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At least 487 records · Page 27Linked to original sources
PubMed2004

Visual disturbances representing occipital lobe epilepsy in patients with cerebral calcifications and coeliac disease: a case series.

Paroxysmal visual manifestations may represent epileptic seizures arising from the occipital lobe. In coeliac disease (CD) bilateral occipital calcifications and seizure semiology consistent with an occipital origin have been described, primarily in Mediterranean countries. By reporting three adult patients from an Australian outpatient clinic with visual disturbances, occipital cerebral calcifications, and CD, this study seeks to emphasise that CD should be considered even when patients of non-Mediterranean origin present with these symptoms. Seizure types included simple partial, complex-partial, and secondarily generalised seizures. The seizure semiology consisted of visual disturbances such as: blurred vision, loss of focus, seeing coloured dots, and brief stereotyped complex visual hallucinations like seeing unfamiliar faces or scenes. Symptoms of malabsorption were not always present. Neurological examination was unremarkable in two patients, impaired dexterity and mild hemiatrophy on the left was noted in one. Routine electroencephalography was unremarkable. In all cases, computed tomography demonstrated bilateral cortical calcification of the occipital-parietal regions. Magnetic resonance imaging showed no additional lesion. All patients had biopsy confirmed CD. Seizure control improved after treatment with gluten free diet and anticonvulsants. This report illustrates the association between seizures of occipital origin, cerebral calcifications, and CD even in patients not of Mediterranean origin.

Adult↗
PubMed1992

Human vision combines oriented filters to compute edges.

The experiments examined the perceived spatial structure of plaid patterns, composed of two or three sinusoidal gratings of the same spatial frequency, superimposed at different orientations. Perceived structure corresponded well with the pattern of zero crossings in the output of a circular spatial filter applied to the image. This lends some support to Marr & Hildreth's (Proc. R. Soc. Lond. B 207, 187 (1980)) theory of edge detection as a model for human vision, but with a very different implementation. The perceived structure of two-component plaids was distorted by prior exposure to a masking or adapting grating, in a way that was perceptually equivalent to reducing the contrast of one of the plaid components. This was confirmed by finding that the plaid distortion could be nulled by increasing the contrast of the masked or adapted component. A corresponding reduction of perceived contrast for single gratings was observed after adaptation and in some masking conditions. I propose the outlines of a model for edge finding in human vision. The plaid components are processed through cortical, orientation-selective filters that are subject to attenuation by forward masking and adaptation. The outputs of these oriented filters are then linearly summed to emulate circular filtering, and zero crossings (zcs) in the combined output are used to determine edge locations. Masking or adapting to a grating attenuates some oriented filters more than others, and although this changes only the effective contrast of the components, it results in a geometric distortion at the zc level after different filters have been combined. The orientation of zcs may not correspond at all with the orientation of Fourier components, but they are correctly predicted by this two-stage model. The oriented filters are not 'orientation detectors', but are precursors to a more subtle stage that locates and represents spatial features.

Adaptation, Ocular↗
PubMed1985

[Disorders of binocular vision in amblyopic patients working at computer terminals].

For the first time two cases are described with disturbances of binocular vision caused by subjective perception of positive scotomata in the amblyopic eye. The visual strain of working at a terminal leads to a slight increase in the squint angle; as a result, a paracentral scotoma may shift into the middle of the binocular visual field and impair the image quality of the fixing eye. Amblyopic subjects presenting with these symptoms are disqualified from working at VDUs. However, not every amblyopic is affected.

Adult↗
PubMed1996

Bone feature analysis using image processing techniques.

In order to establish the correlation between bone structure and age, and information about age-related bone changes, it is necessary to study microstructural features of human bone. Traditionally, in bone biology and forensic science, the analysis if bone cross-sections has been carried out manually. Such a process is known to be slow, inefficient and prone to human error. Consequently, the results obtained so far have been unreliable. In this paper we present a new approach to quantitative analysis of cross-sections of human bones using digital image processing techniques. We demonstrate that such a system is able to extract various bone features consistently and is capable of providing more reliable data and statistics for bones. Consequently, we will be able to correlate features of bone microstructure with age and possibly also with age related bone diseases such as osteoporosis. The development of knowledge-based computer vision-systems for automated bone image analysis can now be considered feasible.

Adult↗
PubMed1987

Residual vision in patients with retrogeniculate lesions of the visual pathways.

Twenty-five subjects have been studied who, as a result of damage to the striate cortex, were 'blind' in extensive areas (scotomata) of the visual fields. Of these 25 subjects, 5 exhibited residual vision in response to transient lights presented within the scotoma, which enabled them to locate the stimuli by hand-reaching or by eye movements; the latter have been measured by electro-oculography. The residual vision underlying their responses was characterized by low flicker-fusion and by sensitivity in detection of movement which increased as target speed was raised. Discrimination for the direction of target movement was poor, but spatial resolution in the discrimination of target displacement was essentially normal. The subjects were unable to recognize or discriminate the spatial structure of targets located within the 'blind' field, and the observed dissociation between spatial discrimination of displacement and pattern is examined in relation to the 'two systems' hypothesis of visual function. There is no obvious correlation between the extent of neuronal damage as revealed by CT scans and the existence of residual vision.

Adult↗
PubMed1986

Carotid artery occlusion and ocular ischemia: therapy control with evoked potentials.

We present a patient with internal carotid artery occlusion and ischemic oculopathy in whom extracranial-intracranial arterial bypass improved vision. Visual evoked potentials were studied to obtain objective criteria for indication and follow-up evaluation and confirmed that the improved vision was due to improved retinal function.

Brain Ischemia↗
PubMed1987

Transient visual loss in ornithine transcarbamoylase deficiency.

We examined a 32-year-old, previously healthy man who developed episodic bilateral visual impairment and confusion. Coincident hyperammonemia led to the diagnosis of ornithine transcarbamoylase deficiency, which was established by enzymatic analysis of a liver biopsy specimen. The available data were insufficient to determine if the metabolic derangement impaired vision at the level of the optic nerves or at the cerebral level.

Adult↗
PubMed1989

Ocular involvement in Castleman's disease. Response to radiotherapy.

A 21-year-old man with known Castleman's disease, a lymphoproliferative disorder with both local and systemic manifestations, presented with decreased vision in the left eye and chromatopsia. He had infiltration of the left disc and choroid with elevation of the retina, multiple bilateral depigmented areas at the level of the choroid or retinal pigment epithelium (RPE) (also thought to represent infiltrates), and left exophthalmos. A serious retinal detachment (RD) evolved, but then responded to radiotherapy, with recovery of good vision. Occult leptomeningeal involvement resolved during a period of observation. There was no systemic evidence of malignant lymphoma.

Adult↗
PubMed2004

Less invasive total hip arthroplasty using navigational tools.

Although traditional total hip arthroplasty offers good visualization of bony landmarks and allows for the accurate orientation and fixation of implants, these benefits are achieved at the expense of extensive soft-tissue dissection and can result in postoperative complications and a delayed return to full function. To address these disadvantages, navigational tools were coupled with a mini-incision technique that allowed accurate bone preparation and orientation of the implant components without direct visualization of the bony landmarks. Additionally, image-guided systems provide three-dimensional information before and during surgery, making it possible to know, in real time, the orientation of implants and to visualize the full bony anatomy. This "computer-enhanced vision" allows surgeons to perform less invasive and eventually minimally invasive total hip arthroplasty with improved accuracy.

Arthroplasty, Replacement, Hip↗
PubMedDate not supplied

[Pathology of the eye in sarcoidosis].

Comprehensive neurologic and ophthalmologic examinations of 100 patients with morphologically verified sarcoidosis showed the most frequent involvement of optic nerves and less incident lesions of the eye proper and its appendages. Vision disorders were detected in 39.0 patients, chiasmal disorders in 12.0%. Fundus oculi abnormalities were found in 27.0% of patients. A specific feature of vision disorders in sarcoidosis was that almost half of the patients did not feel them, which may be explained by a predominantly chronic latent pattern of these disorders and by the fact that, despite manifest disorders of peripheral vision, central vision with correction remained normal for a longer time.

Adult↗
PubMed1996

Visual pathway hemorrhage associated with alcohol-induced coagulopathy.

Hemorrhage confined to the optic pathways is rare. We describe a patient with diffuse hemorrhage of the intracranial optic nerves, optic chiasm, and optic tracts, attributed to alcohol-induced coagulopathy. The hemorrhage resolved completely as the patient's vision improved, and subsequent neuroimaging studies showed atrophy of the affected structures.

Adult↗
PubMed1984

Altitudinal hemianopia caused by occipital infarctions. Clinical and computerized tomographic correlations.

Two patients with altitudinal homonymous hemianopia caused by bilateral occipital infarctions were studied. Their clinical-computerized tomographic correlations showed the anatomic representation of the superior and inferior visual fields in the lower and upper banks of the calcarine fissure, respectively. The patient with the superior-field defect was unusual because he retained normal color vision and facial recognition abilities, despite having bilateral lesions that have classically produced central achromatopsia and prosopagnosia.

Aged↗
PubMed2000

Syndrome simulating pseudotumor cerebri caused by partial transverse venous sinus obstruction in metastatic prostate cancer.

PURPOSE: To report a case of partial transverse venous sinus obstruction causing a syndrome resembling pseudotumor cerebri. METHOD: Case report. A 61-year-old man developed decreased vision, bilateral papilledema, and a highly increased cerebrospinal fluid opening pressure. Brain magnetic resonance imaging (MRI) disclosed a small, extra-axial mass near the torcula, which was dismissed as an incidental meningioma because cerebral angiography showed sinus patency. RESULTS: The patient's vision worsened. Biopsy of the enlarging mass disclosed metastatic prostate cancer. After radiation therapy, the mass shrank, magnetic resonance angiography disclosed reopening of the transverse sinuses, and papilledema resolved, but visual fields remained severely compromised. CONCLUSION: Partial blockage of the dural venous sinus by a small mass near the torcula can cause a sufficient increase in intracranial pressure to produce vision-threatening papilledema.

Adenocarcinoma↗
PubMed1999

Visual field recovery in a patient with bilateral occipital lobe damage.

We report on a patient with an asymmetrical bilateral developmental anomaly of the occipital lobes which led to a loss of almost the entire visual field. MRI and 18FDG scans confirmed the presence of a larger lesion of the visual cortex of the right hemisphere. The patient recovered parts of her visual field with time as measured by computerized perimetry, progressing from near blindness of the right eye to a remarkable recovery of vision. Because the patient had neonatal damage to both occipital lobes, we hypothesized a cortical plasticity process similar to that described in subhuman species.

Adult↗
PubMed2004

Combined central retinal artery and vein occlusion from orbital inflammatory pseudotumour.

Progressive, painful blurred vision and proptosis developed in the left eye of a 32-year-old man over an 8-day period. On initial neuro-ophthalmic evaluation the visual acuity in the left eye was no light perception. Erythema of the periorbital skin, 5 mm of proptosis, and ophthalmoplegia were noted on the left side. Funduscopy revealed occlusion of the central retinal artery and central retinal vein. Computed tomography and magnetic resonance imaging revealed marked distension of the left optic nerve and enhancement of the contents within the left orbit, with clear paranasal sinuses. The diagnosis of orbital inflammatory pseudotumour was made and the orbital signs improved rapidly with 80 mg of prednisone per day. Combined occlusion of the central retinal artery and vein is a rare complication of orbital inflammatory pseudotumour. It is postulated that marked distension of the optic nerve caused mechanical compression of the central retinal vessels leading to the vascular occlusions.

Adult↗
PubMed2005

Pituitary apoplexy in a child presenting with massive subarachnoid and intraventricular hemorrhage.

A case of pituitary apoplexy in a child with massive subarachnoid and intraventricular hemorrhage is reported. The patient presented with a sudden onset of headache, diminution of visual acuity and a bitemporal visual field defect. Computerized tomography revealed a massive subarachnoid hemorrhage with extension of blood into the third ventricle. Angiography did not show an aneurysm. The patient was operated on and altered blood within a necrotic pituitary adenoma was decompressed. His vision and field defect improved along with resolution of headache in the postoperative period.

Adenoma↗
PubMed2000

Isolated optic nerve pseudotumour.

Isolated optic nerve involvement by the idiopathic inflammatory process is a rare finding and very few reports are available. Here a case of an isolated optic nerve inflammatory pseudotumour presenting with gradually progressive unilateral loss of vision is described. It showed dramatic response to a trial of steroids and its differential diagnoses are discussed.

Adult↗