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We performed optic nerve sheath decompression on four patients (five eyes) with visual loss secondary to nonarteritic anterior ischemic optic neuropathy. Four of the five eyes had marked improvement in visual function after the operation. Optic nerve sheath decompression is an effective treatment for patients with nonarteritic ischemic optic neuropathy and progressive visual loss.
To provide magnetic resonance imaging (MRI)-ultrastructural correlations of demyelinating lesions of the intraorbital optic nerve, the authors performed gadolinium-enhanced/T2-weighted fat-suppressed MRI and transmission electron microscopy of the optic nerves of animals with experimental allergic encephalomyelitis. Gadolinium enhancement of the optic nerve adjacent to the globe was seen on fat-suppressed T1-weighted MRI as early as 3 days after antigenic sensitization, increased in severity involving longer segments of nerve at 10 to 14 days, and persisted at 30 days. Gadolinium enhancement preceded T2-weighted signal aberrations. Ultrastructural evaluation of the intraorbital nerve revealed: (1) expansion of the extracellular space and inflammatory infiltrate that correlated with the intensity of gadolinium enhancement; (2) the degree of demyelination correlated with T2-weighted signal aberrations; (3) as deduced from gadolinium enhancement and T2 signal aberrations, breakdown of the blood-brain barrier preceded widespread demyelination; (4) lesions appeared to start at the optic nerve insertion into the globe and then progress toward the orbital apex.
In this study we present a method to achieve a complete transection of optic nerve axons in adult rat, while preserving the vasculature and retaining the continuity of the meninges. Under deep anesthesia, the optic nerve of adult rat is exposed. Using specially designed instruments built from disposable glass microsampling pipettes, a small opening is created in the meninges of the optic nerve, 2-3 mm behind the eye globe. A glass dissector is introduced through the opening and is used to cut all the axons through the whole width of the nerve. Complete transection of the optic nerve axons was achieved, while retaining the continuity of the meninges and avoiding damage to the nerve's vascular supply. Transection was confirmed by transillumination showing a complete gap in the continuity of the nerve axons, and by both morphological and electrophysiological criteria. Nerve transection performed by the conventional technique leads to neuroma formation and hampers regeneration. Crush injury may cause nerve ischemia, which is detrimental to axonal recovery. Both of these disadvantages are avoided by the method of transection presented here. The opening created in the 'meningeal tube' can be used to inject substances that may be of benefit in recovery, rescue and/or regeneration of the injured axons. The model is particularly suitable for in vivo studies on nerve regeneration, and especially for screening of putative therapeutic agents.
Recent studies of the visual system of animal species that live in a subterranean environment show not only regressive but also progressive morphological features. In this regard the aim of the present investigation is to describe the structural organisation of the eye and optic nerve of the adult Cape mole-rat, with special emphasis on both glial cell population and myelination. The main results are: (a) astrocytes show identical features to those occurring in reactive gliosis; (b) optic fibers vary greatly in diameter; (c) very small axons are myelinated and are often surrounded by a thicker sheath than larger optic fibers; (d) a large onion bulb-like structure composed of optic fibers, glia, and ganglion cells is found within the choriocapillary layer. These results suggest that the Cape mole-rat and probably other subterranean rodents may serve as a model to study spontaneous gliosis as well as mechanisms involved in myelination and degenerative processes.
A continuous chemically sensitive optical fiber is used with optical time-of-flight chemical detection (OTOF-CD) for spatially resolved analyte mapping. To enhance signal levels and to improve their reproducibility, two novel principles for signal generation and processing are introduced. In the first, the fluorescene of an analyte-insensitive fluorophore is monitored as a function of the evanescent wave absorption of an analyte-sensitive indicator. The resulting signal levels are well above those encountered in optical time domain reflectometry methods that rely upon backscattering for spatially resolved detection. As a result, the method could significantly expand the range of species that can be detected with absorption reagents used in OTOF sensors. The second method raises signal-to-noise ratios by 3-4.5-fold for measurements made at the far ends of the sensing fiber. It functions by sending probe laser pulses into and monitoring their return sequentially from both ends of the sensing fiber. Because the two pulses provide complementary information, only the first half of each of the collected waveforms is used for analyte quantitation. The introduced concepts were experimentally verified with a distributed sensor constructed from a 40-m-long continuous chemically sensitive optical fiber. This sensing element was produced by immobilization of an ammonia-sensitive absorbing reagent (phenol red) and an analyte-insensitive fluorophore (rhodamine 640) into the original silicone cladding of the plastic-clad silica fiber.
The aim of this study is to report the clinical outcome of a diabetic patient with optic nerve head neovascularization treated with an intravitreal injection of triamcinolone acetonide. A 52-year-old patient presented with clinically significant diffuse macular edema and optic nerve head neovascularization due to proliferative diabetic retinopathy in her right eye. Despite grid laser photocoagulation in the macular region macular edema progressed and visual acuity declined. The patient received a single intravitreal injection of 4 mg triamcinolone acetonide with topical anesthesia. After injection of triamcinolone acetonide visual acuity increased and macular edema decreased. Furthermore optic nerve head neovascularization had markedly regressed. No complication was observed during follow-up period. Intravitreal injection of triamcinolone acetonide may be useful for treatment of optic nerve head neovascularization in patients with proliferative diabetic retinopathy.
The morphology of the circle of Haller and Zinn and its variations were examined using methyl-methacrylate microvascular corrosion casting of human orbits obtained at post-mortem. It was found to be an elliptical microvascular anastomosis formed by branches of the medial and lateral para-optic short posterior ciliary arteries. The ellipse was divided into superior and inferior parts by the entry points of these branches into the eye, providing an altitudinal blood supply to the retrolaminar optic nerve. Morphological variations in terms of form, position and branches existed between subjects and between eyes from the same subject. The clinical implications of an elliptical 'circle' of Haller and Zinn providing an altitudinal blood supply to the retrolaminar optic nerve are relevant to the pathogenesis of altitudinal visual field defects in anterior ischaemic optic neuropathy.
BACKGROUND: Optic neuropathy has been reported to occur during antiarrhythmic therapy with amiodarone. Whether or not there is a causal relationship has been discussed controversely. PATIENTS: Three patients presented with a visual impairment three to seven months after starting amiodarone therapy. In all three patients both optic discs were swollen and showed hemorrhages on the margin. After discontinuing amiodarone, the vision improved and the swelling of the optic discs resolved. CONCLUSION: The bilateral occurrence at the same time, the close time correlation with the amiodarone application and the improvement after discontinuing amiodarone suggest that our three patients suffered from a toxic effect of amiodarone rather than an incidental other disease, as for instance ischemic optic neuropathy.
PURPOSE: To evaluate whether keratometric readings as a measure of corneal shape are associated with optic disc dimensions and with the degree and rate of perimetric progression of chronic open-angle glaucoma or ocular hypertension. METHODS: The hospital-based observational study included 1826 eyes of 936 patients with ocular hypertension, patients with chronic open-angle glaucoma, or normal individuals. For 733 ocular hypertensive or glaucomatous eyes, follow-up examinations were performed with a mean follow-up time of 58.0+/-34.7 months. Observation procedures were keratometry, morphometric optic disc analysis, tonometry, and perimetry. RESULTS: In the normal study group, area of the neuroretinal rim, alpha zone and beta zone of parapapillary atrophy, and retinal vessel diameter were not significantly associated with keratometric readings. In the entire study population, the optic disc area was significantly (P<0.001; r=-0.27) correlated with low keratometric readings as expressed in diopters. Keratometric readings were significantly (P<0.001 adjusted for age, intraocular pressure, baseline damage, and corneal asphericity) smaller in the normal-pressure glaucoma group than in the normal study group and in the groups with ocular hypertension or primary and secondary open-angle glaucoma. Rate of perimetric progression was not significantly associated with low keratometric readings, either in simple or in multiple Cox regression analysis, controlling for baseline damage, ocular hypertension, age, corneal asphericity, and intraocular pressure. CONCLUSIONS: Large optic disc area is statistically significantly, but clinically weakly, correlated with low keratometric readings (diopters). In Caucasian individuals with ocular hypertension and patients with chronic open-angle glaucoma, the rate of development or progression of glaucomatous visual field defects is not significantly associated with keratometric readings.
Chronic total occlusions are difficult to treat and continue to challenge the interventional cardiologist. The primary difficulty is safely crossing the total occlusion with a guidewire before any revascularization can begin. One of the main reasons conventional and newer guidewires have not proven effective is simply the lack of visualization to safely steer the guidewire across the occlusion. This limitation can be overcome with new technology using a "forward-looking" fiber-optic guidance. The Safe-Steer TO (Total Occlusion) Crossing System is a new guidance system that uses optical coherence reflectometry to steer a guidewire through total occlusions. Optical coherence reflectometry uses algorithms to determine tissue types (plaque vs arterial wall) by measuring the intensity of the reflection of near-infrared light. The authors' clinical experience with the Safe-Steer System has met considerable success. With their initial 28 patients (7 women, 21 men) with known chronic total occlusions and confirmed ischemia, the primary success rate for the crossing the occlusion was 86% (24/28 cases). The average occluded lesion length was 41.1 +/- 30.8 mm. Our initial clinical experience demonstrates that the optical guidewire is a viable technology in the treatment of chronic total occlusions.
Ten patients (14 eyes) with chronic simple glaucoma are described, each with features atypical for this disease and more suggestive that each had suffered an acute ischaemic optic neuropathy. Diagnosis of an acute ischaemic optic neuropathy in these cases is important, as treatment of ocular hypertension in the contralateral 'normal' eye may prevent a similar attack. Optic nerve disease and visual loss in chronic simple glaucoma probably occur as a result of several different mechanisms. Sudden field loss following an acute ischaemic optic neuropathy may be only one of them.
AIMS: The efficacy of an artificial intelligence technique, neural network analysis, was examined in differentiating two optic neuropathies with overlapping clinical profiles-idiopathic optic neuritis (ON) and non-arteritic anterior ischaemic optic neuropathy (AION). METHODS: A neural network was trained with data from 116 patients with 'gold standard' diagnoses of ON or AION. It was then tested with data from 128 patients with presumed ON or AION, and the correlation of the network's diagnosis with that of expert clinicians tabulated. RESULTS: The network agreed with the clinicians on 97.8% (88 of 90) of the patients with presumed ON and 94.7% (36 of 38) of the patients with presumed AION. Youth, female sex, better initial acuity, a central scotoma, subsequent improvement in acuity, or progressive disease biased the network towards a diagnosis of ON, while advanced age, male sex, presence of hypertension, poor initial acuity, an altitudinal field defect, disc oedema, or less improvement in acuity biased the network towards a diagnosis of AION. CONCLUSION: Neural network analysis is a useful technique for classification of optic neuropathies, particularly where there is overlap of clinical findings.
BACKGROUND/AIMS: Patients with autosomal dominant optic atrophy (ADOA) are genetically heterogeneous, but all have disc pallor. A degree of cupping in ADOA can make the distinction from normal tension glaucoma (NTG) clinically difficult. This study aimed to clarify the features of the optic nerve of patients with ADOA at the OPA1 locus. METHODS: 29 patients (58 eyes), from 12 families, were identified in a prospective observational study of patients with ADOA examined by a single observer between 1995 and 1998, in whom genetic analysis showed either evidence for linkage to chromosome 3q28 or mutations in the ADOA gene, OPA1. All of the patients had disc and fundal photographs available for retrospective analysis. Clinical data collected included disc appearance, intraocular pressure, Snellen visual acuity, Hardy-Rand-Rittler colour vision plates, and Humphrey 30-2 visual fields. RESULTS: Mean age at time of examination was 37 years and mean visual acuity was 6/24. Disc morphology showed temporal disc pallor in 30 eyes (52%) and total disc pallor in 28 eyes (48%). At least one disc showed a cup to disc ratio of more than 0.5 in 18 patients (28 discs, 48%). The temporal neuroretinal rim always showed pallor and shallow shelving (or saucerisation) was seen in 46 eyes (79%). Only 12 discs (21%) had deep excavation and baring of blood vessels. All of the patients had normal intraocular pressure and no family history of glaucoma. There was a temporal grey, pigmentary crescent in 12 patients (18 eyes, 31%) and peripapillary atrophy in 20 patients (40 eyes, 69%), but disc margin haemorrhages were not seen. There was no maculopathy or retinopathy. CONCLUSION: The optic disc morphology, described for the first time in this genetically homogeneous population of patients with OPA1 ADOA, shows a distinctive absence of a healthy neuroretinal rim and shallow saucerisation of the optic disc cup, with frequent peripapillary atrophy.
We hemisected either the posterior or anterior portion of the optic chiasm and found that frogs were unresponsive to large looming stimuli anywhere in the visual field. Nonetheless, the animals responded to prey stimuli throughout the visual field. Responses to looming stimuli returned in 1 to 8 weeks post-surgery. After complete transection of the chiasm animals were unresponsive to both prey and large looming stimuli. Frogs responded normally to prey and looming stimuli if less than half the optic chiasm was cut or if the postoptic commissure was cut. Since responses to looming stimuli returned before cut optic fibers could regenerate, these results suggest that visual information concerning prey and large looming objects are mediated by separate optic nerve fiber systems.
PURPOSE: To describe and evaluate a semiquantitative optic nerve grading scheme for assessing axonal loss in endothelin (ET)-1-induced chronic optic neuropathy. METHODS: Optic nerve cross-sections from both eyes of 39 Brown Norway rats unilaterally treated with various concentrations of ET-1 or physiological saline solution via a surgically implanted osmotic minipump were processed for light and transmission electron microscopy (TEM). The optic nerve damage grade, between 0 (no damage) and 10 (total damage), was based on the number of zones of approximately equal damage and the mean percentage of damage within each zone. Grading was performed under light microscopy by three observers and compared with axonal survival determined with TEM using two quantification methods: the sampling method, in which approximately 10% of the section was counted, and the full-count method, in which the whole section was counted (n = 12). Axonal survival was expressed as a ratio of axon counts in the experimental to control eye. Before these comparisons, the inter- and intraobserver agreement rates were determined in another group of 85 and 12 ET-1-treated animals, respectively. RESULTS: The interobserver kappa was 0.66 (95% confidence interval [CI]: 0.58-0.74) for all eyes and 0.55 (95% CI: 0.43-0.67) for the experimental eyes only. The intraobserver kappa was 0.80, 0.81, and 0.80 for all 24 eyes and 0.60, 0.64, and 0.71 for experimental eyes only. The correlation between damage grade in the experimental eye and axonal survival using the TEM sampling method (Spearman's rho = -0.677 for all animals and -0.827 for the subset of animals with full counts only) was lower than that with the full-count method (Spearman's rho = -0.926). When axonal survival was less than 0.7, the sampling method always underestimated the extent of damage. CONCLUSIONS: The grading scheme had good inter- and intraobserver agreement, and high correlation with the TEM methods. It is a practical and time-saving method, requiring less than 1 minute per nerve and is an alternative to sampling methods that can yield significant errors.
PURPOSE: To describe the course of a case of macular elevation and a full-thickness macular hole associated with optic nerve pit. METHODS: Case report. A 28-year-old woman who had laser-assisted in situ keratomileusis surgery 2.5 years ago presented with decreased vision, full-thickness macular hole, and macular detachment in association with optic nerve pit. Complete ophthalmic examination was done and optical coherence tomography (OCT) was performed before and after vitreoretinal surgery. RESULTS: OCT showed that the macular elevation consisted of both separation of the inner and outer retinal layers with neurosensory retinal detachment. There was a full-thickness macular hole. After vitreous surgery and intraocular gas tamponade, the macular elevation completely resolved, and OCT showed the flattening of the outer and inner retinal layers but the macular hole was not closed. CONCLUSIONS: OCT is a reliable technique to study macular elevation with a hole associated with optic nerve pit before and after vitrectomy and gas tamponade.
PURPOSE: To report an insulin-dependent diabetic patient who was referred by the diabetic screening clinic as having proliferative diabetic retinopathy who was found to have bilateral optic disc drusen with optociliary shunt resembling neovascularization on the disc. METHODS: Complete ocular evaluation including a fluorescein angiography was performed. RESULTS: Fundus examination showed signs of mild nonproliferative diabetic retinopathy in the right eye and the presence of well-defined optic disc drusen in both eyes with a peculiar vascular abnormality resembling neovascularization on the right disc. The central retinal vein pulsation was normal on digital examination. Autofluorescence confirmed the presence of the optic disc drusen in both eyes. Fluorescein angiography showed no leakage from the optociliary shunt. The vascular abnormality has remained stable for 2 years. CONCLUSIONS: This case highlights the correlation of optic disc drusen and optociliary shunts which in diabetic patients can be misdiagnosed as neovascularization.
Previous case reports demonstrated the presence of Leber's hereditary optic neuropathy (LHON) associated mitochondrial (mt) DNA mutations in patients presenting with prominent optic neuritis (PON). By screening the mtDNA, we have excluded the presence of these mutations in 22 patients with PON, indicating that the frequency of these mutations is less than 4.5% in our selected patient population. Reviewing the clinical data of these patients revealed that severe optic nerve atrophy developed in association with both the benign and the severely disabling form of Multiple Sclerosis (MS). This observation suggests that the prominent feature of ON in MS may be related to local factors or to a selective vulnerability of the optic nerve in some patients. However, it also may be consequence of a deleterious process associated with inflammatory demyelination in the central nervous system (CNS) of another, genetically probably distinct subgroup of severely disabled patients.