Programming the scalable optical learning operator with spatial-spectral optimization (preprint)

Electronic computers have evolved drastically over the past years with an ever-growing demand for improved performance. However, the transfer of information from memory and high energy consumption have emerged as issues that require solutions. Optical techniques are considered promising solutions to these problems with higher speed than their electronic counterparts and with reduced energy consumption. Here, we use the optical reservoir computing framework we have previously described (Scalable Optical Learning Operator or SOLO) to program the spatial-spectral output of the light after nonlinear propagation in a multimode fiber. The novelty in the current paper is that the system is programmed through an output sampling scheme, similar to that used in hyperspectral imaging in astronomy. Linear and nonlinear computations are performed by light in the multimode fiber and the high dimensional spatial-spectral information at the fiber output is optically programmed before it reaches the camera. We then used a digital computer to classify the programmed output of the multi-mode fiber using a simple, single layer network. When combining front-end programming and the proposed spatial-spectral programming, we were able to achieve 89.9% classification accuracy on the dataset consisting of chest X-ray images from COVID-19 patients. At the same time, we obtained a decrease of 99% in the number of tunable parameters compared to an equivalently performing digital neural network. These results show that the performance of programmed SOLO is comparable with cutting-edge electronic computing platforms, albeit with a much-reduced number of electronic operations.

Time course study of optical coherence tomography angiography in patients with methanol induced optic neuropathy.

INTRODUCTION: In countries where alcoholic beverages are legally prohibited, methanol toxicity usually occurs due to ingesting homemade alcoholic drinks. The initial ophthalmologic symptoms of methanol toxicity typically appear 6-48 h after ingestion, and the severity of symptoms varies widely from mild and painless decreased vision to no-light perception vision. METHODS: This prospective study examines 20 patients with acute methanol poisoning within 10 days of use. Patients underwent ocular examinations, BCVA (Best Corrected Visual Acuity) recording, and OCTA (Optical Coherence Tomography Angiography) of the macula and optic disc. BCVA measurement and imaging were repeated one month and three months after intoxication. RESULTS: There was a statistically significant reduction in superficial parafoveal vascular density (P-value = 0.026), inner retinal thickness (P-value = 0.022), RNFL (Retinal Nerve Fiber Layer) thickness (P-value = 0.031), and an increase in cup to disc ratio (P-value < 0.001), and central visual acuity (P-value = 0.002) in this time course. However, there was no statistically significant difference in FAZ (Foveal Avascular Zone) area (P-value = 0.309), FAZ perimeter (P-value = 0.504), FD-300 (Foveal density, vascular density within a 300 µm wide region of the FAZ) (P-value = 0.541), superficial vascular density (P-value = 0.187), deep foveal vascular density (P-value = 0.889), deep parafoveal vascular density (P-value = 0.830), choroidal flow area (P-value = 0.464), total retinal thickness (P-value = 0.597), outer retinal thickness (P-value = 0.067), optic disc whole image vascular density (P-value = 0.146), vascular density inside the disc (P-value = 0.864), or peripapillary vascular density (P-value = 0.680) at different times. CONCLUSION: Over time, methanol poisoning can cause changes in retinal layers thickness, vasculature, and optic nerve head. The most important changes include cupping of the optic nerve head, reduction in RNFL thickness, and inner retinal thickness.

Infections and glaucoma.

Glaucoma is an intraocular pressure-related ophthalmic disease with multiple causes that results in an optic neuropathy and vision loss. Intraocular pressure elevation is among its strongest risk factors. While glaucoma is mostly primary in etiology, secondary glaucoma is not infrequent. Recognizing its cause is imperative, since treatment is often different depending on the pathophysiologic mechanism. Numerous clinically relevant ophthalmic infections can result in robust inflammatory responses that may result in pressure elevation or intraocular anatomic configurations that predispose to pressure elevation. Knowing the mechanisms by which these infections can lead to glaucoma is critical in treating, and we consolidate what is currently known in regards to how infectious diseases lead to glaucoma.

Optic neuropathies post-Covid 19 - review.

The Corona virus infection started at the end of 2019 in Wuhan - China and spread rapidly throughout the world, generating the Covid 19 pandemic. The manifestations of the Covid disease were extremely varied, from a simple flu, with fever, cough, weakness, headache, joint pain, up to severe pneumonia, with severe acute respiratory syndrome (SARS-Cov2) and even death. The symptomatology of the disease, the evolution and the complications that appeared varied, depending on the associated pathology - diabetes mellitus (DM), hypertension (HT), the age and the immune status of the patient. Aim: The ocular manifestations related to Covid 19 were mostly represented by conjunctivitis, but the neurotropic character of Corona virus could justify the appearance of certain neuro-ophthalmological manifestations, such as: optic neuritis (ON), cranial nerve palsies, visual field (VF) anomalies. The aim of this paper was to research the cases of optic neuropathy post-Covid 19, published in the specialty literature between 2020 and 2022. The following were evaluated: risk factors, distribution by age group and gender, evolution and complications, as well as the clinical forms of optic neuropathies. Materials and methods: We used Google Scholar and PubMed databases to find articles on optic neuropathies related to the Covid-19 infection. We followed the articles published during the pandemic and selected 21 cases, belonging to 17 authors, irrespective of their origin and the language in which they were written. Results: 21 patients affected by ON in the Covid-19 disease, 11 women and 10 men, were mentioned. The optic neuropathies described by the authors were: retrobulbar optic neuropathy, only one associated with myelin oligodendrocyte glycoprotein (MOG), papillitis, neuroretinitis, anterior ischemic optic neuropathy (AION), out of which one arteritic anterior ischemic optic neuropathy (AAION) and the others non-arteritic anterior ischemic optic neuropathy (NAAION), one being related to pronation in an oro-tracheal intubated (OTI) patient with acute respiratory distress syndrome (ARDS). Discussions: The neuro-ophthalmological complications associated with Covid 19 disease can be severe, so the patients should be monitored continuously. Many investigations (serological, immunological and imaging exams) are necessary to exclude other etiologies of ON. Conclusions: A complete ophthalmological exam is mandatory for each patient diagnosed with Covid 19 disease, even if they have ocular manifestations or not. Abbreviations: SARS-Cov2 = severe acute respiratory syndrome; DM = Diabetes mellitus; HT = Hypertension; ON = Optic neuritis; VF = Visual field ; NS = Nervous system; CRP = C-reactive Protein; CL = cytokines; IL = interleukins; TNFɑ = tumor necrosis factor; CNS = central nervous system; ACE = angiotensin-converting enzyme; CRVO = central retinal vein occlusion; MOG = myelin oligodendrocyte glycoprotein; MOG-AD = myelin oligodendrocyte glycoprotein antibody disease; BBB = blood-brain barrier; ARDS = acute respiratory distress syndrome; IOP = intraocular pressure; CVP = central venous pressure; MSOF = multiple systems organ failure; AAION = arteritic anterior ischemic optic neuropathy; NAION = non-arteritic anterior ischemic optic neuropathy; AION = anterior ischemic optic neuropathy; OCT = optical coherence tomography; CT = computer tomography; AFG = angiofluorography; MRI = magnetic resonance imaging; ESR = erythrocyte sedimentation rate; RF = rheumatoid factor; ANA = antinuclear antibodies; ANCA = antineutrophil cytoplasmic antibodies; AQP4 = anti aquaporin 4; NMO = neuromyelitis optica; CSF = cerebrospinal fluid; OTI = oro-tracheal intubated; VA = visual acuity; ONTT = optic neuritis treatment trial; RNFL = retinal nerve fiber layer; ICU = intensive care unit; LE = left eye; RE = right eye; MS = multiple sclerosis; ICH = intracranial hypertension; BCVA = best correction visual acuity; LP = light perception; APD = afferent pupillary defect; BM = biomicroscopy; PDN = prednisone; MTX = methotrexate; MTPN = methylprednisolone; NSAID = non-steroidal anti-inflammatory drugs; CGL = cells ganglion layer; VEP = visual evoked potential; CF = counting fingers.

Visual evoked potential and nerve conduction study findings in patients recovered from COVID-19.

OBJECTIVE: COVID-19 infection is associated with peripheral neuropathy. However, subclinical neurological involvement may occur anytime, and diagnostic methods that reveal this subclinical involvement are not well established. We aimed to assess the subclinical neurological involvement by visual evoked potential (VEP) measurements and nerve conduction studies (NCS) and explore the relationship between neurological electrophysiological findings and the severity of COVID-19 infection. METHODS: Seventy-six patients recovered from COVID-19 infection, and 44 healthy controls were enrolled in the study. Patients were assessed for clinical and demographic parameters. NCS and VEP analyses were performed to detect any peripheral neuropathy or optic neuropathy in both groups. RESULTS: None of the COVID-19 patients had electrophysiological evidence of peripheral neuropathy. However, patients with COVID-19 pneumonia had significant abnormalities in several peripheral nerve measurements compared to patients without pneumonia. Although P100 parameters did not differ significantly between patients and controls, 12 patients with COVID-19 had prolonged P100 latencies. CONCLUSIONS: We detected subclinical afferent visual pathway abnormality evaluated by VEP analysis. In addition, we found subtle electrophysiological features in the NCS of the patients presented with COVID-19 pneumonia. However, our findings did not fortify the diagnosis of peripheral neuropathy or optic neuropathy. Further studies are needed to determine the characteristics of COVID-19-related peripheral neuropathy/optic neuropathy whether it has distinct clinical features and disease course.

SARS-CoV-2 Vaccinated Breakthrough Infections With Fatal and Critical Outcomes in the Department of Antioquia, Colombia (preprint)

The introduction of variants of concern and interest in the Departamento of Antioquia, Colombia, was concomitant with the beginning of the COVID-19 immunization program. Genomic surveillance indicates that none of the emerging variants –alpha, gamma, lambda, mu or delta– were dominant between January and August 2021. The immunization includes CoronaVac, BNT162b2, Ad26.COV2.S and ChAdOx1-S vaccines. By September 10 th , 34.43% inhabitants were fully vaccinated. We characterized, SARS-CoV-2 breakthrough infections in 96 patients, 30 with fatal outcomes, 13 with ICU hospitalization and 53 with mild or asymptomatic disease. Even though gamma and mu variants co-circulated at similar levels, the latter was found to be predominant in patients with fatal outcomes and in those with ICU hospitalizations. We found a significant occurrence of the B.1.625 variant in these patients. Genetic substitutions of therapeutic and immunological concern, E484K and N501Y, are consistently observed in 90.1% and 79.5% of these variants, respectively. Evidence suggests that it is less probable to become infected after 60 days post-treatment with BNT162b2 than with CoronaVac. Importantly, we found that advanced age and comorbidities foster conditions for fatal and ICU outcomes in vaccinated patients. Our observations demonstrate the effectiveness of vaccination and identify patients with higher risks of subsequent breakthrough infections.

A case of endogenous candida endophthalmitis with incidental cytomegalovirus infection and optic neuropathy in a patient recovered from severe COVID-19.

A 62-year-old female diabetic recovered from COVID-19 pneumonia after receiving a prolonged course of steroids. She presented with a clinical picture of left-eye panuveitis with white cotton ball chorioretinal lesions and RAPD suggesting an optic neuropathy (VA HM). Diagnostic vitrectomy was performed to take samples for infective screen and to give intravitreal voriconazole empirically. Smear, culture, and PCR for viral DNA confirmed mixed infection of endogenous Candida endophthalmitis and incidental CMV infection. With further treatment, her corrected vision improved to 6/18 with regressing fungal lesions in serial fundus photographs. Prompt diagnosis and intervention preserved her vision and prevented potential life-threatening complications.

CT and MRI Findings of Invasive Mucormycosis in the Setting of COVID-19: Experience From a Single Center in India.

An increasing incidence of rhinoorbitocerebral mucormycosis (ROCM) among patients with COVID-19 has recently been reported in India. We report the imaging findings for 25 patients with COVID-19 and invasive ROCM at a single hospital in India. Findings included sinus wall erosions (n = 20), air within bony sinus structures (n = 11), and focal mucosal nonenhancement (n = 8). Orbital, vascular, and intracranial complications were also observed. Radiologists should recognize the increasing incidence of ROCM among patients with COVID-19 to facilitate early diagnosis.

Rare presentation of sarcoidosis with optic neuropathy and third nerve palsy.

Sarcoidosis is a systemic, idiopathic and granulomatous disease, which most commonly affects the skin, lungs and lymph nodes but can affect virtually any organ. Neurosarcoidosis can be the presenting or the only clinical manifestation accounting for 5%-15% of sarcoid diagnoses. In contrast to uveitis which is the most common ophthalmic manifestation, neuro-ophthalmic signs are uncommon in sarcoidosis. Optic neuropathy is the most common neuro-ophthalmic sign (70% in one series). Sarcoid-related optic neuropathy commonly presents with a picture similar to optic neuritis. Less commonly, optic nerve involvement occurs secondary to compressive lesions, or from direct granulomatous infiltration. Neuroimaging is crucial to identify the location of the lesion. We describe a case of sarcoid-related compressive optic neuropathy and third nerve palsy and highlight the challenging nature of neurosarcoidosis in a patient without a prior diagnosis of the disease.

The Relationship Between Frailty, Comorbidity and COVID-19 Mortality in Older COVID-19 Patients: Analysis of an Administrative Dataset Using Machine Learning Techniques (preprint)

Introduction: Older adults have disproportionally poor outcomes following hospitalisation with COVID-19, but within this group there is substantial variation. Although frailty and comorbidity are key determinants of mortality, it is less clear which specific manifestations of frailty and comorbidity are associated with the poorest outcomes. The aim of this study was to identify the key comorbidities and functional manifestations of frailty that were associated with in-hospital mortality in older patients with COVID-19.Methods: This was a retrospective study that used the Hospital Episode Statistics administrative dataset from 1st March 2020 to 28th February 2021 for hospital patients in England aged 65 years and over. Frailty was assessed using the Dr Foster Global Frailty Scale (GFS) and comorbidity using the Charlson Comorbidity Index (CCI). Exploratory analysis techniques were used to determine mortality according to the demographic, frailty and comorbidity profile of patients. Features were selected, pre-processed and inputted into a random forest classification algorithm to predict in-hospital mortality.Results: In total 215,831 patients were included. The frailty and comorbidity measures significantly improved the model’s ability to predict mortality in patients. The most important frailty items in the GFS were dementia/delirium, falls/fractures and pressure ulcers/weight loss. The most-important comorbidity items in the CCI were diabetes (without complications), pulmonary disease, heart failure and renal failure. The best-performing model had a predictive accuracy of 70% as well as an area under the curve of 0.78.Discussion: Frailty and comorbidity are associated with poorer COVID-19 outcomes in older adults, even after adjusting for chronological age. The physical manifestation of frailty and comorbidity particularly a history of cognitive impairment and falls, may be useful in identification of patients who may need additional support during their hospital stay.Funding: None to declare.Declaration of Interest: None to declare.

Microphthalmia and Optic Nerve Hypoplasia Induced by Maternal Coronavirus Infection? (preprint)

Possible mother-to-child transmission of severe acute respiratory syndrome-coronavirus type 2 (SARS-CoV-2) during pregnancy is still a matter of debate. We studied the impact of SARS-CoV-2 infection on 56 complete households, including 27 newborns whose mothers were pregnant when exposed to the virus. Three perinatal SARS-CoV-2 transmissions with mild symptoms in affected neonates were recorded (two cases confirmed by PCR, the third one based on clinical findings). In addition, we observed a severe eye malformation (unilateral microphthalmia, optic nerve hypoplasia, and congenital retinopathy) associated with maternal SARS-CoV-2 infection in weeks 5 and 6 of embryonic development. This embryopathy could not be explained by other infectious agents, genetic factors, or drug use during pregnancy. Eight other women with a history of SARS-CoV-2 infection prior to gestational week 12, however, delivered healthy infants.Conclusion: The repeated occurrence of mother-to-child transmission in our cohort with risks that remain incompletely understood, such as long-term effects and the possibility of an embryopathy, should sensitize researchers and stimulate further studies as well as strongly support COVID19 vaccination recommendations for pregnant women.Trial registration number: NCT04741412Date of registration: November 18, 2020

Optic Nerve Head Optical Coherence Tomography Angiography Findings in Patients with Coronavirus Disease 2019 (preprint)

Purpose: To quantify the microvasculature density of the optic nerve head (ONH) using optical coherence tomography angiography (OCTA) analysis.in patients recovered from Coronavirus Disease 2019 (COVID-19) Methods: In a comparative cross-sectional, observational study patients recovered from COVID-19, whom diagnosis of COVID-19 was confirmed by a positive reverse transcription-polymerase chain reaction of a nasopharyngeal sample were included in this study. The. OCTA of ONH was performed at least 2 weeks after recovery from systemic COVID-19. Vascular density (VD) of the all vessels (AV) and small vessels (SV) inside the disc and radial peripapillary capillary (RPC) network density were measured in COVID-19 recovered patients and compared with similar parameters in an age-matched group of normal controls.Results: Twenty-five COVID-19 patients and 22 age-matched normal controls were enrolled in the study and one eye per participant was evaluated. Mean whole image SV VD in the COVID-19 group (49.94 ± 2.22) was not statistically significantly different from that in the control group (49.31 ± 1.93; p-value= 0.308). An increase in RPC VD was found in all AV and SV VD measured, which became statistically significant in whole peripapillary SV VD, peripapillary inferior nasal SV VD, peripapillary inferior temporal SV VD, peripapillary superior nasal SV VD and grid-based AV VD inferior sector (p<0.05 for all comparisons).Conclusion: Unremarkable increase was found in ONH microvasculature in patients who had recovered from COVID-19. These patients may be at risk of ONH vascular complications.

Visual Field Artifacts in Glaucoma With Face Mask Use During the COVID-19 Pandemic.

PURPOSE: The coronavirus (COVID-19) pandemic has changed how outpatient care is delivered in ophthalmology clinics, particularly with glaucoma care. This case series highlights the need for awareness of fogging and improper face mask fit as causes of standard automated perimetry artifacts in patients with ocular hypertension and glaucoma. CLINICAL PRESENTATIONS: Six patients with the diagnosis of ocular hypertension, glaucoma suspect, or glaucoma underwent standard automated perimetry (24-2 or 10-2 SITA, Humphrey Field Analyzer) while wearing ear-loop surgical face masks. Due to patient complaints of fogging during the testing, low test reliability, and unexpected results, the tests were repeated after taping securely the mask to the bridge of the nose. CLINICAL FINDINGS: Fogging may reduce visual field (VF) test reliability and induce artifacts that mimic glaucomatous defects. VF test reliability can be improved and artifacts minimized following mask taping. In 1 case there was worsening of VF defects after mask taping. This suggests that fogging may also disguise true VF defects. CONCLUSIONS: Fogging can result in unreliable VF testing with glaucoma-like artifacts. Secure taping of the face mask to the nose bridge may minimize this problem and reduce unnecessary additional testing and follow-up visits.

Vaccination strategies against COVID-19 and the diffusion of anti-vaccination views (preprint)

Miss-information is usually adjusted to fit distinct narratives and can propagate rapidly through communities of interest, which work as echo chambers, cause reinforcement and foster confirmation bias. False beliefs, once adopted, are rarely corrected. Amidst the COVID-19 crisis, pandemic-deniers and people who oppose wearing face masks or quarantines have already been a substantial aspect of the development of the pandemic. With a potential vaccine for COVID-19, different anti-vaccine narratives will be created and, likely, adopted by large population groups, with critical consequences. Here, we analyse epidemic spreading and optimal vaccination strategies, measured with the average years of life lost, in two network topologies (scale-free and small-world) assuming full adherence to vaccine administration. We consider the spread of anti-vaccine views in the network, using a similar diffusion model as the one used in epidemics, which are adopted based on a persuasiveness parameter of anti-vaccine views. Results show that even if an anti-vaccine narrative has a small persuasiveness, a large part of the population will be rapidly exposed to them. Assuming that all individuals are equally likely to adopt anti-vaccine views after being exposed, more central nodes in the network are more exposed and therefore are more likely to adopt them. Comparing years of life lost, anti-vaccine views could have a significant cost not only on those who share them, since the core social benefits of a limited vaccination strategy (reduction of susceptible hosts, network disruptions and slowing the spread of the disease) are substantially shortened.