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Results for “OPTIC PATHWAY”

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At least 721 records · Page 40Linked to original sources

PubMed1993

Eye movement changes in albinism--a case report with electronystagmographic findings.

Albinism is associated with neural anomalies including foveal hypoplasia and aberrant optic pathway projection that result in a variety of oculomotor instability. We present a 38-years-old man with oculocutaneous albinism who had horizontal jerk-type nystagmus, which showed a reverse in direction by any extraneous light stimulation which was documented by electronystagmogram. The mechanism of the nystagmus in this case is uncertain. These findings in albinism have not been reported previously, to our knowledge, and suggest a defect in the visual pathway system.

Adult↗

PubMed2026

Swimming Upstream to Understand Congenital Anomalies of the Kidney and Urinary Tract: Zebrafish Models for Developmental Biology, Disease Mechanisms, and Functional Interpretation of Genetic Variation.

Congenital anomalies of the kidney and urinary tract (CAKUT) are the leading cause of pediatric chronic kidney disease (CKD) and comprise a heterogeneous group of developmental disorders with a substantial genetic contribution. Advances in next-generation sequencing have facilitated the identification of numerous candidate genes and rare variants associated with CAKUT. However, establishing causality and defining the biological functions of implicated genes remain major challenges. Functional validation is therefore essential to bridge the gap between gene discovery and mechanistic understanding, enabling the interpretation of genetic variation within the context of kidney development and disease. The zebrafish (Danio rerio) has emerged as a powerful in vivo model for studying renal development and interrogating the function of CAKUT-associated genes. Its utility stems from a high degree of genetic and developmental conservation with humans, conserved nephrogenic pathways, optical transparency during embryogenesis, and the relative ease of genetic manipulation. In this review, we provide an overview of zebrafish kidney development within the broader context of vertebrate nephrogenesis, highlighting the key genetic programs governing intermediate mesoderm specification, nephron segmentation, and pronephric morphogenesis. We then systematically examine CAKUT-associated genes that have been modeled in zebrafish, focusing on studies that have linked genetic perturbations to renal development and structural phenotypes. Finally, we discuss the strengths and limitations of zebrafish models for functional genomics and variant interpretation and consider their emerging role in bridging genetic discovery with mechanistic insights into CAKUT pathogenesis.

Animals↗

PubMedDate not supplied

Photorefractive keratectomy for hyperopia using an erodible disc and axicon lens: 2-year results.

BACKGROUND: This paper presents the results over a 2-year follow-up of the first human trial of photorefractive keratectomy (PRK) for correction of hyperopia using an erodible disc excimer laser delivery system (Summit) coupled to an axicon lens. METHODS: We treated 25 eyes of 21 patients for a mean correction of +3.38 +/- 0.97 D (range, +1.00 to +4.00 D). The hyperopic correction was made using an erodible disc inserted on the laser optical pathway; an axicon lens was then used to create a blend transition zone. Eyes were evaluated at 1, 3, 6, and 12 months after surgery. For a smaller series of 11 eyes, we also present 24-month results. RESULTS: Mean refractive error 1 month after treatment (25 eyes) was -2.35 +/- 1.55 D (range, +1.00 to -6.50 D). Eight eyes (32%) had a spectacle-corrected visual acuity loss greater than 1 line. Twelve months after treatment, mean spherical equivalent refraction was -0.47 +/- 0.80 D (range, +1.25 to -2.25 D). Nineteen eyes showed an improvement (range, 3 to 8 lines) in uncorrected distance visual acuity and 23 showed improvement in uncorrected vision at reading distance (1 to 7 lines). CONCLUSION: This technique proved effective in reducing hyperopia, but predictability must be demonstrated in a larger treatment group. Safety was confirmed by the absence of delayed reepithelialization and the absence of spectacle-corrected visual acuity loss greater than 1 line at 1 year after surgery.

Adult↗

PubMed1990

NIH conference. Neurofibromatosis 1 (Recklinghausen disease) and neurofibromatosis 2 (bilateral acoustic neurofibromatosis). An update.

The neurofibromatoses comprise at least two autosomal dominant disorders affecting an estimated 100,000 Americans with clinical manifestations that may require care from every type of clinician. Neurofibromatosis 1 and neurofibromatosis 2 have in common the occurrence of many neurofibromas but are distinctly different clinical disorders. The disease genes are on different chromosomes. Magnetic resonance imaging, particularly with gadolinium enhancement, has generally supplanted other techniques for visualizing brain, spinal, and other neural tumors in both disorders. The technique has rekindled the controversy over the nature and frequency of optic pathway tumors in patients with neurofibromatosis 1 and has revealed, throughout the brains of young patients, bright lesions that have uncertain clinical consequences and unknown pathologic bases. In patients with neurofibromatosis 2, small acoustic neuromas can be seen, leading to the possibility of excision with preservation of hearing and facial nerve function. Abnormal hearing may occur to excess in patients with neurofibromatosis 1, but acoustic neuroma has never been documented. In patients with neurofibromatosis 2, a battery of audiologic tests has a high positive predictive power. Lisch nodules or iris hamartomas, probably a universal sign in adults with the neurofibromatosis 1 gene, cause no problem with vision. Posterior capsular lens opacity in patients with neurofibromatosis 2 is a helpful diagnostic sign and a potential source of additional handicap in persons at risk for impaired hearing. Progress in the clinical delineation of the disorders has been matched with considerable research into the still obscure pathogenesis of the disorders. Such rapid advances may necessitate reconsideration of the conclusions of the National Institutes of Health Consensus Development Conference on Neurofibromatosis, especially those on the categories of persons in which a neurofibromatosis should be considered and the need for caution in recommending surgery. Watchful waiting may often be the best management for acoustic neuromas in neurofibromatosis 2.

Chromosome Aberrations↗

PubMed1998

[Visual evoked potentials as an indicator of supratentorial and infratentorial herniation].

The VEP was investigated in 172 patients with infratentorial and in 100 patients with supratentorial space occupying lesions. In each group 65% of the patients showed marked or even extensive changes in VEP. An immediate relation of the lesion to the optochiasmatic system or a hydrocephalus was noted in a few cases only. In contrast the VEP of patients with a clear transtentorial herniation showed severely pathological changes, occasionally up to complete loss of the potential. The VEP changes were reversible on removal of the space occupying lesions in all patients. The constellation of VEP changes in subgroups of patients with different types of the space occupying lesions, as well as the observed symmetry of the VEP changes, allow the assumption that the functional inhibition of the optic pathway occurs in the perimesencephalic part via their compression or stretching. The assumption is supported by pathoanatomical MRT findings in some cases. It seems, therefore, that VEP investigations enable the registration of a compression or torsion of the cranial mesencephalon (mesencephalo-diencephalic mechanical irritation) or the presence of a clinical silent transtentorial herniation in space occupying lesions. The loss of the VEP appears to yield an early and certain signal of the progressing mid-brain syndrome.

Brain Neoplasms↗

PubMed2000

Continuous monitoring of the stimulated area in multifocal ERG.

INTRODUCTION: Multifocal electroretinography (MF-ERG) is widely used in the detection of local retinal dysfunction. However, the position of the stimulus on the retina and the stability of fixation are usually not directly accessible. Thus, devices have been designed for a continuous fundus visualization during recording. METHODS: MF-ERGs were recorded with a RetiScan system connected to two different Scanning-laser ophthalmoscopes (SLOs) that use either a red (633 nm) or green (415 nm) laser for stimulation, and a VERIS 4 system connected to a piggyback stimulator prototype that added the stimulus to the optical pathway of the SLO by means of a wavelength-sensitive mirror. Fundus visualization was achieved with the infrared lasers of the SLOs (780 and 835 nm). RESULTS: The most extensive study so far with a green laser stimulus in a cat model of retinal degeneration demonstrated the capability of the device to detect retinal landmarks and the different stages of degeneration. Also, the advantages of exactly reproducible stimulus positioning for averaging within and comparison between disease groups became apparent. The results with the same setup in transgenic mice suggest a pure cone origin of the responses. In humans, recordings show that fixation is sufficiently good in most subjects. It is not clear yet whether red or green laser stimulation (or both) is preferable. The results with the prototype were very similar to the MF-ERGs obtained with a standard CRT screen. CONCLUSIONS: All three devices allowed us to record MF-ERGs with continuous fundus monitoring. Although further refinements are necessary, it is obvious that fundus controlled methods will improve the reliability of MF-ERG in future research on glaucoma, transplantation studies, and evaluation of gene therapy.

Animals↗

PubMed2002

[Delineation of the cisternal architecture with three-dimensional CT cisternography and its transparent imaging].

We used three-dimensional imaging of the cisternal architecture with perspective volume rendering of CT cisternography in patients with unruptured cerebral aneurysms. Selective changes in the opacity chart of computed tomographic values, based on the use of a function of downward slope, represented the contour of the structures located in the cisternal space. In addition to this, using a spiked peak curve, it was possible to show the contour of the outer wall of the cisternal structures as a series of rings, which provided a transparent view inside and/or outside the cistern through the spaces between the rings. Transparent imaging technique allowed direct visualization of the underlying objects and offered an extensive perspective view of the anatomical architecture of the cisternal structure, including an aneurysm, major basal arteries and optic pathway, in a single view. Three-dimensional CT cisternography may be a useful adjunct for the diagnosis of the cisternal architecture in relation to the surrounding cerebrospinal fluid, and for simulation of the surgical procedures considered for lesions occupying intra-cisternal space, including cerebral aneurysms.

Aged↗

PubMed2001

[Analysis of MRI for tumor of the sellar region].

PURPOSE: To introduce the characteristics of magnetic resonance imaging(MRI) for the tumors of the sellar region. METHODS: A retrospective analysis of 86 cases with the tumors of the sellar region was carried out. RESULTS: The pituitary tumor including the pituitary micro-adenoma and pituitary macro-adenoma was a common tumor of the sellar region. The pituitary micro-adenoma usually does not affect visual function; but the pituitary macro-adenoma often damages the optic pathway and reduces the visual function. The rest of the sellar region appears special feature on MRI. CONCLUSION: MRI is a useful method in diagnosing the tumors of the sellar region.

Adenoma↗

PubMedDate not supplied

[Multiple symmetric lipomatosis associated to polyneuropathology, atrophy of the cerebellum and mitochondrial cytopathy].

INTRODUCTION: Multiple symmetric lipomatosis (MSL), which is predominantly found in middle aged males, is characterised by accumulations of fat in the neck, shoulders and other parts of the trunk, and sometimes associated with different neurological manifestations, both central and peripheral. Although its aetiology is unknown, it has been described as associated with mitochondrial cytopathies. AIMS. To describe the case of a young female with MSL associated with mitochondrial encephalomyopathy. CASE REPORT: Girl aged 14 with MSL, ataxia, patellar hyperreflexia, bilateral Babinski sign, pes cavus, axonal peripheral neuropathy, involvement of the optic pathway, atrophy of the cerebellum, subsarcolemmal mitochondrial accumulations in the untrastructural examination of the vastus lateralis muscle and partial deficit of complex I in the mitochondrial respiratory chain. As regards molecular genetic aspects, the most frequent mutations of the ATPase 6 gene in lymphocytes, and mtDNA deletions and tRNALys and tRNALeu(UUR) mutations in muscles were excluded. CONCLUSIONS: Despite the fact that MSL is an entity normally found in adults, the possibility of its being diagnosed in the paediatric age must be taken into account. This case is probably the second time MSL has been observed associated with mitochondrial cytopathy in this age bracket.

Adolescent↗

PubMed1992

The retino-hypothalamic tract is involved in prolactin regulation in fetal sheep.

To investigate the role of the retino-hypothalamic tract on fetal prolactin regulation, we examined the effect of ocular enucleation on fetal plasma prolactin. Eleven fetuses of Suffolk ewes were chronically catheterized during fall, and six of them were subjected to bilateral ocular enucleation. All ewes were kept at 12h:12h light:dark cycle (lights on at 0800 and off at 2000). The experiments were performed 5-9 days after surgery (GA control fetuses 125 +/- 1.5, optical enucleation 121.3 +/- 1.5 days). Blood samples were taken from fetuses hourly around the clock, and plasma prolactin and cortisol were measured by radioimmunoassay (RIA). Luteinizing hormone (LH) and Growth hormone (GH) were measured in pooled plasma samples from control and enucleated fetuses by RIA. Average plasma prolactin was 5-fold lower in enucleated than in control fetuses (9.6 +/- 0.5 and 54.2 +/- 3.3 ng/ml, SEM; P < 0.005). Both control and enucleated fetuses presented circadian rhythm of prolactin with acrophase between 1400 and 1830 h. An enucleated fetus was tested for response of prolactin to TRH. Prolactin increased as described in the literature. There was no change in plasma concentration of cortisol, LH or GH after ocular enucleation. Our data indicate that the optical pathway participates in prolactin regulation in the fetal sheep.

Animals↗

PubMed1976

[Local adaptation curves evoked by the pupillo-motor reflex].

We have studied local dark-adaptation curves using the pupillary reflex. The results obtained indicate that the dark-adaptation curves produced by central and peripheral stimulation are variable and are in principle similar to the psychophysical curves obtained in matching conditions. This result demonstrates that the pupillary reflex is triggered by two different types of receptors which have the same characteristics as the cones and the rods, and that the system of the pupillary receptors and the optical pathways is identical.

Adult↗

PubMed1992

[Pattern shift visual evoked potentials in diabetes mellitus].

Functional exploration of the optic pathways with pattern shift visual evoked potentials (PSVEP) has been rapidly accepted as a non-invasive method of investigation of diabetics. For this article, we conducted the PSVEPs study on 46 cases of NIDDM and 13 cases of IDDM. The peak latency, interpeak latency and evoked amplitude of P100 were analyzed in each case. For further correlation, the motor and sensory nerve conduction velocities of the median nerve, blood sugar, serum HbA1c, and duration of DM were measured simultaneously. Two nondiabetic control groups which matched the age and sex of the NIDDM and IDDM groups were used for comparison. In the IDDM group, the results showed prolongation of all peak and interpeak latencies (IPL) except the peak latency of N75 on the right side. The P100 amplitude was reduced as compared with the age-matched young control group. The interocular P100 latency difference (ILD) was not statistically significant between the IDDM group and the age-matched control group. The results of the NIDDM group revealed prolongation of all peak latencies and IPLs. The P100 amplitude and ILD showed no statistically significant difference between NIDDM and the age-matched control group. The prolongation of N 75 peak latency exhibited a linear correlation with duration, HbA1c and median nerve SNCV.

Adult↗

PubMed2006

Pre- and intraoperative processing and integration of various anatomical and functional data in neurosurgery.

A software system is presented, capable of integrating various information sources for neurosurgical procedures. These include anatomical data such as a standard 3D DICOM image stacks, atlas data, as well as functional information (e.g. fmri, MEG, EEG). The system is programmed in C++ using Open GL for visualisation, and was developed in a close cooperation with a neurosurgical department to match existing needs. Preoperatively the data may be combined, registered by a rigid or elastic matching process, enriched by user specified planning information such as annotations or trajectories, and visualised in a standard fashion using different segmentation schemes, interactive rotation, zooming etc. Selected portions of the gathered and generated information may then be exported for neuronavigation input in DICOM or a vendor specific format. Intraoperatively, this information may, on the one hand, be simply used as an integrational part of the routinely used navigational data. On the other hand, the system is also capable of interacting with the navigational system to integrate the actual spatial information of the ongoing procedure into the preoperative data, thus allowing further planning and visualisation beyond the scope of the navigational unit. Furthermore, intraoperatively updated information such as intraoperative MR images or electrophysiological data may be integrated and correlated to the existing information. Ongoing developments comprise redistribution of the relevant data for injection onto the screen of the navigational system or into the optical pathway of the (3D capable) microscope display/ocular. This also includes information about the actual automatically optimized accuracy of the navigation process in relation to the head markers in use.

Humans↗

PubMed1991

Visual evoked potential responses in pregnant women.

Sensory functions and their electrophysiological correlates have not been adequately documented during pregnancy. The present study reports visual evoked potential responses to pattern reversal (VEP-P) in ten third trimester pregnant women and changes in latency of NPN complex when compared with these responses in the non pregnant state. Visual evoked potentials were recorded from O1-A1 and O2-A2 scalp areas, using Ag/Agcl disc electrodes to transient pattern of black and white checkerboard with 32' size and reversal rate 1Hz. Two trials of VEP-P responses to 256 transient pattern stimuli given to each eye, were analysed and averaged by the computer of visual evoked potential recorder (MEB 5200 Nihon Kohden Japan). The latencies of various positive and negative waves, along with P1 amplitude, obtained in pregnant women, were compared with those obtained in ten non-pregnant women. The latencies of initial NPN complex (N1P1 & N2) were significantly reduced in pregnant women, indicating that pregnancy facilitates conduction process in the optic pathways.

Adult↗

PubMed1991

Medulloblastoma presenting as blindness of rapid evolution. A case report.

An 18-year-old man reported rapid decrease of visual acuity that progressed to total blindness in 1 month. Computed tomographic scanning showed two neoplastic masses: a large one, intra- and suprasellar, and a smaller cerebellar nodule. Histologically, the former proved to be a large metastasis of the small cerebellar medulloblastoma, which infiltrated and compressed the chiasm. Direct compression of the optic pathways by metastasis of a medulloblastoma is a rare event.

Adolescent↗

PubMed1990

[Encephalic lesions in neurofibromatosis: clinical manifestations and typical magnetic resonance findings].

Neurofibromatosis is the commonest neuroectodermal disease. It is characterized by dysplasias and/or tumors of organs and tissues derived from the embryonic ectoderm, mesoderm and endoderm, and most frequently presents with nervous system and cutaneous lesions. It can be classified as neurofibromatosis type 1 (NF-1 or von Recklinghausen disease) and neurofibromatosis type 2 (NF-2 or bilateral acoustic neurofibromatosis). In order to assess clinical presentation of the disease and diagnostic value of Magnetic Resonance Imaging (MRI), the authors retrospectively evaluated the clinical records and the cranial MR studies of 21 patients with neurofibromatosis (18 with NF-1 and 3 with NF-2). Distinctive abnormalities between the two types were found in both clinical presentation and MR studies. Clinically, NF-1 patients presented most often with blindness, while NF-2 patients were deaf and had fewer cutaneous lesions. The evaluation of MR studies showed that NF-1 patients were more likely to be affected with intracranial gliomas, predominantly of the optic pathways. Moreover, foci of prolonged T2 relaxation were frequently observed, primarily in the globus pallidus of the basal ganglia and in the dentate nucleus of the cerebellum. Some of the foci in the globi pallidi exhibited increased signal intensity on T1-weighted images as well. NF-2 patients more frequently presented with bilateral acoustic schwannomas, meningiomas and cerebral white matter foci of prolonged T2 relaxation, but they did not have dentate and basal ganglia lesions. The authors conclude that as a rule the manifestations of NF-1 and NF-2 on cranial MRI are separate and distinct; they do not overlap. MRI is an useful clinical tool for the diagnosis and the follow-up of patients with neurofibromatosis.

Adolescent↗

PubMedDate not supplied

[NMR of phakomatoses].

23 patients affected by phakomatoses were studied with NMR, including tuberous sclerosis (11 cases), Sturge-Weber's disease and Von Recklinghausen's neurofibromatosis (6 cases). SE sequence was used performing T1-WIs with TR = 350-750 ms and TE = 20-30 ms and T2-WIs with TR = 1500-2100 ms and TE = 50-100 ms. Tuberous sclerosis was characterized in each case by the presence of hiperintense areas in T2-WIOs, associated in 9 cases to subependimal microcalcifications. Sturge-Weber-disease showed: cerebral or lobar emiatrophia, abnormal vascularization and cortical calcifications. Cerebral neurofibromatosis was characterized by extra-assial tumors, associated in 4 cases to gliomas of the optical pathways. The AA. conclude that NMR is the choice examination in the evaluation of phakomatoses.

Adolescent↗

PubMed1990

Layer-by-layer analysis of macular diseases with objectively measured visual functions.

New methods were developed to measure layer-by-layer visual function in macular diseases objectively and quantitatively. A prototype apparatus for foveal cone densitometry that combines a modified fundus camera, independent optic pathways and a personal computer was assembled. Using a two-way density technique, the density and regeneration time of the foveal cone pigment can be measured objectively. Data on layer-by-layer visual function can be obtained when a-wave, b-wave and oscillatory potentials are recorded by focal macular electroretinography (FMERG). Since the retinal origin of each component is different, the comparative measurement of these components indicates which layer of the macula is disturbed. The simultaneous recording of FMERG and visual evoked response (VER) might be useful in determining which part of the visual pathway is impaired. These methods of measurement were reviewed and some examples of layer-by-layer analysis were shown.

Adult↗