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PubMed1989

[Computerized digital image analysis of optic nerve heads with a three-dimensional image analyzer, IMAGEnet and a comparison with the Optic Nerve Head Analyzer].

Computerized digital image analysis of the optic nerve heads of 17 eyes with various sizes of optic disc cupping was performed using two kinds of three dimensional image analyzers, the IMAGEnet and the Optic Nerve Head Analyzer (ONHA). Intraphotographic error variances of measurements with both instruments were evaluated by measuring each image of the optic discs twice. The mean coefficient of variation (CV) with the IMAGEnet for the vertical cup/disc ratio, the horizontal cup/disc ratio, the cup volume, the rim area, and the rim area/disc area ratio were 3.75%, 3.03%, 7.89%, 2.55% and 1.36%, respectively. With the ONHA, the mean CV for the total cup/disc ratio, the cup volume, the rim area, and the rim area/disc area ratio were 0.82%, 0.21%, 2.39%, and 1.56%, respectively. The value of the cup/disc ratio and the cup volume obtained by the IMAGEnet was smaller than those by the ONHA (p greater than 0.1). Conversely, the rim area and rim area/disc area ratio measured by the IMAGEnet were statistically significantly larger than those by the ONHA (p = 0.01). Statistically significantly positive correlation was demonstrated for measurements made by both instruments in all disc parameters (p less than 0.01). These results seem to indicate the high reliability of the two instruments, however, further investigation is needed for the evaluation of the accuracy of measurements.

Glaucoma↗
PubMed1979

Interactions between optic fibres controlling the locations of their terminals in the goldfish optic tectum.

Removal of the caudal half of a goldfish optic tectum induces optic fibres from the entire contralateral retina to terminate retinotopically within the remaining half. This compression has been viewed by some as the result of competition between the fibres and by others as a consequence of changes, induced by the surgery, in tectal labels guiding fibres to terminal sites. To distinguish between these possibilities, the time-course of compression has been measured by electrophysiological mapping of the visual projection. In some fish, fibres terminating in the rostral half-tectum remained intact when the caudal half was removed. In others, the optic nerve was cut at the time of tectal surgery: even after its regeneration into a half-tectum, optic terminals were first detected in the regions they normally occupy. The subsequent reorganization was gradual and retinotopic order was maintained. However, it was slower where some fibres had never been cut. In a third series the nerve was cut 18 days before the tectal halving to reveal any dependence of compression on progressive changes in the halved tectum; but its time-course from nerve section was found to be independent of the time within the regeneration period at which the tectum was halved. In a fourth series the nerve was cut at the time of tectal halving and then cut again after 85--97 days when compression was complete to reveal any permanent change in the halved tectum. No change was evident: the previous compression did not preclude subsequent regeneration of an uncompressed projection and its gradual recompression as before. In a fifth series, repeated crushing of fibres normally ending in the missing caudal tectum temporarily prevented compression among the remainder, while crushing of fibres destined for rostral tectum caused transposition of the remaining projection to the rostral half. Surgically induced changes in the labels which are thought to guide growing fibres to their normal tectal regions do not account for these results. Indeed, this guidance persists unchanged for fibres regenerating a second time after compression. Since compression is delayed while certain fibres are withheld, it appears instead to be the direct result of competition between the fibres. The maintenance of retinotopic order in compression, despite unchanged tectal guidance, may require selective interactions between fibres from different retinal regions which could contribute to the refinement of the normal visual projection.

Animals↗
PubMed1989

Optic nerve decompression may improve the progressive form of nonarteritic ischemic optic neuropathy.

Optic nerve sheath decompression surgery improved visual function for 12 of 14 patients with progressive nonarteritic ischemic optic neuropathy (NAION). Visual recovery was maintained in all patients during a follow-up period of 6 to 18 months (average, 11 months). Seven patients had experienced a previous NAION in the eye that was not operated on that did not improve spontaneously. Surprisingly, 2 of these 7 eyes with long-standing decreased vision demonstrated some visual improvement after surgery on the contralateral, acutely affected eye. Spontaneous visual improvement did not occur in an age- and sex-matched control group of 12 patients with similar entry-level visual acuity and field loss. Only 1 of 3 patients with sudden, nonprogressive visual loss secondary to NAION improved after surgery. In a control group with nonprogressive NAION, 2 of 15 eyes (14 patients) demonstrated spontaneous improvement. Optic nerve sheath decompression improves visual loss due to progressive NAION, a disorder without any previously effective therapy. However, for acute, nonprogressive NAION, surgery for a small number of patients did not improve the natural history of the disease.

Adult↗
PubMed1998

Visual field defects in optic neuritis and anterior ischemic optic neuropathy: distinctive features.

BACKGROUND: We analyzed the value of visual-field defects in the differential diagnosis of optic neuritis (ON) and non-arteritic anterior ischemic optic neuropathy (AION). METHODS: Ninety-nine consecutive patients with acute-onset optic neuropathy formed the basis for this study. Compressive and vasculitic neuropathies were excluded. Eighty-six patients fulfilled the criteria for either ON (50 patients): < or = 35 years, normal disk, recovery of visual function, or AION (36 patients): > or = 60 years, swelling of the disk, no recovery of visual function. Without knowledge of other clinical data, visual fields obtained by Gold-mann perimetry were classified into five types of defects (forced choice). With the correct diagnosis at hand, fields were reviewed for characteristic features. RESULTS: Forced-choice classification into defect types [%]: Central scotoma ON 68, AION 18; superior altitudinal defect ON 13 AION 7; inferior altitudinal defect ON 8, AION 52; peripheral defect ON 1, AION 5; diffuse defect ON 10, AION 18. Search for pathognomonic defects: a scotoma centered on the fixation point with a sloping border occurred exclusively in ON (25 of 50 patients). An inferior altitudinal defect with a sharp border along the horizontal meridian, particularly in the nasal periphery, occurred only in AION (10 of 36 patients). A steep centrocecal scotoma occurred in 3 of the 36 AION cases and not at all in the ON cases. Scotomas in the center breaking through to the periphery, superior altitudinal defects (with a sloping border along the horizontal meridian) and diffuse depressions verging on blindness occurred in both ON and AION. CONCLUSION: A sctoma centered on the fixation point with a sloping border is highly characteristic of ON, while an inferior altitudinal defect with a sharp border along the horizontal meridian, particularly in the nasal periphery, is highly characteristic of AION. To identify these diagnostic criteria, it can be necessary to examine full fields. With restriction of perimetry to 30 degrees a large central scotoma can be mistaken for a diffuse defect and the border in the nasal periphery can be missed.

Acute Disease↗
PubMed2005

Measurement of the scleral canal using optical coherence tomography in patients with optic nerve drusen.

PURPOSE: The etiology of optic nerve drusen (OND) is unknown. A leading hypothesis is that eyes with OND have a small scleral canal. The small scleral canal presumably leads to optic nerve fiber compression, ganglion cell degeneration, extrusion of axonal mitochondria, and calcification of the extruded mitochondria. To determine if subjects with OND have scleral canals that are smaller than subjects without OND, we used optical coherence tomography (OCT) to measure the scleral canal in subjects with and without OND. DESIGN: Prospective, observational case control study. METHODS: The study was conducted with subjects recruited from the clinics of the John A. Moran Eye Center, University of Utah Department of Ophthalmology and Visual Sciences. The study population included 25 subjects with OND, 13 unaffected first-degree relatives of OND subjects, and 17 control subjects. All subjects underwent measurement of the scleral canal with OCT. The main outcome measure was the scleral canal area calculated by OCT. RESULTS: The average areas of the scleral canals were as follows: control eyes: 1.832 mm(2), unaffected eyes of subjects with unilateral OND: 1.836 mm(2), eyes of unaffected first-degree relatives: 2.067 mm(2), and eyes with OND: 2.520 mm(2). The scleral canal area of unaffected eyes of subjects with unilateral drusen was not significantly different from the control. The eyes of first-degree relatives and eyes with OND both had scleral canal areas significantly larger than the control. CONCLUSIONS: Scleral canal size is probably not an etiologic factor in the pathogenesis of OND.

Adolescent↗
PubMed2003

Optical bio-sniffer for ethanol vapor using an oxygen-sensitive optical fiber.

An optical bio-sniffer for ethanol was constructed by immobilizing alcohol oxidase (AOD) onto a tip of a fiber optic oxygen sensor with a tube-ring, using an oxygen sensitive ruthenium organic complex (excitation, 470 nm; fluorescent, 600 nm). A reaction unit for circulating buffer solution was applied to the tip of the device. After the experiment in the liquid phase, the sniffer-device was applied for gas analysis using a gas flow measurement system with a gas generator. The optical device was applied to detect the oxygen consumption induced by AOD enzymatic reaction with alcohol application. The sensor in the liquid phase was used to measure ethanol solution from 0.50 to 9.09 mmol/l. Then, the bio-sniffer was calibrated against ethanol vapor from 0.71 to 51.49 ppm with good gas-selectivity based on the AOD substrate specificity. The bio-sniffer with the reaction unit was also used to monitor the concentration change of gaseous ethanol by rinsing and cleaning the fiber tip and the enzyme membrane with buffer solution.

Alcohol Oxidoreductases↗
PubMed2000

Optic nerve sheath fenestration for a reversible optic neuropathy in radiation oncology.

To the authors' knowledge, there is a paucity of published accounts of management of radiation-induced optic neuropathy (RION) by optic nerve sheath fenestration (ONSF) in the conventional medical literature. With higher doses of radiation being given by using conformal techniques, more radiation-induced optic neuritis and neuropathy will be identified. We report here the successful use of ONSF to restore vision to three consecutive patients with pending anterior RION, and the importance of early identification and intervention in these potentially reversible cases.

Adult↗
PubMed2007

Usefulness of optical coherence tomography parameters of the optic disc and the retinal nerve fiber layer to differentiate glaucomatous, ocular hypertensive, and normal eyes.

PURPOSE: To assess Stratus optical coherence tomography (OCT) original parameters for identifying glaucomatous damage and to evaluate differences among glaucomatous, ocular hypertensive, and normal eyes. DESIGN: Cross-sectional prospective study. SUBJECTS AND METHODS: The study was conducted at 2 centers. The study population consisted of 55 normal individuals, 95 patients with ocular hypertension (OHT), and 79 patients with glaucoma. Retinal nerve fiber layer (RNFL) and optic nerve head OCT protocols were used to evaluate all study participants. Measurements taken were RNFL thickness, several ratios, RNFL asymmetry between both eyes, rim volume, rim width, disc area, cup area, rim area, cup/disc (C/D) area ratio, and horizontal and vertical C/D ratios. The main outcome measures were the differences in OCT parameters among groups and the areas under the receiver operating characteristic curves (AROC). RESULTS: Mean RNFL thickness around the disc, and superior and inferior RNFL thickness, were significantly thinner in glaucomatous eyes than in OHT or normal eyes (P<0.001). Rim parameters were significantly smaller in glaucomatous eyes than in normal (P<0.001) and OHT eyes (P=0.01). C/D ratios were significantly greater in glaucomatous eyes than in OHT (P<0.001) and normal (P<0.001) eyes. Significant differences were found between normal and OHT eyes in 7 disc parameters. No difference was found among groups in parameters describing RNFL asymmetry between both eyes. The AROC curves of the other RNFL and disk parameters ranged from 0.741 to 0.85. CONCLUSIONS: Almost all RNFL and disc parameters showed significant differences and discriminated between glaucomatous and normal eyes. There were significant differences in some optic nerve parameters, but no RNFL parameters, between normal and OHT eyes.

Aged↗
PubMed2005

Fiber-optic-bundle-based optical coherence tomography.

A fiber-optic-bundle-based optical coherence tomography (OCT) probe method is presented. The experimental results demonstrate this multimode optical fiber-bundle-based OCT system can achieve a lateral resolution of 12 microm and an axial resolution of 10 microm with a superluminescent diode source. This novel OCT imaging approach eliminates any moving parts in the probe and has a primary advantage for use in extremely compact and safe OCT endoscopes for imaging internal organs and great potential to be combined with confocal endoscopic microscopy.

Animals↗
PubMed1990

Corticosteroid therapy in optic neuritis (optic neuropathy).

Corticosteroid treatment of acute idiopathic optic neuritis is still highly controversial. Controlled studies have indicated that visual acuity has been restored more rapidly after corticoid treatment. Long-term results however do not differ with the untreated control group. Corticoids are essential in the treatment of ischemic optic neuropathy, especially when occurring with auto-immune diseases or giant cell arteritis. Some authors believe that corticoids can be helpful during the acute phase of an idiopathic anterior ischemic optic neuropathy.

Adrenal Cortex Hormones↗
PubMed2005

Optically active oligomer units in aggregates of a highly unsaturated, optically inactive carotenoid phospholipid.

Enantiomers of glycerophospholipids show low or no optical activity. Accordingly, optical activity was not observed with the R enantiomer of a highly unsaturated carotenoyl lysophospholipid in solution. In spite of this, strong Cotton effects are detected in water. The amphiphilic carotenoid-phospholipid monomers associate to form aggregates, whose optical activity is attributed to oligomeric entities. These small helical assemblies cannot exist independently. Yet, the calculated octamer represents the simplest repeating primary unit that sufficiently expresses the absorption properties and supramolecular optical activity.

Choline↗
PubMed1993

OKN-related neurons in the rat nucleus of the optic tract and dorsal terminal nucleus of the accessory optic system receive a direct cortical input.

It has been previously assumed that the asymmetry of the monocular optokinetic nystagmus (OKN) of lateral-eyed mammals is caused by an absence of visual cortex projections to directional selective neurons in the pretectal nucleus of the optic tract and dorsal terminal nucleus of the accessory optic system (NOT-DTN). In contrast to this generally accepted hypothesis, we present multiple evidence that OKN-related neurons in the rat NOT-DTN in fact do receive input from the visual cortex. We studied the corticofugal projection to NOT-DTN physiologically, with extracellular single unit recording and electrical stimulation of the optic chiasma and the visual cortex, and anatomically, using retrograde and anterograde tracing techniques. In particular we focussed our attention on the NOT-DTN neurons, which control eye movements during OKN. All OKN-related NOT-DTN cells were activated after optic chiasma stimulation. Forty-five percent of these neurons were also activated after stimulation of the visual cortex (VC). The majority of neurons activated from VC (80%) also responded to monocular stimulation of either eye. On the contrary, most of the neurons that responded to stimulation of the contralateral eye only were not activated from VC. After injection of fluorescent latex microspheres into the NOT-DTN, retrogradely labeled neurons were found in areas 17, 18, and 18A of the visual cortex. Phaseolus vulgaris leucoagglutinin injected into the visual cortex anterogradely labeled fibres and terminals throughout the NOT-DTN complex. Labeled boutons were found in close proximity to OKN-related NOT-DTN cells, selectively stained after horseradish peroxidase (HRP) injections into the inferior olive. Our results demonstrate that NOT-DTN cells in the rat, which are involved in the generation of horizontal OKN, receive a direct input from the ipsilateral visual cortex.

Animals↗
PubMed2006

Effect of optical clearing agents on the in vivo optical properties of squamous epithelial tissue.

BACKGROUND AND OBJECTIVES: Optical clearing agents (OCAs) have previously been shown to increase depth penetration within turbid tissue ex vivo. This paper quantifies tissue optical properties of the hamster cheek pouch model in order to provide a means to assess the effect of OCAs quantitatively in vivo. STUDY DESIGN/MATERIALS AND METHODS: Diffuse reflectance spectra were obtained from both cheeks of 12 hamsters before and after immersion in dimethyl sulfoxide (DMSO), glycerol or a phosphate buffer saline (PBS) control for 20 minutes. A Monte Carlo model was then utilized to derive the wavelength dependent reduced scattering and absorption coefficients. RESULTS: DMSO caused a statistically significant decrease in the absorption and reduced scattering coefficients derived by the model. Glycerol caused a statistically significant increase in the wavelength dependent absorption coefficient, but no statistically significant changes in the reduced scattering coefficient. CONCLUSIONS: DMSO and glycerol act upon tissues differently as reflected by the tissue optical properties, implying that not all OCAs are equally effective in optically clearing tissues.

Absorption↗
PubMed1981

Relation of single unit properties to the oculomotor function of the nucleus of the basal optic root (accessory optic system) in chickens.

Single unit recordings in the nucleus of the basal optic root (nBOR) of the accessory optic system in chickens suggest that it has a role in vertical stabilizing eye movements. Cells have unusually large receptive fields and never respond to small stationary stimuli. They respond best to large richly patterned stimuli moving slowly (2-4 degrees/s) in vertical directions. Cells responsive to upward movement tend to be located in the dorsal portion of nBOR, which projects to motor areas producing upward eye movement, whereas cells responsive to downward movement tend to be located in the ventral portion of nBOR, which projects to motor areas producing downward eye movement; this suggests that these synapses onto oculomotor neurons are excitatory. In many nBOR units, the preferred and null directions are not opposite to each other. These directional asymmetries seem to be correlated with other properties of the units in a manner that supports the idea that the accessory optic system is arranged according to a vestibular coordinate system. This finding complements the abundant anatomical and physiological evidence linking the accessory optic system to the vestibular system.

Animals↗
PubMed1983

Topo-optical reactions and polarization optical analysis of human lymphocytes.

The latent birefringence of lymphocyte membranes of various species may readily be studied and analysed by various topo-optical reactions. The membranes of glutaraldehyde-fixed and PBS-washed lymphocytes show continuous birefringence with thiazine- and quinoline dyes. According to polarization optical analysis thiazine dye-stained cells are radially positive, whereas quinoline dye-stained cells are radially negative spherites, i.e. thiazine dye molecules are in a perpendicular, quinoline dye molecules in a parallel orientation relative to the membrane surface. These findings suggest that in lymphocyte membranes glycoproteins are primarily responsible for the topo-optical reactions. The actual conformational state of the glycoprotein components is a decisive factor not only in dye binding but also in the orientation of dye molecules. Heparin treatment directs attention to an important interaction between heparin and membrane glycoproteins. With the aid of the critical electrolyte concentration (CEC) technique we were able to demonstrate an ultrastructural differences between human erythrocyte and human lymphocyte membranes. After this procedure the birefringence of erythrocyte membranes was lost, whereas that of lymphocyte membranes did not change. There were no differences between the topo-optical reactions of T and B lymphocytes.

Cell Membrane↗
PubMed1991

Micromanipulation of mitotic chromosomes in PTK2 cells using laser-induced optical forces ("optical tweezers").

To study the potential use of optical forces to manipulate chromosome movement, we have used a Nd:YAG laser at a wavelength of 1.06 microns focused into a phase contrast microscope. Metaphase and anaphase chromosomes were exposed while being monitored by video microscopy. The results indicated that when optical forces were applied to late-moving metaphase chromosomes on the side closest to the nearest spindle pole, the trapped chromosomes initiated movement to the metaphase plate. The chromosome velocities were two to eight times the normal rate depending on the chromosome size, geometry, and trapping site. At the initiation of anaphase, a pair of chromatids could be held by the optical trap and kept motionless throughout anaphase while the other pairs of chromatids separated and moved to opposite spindle poles. As a result, the trapped chromosome either was incorporated into one of the daughter cells or was lost in the cleavage furrow, or the two chromatids eventually separated and moved to their respective daughter cells. If the trap was removed at the beginning of anaphase B, the chromosome moved back to the poles. Our experiments demonstrate that the laser-induced optical force trap is a potential new technique to study noninvasively the mitotic spindle of living cells.

Analysis of Variance↗
PubMedDate not supplied

Determination of the optical properties of CuA(II) in bovine cytochrome c oxidase using magnetic circular dichroism as an optical detector of paramagnetic resonance.

This paper describes the use of a novel magnetic circular dichroism-microwave double resonance (MCD-ODMR) experiment to study the optical properties of the EPR detectable copper center, CuA2+, in bovine cytochrome c oxidase. By irradiating the sample with a monochromatic microwave beam of appropriate frequency it is possible to quench partially the MCD intensity of the features due to CuA2+. In this way the MCD bands from this center have been identified even in the presence of overlapping optical transitions from the haem centers of this enzyme. The resulting spectrum compares well with that reported some years ago from this laboratory and obtained by measuring MCD magnetisation characteristics. In addition the shapes of the MCD-ODMR lines obtained in a plot of MCD intensity against magnetic field strength have been analyzed to yield the relative polarizations of the optical transitions of CuA2+ which contribute to the MCD spectrum. All of the bands observed between 450 and 850 nm are predominantly polarized in the xy plane perpendicular to the direction of the g-tensor component of CuA2+ at g parallel = 2.18. This suggests that all of the CuA2+ ligands that contribute to the optical charge-transfer transitions in the visible region lie approximately in the basal plane. Possible structures for CuA2+ can now be suggested.

Animals↗
PubMed2006

Optic cup and lens development requires Pax6 expression in the early optic vesicle during a narrow time window.

Pax6 mutations cause complex ocular malformations, but it is uncertain whether early eye development normally requires Pax6 function in both the optic vesicle (OV) and the lens epithelium, or only in the latter. To investigate this question, we electroporated the OV with anti-Pax6 or control morpholinos before the onset of lens placode formation. Pax6 downregulation was already detectable in the OV 10 h after anti-Pax6 treatment, and was accompanied by a significant increase in the death of OV cells. A small eye-like phenotype developed thereafter, whose severity was developmental stage-dependent. When treatment was applied at Hamburger Hamilton (HH) stage 10, there was no optic cup formation, and lens development was abortive despite normal Pax6 expression in the lens epithelium. Treatment at HH stage 11 resulted in structurally normal lens and optic cup, although the latter showed abnormal expression domains for several transcription factors. Early eye development therefore requires cell-autonomous Pax6 function not only in the lens but also in the optic vesicle, where it plays a hitherto unknown role in cell survival. The results, moreover, indicate that there is a critical stage during which Pax6 expression in the OV is necessary for normal lens development.

Animals↗