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At least 109 records · Page 6Linked to original sources
PubMed1995

Synapses of optic axons with GABA- and glutamate-containing elements in the optic tectum of Bufo marinus.

The central termination and the transmitter content of the optic fibers and the neurochemical nature of their synaptic targets was investigated in the optic tectum of the toad Bufo marinus. Retinal ganglion cells were retrogradely filled from the tectum with the fluorescent dye DiI and the retinal wholemounts were immunostained for glutamate. Most of the dye-filled cells could be double labeled. In addition, double-labeling for gamma-aminobutyric acid an glutamate were also made, when colocalization of these markers was not observed in the neurons of the retinal ganglion cell layer. In order to identify retinal terminals in the optic tectum, optic axons were retrogradely filled with horseradish peroxidase. Postembedding immunocytochemistry showed that 88% of the optic axon terminals were glutamate-like immunoreactive, 6% gamma-aminobutyric acid-immunoreactive and 6% were negative for both GABA and glutamate. Optic fibre terminals synapsed on gamma-aminobutyric acid- or glutamate-containing postsynaptic profiles (58% and 7%, respectively), while the rest on immunonegative elements. Optic fibres containing glutamate rarely synapsed with glutamate-like immunoreactive postsynaptic elements. In contrast, 67% of the gamma-aminobutyric acid-immunoreactive optic terminals synapsed onto gamma-aminobutyric acid-positive dendrites. It has been observed after combination of anterograde tracer transport and double-label immunocytochemistry, that 57% of the optic terminals synapsed on gamma-aminobutyric acid-immunoreactive elements and 38% on dendrites containing neither gamma-aminobutyric acid- nor glutamate-immunoreactive materials. These results suggest that (1) a large number of ganglion cells use glutamate and some gamma-aminobutyric acid as a transmitter, (2) a substantial proportion of the optic axons terminate on gamma-aminobutyric acid-containing inhibitory interneurons in the tectum, (3) some intrinsic neurons in the tectum are glutamate-like immunoreactive. We also propose, that (4) gamma-aminobutyric acid-immunoreactive optic axons may form an effective disinhibitory circuit in the tectum by synapsing preferentially with local inhibitory interneurons.

Animals↗
PubMed1998

A histopathologic and morphometric differentiation of nerves in optic nerve hypoplasia and Leber hereditary optic neuropathy.

OBJECTIVES: To characterize and quantitate optic nerve histopathologic and morphometric differences between optic nerve hypoplasia (ONH) as an early and congenital form of intrinsic axonal loss and Leber hereditary optic neuropathy (LHON) as a late and acquired form of intrinsic axonal loss. MATERIALS AND METHODS: Optic nerves from 3 sources were examined: a 42-year-old healthy woman (control), a 53-year-old woman with ONH diagnosed postmortem, and a 74-year-old woman with LHON. The optic nerves were processed, embedded, and stained with a 1% solution of paraphenylene diamine. Histopathologic and morphometric analyses were performed via light microscopy and a semiautomatic computer image analysis system. RESULTS: The ONH showed severe axonal depletion without degenerated profiles in an inferonasal sector, with only a small superotemporal sector having a near normal appearance. The LHON revealed general axonal depletion centrally, fibrocytic scarring, scattered "degeneration dust," and evidence of minimal inflammation, with residual axons limited to superior and temporal peripheral clusters. Morphometric analysis revealed total fiber populations of 98,000 in the ONH optic nerve and 48,000 in the LHON optic nerve, representing 90% and 95% reductions, respectively, compared with the control optic nerve (1.2 million fibers). CONCLUSIONS: Optic nerve hypoplasia and LHON present 2 distinguishable and distinctive patterns of nerve fiber distribution and axonal dropout. The lack of degenerated axons in ONH indicates that any axonal death probably occurred through apoptosis during development. In LHON, degenerated axons and minimal grade of inflammation were obvious, implicating a more "active" pathologic process. This study describes distinctions between these 2 optic neuropathies.

Adult↗
PubMed1988

Anterior ischemic optic neuropathy: nonarteritic form in small and giant cell arteritis in normal sized optic discs.

By estimating cup/disc ratios in fellow eyes it has been assumed that nonarteritic anterior ischemic optic neuropathy (AION) occurs more often in small optic nerve heads. Correcting the photographic magnification we used absolute size units to measure 33 affected and 25 fellow optic discs with nonarteritic AION and 7 affected and 7 fellow optic nerve heads with arteritic AION. The affected and fellow discs with nonarteritic AION (2.37 + -0.29 mm2 and 2.31 + -0.31 mm2) were significantly (p less than 0.001, Mann-Whitney-test) smaller than 457 normal optic nerve heads (2.69 + -0.70 mm2). They were significantly (p less than 0.001; Mann-Whitney-test) larger than optic nerve heads with pseudopapilledema or drusen. Affected and fellow optic nerve heads with arteritic AION were not significantly different in size from normal discs but significantly (p less than 0.005) larger than the discs affected by nonarteritic neuropathy. There were no significant form differences between the pathologic and normal discs. Optic disc morphometry can be helpful in the differentiation of nonarteritic and arteritic AION: Nonarteritic AION occurs more often in small optic discs, arteritic AION is more often in normal sized optic nerve heads.

Aged↗
PubMed1985

Inter-individual variation in blood supply of the optic nerve head. Its importance in various ischemic disorders of the optic nerve head, and glaucoma, low-tension glaucoma and allied disorders.

There is no one standard pattern of the blood supply of the optic nerve head in all human eyes. There is a marked inter-individual variation in the blood supply of the optic nerve head, and the various factors which produce this include variations in (I) the anatomical pattern of blood supply, (II) the pattern of posterior ciliary artery (PCA) circulation (the main source of blood supply to the optic nerve head), and (III) the blood flow. The variations in the pattern of PCA circulation include the variations in (a) number of PCAs supplying an eye, (b) area of supply to the optic nerve head by each PCA, (c) location of the watershed zones between the various PCAs in relation to the optic nerve head, and (d) blood pressure in various PCAs as well as short PCAs. The variations in the blood flow in the optic nerve head can be produced by changes in (i) the intraocular pressure, (ii) mean blood pressure in the capillaries of the optic nerve head and (iii) peripheral vascular resistance. These variations are discussed in detail. A lack of appreciation of these complexities of the blood supply of the optic nerve head in health and disease is responsible for many of the current problems in the understanding of the role of vascular disturbances in anterior ischemic optic neuropathy, glaucoma, low-tension glaucoma and various ischemic disorders of the optic nerve head.

Adolescent↗
PubMed2000

MRI of the intraorbital optic nerve in patients with autosomal dominant optic atrophy.

Measurements of the intraorbital optic nerve were made using high-resolution coronal MRI in 10 adults with autosomal dominant optic atrophy. Comparisons were made with previous studies of 10 normal adult subjects. The cross-sectional diameters of the optic nerve and the perineural subarachnoid space were measured and a ratio of there diameters at anterior, mid and posterior positions along the optic nerve was determined. We found a statistically significant difference in the mean optic nerve: sheath ratio between the control group and patients with autosomal dominant optic atrophy. At anterior, mid and posterior locations along the optic nerve it is significantly smaller in patients with optic atrophy. We have demonstrated that the loss of ganglion cells, previously documented in dominant optic atrophy, is associated with a significant loss of optic nerve tissue and thinning of the nerve along its length.

Case-Control Studies↗
PubMed2001

Optic disc morphology after arteritic anterior ischemic optic neuropathy.

OBJECTIVE: To evaluate the appearance of the nerve head in patients after giant cell arteritis-induced arteritic anterior ischemic optic neuropathy (A-AION). DESIGN: Noncomparative clinical case series. PATIENTS: The study comprised 29 patients who presented with unilateral A-AION and temporal artery biopsy-proven giant cell arteritis. Stereoscopic optic disc photographs, taken of both the affected and unaffected eyes at the onset of the disease and after a follow-up period of 20.10 +/- 25.36 months (median, 11 months; range, 2-102 months), were morphometrically evaluated. MAIN OUTCOME MEASURES: Size and shape of the optic disc, neuroretinal rim, optic cup, and alpha and beta zones of parapapillary atrophy. RESULTS: In the eyes after A-AION, at the end of the study, the neuroretinal rim was significantly (P = 0.002) smaller, and the optic disc cup area was significantly (P = 0.001) larger than those of the contralateral unaffected eyes. Alpha zone and beta zone of parapapillary atrophy did not vary significantly (P > 0.50). CONCLUSIONS: A-AION, like glaucomatous optic neuropathy, results in neuroretinal rim loss and optic disc cupping. However, in contrast to glaucoma, A-AION is not associated with an enlargement of parapapillary atrophy. The reasons and mechanisms responsible for these similarities and dissimilarities are discussed. Marked clinical, morphologic, and histopathologic similarities in optic disc cupping and loss of neuroretinal rim between A-AION and glaucomatous optic neuropathy are highly suggestive of a common mechanism for the development of the two diseases (i.e., ischemia of the optic nerve head). The subject is discussed at length.

Aged↗
PubMed2003

Visual function in patients with optic nerve pallor (optic atrophy).

This cross-sectional study assessed the relationship between the degree of optic nerve pallor (optic atrophy) and visual function. Using a set of "gold standard" stereoscopic slides, the severity of optic atrophy for 270 eyes, each having sustained a bout of optic neuropathy, was graded. Good visual acuity was found in 55/86 (64.0%) mild, 54/119 (45.4%) moderate, and 21/65 (32.3%) marked optic atrophy eyes. Good visual field was found in 6/28 (21.4%) mild, 4/43 (9.3%) moderate, and 2/28 (7.1%) marked optic atrophy eyes. Good color vision was found in 31/46 (67.4%) mild, 12/62 (19.4%) moderate, and 7/31 (22.6%) marked optic atrophy eyes. A significant rank correlation was observed between optic atrophy and visual acuity (P < 0.001; rs = 0.356), visual field (P < 0.001; rs = -0.398), and color vision (P < 0.001; rs = -0.492). As the graded severity of optic atrophy increases, the proportion of eyes with good visual function decreases. Visual field, rather than visual acuity or color vision, appears to be a better indicator of the severity of visual loss, when optic atrophy is present.

Cross-Sectional Studies↗
PubMed1990

[MRI lesions of the optic nerves in optic neuritis].

Magnetic resonance imaging (MRI) was performed in 14 patients with optic neuritis. Three patients suffered from multiple sclerosis but the etiologies of the remaining 11 cases could not be identified. They were bilateral in 6, and unilateral in 8. The MR images were compared with the symptomatic lesions of optic neuritis and pattern reversal VECP. The STIR mode (short time inversion recovery), was employed for the MRI in the orbit and T2-weighted mode in the brain. In 11 eyes with hyperemia of the optic disc, 7 eyes showed a high signal in the optic nerve with the MRI, and 9 eyes showed an abnormal pattern VECP. Seven eyes with normal disc and two eyes with a pale disc showed a high signal in the optic nerve with MRI, those 9 eyes had abnormal pattern VECP. The high signal in the optic nerve was not related to visual acuity or visual field abnormalities of patients. However, the degree of the high signal of the optic nerve lesion in MRI was associated with the clinical course and prognosis of the optic neuritis. The degree of the high signal of the optic nerve lesion decreased with the recovery of visual acuity in optic neuritis.

Adolescent↗
PubMed1986

Age-related fiber order in the ferret's optic nerve and optic chiasm.

Although the mammalian optic tract shows a grouping of fibers by age, with newer fibers nearer the pial surface, the possible rules for fiber ordering in the mammalian optic nerve have not been well defined. In this study, preferential labeling of the older retinal fibers in the ferret, a close relative of the cat, shows that the age-related fiber order in the ferret's optic tract reflects a systematic sorting of fibers by age that occurs in the optic nerve, and that is maintained through the optic chiasm. The older retinofugal fibers, dispersed throughout the nerve near the retina, come to be limited to the perimeter of the nerve as it passes through the optic foramen, while newer fibers come to lie nearest the center of the nerve. These newest fibers approach the ventral surface of the brain nearer the optic chiasm. In the chiasm, as in the tract, the oldest fibers lie furthest from the pial surface of the brain, while newer fibers lie nearer the surface. The age-related fiber ordering in the ferret's optic nerve, with the newest fibers initially being furthest from the surface at the optic foramen, differs from age-related orderings seen in nonmammalian vertebrates, where the newest fibers are always nearest the surface. The changing patterns of fiber ordering along the ferret's optic nerve may relate to changes in the underlying glial structure of the developing nerve.

Age Factors↗
PubMed2005

Optic radiation changes after optic neuritis detected by tractography-based group mapping.

Postmortem data suggest that trans-synaptic degeneration occurs in the lateral geniculate nucleus after optic nerve injury. This study investigated in vivo the optic radiations in patients affected by optic neuritis using fast marching tractography (FMT), a diffusion magnetic resonance imaging (MRI) fiber tracking method, and group mapping techniques, which allow statistical comparisons between subjects. Seven patients, 1 year after isolated unilateral optic neuritis, and ten age and gender-matched controls underwent whole-brain diffusion tensor MR imaging. The FMT algorithm was used to generate voxel-scale connectivity (VSC) maps in the optic radiations in each subject in native space. Group maps of the left and right optic radiations were created in the patient and control group in a standardized reference frame using statistical parametric mapping (SPM99). The reconstructed optic radiations in the patient group were localized more laterally in the posterior part of the tracts and more inferiorly than in the control group. Patients showed reduced VSC values in both tracts compared with controls. These findings suggest that the group mapping techniques might be used to assess changes in the optic radiations in patients after an episode of optic neuritis. The changes we have observed may be secondary to the optic nerve damage.

Adult↗
PubMed1993

Progressive and static nonarteritic ischemic optic neuropathy treated by optic nerve sheath decompression.

PURPOSE: Optic nerve sheath fenestration has been advocated as an effective treatment for progressive nonarteritic ischemic optic neuropathy (NAION) and anecdotally effective for selected patients with NAION who have not had progressive visual loss. To determine whether optic nerve sheath decompression is of any benefit in patients with NAION, the authors reviewed their experience, surgically treating 23 patients with progressive NAION and 15 patients with static or nonprogressive NAION. RESULTS: Patients with progressive NAION had a significant improvement in visual function as measured by Snellen visual acuity after optic nerve sheath decompression (P = 0.0005). There was no statistically significant improvement in visual field mean deviation (P = 0.11). The 15 patients undergoing optic nerve sheath decompression for static NAION failed to demonstrate significant improvement in either visual acuity (P = 0.90) or visual field mean deviation (P = 0.87). Preoperative standardized echography was used to measure the optic nerve sheath diameter and ascertain its compressibility (30 degrees test). There was a significant difference in compressibility between eyes with static NAION and eyes with progressive NAION (P = 0.001). Accumulation of optic nerve sheath fluid was documented in three eyes initially presenting with NAION and then with development of progressive visual dysfunction. CONCLUSION: Optic nerve sheath decompression improves visual acuity but has little effect on overall visual function in patients with progressive NAION. Optic nerve sheath decompression does not improve visual field or acuity in patients with static NAION. Detection of significant intrasheath fluid by standardized echography helps to objectively differentiate patients with NAION who may benefit from optic nerve sheath decompression.

Adult↗
PubMed1995

The dyschromatopsia of optic neuritis: a descriptive analysis of data from the optic neuritis treatment trial.

PURPOSE: We sought to characterize the dyschromatopsia of optic neuritis, to determine the type and severity of color defect present and its relation to central vision and spatial acuity, to examine changes in this dyschromatopsia over time, and to determine the applicability of Köllner's rule to patients with optic neuritis. METHODS: We analyzed the raw data on color vision performance as assembled within the Optic Neuritis Treatment Trial (ONTT). The ONTT was designed to evaluate corticosteroids as a treatment for acute demyelinating optic neuritis and to allow long-term outcome and natural history analyses. Between July 1, 1988 and June 30, 1991, 488 patients were enrolled in this trial. All patients underwent extensive neurologic and ophthalmologic examinations including standardized testing of visual function that included testing of color vision. The ONTT population thus afforded a unique opportunity to characterize acquired dyschromatopsias in a large, homogenous, well-characterized cohort of patients with optic neuritis. We used quantitative analysis of FM-100 scores from this patient cohort to determine the severity of the dyschromatopsia, the selectivity of the dyschromatopsia (polarity of errors) and the type of dyschromatopsia (axis of confusion) by employing quadrant analysis of FM-100 scores. RESULTS: The results of high-and low-selectivity analyses of the FM-100 data showed that during the acute phase of optic neuritis, blue/yellow, red/ green, and non-selective color defects occurred; among patients with pure defects, blue/yellow defects were more frequent than red/green defects. At 6 months after the acute event, however, analyses showed that red/green defects were more common than blue/yellow defects. Among patients with selective color defects both acutely and at 6 months, the defect was as likely to change over time as remain the same. The likelihood of persistent dyschromatopsia at 6 months was related to the severity of initial central acuity loss, but the type of dyschromatopsia present (red/green versus blue/yellow) was not. CONCLUSIONS: Our results suggest that at the time of the acute attack of optic neuritis, the majority of selective color defects were blue/yellow defects, whereas at 6 months, more of the selective defects were red/green defects, though both types of defects (as well as nonselective defects) were seen acutely and at 6 months. Despite the rigorous inclusion criteria of the ONTT, the large number of patients we studied, correlation of color vision with visual acuity, and longitudinal follow up, this study showed that no single type of color defect was consistently associated with optic neuritis. Demyelinating optic neuritis does not obey Köllner's rule. Moreover, the type of defect present changed in some patients over the course of recovery. Thus, the type of defect may not even be consistent in individual patients as they recover. The type of defect appeared to be related to spatial vision at the time of the test, but the type of defect present at 6 months was not related to the severity of the initial visual loss. Therefore, in evaluating color defects associated with optic neuritis, the level of central visual function must be considered.

Acute Disease↗
PubMed2000

Progressive optic nerve cupping and neural rim decrease in a patient with bilateral autosomal dominant optic nerve colobomas.

PURPOSE: To document progressive optic nerve cupping and neural rim decrease in a patient with normal intraocular pressures and bilateral autosomal dominant optic nerve colobomas. METHODS: The ophthalmology records, stereoscopic fundus photographs, and visual fields of a 27-year-old woman with familial (autosomal dominant) optic nerve colobomas were reviewed. The appearance of the optic nerves was documented over a 13-year period (1985 to 1998). RESULTS: Despite repeatedly normal intraocular pressures, the patient showed progressive optic nerve cupping and neural rim decrease in both eyes. Visual field testing was available over a 5-year period (1993 to 1998) and was abnormal, but no progression was seen. CONCLUSIONS: This case of progressive cupping and neural rim decrease in a patient with autosomal dominant optic nerve coloboma in both eyes may provide insight into the optic nerve cupping associated with normal tension glaucoma. Careful follow-up of patients with optic disk colobomas or patients is indicated to detect possible optic nerve changes or field loss.

Adult↗
PubMed1997

Evaluation of coexisting optic nerve head drusen and glaucoma with optical coherence tomography.

OBJECTIVE: Optic nerve head drusen often make evaluation of the nerve head difficult to interpret. In addition, visual field defects are known to occur in patients with optic disk drusen, resembling glaucomatous damage. The authors report two cases of coincident optic nerve head drusen and glaucoma, in which the use of optical coherence tomography (OCT) in evaluating the nerve fiber layer was beneficial. PARTICIPANTS: Two patients with both optic nerve head drusen and glaucoma, one with primary open angle glaucoma, the other with pseudoexfoliation glaucoma were evaluated. Both patients had asymmetric optic disk drusen, with clinically visible drusen only in one eye. INTERVENTION: Ophthalmologic examination, color and red-free photography, automated Humphrey visual field testing and OCT were performed. RESULTS: Nerve fiber layer loss as measured by OCT was found to be greater than expected by the appearance of the optic nerve head and red-free photography, with visual fields consistent with findings in case 1. In case 2, visual fields were full, despite nerve fiber layer thinning seen by OCT and red-free photography. CONCLUSIONS: There can be significant nerve fiber layer thinning in patients with both glaucoma and optic disk drusen, despite the appearance of the optic nerve head in these patients. The cup margin may be obscured by the drusen, giving rise to a falsely full-appearing disk. In such cases, OCT may provide a useful means to quantitatively measure the nerve fiber layer thickness and to aid in the management of these patients by detecting nerve fiber layer thinning earlier than would otherwise be possible.

Aged↗
PubMedDate not supplied

Dimensions of the optic nerves, chiasm, and tracts: MR quantitative comparison between patients with optic atrophy and normals.

OBJECTIVE: The dimensions of the optic nerves, chiasm, and tracts were determined in normal patients and in patients with clinical evidence of optic atrophy to establish whether there was a significant difference between the two groups. MATERIALS AND METHODS: The authors analyzed thin section coronal MRI of 110 patients. Seventy-seven patients were normal, 20 had visual impairment without funduscopic evidence of optic atrophy, and 13 had visual impairment with funduscopic evidence of optic atrophy. RESULTS: The normal mean dimensions were (height x width): optic tracts 2.8 x 5.1 mm; nerves 3.0 x 5.9 mm; chiasm 3.5 x 15.0 mm. The mean dimensions in the optic atrophy group were significantly less (p < 0.01): optic tract 2.1 x 4.7 mm; nerve 2.7 x 5.8 mm; chiasm 2.6 x 12.6 mm. CONCLUSION: The reduced mean dimensions in the optic atrophy group are statistically significant but due to individual variability and errors inherent in measuring small structures, these measurements may be difficult to apply clinically. The most clinically useful measurement is the chiasm width. A width < 13.5 mm correlates well with funduscopic evidence of optic atrophy.

Adolescent↗
PubMed1997

MRI of optic nerve enlargement in optic neuritis.

We report two cases of optic neuritis with optic nerve enlargement on MRI. Both had a clinical course typical for optic neuritis but also had a neuroradiologic finding most commonly seen with optic nerve glioma or meningioma, which initially led to an incorrect diagnosis. We review the six previous reported cases of optic nerve enlargement in optic neuritis. Including our cases, six of eight reported cases were in children with severe initial visual loss. Optic nerve enlargement is a rare finding in optic neuritis that might be a subtype of optic neuritis.

Child↗
PubMedDate not supplied

Optical coherence tomography study of optic disc melanocytoma.

Optic disc melanocytoma is a well-known clinical entity occurring as a deeply pigmented lesion on the optic nerve head. A 40-year-old man with a pigmented lesion overlying the left optic disc was evaluated with optical coherence tomography. The single high reflectance band from the anterior edge of the disc lesion with optical back shadowing behind on optical coherence tomography helped to pinpoint the diagnosis of the lesion as optic disc melanocytoma. Quantitative assessment of the mass with optical coherence tomography for its growth did not show any increase in size horizontally or vertically after 6 months. Optical coherence tomography is useful for obtaining the exact measurements of the mass lesion and may be used as a tool to follow the progress and growth pattern of the lesion.

Adult↗
PubMed2005

Extraocular dorsal signal affects the developmental fate of the optic vesicle and patterns the optic neuroepithelium.

Dorsal-ventral (DV) specification in the early optic vesicle plays a crucial role in the proper development of the eye. To address the questions of how DV specification is determined and how it affects fate determination of the optic vesicle, isolated optic vesicles were cultured either in vitro or in ovo. The dorsal and ventral halves of the optic vesicle were fated to develop into retinal pigment epithelium (RPE) and neural retina, respectively, when they were separated from each other and cultured. In optic vesicles treated with collagenase to remove the surrounding tissues, the neuroepithelium gave rise to cRax expression but not Mitf, suggesting that surrounding tissues are necessary for RPE specification. This was also confirmed in in ovo explant cultures. Combination cultures of collagenase-treated optic vesicles with either the dorsal or ventral part of the head indicated that head-derived factors have an important role in the fate determination of the optic vesicle: in the optic vesicles co-cultured with the dorsal part of the head Mitf expression was induced in the neuroepithelium, while the ventral head portion did not have this effect. The dorsal head also suppressed Pax2 expression in the optic vesicle. These observations indicate that factors from the dorsal head portion have important roles in the establishment of DV polarity within the optic vesicle, which in turn induces the patterning and differentiation of the neural retina and pigment epithelium.

Animals↗