Visual electrophysiology in the assessment of toxicity and deficiency states affecting the visual system

Visual disturbance or visual failure due to toxicity of an ingested substance or a severe nutritional deficiency can present significant challenges for diagnosis and management, for instance, where an adverse reaction to a prescribed medicine is suspected. Objective assessment of visual function is important, particularly where structural changes in the retina or optic nerve have not yet occurred, as there may be a window of opportunity to mitigate or reverse visual loss. This paper reviews a number of clinical presentations where visual electrophysiological assessment has an important role in early diagnosis or management alongside clinical assessment and ocular imaging modalities. We highlight the importance of vitamin A deficiency as an easily detected marker for severe combined micronutrient deficiency.

In the Wake of Visual Failure

This article examines the role of the visual in instances of recorded anti-Black racial violence and pushes against dominant discourses of the technological rescue narrative—that technology and more visibility will lead to different outcomes of accountability, protection, and safety. Instead, this article argues that the tightly bound association of anti-Black racial violence's recognizability to the visual has created a dynamic that simultaneously moves us closer to and further away from its ontological truths. Examining Twitter as a multisensorial platform and its users’ imaginative engagements with the #IfIDieInPoliceCustody hashtag memorializing Sandra Bland's death, the author identifies that users craft an anticipatory nonspectatorship, a mode of imaginative witnessing arising from the contexts of technological and visual failure and the situated imaginations of Black epistemologies. These users register a deep suspicion of the evidentiary and refuse the spectacular of racial violence's visual form, instead highlighting its ubiquitous and quotidian nature by asserting themselves into their own scenes of visual failure and becoming witnesses to their own imagined deaths. Finally, in identifying the visual failures surrounding Sandra Bland's jail cell, the author illuminates how the ontology of the glitch can demonstrate the mechanics of white supremacy's operations.

THE TRUCK TRAILER SUSPENSION AXLES FAILURE ANALYSIS AND MODELLING

The purpose of trucks is very diverse, but the main purpose is freight transportation. When cargos are transported, the truck’s suspensions are heavily loaded, so failures also occur most often in the suspension elements. For axles of trailers – tubular construction failures occur, they crack. Axle failure investigations are required to determine the cause of the failure. The paper analyses three-axle truck trailer suspension. Axle failure analysis and axial deformation modelling were performed to determine trends and causes of truck trailer suspension axle failures. Different cases with axles of tubular construction with wall thicknesses of 9 and 11 mm were modelled. The paper presented visual failure analysis of truck trailers suspension axles and finite element modelling results of axle’s deformation of different geometrical parameters. The results were discussed and conclusions were drawn.

Management of sellar and suprasellar lesions

Background Pathology in the sellar and suprasellar regions accounts for several disabling and distinctive neurological syndromes characterized by visual failure and upper cranial neuropathies. These features have a major impact on functional outcome more than the commonly associated endocrine morbidity. Objective this study aimed to present the incidence of various lesions in the sellar and suprasellar area and evaluate the different protocols for management of these lesions. Methods The study will include 40 cases of sellar& suprasellar lesions that will be admitted and treated in the neurosurgical departments in Ain Shams University Hospital as well as El-Galaa armed forces hospitals and 57375 Children Cancer Hospital between 12/2015-9/2018 Results: Pituitary adenoma was the most frequent(42.5%), followed by craniopharyngioma(30%), then Meningioma(12.5%) with other low frequent diagnoses , Headache was the most common complaint followed by blurring of vision, diplopia and nausea & vomiting. MRI sella was the most valuable investigation. 3 approaches were used and trans-sphenoidal approach was the most common used approach. Postoperative radiotherapy was significantly most frequent in Craniopharyngioma followed by pituitary adenoma and least frequent in meningioma. Conclusion we have reached to conclusion from this study, that transsphenoidal approach was suitable for most pituitary adenomas and Its main indication was mainly midline sellar and suprasellar tumors with limited lateral or posterior extension. The pterional approach was suitable for meningiomas and craniopharyngiomas and Its indication was a supra-or parasellar lesions with both lateral and posterior extension specially those reaching the clivus. Total excision was most frequent in pituitary adenoma followed by meningioma and least frequent in craniopharyngioma. Postoperative radiotherapy was significantly most frequent in Craniopharyngioma followed by Pituitary Adenoma and least frequent in meningioma.

Long-term visual outcomes of the Boston type I keratoprosthesis in Canada

Background/aimsTo evaluate long-term visual outcomes of Boston type I keratoprosthesis (KPro) surgery and identify risk factors for visual failure.MethodsSingle surgeon retrospective cohort study including 85 eyes of 74 patients who underwent KPro implantation to treat severe ocular surface disease, including limbal stem cell deficiency, postinfectious keratitis, aniridia and chemical burns. Procedures were performed at the Centre hospitalier de l'Université de Montréal from October 2008 to May 2012. All patients with at least 5 years of follow-up were included in the analysis, including eyes with repeated KPro. Main outcome measures were visual acuity (VA), visual failure, defined as a sustained worse than preoperative VA, postoperative complications, and device retention.ResultsMean follow-up was 7.2±1.3 years (±SD). Mean VA was 2.1±0.7 (logarithm of minimal angle resolution) preoperatively and 1.9±1.2 at last follow-up. There were 2.4% of patients with VA better than 20/200 preoperatively and 36.5% at last follow-up. Maintenance of improved postoperative VA was seen in 61.8% of eyes at 7 years. Preoperative factors associated with visual failure were known history of glaucoma (HR=2.7 (1.2 to 5.9), p=0.02) and Stevens-Johnson syndrome (HR=7.3 (2.5 to 21.4) p<0.01). Cumulative 8-year complication rates were 38.8% retroprosthetic membrane formation, 25.9% hypotony, 23.5% new onset glaucoma, 17.6% retinal detachment, 8.2% device extrusion and 5.9% endophthalmitis. The majority (91.8%) of eyes retained the device 8 years after implantation.ConclusionAlmost two-thirds of patients had improved VA 7 years after KPro implantation. Preoperative risk factors for visual failure were known glaucoma and Stevens-Johnson syndrome.

Visual failure following an invasive macroadenoma of the pituitary gland: A case report

A macroadenoma is a common disease with one type of invasion. In this case, a visual failure in both eyes followed a severe multiple invasion of macroadenoma which has all three types of invasion (sphenoid sinus, suprasellar, and cavernous sinus invasions).