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At least 1,621 records · Page 90Linked to original sources

PubMed1998

[Neurinoma arising from the first branch of the trigeminal nerve: a case report].

A case of a neurinoma arising from the first branch of the trigeminal nerve in a 40-year-old female is reported. The patient was admitted with the chief complaint of loss of Lt. visual acuity and mild hypoesthesia in the area of the first branch of the trigeminal nerve. A CT scan and MRI revealed a tumor extending through the superior orbital fissure into the orbita. Subtotal resection of the tumor was performed by a fronto-orbito-zigomatic approach and a histological diagnosis of neurinoma was made. Although the hypoesthesia remained, the visual acuity was markedly improved postoperatively. A neurinoma arising from the first branch of the trigeminal nerve is very rare. To our knowledge, including our case, only five cases which were described for clinical and diagnostic features and surgical management have been reported. There were three males and two females, and the age ranged from 1 to 57 years. Neurologically, all cases presented hypoesthesia in the area of the first branch of the trigeminal nerve and exophthalmus on admission. Visual disturbance was found in three cases. Radiologically, the enlargement of the superior orbital fissure was revealed in two cases. Angiography performed in three cases demonstrated the avascular mass. Three patients received CT scan and only the present case used MR imaging. Surgical resection was performed in all cases through various approaches. The fronto-orbito-zygomatic approach which was chosen in our case was useful for obtaining a sufficient operative view. As in our case, excellent outcome was achieved in three other cases due to successful tumor resection.

Adult↗

PubMed1993

Computer modeling of laser damage to the eye.

The effects of laser damage in the eye have been studied with an electrophysiological measure, the Visual Evoked Potentials (VEP). The VEP is generated by placing surface electrodes at the back of a subject's head, and having the subject watch a pattern of alternating light and dark bars. The spatial frequency of the bar pattern, measured in cycles per degree, increases as the bars become finer. The bar pattern changes in time, as the light bars become dark, and visa versa. The rate of this change is the temporal frequency, measured in Hertz. The VEP amplitudes referred to in this paper are a sum of the first three even harmonics of the temporal frequency (since the pattern change two times for every temporal cycle). As spatial frequency increases, a point will be reached where the subject will no longer be able to resolve the bars, and the VEP amplitude will become indistinguishable from noise. This spatial frequency is a measure of visual acuity. A computer model has been developed to simulate vision loss from lesions on the retina. It has been checked against experimental data from Rhesus monkeys with burns made under laboratory conditions. Vision was checked before and after the burns with VEP at a temporal frequency of six Hertz. This model divides the visual field into concentric rings centered about the visual axis. Each ring contributes to the VEP by an amount that depends on its eccentricity, or radius in degrees, as well as the spatial frequency.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

Optic nerve blindness following a malar fracture.

Optic nerve blindness following a malar fracture is an uncommon and usually permanent complication. When the loss of vision is immediate and total, the prognosis is poor. The case of a patient who suffered immediate and complete loss of vision after a malar fracture is presented. Computed tomography revealed compression of the optic nerve by bony fragments. No improvement was observed after megadose steroids and surgical treatment. The incidence, pathogenesis, diagnostic approach and therapeutic possibilities are discussed and the importance of establishing precisely the moment of the loss of vision is stressed.

Adult↗

PubMed2004

Corresponding-pair procedure: a new approach to simulation of dichromatic color perception.

The dichromatic color appearance of a chromatic stimulus T can be described if a stimulus S is found that verifies that a normal observer experiences the same sensation viewing S as a dichromat viewing T. If dichromatic and normal versions of the same color vision model are available, S can be computed by applying the inverse of the normal model to the descriptors of T obtained with the dichromatic model. We give analytical form to this algorithm, which we call the corresponding-pair procedure. The analytical form highlights the requisites that a color vision model must verify for this procedure to be used. To show the capabilities of the method, we apply the algorithm to different color vision models that verify such requisites. This algorithm avoids the need to introduce empirical information alien to the color model used, as was the case with previous methods. The relative simplicity of the procedure and its generality makes the prediction of dichromatic color appearance an additional test of the validity of color vision models.

Journal Article↗

PubMed2001

Delayed retrobulbar hematoma after blepharoplasty.

PURPOSE: To describe a case of late orbital hematoma after blepharoplasty and review the literature on this subject. METHODS: A healthy woman developed an orbital hematoma and loss of vision 7 days after an elective blepharoplasty. Computed tomography and magnetic resonance images of the orbits were obtained 1 day after the vascular accident. RESULTS: Computed tomography and magnetic resonance images clearly demonstrated that the site of the hemorrhage was the superior nasal fat pad. Blood from this region molded the globe and accumulated in the intraconal space behind the posterior sclera. The patient was successfully treated with conservative measures only. CONCLUSIONS: Orbital hematoma, which is the main cause of loss of vision after blepharoplasty, can be a late postoperative complication.

Adult↗

PubMedDate not supplied

[Early changes in the visual field in chronic diabetic neuroretinopathy].

The present study reveals components of defects in the field of vision in chronic diabetic optic neuropathy. In the main cases of diabetic eye-lesion pathologic changes in the retina disappear optic neuropathy changes. Early investigation of changes in the field of vision in diabetic optic neuropathy patients with computer programs is very important.

Adolescent↗

PubMed1985

Computed tomographic diagnosis of buried drusen of the optic nerve head.

We present three patients with optic nerve drusen. On the basis of headaches, transient obscurations of vision, or visual field loss the patients underwent orbital computed tomographic (CT) scanning. This procedure confirmed the presence of buried drusen in the four optic discs that had yielded poor ophthalmoscopic and angiographic evidence of drusen; drusen had been observed in the other two discs. The indications for CT scanning in the presence of visible or buried drusen of the optic nerve head are discussed.

Adolescent↗

PubMed1995

Invasive rhinosino-orbital aspergillosis with precipitous visual loss.

OBJECTIVE: To describe the clinicopathological and radiologic features in five cases of primary and secondary orbital aspergillosis. DESIGN: Case series. SETTING: Ophthalmology department of a university hospital. PATIENTS: Five patients over 65 years of age with invasive rhinosino-orbital aspergillosis. RESULTS: Presenting features were abrupt onset of proptosis, ophthalmoplegia and blepharoptosis with precipitous visual loss. All had debilitating periorbital pain or headache, but none had orbital inflammatory signs or appeared "toxic." Predisposing causes included alcoholism, low-dose prednisone therapy and insulin-dependent diabetes mellitus. One patient, suspected of having mucormycosis based on tissue biopsy and results of potassium hydroxide preparations, harboured Aspergillus fumigatus, which grew on culture. Secondary bacterial infections developed in three patients. Three patients died from their disease despite aggressive surgical treatment, including exenteration and sinus extirpation. The one patient with primary orbital aspergillosis survived after exenteration. CONCLUSIONS: Sinonasal aspergillosis with orbital extension and primary orbital aspergillosis have a precipitous clinical course that mimics that of mucormycosis and may be fatal despite early exenteration. Computed tomography and magnetic resonance imaging of the sinuses, orbit and head provide complementary diagnostic signs. While results of potassium hydroxide preparations and tissue biopsy guide treatment of fungal infection, definitive diagnosis requires fungal culture. Relatively good vision may be associated with massive orbital and secondary intracranial extension.

Aged↗

PubMed2004

Bimanual directional interference: the effect of normal versus augmented visual information feedback on learning and transfer.

When performing movements with different spatial trajectories in both upper limbs simultaneously, patterns of interference emerge that can be overcome with practice. Even though studies on the role of augmented feedback in motor learning have been abundant, it still remains to be discovered how overcoming such specific patterns of spatial interference can be optimized by instructional intervention. In the present study, one group acquired a bimanual movement with normal vision, whereas a second group received augmented feedback of the obtained trajectories on a computer screen in real time. Findings revealed that, relative to normal vision, the augmented feedback hampered skill learning and transfer to different environmental conditions. These observations are discussed in view of the benefits and pitfalls of augmented feedback in relation to task context and instructional condition.

Adolescent↗

PubMed2004

Design of and normative data for a new computer based test of ocular torsion.

PURPOSE: To evaluate a new clinically practical and dynamic test for quantifying torsional binocular eye alignment changes which may occur in the change from monocular to binocular viewing conditions. METHODS: The test was developed using a computer with Lotus Freelance Software, binoculars with prisms and colored filters. The subject looks through binoculars at the computer screen two meters away. For monocular vision, six concentric blue circles, a blue horizontal line and a tilted red line were displayed on the screen. For binocular vision, white circles replaced blue circles. The subject was asked to orient the lines parallel to each other. The difference in tilt (degrees) between the subjective parallel and fixed horizontal position is the torsional alignment of the eye. The time to administer the test was approximately two minutes. RESULTS: In 70 Normal subjects, average age 16 years, the mean degree of cyclodeviation tilt in the right eye was 0.6 degrees for monocular viewing conditions and 0.7 degrees for binocular viewing conditions, with a standard deviation of approximately one degree. There was no "statistically significant" difference between monocular and binocular viewing. CONCLUSION: This computer based test is a simple, computerized, non-invasive test that has a potential for use in the diagnosis of cyclovertical strabismus. Currently, there is no commercially available test for this purpose.

Adolescent↗

PubMed2003

Do video display units cause visual problems? - a bedside story about the processes of public health decision-making.

PURPOSE: Since the 1980s, it has been common for employers to provide eyesight testing for operators of screen-based equipment (SBE). This practice arose because many SBE operators reported symptoms of visual discomfort at work and there was apprehension that radiation emitted by SBE might be harmful to vision. Visual screening of SBE operators has been encouraged by government guidelines and in some countries, is required by legislation. This paper questions whether this practice should continue. METHOD AND RESULTS: A review of the literature shows: 1. SBE does not emit radiation in sufficient quantity to be harmful and there is no credible epidemiological evidence that work with SBE will damage the eyes; 2. SBE operators often report symptoms of visual discomfort but office workers who do not use SBE also report visual symptoms with the same or slightly lower frequency; 3. about 20 per cent of office workers have some uncorrected defect of vision that can contribute to the occurrence of visual discomfort at work and optometric intervention to correct these defects does reduce the occurrence of visual symptoms. However, defects of vision are not the only cause of visual symptoms at work. Other contributing factors are poor workplace ergonomics and psychosocial stress arising from poor work systems or poor inter-personal relationships at work. CONCLUSIONS: There is no compelling public health justification for requiring vision screening of SBE operators but it could be introduced as one element of a more comprehensive strategy to enhance visual comfort at work. If it is introduced, it should be for all employees engaged in visually demanding tasks, not just SBE users. An alternative to eyesight testing of employees is to encourage but not require employees to obtain eye care privately on their own initiative. This option has the advantage of restoring autonomy to employees to arrange their own eye care. Eyesight testing of employees in vision-critical occupations should be undertaken to ensure safety. In occupations in which there is a risk of eye injury, vision screening should be undertaken to provide a pre-injury record of vision.

Australia↗

PubMed2004

A comparison of two factorial designs, a complete 3 x 3 factorial and a central composite rotatable design, for use in binomial response experiments in aquatic toxicology.

Using an amphibian toxicity testing protocol, comparative studies were conducted to assess the predictive precision, degree of similarity of results and efficiency of a central composite rotatable design (CCRD) in relation to a conventional complete 3x3 factorial design. Data were treated with response surface analysis using generalized linear models (glm) and application of profile deviance to generate confidence intervals. Design comparisons were based on studies conducted using the Frog Embryo Teratogenesis Assay-Xenopus (FETAX) protocol to examine the interaction of three toxicants at pH levels ranging from 4.5 to 8.5. Test substances included two commercial herbicide formulations based on glyphosate ([N-phosphonomethyl]glycine) isopropylamine salt (Vision, Rodeo) as well as a polyethoxylated tallow amine surfactant blend (MON 0818), which is a key component of the Vision formulation. The generated models from both the CCRD and the factorial designs produced toxicity estimates similar to each other and to previously published results. Trends were also similar to published results in that the surfactant, MON 0818, was comparatively more toxic than Vision, which was more toxic than Rodeo. Further, all toxicants induced higher mortality under alkaline as opposed to acidic conditions. The CCRD was between 66 and 124% more efficient in the Vision and Rodeo experiments in comparison to the complete 3x3 factorial. Thus, the factorial experiment would have required at least 66% more observations to obtain the same precision. There appeared to be no efficiency gain with the use of the CCRD for MON 0818. The CCRD had tighter confidence intervals in 9 of 12 cases across all test substances. Computer simulations using the experimental data for Vision demonstrated that the LCalpha estimates generated from the 1,000 simulated data sets were very close to the "true" value for both designs. This was based on small bias and mean squared error calculations. Coverage probabilities in both designs were between 91.6 and 95.6%, close to the nominal coverage of 95%. Efficiency comparisons of the simulated Vision data sets demonstrated that the CCRD was more efficient in 93.3% of the comparisons. We suggest that a CCRD using glm and profile deviance for statistical analyses be considered an effective and efficient alternative in toxicity studies where interactive effects are of interest.

Abnormalities, Drug-Induced↗

PubMed1994

A case of uveitis associated with idiopathic retroperitoneal fibrosis.

We treated a patient with nongranulomatous panuveitis associated with idiopathic retroperitoneal fibrosis who had symptoms of abdominal pain, severe fever, leg edema, and blurred vision. A high C-reactive protein level, a high erythrocyte sedimentation rate, anemia, and abnormalities of the immune system were seen. Retrograde pyelography disclosed persistent ureteral obstruction. A computed tomographic scan and magnetic resonance imaging showed a dense plaque of fibrous tissue around the kidney and hydronephrosis. Biopsy disclosed fibrosis infiltrated with lymphocytes, plasma cells, histiocytes, and eosinophils. A moderate degree of cellular inflammation in the anterior chamber and cystoid macular edema were present at ocular examination. We believe idiopathic retroperitoneal fibrosis to be a new cause of uveitis of suspected autoimmune origin.

Blood Sedimentation↗

PubMed1990

[Post-traumatic decompression of the optic nerve. Ophthalmologic and x-ray computed tomographic evaluation. Results in a series of 23 cases].

Post traumatic optic nerve compression gives a Clinic picture of physiological section. CT Scan is consistent with optic canal lesion when considering direct signs (bony fragments compressing the nerve) or indirect (fractures and hematoma of posterior orbital wall, of posterior ethmoid, and sphenoid). 23 patients had a surgical decompression through transethmoidosphenoidal approach. A lesion of optic canal was found in 22 out of 23 cases. Improvement of vision was noted in 12 cases.

Adolescent↗

PubMed1989

Computing motion in the primate's visual system.

Computing motion on the basis of the time-varying image intensity is a difficult problem for both artificial and biological vision systems. We will show how one well-known gradient-based computer algorithm for estimating visual motion can be implemented within the primate's visual system. This relaxation algorithm computes the optical flow field by minimizing a variational functional of a form commonly encountered in early vision, and is performed in two steps. In the first stage, local motion is computed, while in the second stage spatial integration occurs. Neurons in the second stage represent the optical flow field via a population-coding scheme, such that the vector sum of all neurons at each location codes for the direction and magnitude of the velocity at that location. The resulting network maps onto the magnocellular pathway of the primate visual system, in particular onto cells in the primary visual cortex (V1) as well as onto cells in the middle temporal area (MT). Our algorithm mimics a number of psychophysical phenomena and illusions (perception of coherent plaids, motion capture, motion coherence) as well as electrophysiological recordings. Thus, a single unifying principle 'the final optical flow should be as smooth as possible' (except at isolated motion discontinuities) explains a large number of phenomena and links single-cell behavior with perception and computational theory.

Algorithms↗

PubMed2000

Reversal of optic canal stenosis in osteopetrosis after bone marrow transplant.

PURPOSE: To describe a patient with infantile osteopetrosis and optic atrophy secondary to optic canal stenosis who demonstrated optic canal enlargement after bone marrow transplant. METHODS: Case report. A 3-month-old infant with infantile "malignant" osteopetrosis underwent ophthalmic examination, including visual evoked potentials, electroretinogram, and computed tomography (CT). Bone marrow transplant was performed at 8 months of age. RESULTS: Examination revealed visual loss and optic atrophy, left eye greater than right eye, secondary to optic canal stenosis. Flash visual evoked potentials revealed a normal waveform in both eyes with increased latency in the left eye. Electroretinogram was normal in both eyes. CT after bone marrow transplant showed enlargement of the optic canals. Vision remains stable 43 months after bone marrow transplant. CONCLUSIONS: Bone marrow transplant in infantile osteopetrosis may be followed by reversal of optic canal stenosis and preservation of vision.

Bone Marrow Transplantation↗

PubMed2004

Minimalism context-aware displays.

Despite the rapid development of cyber technologies, today we still have very limited attention and communication bandwidth to process the increasing information flow. The goal of the study is to develop a context-aware filter to match the information load with particular needs and capacities. The functions include bandwidth-resolution trade-off and user context modeling. From the empirical lab studies, it is found that the resolution of images can be reduced in order of magnitude if the viewer knows that he/she is looking for particular features. The adaptive display queue is optimized with real-time operational conditions and user's inquiry history. Instead of measuring operator's behavior directly, ubiquitous computing models are developed to anticipate user's behavior from the operational environment data. A case study of the video stream monitoring for transit security is discussed in the paper. In addition, the author addresses the future direction of coherent human-machine vision systems.

Awareness↗

PubMed2006

Computer-assisted surgery of the paranasal sinuses: technical and clinical experience with 368 patients, using the Vector Vision Compact system.

INTRODUCTION: This paper presents our experience with a navigation system for functional endoscopic sinus surgery. In this study, we took particular note of the surgical indications and risks and the measurement precision and preparation time required, and we present one brief case report as an example. MATERIALS AND METHODS: Between 2000 and 2004, we performed functional endoscopic sinus surgery on 368 patients at the Ludwig Maximilians University, Munich, Germany. We used the Vector Vision Compact system (BrainLAB) with laser registration. The indications for surgery ranged from severe nasal polyps and chronic sinusitis to malignant tumours of the paranasal sinuses and skull base. RESULTS: The time needed for data preparation was less than five minutes. The time required for preparation and patient registration depended on the method used and the experience of the user. In the later cases, it took 11 minutes on average, using Z-Touch registration. The clinical plausibility test produced an average deviation of 1.3 mm. The complications of system use comprised one intra-operative re-registration (18 per cent) and one complete failure (5 per cent). Despite the assistance of an accurate working computer, the anterior ethmoidal artery was incised in one case. However, in all 368 cases, we experienced no cerebrospinal fluid leaks, optic nerve lesions, retrobulbar haematomas or intracerebral bleeding. There were no deaths. DISCUSSION: From our experience with computer-guided surgical procedures, we conclude that computer-guided navigational systems are so accurate that the risk of misleading the surgeon is minimal. In the future, their use in certain specialized procedures will be not only sensible but mandatory. We recommend their use not only in difficult surgical situations but also in routine procedures and for surgical training.

Adolescent↗