Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “OPTICS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,531 records · Page 85Linked to original sources
PubMed2000

Progression of visual evoked potential abnormalities in multiple sclerosis and optic neuritis.

To investigate visual signal processing in patients with optic neuritis, suspected multiple sclerosis, confirmed multiple sclerosis (MS), and optic neuritis combined with MS, pattern reversal visual evoked potentials (VEPs) were recorded in patients and normal subjects. The amplitude and latency of the first positive peak, P100 were determined to assess electrical conduction in patients as compared to normal subjects. Suspected MS patients did not differ from normal subjects in peak latencies or amplitudes. The P100 amplitude was reduced in optic neuritis, confirmed MS and optic neuritis combined with confirmed MS. The P100 and N145 latencies were prolonged in optic neuritis patients and confirmed MS patients as compared to normal subjects. The main characteristic of optic neuritis was P100 amplitude reduction, and of confirmed MS was P100 latency delay. There was a progression of the P100 latency delay and of the P100 amplitude decrement in optic neuritis, confirmed MS, and optic neuritis combined with confirmed MS. These results indicate a progression of demyelination in optic neuritis, confirmed MS, and optic neuritis combined with confirmed MS.

Adolescent↗
PubMed2001

[The Autocad system for planimetric study of the optic disc in glaucoma: technique and reproducibility study].

PURPOSE: To develop a lens planimetry technique for the optic disc using AutoCAD. To determine variability magnitude of the optic disc morphological measurements. METHODS: We employed AutoCAD R.14.0 Autodesk: image acquisition, contour delimitation by multiple lines fitting or ellipse adjustment, image sectorialization and measurements quantification (optic disc and excavation, vertical diameters, optic disc area, excavation area, neuroretinal sector area and Beta atrophy area). Intraimage or operator and interimage o total reproducibility was studied by coefficient of variability (CV) (n=10) in normal and myopic optic discs. RESULTS: This technique allows to obtain optic disc measurement in 5 to 10 minutes time. Total or interimage variability of measurements introduced by one observer presents CV range from 1.18-4.42. Operator or intraimage measurement presents CV range from 0.30-4.21. Optic disc contour delimitation by ellipse adjustment achieved better reproducibility results than multiple lines adjustment in all measurements. CONCLUSIONS: Computer assisted AutoCAD planimetry is an interactive method to analyse the optic disc, feasible to incorporate to clinical practice. Reproducibility results are comparable to other analyzers in quantification optic disc morphology. Ellipse adjustment improves results in optic disc contours delimitation.

Glaucoma↗
PubMed2001

[Past, present, and future in Leber's hereditary optic neuropathy].

Leber's disease is a disease of optic atrophy first reported by Theodor Leber in 1871. Since then, 130 years have passed. Recently, several new findings about the pathology, causes, and heredity of this disease have been made. In 1988 Wallace and others reported a new mutation of 11778 base pairs of mtDNA of patients with Leber's disease. Since then, the study of this disease has progressed remarkably. In this review clinical studies on Leber's disease which were carried out in our department from 1990 are summarized. 1. Genetic diagnosis and clinics Two hundred and twenty-four cases were examined, including patients at our hospital, for the 8 years between 1990 and 1998. Among them, 72 cases were diagnosed as Leber's disease. There were 3 cases (4%) of 3460 mutations, 63 cases(83%) of 11778 mutations, and 6 cases(8%) of 14484 mutations as primary mutations. The reasons for performing the genetic diagnosis were mostly the need for a definite diagnosis of Leber's disease and research on the genesis of optic nerve atrophy of unknown origin. Concerning the secondary mutations, it was confirmed that these mutations were polymorphic as seen in European and American patients. There is a problem of heteroplasmy about the mtDNA mutation. We developed a simple and exact method to evaluate heteroplasmy by using polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP). In a study of peripheral blood samples in one family, Leber's disease does not appear under conditions of less than 60% mtDNA mutation. As for the three kinds of mutation in Leber's disease, cases of recovery of a visual acuity of 0.3 and above were only 7% in 11778 mutations, but 38% in 3460 mutations and 50% in 14484 mutations. It is assumed that visual prognosis depends on the kind of mutation. 2. Characteristics of visual evoked potential(VEP) In pattern VEP in the acute stage, latency was not delayed very much, but the amplitude was low. On the other hand, in the acute stage of optic neuritis, the latency was very much delayed and the amplitude was diminished. Therefore, I deduced that not only demyelination of the optic nerve fibers but also papilla-macula bundle defects may play an important role. In flash VEP, only the amplitude was low, but latency was normal. 3. Image analysis of the optic nerve In high resolution T2-weighted fast spin-echo magnetic resonance imaging(MRI), the image of the optic nerve can be clearly demonstrated within a short operation time. In MRI in the acute stage of Leber's disease, the image of the optic nerve appeared almost normal. But in the course of time, patients with Leber's disease showed markedly high signals in the optic nerve on the T2-weighted fast spin-echo MRI, and in the atrophic stage the image of the optic nerve showed thinning. The results in this study support the hypothesis that a primary lesion in Leber's disease may be intraocular. 4. Possibility of therapy at the present time The effectiveness of using idebenone combined with vitamin B2, vitamin C, and isopropyl unoprostone(Rescula) for recovery of the circulation of the optic nerve head for patients in the acute stage was compared with untreated patients. In patients with visual acuity of 0.3 and more, there was no statistical difference between the two groups. The recovery interval up to 0.3 was significantly shorter in the treated group than in the untreated group. I suggest that this kind of treatment may aid spontaneous recovery. Among 15 cases of Leber's disease which occurred in the patients teens, at least one eye in 8 cases(53%) recovered to 0.3 or more. Among the 8 recovered cases, 5 cases were from the treated group. On the other hand, 6 cases were treated and 5 cases recovered visual acuity. It is said that the patients developing the disease at younger ages have a tendency toward visual recovery. Pharmacological treatment can aid recovery. 5. Visual function after the recovery of visual acuity The recovery of visual acuity in Leber's disease has the characteristics of fenestrated central scotoma. The visual acuity can be recovered by the appearance of a small part of sensitive area inside the absolute central scotoma. This phenomenon coincides with the results of VEP which does not recover in spite of recovery of vision. Good visual acuity or bad visual acuity depends not only on the recovery of the total area of the central part but on the existence of an area with good sensitivity. In the results of a Humphrey visual field analyzer(10-2) obtained from 8 recovering patients, the part nasal to the fovea was more sensitive than the temporal area. In the early stage of visual recovery, scanning laser ophthalmoscope(SLO) microperimetry can detect this sensitive area, and with the enlargement of this sensitive area, the Humphrey visual field analyzer(10-2) can also detect this recovery area. 6. Strategy for gene therapy We have succeeded in cloning a human retina-specific amine oxidase gene which was found specifically in retinal ganglion cells. By using this promoter, we are now developing a vector specific to the ganglion cells. The fact that there is spontaneous recovery shows the possibility that some papillamacular bundle may exist. In Leber's disease, retinal ganglion cells may die from the mechanism of apoptosis. Therefore it may be possible to treat this disease by transferring the apoptosis block gene to ganglion cells for protection, and to protect the cells from death by apoptosis.

DNA, Mitochondrial↗
PubMed1999

[Computer-aided 3-D reconstruction and measurement of optic canal and intracanalicular structures].

OBJECTIVE: To reconstruct the human optic canal and its inner structures, and to provide knowledge of this region in detail for optic nerve decompression and further understanding on the pathologic mechanisms of indirect optic nerve injury. METHODS: 6 optic canals and its inner structures were reconstructed by using a computer-aided 3-dimensional (3-D) reconstruction system. Quantitative measurement for the canal wall thickness, bony canal transverse area, optic nerve transverse area, dual sheath transverse area, subarachnoid space transverse area, and subarachnoid space volume were done by means of the computer morphometric analysis system. The detailed spatial relations among intracanalicular structures were also carefully identified on the 3-D models. RESULTS: The thinnest portion of the canal was the middle part of the medial wall (0.45 +/- 0.35)mm, and the narrowest space was in the middle part of the optic canal [the transverse area was (18.21 +/- 2.50) mm(2)]. The volume of subarachnoid space which can be considered the compensatory space for distention incurred by the hemorrhage, optic nerve edema, or hematoma was (21.16 +/- 4.31) mm(3). At the cranial opening, the middle part and orbital opening, its transverse area was (4.45 +/- 1.12) mm(2), (2.68 +/- 1.32) mm(2), (1.23 +/- 0.83) mm(2), respectively. CONCLUSIONS: In the middle part, the restraining of the bony canal on injured nerve may be the most powerful. Since the compensatory space was limited, even a tiny amount of blood or swelling of the nerve may cause optic compression. Because the compensatory space for distention gradually decreases from cranial end to orbital end, the middle part and the anterior part of the optic canal and dural sheath are critical in optic nerve decompression.

Humans↗
PubMed1992

Size of glaucomatous optic discs.

In normal eyes, the optic disc size shows a high interindividual variability. In the diseased eye, some optic nerve anomalies and diseases occur preferentially in small optic discs, and some are more common in large optic nerve heads. We conducted a study to determine whether glaucoma subtypes are correlated with the optic disc size or not. Stereo optic disc photographs of 997 eyes with primary open-angle glaucoma, 44 eyes with normal-tension glaucoma, 129 eyes with pseudoexfoliative glaucoma, and 850 normal eyes were examined. Compared to eyes with primary open-angle glaucoma (mean optic disc area: 2.63 +/- 0.61 mm2), the optic disc was significantly larger in eyes with normal-tension glaucoma (2.96 +/- 0.73 mm2; P < 0.05), and it was smaller but not significantly smaller in eyes with pseudoexfoliative glaucoma (2.53 +/- 0.51 mm2). Eyes with primary open-angle glaucoma and normal eyes (2.69 +/- 0.69 mm2) did not differ significantly in optic disc size. The abnormally large optic disc in eyes with normal-tension glaucoma may be important diagnostically and pathogenetically.

Adult↗
PubMed1991

Unilateral optic nerve hypoplasia and hydrocephalus in a Pekingese.

A 3-year-old, castrated male Pekingese was examined 2 days after automobile-induced trauma. Multiple pelvic injuries and visual deficits in the right eye were identified. During a subsequent postmortem examination, multiple pelvic fractures were confirmed; however, there was no evidence of head injury. Both globes were bilaterally symmetrical and grossly normal. The intraorbital and intracranial portions of the right optic nerve were threadlike and rudimentary in appearance, while the left optic nerve was grossly normal. Moderate dilatation of the left lateral ventricle was noted. Microscopically the right optic nerve and left nerve tract contained few identifiable nerve fibers. The right optic disc was depressed, and there was thinning of the optic nerve fiber and ganglion cell layers of the retina. No microscopic abnormalities were evident in the left optic nerve, optic disc, retina and right optic tract. The histologic changes in the right eye are consistent with optic nerve hypoplasia. The relationship between the optic nerve/optic tract lesions and the hydrocephalus is unknown.

Accidents, Traffic↗
PubMed1986

Changes in optic disc in ocular hypertension and glaucoma.

Most ophthalmologists use subjective methods to evaluate the optic disc for abnormalities and changes that occur in ocular hypertension and glaucoma. We have developed new techniques that allow more accurate evaluation of the blood supply to the optic disc and of changes in disc cupping and pallor. To evaluate the blood supply we use the technique of fluorescein angiography of the optic disc. With this technique, we have found that fluorescein defects commonly appear in open-angle glaucoma and ocular hypertension and are more frequent and larger in glaucomatous and ocular hypertensive discs than in normal optic discs. Fluorescein angiography demonstrates distinct changes in the blood supply to the optic disc in the glaucomatous or ocular hypertensive eye. Cupping of the optic disc is measured by photogrammetry from stereophotographs, which provide three-dimensional measurements not only of the volume of the cup, but of the depth, the slopes of the walls of the optic cup, and the area of the surface opening. This technique also allows us to determine a volume profile of the cup: that is, its cross-sectional area from top to bottom. The volume profile characterizes the shape of the optic cup and shows distinct differences in shape between normal, ocular hypertensive and glaucomatous cups. Pallor is measured by computerized image analysis. This technique allows us to determine the percent area of pallor of the optic disc. These three techniques permit us not only to evaluate abnormalities, but to measure changes over time in the optic disc in ocular hypertension and glaucoma, thereby increasing our diagnostic capability and improving patient management.

Computers↗
PubMed1982

Development of the optic nerve in Xenopus laevis. I. Early development and organization.

Development of the Xenopus laevis optic nerve was studied by light and electron microscopy from embryonic stage 26, before the retina has formed, to juveniles, 8 months postmetamorphic. Low-power EM photographs of sections through the retinal optic nerve (RON), middle optic nerve (MON) and chiasmatic optic nerve (CON) were prepared at different stages and the areas containing large axons (0.5 micron) were traced in optic nerve reconstructions. Ordering of fibre size along a dorsoventral axis was noted in the embryonic nerve, and this pattern persisted throughout development. Most large fibres, myelinated and unmyelinated, occupy an eccentric dorsocentral position in the MON while small axons are seen in a ventral peripheral crescent. In the CON, the dorsal one third to one half is occupied by large fibres while the ventral CON contains small fibres exclusively. If, as assumed, large axons are older than small axons (0.1-0.3 micron), then patterns of large and small axons along the nerve might reveal a chronotopic fibre ordering. Chronotopic ordering was confirmed by autoradiographic analysis of the distribution of old, labelled fibres and young, unlabelled newly arriving fibres in optic nerves between stage 51 and 57. The young-old labelling pattern corresponds to the small and large axon patterns respectively, in all sections of the optic nerve. Chronotopic ordering of fibres in the developing optic nerve can be explained, in part, by the dorsoventral asymmetric marginal growth of the developing retina and the phenomenon of fibre following as ganglion cell axons join near neighbour fascicles in the retina, converge at the optic disc and grow through the optic nerve.

Animals↗
PubMed1980

Regeneration of an abnormal ipsilateral visuotectal projection in Xenopus is delayed by the presence of optic fibres from the other eye.

Optic fibre regeneration was studied by [3H]proline autoradiography and by mapping electrophysiologically the direct visuotectal projections to the contralateral and ipsilateral tecta 12-16 weeks after sectioning the right optic nerve in Xenopus two to four weeks after metamorphosis. The experiments were carried out in three groups: (A) optic nerve section in newly metamorphosed animals with embryonic left-eye enucleation; (B) optic nerve section with simultaneous left-eye enucleation; and (C) optic nerve section with delayed left-eye enucleation 5-31 days prior to sacrifice. In all but three animals regenerated optic fibres were demonstrated morphologically both in the contralateral and ipsilateral tecta. The contralateral visuotectal projection was fully restored within the 12-16 weeks in all animals. In animals with embryonic enucleation or in those where the enucleation was carried out simultaneously with optic nerve section, a direct ipsilateral visuotectal projection was established at the same time as the restoration of the contralateral projection. In contrast, no direct ipsilateral visuotectal projection was detectable in the presence of optic fibres from the other eye in the doubly innervated tecta. However, 14-31 days after the removal of the incumbent optic fibres by left-eye enucleation a direct visuotectal projection from the right eye to the ipsilateral tectum was established, and its polarity corresponded to the normal contralateral retinotectal projection. The apparent disparity between morphological and electrophysiological findings in the doubly innervated tectum suggests that superimposed optic fibres are unable to form normal synaptic relations with tectal neurons during early regeneration, delaying the establishment of the induced direct ipsilateral visuotectal projection.

Action Potentials↗
PubMed1994

[The refinement of retinotectal projection on tectal whole mount during the regeneration of the goldfish optic nerve labeled with DiI anterogradely].

The refinement of retinotectal projection during the regeneration of the goldfish optic nerve was studied with microinjection of the lipophilic dye DiI (1,1-dioctadecyl-3,-3,-3',-3',-tetramethylindo-carbocyanine perchlorate) into the dorsal retina to label a few of retinal ganglion cells, which could be transported anterogradely to their terminal arbors on the tectum. The regenerated optic nerve fibers on the tectal whole mount were examined at various time intervals (from 7 to 365 days) following an optic nerve crush. At the early regeneration stage (2 to 8 weeks postcrush), the regenerated optic fibers travelled in abnormal paths through both appropriate ventral and inappropriate dorsal hemitecta, but the majority of the fibers (about 60% to 70%) were found in the appropriate ventral hemitectum. At the late regeneration stage (2 months afterward postcrush), after refinement of regenerated optic fibers, the retinotectal projection was reestablished preciously as in the normal fish. Present study shows that the refinement of the retinotectal projection manifests in three major changes: 1) The disappearance of the regenerated optic fibers at the inappropriate tectal positions; 2) The disappearance of the side branches on the optic fiber shaft; 3) The formation of overlapping terminal arbors by the optic fibers that arrived at the retinotopic target. These results suggest that there may be two kinds of factors in the tectum: One is a common guiding factor which distributes over all the tectum and guides the regenerated optic fibers growing into the tectum at early regeneration; another is a position-specific neurotrophic factor which guides the regenerated optic fibers arriving at the retinotopic target at late regeneration.

Animals↗
PubMed1996

Relationship of the optic nerve to the posterior paranasal sinuses: a CT anatomic study.

PURPOSE: To delineate the relationship between the optic nerves and the posterior paranasal sinuses using CT data. METHODS: Direct coronal sinus CT scans of 150 consecutive patients with chronic inflammatory sinus disease were reviewed by two radiologists. Axial oblique reconstructions along the course of the optic nerve were obtained for the first 100 patients. The direct relationship between the optic nerve and the posterior ethmoid and sphenoidal sinuses was recorded, as were identations into the sinus wall, course of the nerve through the sinus region, pneumatization of the anterior clinoid process, and bone dehiscence. RESULTS: The relationship of the optic nerve to the posterior paranasal sinus fell into one of four discrete categories, type 1 through type 4. All 300 nerves were intimately related to the sphenoidal sinus. A small minority (3%) were in contact with the posterior ethmoidal sinus. Only type 4 nerves had contact with the posterior ethmoid air cell. Type 1 nerves course adjacent to the sphenoid sinus without indentation of the wall (228 nerves, 76%). Type 2 nerves course adjacent to the sphenoidal sinus, causing indentation of the sinus wall (44 nerves, 15%). Type 3 nerves course through the sphenoid sinus (19 nerves, 6%). Type 4 nerves course immediately adjacent to the sphenoidal sinus and the posterior ethmoidal air cell (9 nerves, 3%). Bone dehiscence over the optic nerve was found in 24% of the nerves; 4% of the optic nerves in our study had an associated pneumatized anterior clinoid process and 77% of these had an associated dehiscence over the optic canal. CONCLUSIONS: In all our cases the course of the optic nerve was adjacent to the sphenoidal sinus. Only 3% were in contact with the posterior ethmoidal sinus. Anatomic configurations that predispose the optic nerve to injury include type 2 or 3 optic nerves, bone dehiscence over the nerve, and pneumatization of the anterior clinoid process. These configurations are common and should be routinely sought out so that devastating complications from sinus surgery can be avoided.

Adult↗
PubMed1996

An endothelin-1 induced model of optic nerve ischemia in the rabbit.

PURPOSE: To evaluate blood flow reduction and topographic optic nerve changes after the local administration of endothelin-1 in vivo, delivered to the perineural region of the anterior optic nerve in the rabbit. METHODS: Endothelin-1 (five rabbits) in a dosage of 0.1 microgram/day or balanced salt solution (two rabbits) was delivered to the perineural region of the anterior optic nerve with osmotically driven minipumps. Optic nerve blood flow was determined by the colored microspheres technique after 14 days of local endothelin-1 or balanced salt solution administration to the microvasculature of the optic nerve. In addition, optic nerve blood flow was determined in two rabbits that had no minipump implants. The morphologic changes induced by reduction of blood flow were assessed in five additional rabbits implanted with osmotically driven minipumps containing endothelin-1 (0.1 microgram/day). These rabbits were observed for 8 weeks, and the morphologic optic nerve changes were monitored with a confocal scanning laser ophthalmoscope. RESULTS: Independent of intraocular pressure, endothelin-1 induced a decrease in blood flow of approximately 38% in the experimental eye, compared to the decrease induced by balanced salt solution or to the decrease in rabbits without minipumps (analysis of covariance, P = 0.0092). Multivariate statistical analysis showed a significant change in topometric parameters (cup area, cup depth, rim volume) obtained with a confocal scanning laser ophthalmoscope, indicating an increase in optic nerve cupping and a decrease of the perineural rim volume in the experimental eyes (P = 0.017). CONCLUSIONS: The current results suggest that morphologic optic nerve alterations can be induced experimentally in the rabbit model after ischemia produced by the local administration of endothelin-1 to the perineural region of the anterior optic nerve.

Animals↗
PubMed2006

Detection and quantification of retinal nerve fiber layer thickness in optic disc edema using stratus OCT.

OBJECTIVE: To investigate the ability of optical coherence tomography (OCT) to assess changes in retinal nerve fiber layer (RNFL) thickness in optic disc edema. METHODS: Prospective observational case series in a private eye clinic (Centro Salus). Twelve consecutive eyes (9 patients) with optic disc edema were analyzed, including 6 patients with anterior ischemic optic neuropathy, 1 patient with multiple sclerosis-associated papillitis, and 2 patients with bilateral papilledema. Peripapillary scans of the RNFL were obtained using Stratus OCT (software version 3.0; Carl Zeiss Meditec, Dublin, Calif). Repeated measurements were performed in 7 patients during a follow-up ranging from 8 to 30 weeks. The main outcome was RNFL thickness measurement. RESULTS: Optical coherence tomography detected and quantified diffuse thickening of the RNFL. Compared with eyes in a control group of 75 healthy subjects, eyes with optic disc edema showed a significant increase in the mean RNFL thickness in all quadrants (temporal, P = .002; superior, P<.001; nasal, P<.001; and inferior, P<.001). In patients who were followed up, progressive thinning was observed as the disease evolved toward optic atrophy or clinical resolution. CONCLUSIONS: Optical coherence tomography can identify and measure RNFL edema. This ability of OCT may help elucidate pathophysiological mechanisms in optic disc edema and provide a valuable aid to clinicians.

Adult↗
PubMed1985

The morphology of growth cones of regenerating optic nerve axons.

The morphology of growth cones of regenerating optic nerve axons was examined by light and electron microscopy in adult frogs (Rana pipiens), using a horseradish peroxidase (HRP) fiber-filling method, during early and later phases of regeneration. Optic nerve regeneration was initiated unilaterally by crushing the optic nerve in mid-orbit. Fiber filling was accomplished by severing the affected nerve closer to the eye 24-48 hrs. prior to sacrifice and applying HRP to the central stump. Regenerating axons and their growth cones were observed in the optic nerves, chiasma, tract, pretectal neuropil, and optic tectum. Growth cones of normal-appearing axons varied in shape and size. Flattened, foliate growth cones similar to those commonly described in vitro were observed in the pretectal neuropil and optic tectum. Other growth cones having vermiform, lanceolate, spatulate, and bulbous forms were observed throughout the optic pathway at all stages examined, although the longer (up to 70 micrograms) wormlike structures appeared only in the optic tract during the early period of outgrowth. Nearly complete serial-section reconstructions were obtained for two growth cones in the contralateral optic tectum at 8 wks. regeneration time. One was thinly flattened (to 30-50 nm in places) and extended broadly (8 micrograms in diameter) in contact with a neuronal perikaryon. The other formed a hood over the blind end of a severed, nonregenerating myelinated axon, which was normal-appearing except at its end within the confines of the growth cone. Morphological variation among the growth cones is discussed in relation to other descriptive in vivo studies and views concerning growth cone motility.

Animals↗
PubMed1999

Features of amiodarone-induced optic neuropathy.

PURPOSE: To report clinical features of amiodarone-induced optic neuropathy and outline the differentiation of amiodarone optic neuropathy from nonarteritic anterior ischemic optic neuropathy. METHOD: We reviewed data from 73 patients reported to have developed an optic neuropathy while taking amiodarone. RESULTS: Amiodarone optic neuropathy is characterized by an insidious onset, slow progression, bilateral visual loss, and protracted disk swelling that tends to stabilize within several months of discontinuing the medication. Nonarteritic ischemic optic neuropathy is characterized by acute, unilateral visual loss that is usually complete at onset, with resolution of disk edema over several weeks. CONCLUSION: Unique clinical features of amiodarone-induced optic neuropathy may help clinicians diagnose and distinguish between amiodarone-induced optic neuropathy and nonarteritic anterior ischemic optic neuropathy.

Amiodarone↗
PubMed2004

Congenital disorders of the optic nerve: excavations and hypoplasia.

The principal congenital abnormalities of the optic disc that can significantly impair visual function are excavation of the optic disc and optic nerve hypoplasia. The excavated optic disc abnormalities comprise optic disc coloboma, morning glory syndrome, and peripapillary staphyloma. Optic nerve hypoplasia manifests as a small optic nerve, which may or may not be accompanied by a peripapillary ring (the double ring sign). In addition, the optic disc cupping, which occurs as a sequel to some cases of periventricular leucomalacia, can arguably be classified as a type of optic nerve hypoplasia. All of these conditions can be unilateral or bilateral and can impair visual function mildly or severely. It is essential that children with poor vision due to any of these conditions are managed by treating refractive errors, giving occlusion therapy in selected cases, and optimising the conditions at home and at school in an attempt to ensure that impaired vision does not impede development or education.

Child, Preschool↗
PubMed2004

Hereditary optic neuropathies.

AIMS: To provide a clinical update on the hereditary optic neuropathies. METHODS: Review of the literature. RESULTS: The hereditary optic neuropathies comprise a group of disorders in which the cause of optic nerve dysfunction appears to be hereditable, based on familial expression or genetic analysis. In some hereditary optic neuropathies, optic nerve dysfunction is typically the only manifestation of the disease. In others, various neurologic and systemic abnormalities are regularly observed. CONCLUSION: The most common hereditary optic neuropathies are autosomal dominant optic atrophy (Kjer's disease) and maternally inherited Leber's hereditary optic neuropathy. We review the clinical phenotypes of these and other inherited disorders with optic nerve involvement.

Dysautonomia, Familial↗
PubMed1999

Computer-aided three-dimensional reconstruction and measurement of the optic canal and intracanalicular structures.

OBJECTIVE: To reconstruct the human optic canal and its inner structures and to provide detailed knowledge of this region for optic nerve decompression. METHODS: Six optic canals and their inner structures were reconstructed using a computer-aided three-dimensional reconstruction system. Quantitative measurement of the canal wall thickness, bony canal transverse area, optic nerve transverse area, dural sheath transverse area, subarachnoid space transverse area, and subarachnoid space volume was done using the computer morphometric analysis system. The detailed spatial relationship among intracanalicular structures was also carefully identified on the three-dimensional models. RESULTS: The thinnest portion of the canal was the middle part of the medial wall (0.45 +/- 0.14 mm) and the narrowest space was in the middle part of the optic canal (the transverse area was 18.21 +/- 1.20 mm2). The volume of subarachnoid space that can be considered the compensatory space for distention incurred by the hemorrhage, optic nerve edema, or hematoma was 21.16 +/- 4.31 mm3. At the cranial opening, the middle part, and the orbital opening, its transverse area was 4.45 +/- 0.46 mm2, 2.68 +/- 0.54 mm2, and 1.23 +/- 0.34 mm2 respectively. CONCLUSIONS: Because the compensatory space was limited, even a tiny amount of blood or swelling of the nerve may cause optic nerve compression. Because the compensatory space for distention gradually decreases from cranial end to orbital end, the middle part and the anterior part of the optic canal and dural sheath are critical in optic nerve decompression.

Adult↗