the best of our knowledge, this is the first case of corneal melt secondary to EGPA to have been reported.

Disc Configuration as a Risk and Prognostic Factor in NAION: The Impact of Cup to Disc Ratio, Disc Diameter, and Crowding Index.

Purpose: The presence of the so called disc at risk (a small disc with no cupping) has been considered the main risk factor for the development of non-arteritic anterior ischemic optic neuropathy (NAION). However its role as a prognostic factor has not been studied. Our aim was to determine the weight of disc configuration as a risk and a prognostic factor for NAION. Methods: Case control study. Forty eyes of 40 patients who were diagnosed with NAION between 2008 and 2017, and 120 controls (3 controls for each patient) were included in the study. Disc diameter (DD), cup to disc ratio (CDR), and peripapillar retinal nerve fiber layer thickness (RNFLT) of the non-affected eye were measured using optic coherence tomography (3D OCT 2000, Topcon). Crowding index (CI) was defined as the quotient of average RNFLT and disc area. Mean deviation (MD) at the time of diagnosis and at least three months later was determined using a Humphrey Visual Field Analyzer (SITA standard 24-2 strategy). Visual acuity (VA) was measured using Snellen charts and transformed into LogMAR values. Results: Only CDR was found to be a risk factor for NAION. No correlationship was found between CI and visual loss. Conclusions: DD and CI did not show value as either prognostic or risk factors. Glial tissue may be a part of the content of the optic disc as important as axons. Our results are in line with the latest studies about NAION pathophysiology. Contrary to classic thinking, these papers have not found smaller disc diameters, but smaller values of lamina cribosa depth in NAION patients.

Short-term Optic Disc Cupping Reversal in a Patient With Mild Juvenile Open-angle Glaucoma Due to Early Idiopathic Intracranial Hypertension.

PURPOSE: The purpose of this study was to report a case of optic disc cupping reversal in an adult without significant intraocular pressure-lowering treatment. PATIENT: A 20-year-old female with a history of mild juvenile open-angle glaucoma who developed subjective blurred vision and a decrease in cupping of her optic discs. RESULTS: Dilated examination demonstrated decreased cup-to-disc ratios in both eyes with a slight blurring of the disc margin in the right eye. The appearance of both optic discs returned to baseline after weight loss therapy. CONCLUSIONS: An unexplained reduction of optic nerve cup-to-disc ratio should prompt a workup for other etiologies, such as increased intracranial pressure. Baseline photographs not subjected to computerized scan obsolescence are extremely useful in monitoring the long-term appearance of asymmetric optic discs as an adjunct to the clinical examination.

Salzmann's nodular degeneration of cornea associated with thyroid eye disease.

Salzmann's nodular degeneration (SND) typically occurs in patients who are female, 50-60 years old, and have a history of corneal inflammation and irritation. Multiple case reports have documented associations between SND and trachoma, viral infections, trauma, contact lens wear, corneal surgeries and corneal exposure. The authors describe a patient with bilateral SND confirmed by anterior segment optical coherence tomography (OCT) imaging in the context of thyroid eye disease (TED) and history of LASIK. Treatment involved propylthiouracil (PTU), artificial tear use, loteprednol etabonate ophthalmic gel, eyelid taping and selenium supplementation and prospective superficial keratectomy with diamond burr polish.

Comparison of contrast sensitivity in ß-thalassemia patients treated by deferoxamine or deferasirox.

PURPOSE: To compare contrast sensitivity (CS) in multi-transfused ß-thalassemia patients who received deferoxamine with those who received Osveral. METHODS: In this cross sectional study a total of 60 ß-thalassemia patients (30 used deferoxamine and 30 used deferasirox) were regarded as case group and 30 age and sex matched healthy subjects were selected as control group. All subjects had a set of examinations including refraction, visual acuity, Biomicroscopy, ophthalmoscopy and CS. Contrast threshold was assessed with the use of Freiberg visual acuity and contrast test under the mesopic light condition for three frequencies; 1, 5, 15cpd. All data analysis was performed using SPSS, version 17. RESULTS: In visual acuity tests, thalassemic patients did not have any problem. Contrast threshold was higher in thalassemic patients who infuse deferoxamine (1.87±0.63, 1.46±0.81, and 2.96±1.68 in 1, 5, and 15cpd, respectively) than that of those who intake deferasirox (1.74±0.80 (P=0.743), 0.99±0.74 (P=0.047), and 2.42±1.36 (P=0.321) for 1, 5, and 15cpd, respectively), and also than healthy patients (1.33±0.58 (P=0.009), 0.95±0.68 (P=0.022), and 2.24±1.23 (P=0.135) for 1, 5, and 15cpd, respectively). Comparing those who used deferasirox with healthy subjects, contrast threshold was higher in deferasirox group at all special frequencies (P>0.05). No significant relationship was observed between CS values and duration of transfusion, serum ferritin concentration and dose of chelation therapy (P>0.05). CONCLUSIONS: CS tests can detect visual disturbance in thalassemic patients before the impairment of visual acuity. It is suggested that CS tests be included in their regular eye examination.

Optic Nerve Degeneration and Reduced Contrast Sensitivity Due to Folic Acid Deficiency: A Behavioral and Electrophysiological Study in Rhesus Monkeys.

Purpose: The purpose of the research was to elucidate the role of folic acid (B9) deficiency in the development of nutritional optic neuritis and to characterize the neurophysiological consequences of optic nerve degeneration in the cortical visual system. Methods: A combined behavioral and electrophysiological approach was applied to study luminance contrast sensitivity in two macaque monkeys affected by nutritional optic neuritis and in two healthy monkeys for comparison. For one monkey, a follow-up approach was applied to compare visual performance before onset of optic neuropathy, during the disease, and after treatment. Results: Optic nerve degeneration developed as a consequence of insufficient dietary intake of folic acid in two exemplars of macaque monkeys. The degeneration resulted in markedly reduced luminance contrast sensitivity as assessed behaviorally. In one monkey, we also measured visual activity in response to varying contrast at the level of single neurons in the cortical visual system and found a striking reduction in contrast sensitivity, as well as a marked increase in the latency of neuronal responses. Prolonged daily folate supplementation resulted in a significant recovery of function. Conclusions: Folic acid deficiency per se can lead to the development of optic nerve degeneration in otherwise healthy adult animals. The optic nerve degeneration strongly affects contrast sensitivity and leads to a distinct reduction in the strength and velocity of the incoming signal to cortical visual areas of the macaque brain, without directly affecting excitability and functional properties of cortical neurons.

Improving eye care in residential aged care facilities using the Residential Ocular Care (ROC) model: study protocol for a multicentered, prospective, customized, and cluster randomized controlled trial in Australia.

BACKGROUND: Older adults in residential aged care facilities have unnecessarily high levels of vision impairment (VI) which are largely treatable or correctable. However, no current comprehensive eye health service model exists in this setting in Australia. We aimed to determine the clinical, person-centered, and economic effectiveness of a novel eye care model, the Residential Ocular Care (ROC). METHODS/DESIGN: This protocol describes a multicentered, prospective, randomized controlled trial. A total of 395 participants with distance vision < 6/12 (0.30 LogMAR) and/or near vision N8 (1.00 M) or worse will be recruited from 38 urban and rural aged care facilities across Victoria, Australia. Aged care facilities will be randomized (1:1) to one of two parallel groups. Participants in the ROC group will receive a comprehensive and tailored eye care pathway that includes, as necessary, refraction and spectacle provision, cataract surgery, low vision rehabilitation, and/or a referral to an ophthalmologist for funded treatment. Usual care participants will be referred for an evaluation to the eye care service associated with the facility or an eye care provider of their choice. The primary outcome will be presenting near and distance vision assessed at the two- and six-month follow-up visits, post baseline. Secondary outcomes will include vision-specific quality of life, mobility, falls, depression, and eye care utilization at two and six months. An incremental cost-effectiveness analysis will also be undertaken. DISCUSSION: The ROC study is the first multicentered, prospective, customized, and cluster randomized controlled trial in Australia to determine the effectiveness of a comprehensive and tailored eye care model for people residing in aged care facilities. Results from this trial will assist health and social care planners in implementing similar innovative models of care for this growing segment of the population in Australia and elsewhere. TRIAL REGISTRATION: Australian and New Zealand Clinical Trials Registry, ACTRN12615000587505 . Registered on 4 June 2015 - retrospectively registered.

Valsalva haemorrhagic retinopathy in pregnancy after yoga.

A 35-year-old pregnant Caucasian woman at 27 weeks gestation presented with sudden onset painless loss of vision and a large floater in her left eye while doing yoga. She was found to have a dense vitreous haemorrhage with a small preretinal haemorrhage. Ultrasound imaging confirmed the haemorrhage and showed no other retinal damage. She was diagnosed with valsalva haemorrhagic retinopathy and was treated conservatively. After 5 months of follow-up, this woman had had a normal delivery and her haemorrhages and vision loss had resolved.

(Re)-wiring a brain with light: Clinical and visual processing findings after application of specific coloured glasses in patients with symptoms of a visual processing disorder (CVPD): Challenge of a possible new perspective?

The present investigation examined whether changes of electrophysiological late event related potential pattern could be used to reflect clinical changes from therapeutic intervention with coloured glasses in a group of patients with symptoms of central visual processing disorder. Subjects consisted of 13 patients with average age 16years (range 6-51years) with attention problems and learning disability, respectively. These patients were provided with specified coloured glasses which were required to be used during day time. Results indicated that specified coloured glasses significantly improved attention performance. Furthermore electrophysiological parameters revealed a significant change in the late event related potential distribution pattern (latency, amplitudes). This reflects a synchronization of together firing wired neural assemblies responsible for visual processing, suggesting an accelerated neuromaturation process when using coloured glasses. Our results suggest that the visual event related potentials measures are sensitive to changes in clinical development of patients with deficits of visual processing wearing appropriate coloured glasses. It will be discussed whether such a device might be useful for a clinical improvement of distraction symptoms caused by visual processing deficits. A model is presented explaining these effects by inducing the respiratory chain of the mitochondria such increasing the low energy levels of ATP of our patients.