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At least 271 records · Page 15Linked to original sources
PubMed1993

An investigation of horizontal combined eye-head tracking in patients with abnormal vestibular and smooth pursuit eye movements.

We investigated the interaction of smooth ocular pursuit (SP) and the vestibulo-ocular reflex (VOR) during horizontal, combined eye-head tracking (CEHT) in patients with abnormalities of either the VOR or SP movements. Our strategy was to apply transient stimuli that capitalized on the different latencies to onset of SP and the VOR. During CEHT of a target moving at 15 deg/sec, normal subjects and patients with VOR deficits all tracked the target with a gain close to 1.0. When the heads of normal subjects were suddenly and unexpectedly braked to a halt during CEHT, the eye promptly began to move in the orbit to track the target, but eye-in-orbit velocity transiently fell to about 60-70% of target velocity. In patients with deficient labyrinthine function, following the onset of the head brake, eye movements to track the target were absent, and SP movements were not generated until about 100 msec later. In patients with deficient SP, CEHT was superior to SP tracking with the head stationary; after the onset of the head brake, tracking eye movements were initiated promptly, but eye velocity was less than 50% of target velocity and increased only slightly thereafter. These results indicate that at least two mechanisms operate to overcome the VOR and allow gaze to track the target during CEHT: (1) the SP system provides a signal to cancel a normally-operating VOR (this cancellation signal is not needed by labyrinthine-deficient patients who have no VOR to cancel), and (2) a reduction of the gain of the VOR is achieved, an ability that is preserved even in patients with cerebral lesions that impair SP.

Adult↗
PubMed1990

The pigeon's eye viewed through an ophthalmoscopic microscope: orientation of retinal landmarks and significance of eye movements.

The retina of live, anaesthetized pigeons was inspected with an ophthalmoscopic microscope mounted on a goniometer. Retinal landmarks (optic axis, pecten, fovea, border between the yellow and red field) and the ora terminalis were projected into the visual field of the eye and related to existing data. The resting position of the eye is determined by an orientation of the pecten 45 degrees to the horizontal plane and the optic axis pointing to the horizon with an azimuth angle of 70 degrees relative to the bill. The binocular overlap is maximal (approximately 30 degrees) some 15 degrees above the eye-bill axis. In the resting position of the eye the red field is directed to the lower frontal visual field with only marginal binocular overlap. Binocular overlap of the area dorsalis with the red field, however, during frontal fixation is brought about by eye movements in the range we have demonstrated. The fixation point is 10 degrees below the eye-bill axis.

Animals↗
PubMed1995

The non-visual impact of eye orientation on eye-hand coordination.

When a peripheral visual stimulus is briefly presented in an empty surround, and an observer is required, after a delay of a few seconds, to point toward the remembered location of that target, the responses are strongly influenced by eye orientation at the time of pointing. Remembered locations, as indicated in total darkness, are typically more precise (more reproducible across trials) when the subject's eyes are aimed toward the target before pointing, than when initial fixation (straight ahead) is maintained during pointing. Furthermore, when the eyes are aimed toward the target, the indicated directions are usually biased toward less eccentric locations than those indicated with eyes aimed straight ahead. These differences in scatter and in bias arise regardless of whether the eye movement toward target location, which precedes pointing, is made while the target is visible or occurs thereafter in total darkness, thus demonstrating that non-visual stimuli associated with eye orientation affect the spatial memory used by the skeletal muscle system.

Adolescent↗
PubMed1985

Ability of in vitro (corneal injury--eye organ--and chorioallantoic membrane) tests to represent histopathological features of acute eye inflammation.

The spontaneous removal of substances from the eye in vivo and histopathological responses to mild or moderate irritants were examined to define the main features that may be reflected in a valid in vitro test for irritant potential. Solutions or fine particulate suspensions applied to the rabbit eye are quickly removed from the central corneal surface by the blink reflex, gravity and drainage. The histological changes in the first 24 hours of mild-to-moderate irritation show some thinning of, but no severe irreversible damage to, the corneal epithelium. Other changes are oedema, congestion, some leucocyte infiltration and variable degeneration and desquamation of the conjunctival epithelium. In vitro cell-culture cytotoxicity tests are a useful screen for direct cytotoxic damage to epithelial cells but there are anomalies between the results of such tests and in vivo eye responses. Test systems using inhibition of DNA synthesis in cultured fibroblasts and histamine release from mast cells have shown poor correlation between in vitro and in vivo test results. The in vitro corneal injury (eye organ) test of Burton et al. (Fd Cosmet. Toxicol. 1981, 19,471) predicts very effectively the activity of moderate-to-severe irritants, and that of mild irritants when the contact time is modified or fluorescein or histology are used. This method demonstrates the response of a specialized tissue of the eye and facilitates the examination of powders, acids and alkalies, for which cell systems are not suitable. So far the chorioallantoic membrane of the egg has not been found to predict for pure chemicals the activities demonstrated in in vivo or in vitro tests on the eye; the main change seen in the egg membrane is necrosis, with little evidence of inflammation.

Acute Disease↗
PubMed1996

The chicken enucleated eye test (CEET): a practical (pre)screen for the assessment of eye irritation/corrosion potential of test materials.

The enucleated eye test with chicken eyes (CEET) obtained from an abattoir proved to be a valuable and practical alternative for the 'traditional' enucleated eye test with eyes of laboratory rabbits. Since 1992, the CEET has been incorporated in standard contract toxicity testing at the Toxicology Division of the TNO Nutrition and Food Research Institute as a (pre)screen for the Draize eye test with rabbits. The results of the first 44 compounds tested showed excellent correlation with the in vivo results. The CEET identified non-irritating or severely irritating compounds, and predicted (slightly to moderately) irritating compounds. Statistical analysis of the CEET and the rabbit in vivo scores showed high linear correlations between the critical values of both tests and confirmed the relevance of this assay with respect to ocular effects. In general, tiered in vitro/in vivo testing was considered a meaningful approach for further validation of alternative methods and for reducing the use of suffering of laboratory animals to a minimum. Tiered testing of compounds in cases of eye irritation hazard assessment should be incorporated in the legislation of the European Community.

Animal Testing Alternatives↗
PubMed1991

The eye in the brain: retinoic acid effects morphogenesis of the eye and pathway selection of axons but not the differentiation of the retina in Xenopus laevis.

We have analyzed the effects of all-trans retinoic acid (RA) on the morphogenesis, differentiation and projection of the eye of Xenopus. RA was applied in concentrations of 10(-5), 5 x 10(-6) and 10(-6) M at stages 9-17. Animals were reared until stages 40-48. RA applied before stage 11 1/2, abated completely formation of an eye or a retina, at later stages it led to the formation of microphthalmic eyes. Even in the absence of an eye parts of the forebrain had characteristics of the retina, but rods and cones reached then into the lumen of the third ventricle. The projection of eyes of RA-treated animals was revealed with rhodamine dextran amine. Ganglion cell axons projected bilaterally to the tectum, to the hindbrain, the contralateral retina and, occasionally, to the olfactory bulb. RA affects both morphogenesis of the eye and pathway selectivity of ganglion cell axons but not differentiation of the neural retina.

Animals↗
PubMed2005

Lipid tear deficiency in persistent dry eye after laser in situ keratomileusis and treatment results of new eye-warming device.

PURPOSE: To determine whether lipid tear deficiency is a significant pathogenic factor in persistent dry eyes after laser in situ keratomileusis (LASIK). SETTING: Ocular Surface Center, Miami, Florida, USA. METHODS: Thirty-four eyes of 17 patients (mean 46.35 years +/- 11 [SD]) complaining of persistent dryness more than 12 months after LASIK were prospectively studied by symptom scoring and kinetic analysis of tear interference image, tear breakup time, and fluorescein clearance test. Once patients had been clear of inflammation and treated for aqueous tear deficiency, lipid tear deficiency was further confirmed and treated with Eyefeel (Kao, Inc.), an eye-warming device, 4 times daily for 4 weeks. RESULTS: Sixteen patients were asymptomatic before LASIK but dryness persisted for 41 +/- 19.3 months. Delayed tear clearance was observed in 15 patients (88.2%) and floppy lids in 12 patients (70.5%). Aqueous tear deficiency was reconfirmed in 16 eyes (53.3%). After Eyefeel treatment, there was a subjective improvement of ocular surface diseases index from 60.6 +/- 10.6 to 25.8 +/- 18.5 (P = .0007). Tear breakup time was improved from 2.4 +/- 3.9 seconds to 7.9 +/- 3.6 seconds (P = .004). There was a tear interference pattern change from a vertical lipid tear deficiency to a horizontal normal in 7 eyes. There was a mean lipid spread time improvement from 1.3 +/- 0.4 sec to 0.8 +/- 0.4 sec (P = .001), and there was a mean lipid thickness improvement from 63.5 +/- 23 nm to 79.5 +/- 27 nm (P = .04). CONCLUSION: Persistent nature of dry eye after LASIK is attributed to in part to delayed tear clearance, undercorrected aqueous tear deficiency, and nonrecognized lipid tear deficiency.

Adult↗
PubMed2005

The eyes of a patrolling butterfly: visual field and eye structure in the Orange Sulphur, Colias eurytheme (Lepidoptera, Pieridae).

Sensory information plays a critical role in determining an animal's behavior on both proximate and evolutionary timescales. Butterflies, like many other insects, use vision extensively over their lifetimes, and yet relatively little work has been published to date on their visual capabilities. We describe the visual system of a pierid butterfly, Colias eurytheme, with the ultimate goal of better understanding its role in shaping the behavior of this animal. We made several measurements: visual field dimensions, eye surface area, interommatidial angle (Deltaphi), facet diameter (D), and eye parameter (p). C. eurytheme had a large visual field and considerable regional variation in visual acuity, as inferred by Deltaphi and D. When compared to females, males had larger eye surface areas, smaller Deltaphi, and larger D in all regions except ventrally. Both sexes had proportionally large eye surface areas compared to other butterflies. Minimum p in males was small, indicating that some regions of their eyes may operate close to the diffraction limit. Finally, we found that both eye surface area and D scaled positively, but with negative allometry to body size. We discuss the relevance of these visual characteristics to the biology and behavior of C. eurytheme.

Animals↗
PubMed2004

Age-related effects of bilateral frontal eye fields lesions on rapid eye movements during REM sleep in rhesus monkeys.

Rapid eye movement (REM) is one of the most characteristic features of REM sleep, but the mechanisms underlying its regulation remain unclear. The present study aims to investigate whether the frontal eye field (FEF) is involved in the regulation of the rapid eye movements during REM sleep. To address this question, we ablated the FEF in four rhesus monkeys and observed the effects of the lesions on sleep architecture. After lesions, two adult monkeys did not show any lesion effect. However, in the other two adolescent monkeys, both the total duration and percentage of the rapid eye movements during REM sleep were decreased moderately. The result suggests that the relation between the FEF and the regulation of the rapid eye movements during REM sleep may be affected by age factor, also indicating that both the functions of the FEF and the mechanisms underlying the control of rapid eye movements during REM sleep might not be the same throughout the whole life span of an animal.

Age Factors↗
PubMed1992

Changes in pupillary diameter in relation to eye-movement and no-eye-movement periods in the human fetus at term.

OBJECTIVE: The aim of our study was to reveal whether pupils dilate and constrict in a time sequence in the human fetus and to assess the relationship between changes in pupillary diameter and eye-movement-no-eye-movement periods. STUDY DESIGN: We simultaneously observed pupil and eye movement with real-time ultrasonography in 30 human fetuses at 36 to 41 weeks' gestation. Eighteen were excluded because of data loss. Statistical analysis of pupillary diameter changes were made on the remaining 12 fetuses with the least median of squares regression. RESULTS: Pupillary diameters were found to be differentiated with statistical significance into two groups: 9.7% for the dilated pupil (median 3.0 mm) and 90.3% for the constricted pupil (1.7 mm). The percentage of dilated pupils during the eye-movement period (14.3%) was significantly greater than that during the no-eye-movement period (2.3%; Wilcoxon rank sum test, p < 0.0001). CONCLUSION: These findings indicate a close relation between pupillary dilatation and eye-movement periods in the human term fetus.

Eye Movements↗
PubMed1997

Dachshund and eyes absent proteins form a complex and function synergistically to induce ectopic eye development in Drosophila.

The eyeless, dachshund, and eyes absent genes encode conserved, nuclear proteins that are essential for eye development in Drosophila. Misexpression of eyeless or dachshund is also sufficient to induce the formation of ectopic compound eyes. Here we show that the dachshund and eyes absent genes act synergistically to induce ectopic retinal development and positively regulate the expression of each other. Moreover, we show that the Dachshund and Eyes Absent proteins can physically interact through conserved domains, suggesting a molecular basis for the genetic synergy observed and that a similar complex may function in mammals. We propose that a conserved regulatory network, rather than a linear hierarchy, controls retinal specification and involves multiple protein complexes that function during distinct steps of eye development.

Animals↗
PubMed1988

[The parapapillary region of normal and glaucoma eyes. I. Planimetric values of 312 glaucoma and 125 normal eyes].

Magnification-corrected planimetry of the parapapillary region was performed according to Littmann's method in 312 unselected eyes with chronic primary open-angle glaucoma and in 125 normal eyes of an age- and refraction-matched control group using optic disk photographs. The glaucoma group was divided into five pathomorphologic subgroups. High myopics (less than -8.00 D) and "ocular hypertensives" had been excluded. The coefficient of variation ranged intraindividually from 0.0 to 0.17 and interindividually from 0.0 to 0.16. Two different morphologic variants were defined and examined: 1) Zone "Alpha" with incipient to advanced parapapillary chorio-pigmentepithelio-retinal atrophy - characterized by irregular hypo- and hyperpigmentation - was statistically proven in the control group (0.60 +/- 0.44 mm2; p less than 0.05; Wilcoxon-Mann-Whitney test) to be smaller than in the glaucoma group (0.81 +/- 0.70 mm2). It increased significantly (p = 0.0000) with advancing glaucoma stage. In the glaucoma and normal group it was broadest in the temporal horizontal sector (p less than 0.001; Wilcoxon test), followed by the temporal lower (p less than 0.001), temporal upper (p less than 0.001) and nasal sectors (p less than 0.001). There was no significant difference in prevalence between the two groups. 2) Zone "Beta" with subtotal to total parapapillary chorio-pigment-epithelio-retinal atrophy was also smaller in the normal eyes (0.18 +/- 0.52 mm2, prevalence: 20.0%; p = 0.0000) than in the glaucomatous ones (0.85 +/- 1.42 mm2, prevalence 66.7%) and was also, in both groups, broadest in the temporal horizontal sector, followed by the temporal lower, temporal upper and nasal sectors. In the control group it was smaller than zone "Alpha" (p less than 0.00001), while in the glaucoma group there was no difference. 3) The difference between normal eyes and earliest glaucoma stage I was for zone "Beta" (p = 0.0000); the difference between the normal eyes and those of glaucoma stage II was significant for both zones (p = 0.0000 and p less than 0.05, respectively). In both groups and in all glaucoma stages both zones were larger in the lower half of the optic disk than in the upper half. 4) "Conus pigmentosus" and the peripapillary scleral rim in normal and glaucomatous eyes showed no significant difference as regards their area and frequency. The parapapillary chorio-pigmentepithelio-retinal alterations are precursors of, or are equivalent to the so-called "halo glaucomatosus".(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1991

Dipole modelling of eye activity and its application to the removal of eye artefacts from the EEG and MEG.

The spatio-temporal dipole model approach has been used to identify the difference dipoles arising from changes in the ocular dipoles due to eye movements and blinks. Based on these results a method has been developed to remove eye artefacts from electrical or magnetic data. The method avoids distortions due to the head model by determining the spatial distribution of the signals from the eyes empirically. Using simultaneous modelling of the EEG or MEG activity with dipole sources distributed within the head together with the empirically determined spatial eye components, the eye activity can be estimated and removed from the EEG or MEG. This greatly reduces the distortion to the topography that is a concomitant of previous eye artefact correction methods. The advantages of the method are illustrated using simulated and real electrical data.

Analysis of Variance↗
PubMed1998

Role of the eye muscles in thyroid eye disease: identification of the principal autoantigens.

Thyroid-associated ophthalmopathy (TAO) is a progressive orbital disorder associated with Graves' hyperthyroidism and, less often, Hashimoto's thyroiditis in which autoantibodies react with orbital antigens and lead to exophthalmos and eye muscle inflammation. Eye muscle (EM) membrane proteins initially reported as 55 and 64 kd are the best markers of ophthalmopathy. The "64-kd protein" is now shown to be the flavoprotein subunit of mitochondrial succinate dehydrogenase and to have a correct molecular weight of 67 kd. We have cloned a fragment of a novel eye muscle protein, which we call G2s, and sequenced 1.4 kb of the full length cDNA. G2s does not share any significant homologies with other reported proteins. The 5.9 kb G2s mRNA, that corresponds to a protein of approximately 220 kd, is expressed in EM, other skeletal muscle and thyroid, but not in other tissues tested. We have also cloned and sequenced a 63-kd eye muscle protein identified as the calcium binding protein calsequestrin. Antibodies against calsequestrin were found in 40% of patients with active ophthalmopathy, but in 0% of normal subjects. Finally, we have sequenced a 19 amino acid fragment of a 55-kd porcine eye muscle membrane protein that exactly matched porcine and human sarcalumenin, a 160-kd glycoprotein localized in the lumen of the longitudinal sarcoplasmic reticulum of the skeletal muscle fiber where it binds calcium. A 53-kd glycoprotein fragment of the molecule corresponds to the 55-kd protein. In a preliminary study, serum antibodies against purified sarcalumenin were detected in 40% of patients with active TAO of less than 1 year duration, but in no controls tested. We porpose that the primary autoantigen in TAO is G2s, which would also explain the association of ophthalmopathy with thyroid autoimmunity, and that antibodies against the intracellular proteins flavoprotein, calsequestrin, and sarcalumenin are secondary markers of an immune-mediated reaction in eye muscle in patients with thyroid autoimmunity.

Autoantigens↗
PubMed1997

Dry eye syndrome, tear film, pharmacology of eye drops, and toxicity.

Over the past years, the main parameters used for the diagnosis of dry eye have been outlined: there is now substantial effort to bring them into correlation with each other, resulting in easier diagnosis of the diseases that appear to cause dry eye. Although increasing awareness of the plethora of dry eye diseases makes the differential diagnosis and the treatment difficult, the increased availability of optimized artificial tears and tear substitutes, especially viscoelastics, does allow easier relief of the most serious symptoms of dry eye disease. Improved topical treatment, in turn, allows various treatments, such as excimer laser treatment, to be performed, even in dry eyes. This, together with the identification of tear substitutes as a major research target and a better understanding for the psychological tasks of chronic dry eye diseases, offers a good basis toward further improvements.

Dry Eye Syndromes↗
PubMed2004

Velocity necessary for a BB to penetrate the eye: an experimental study using pig eyes.

PURPOSE: To determine the V-50 threshold velocity needed for a steel BB to penetrate the eye of a 230-pound pig. METHOD: BBs were shot at a distance of 10 feet into the corneas of pig eyes with a pump-action BB gun. RESULTS: The V-50 velocity for corneal penetration and serious disruption of the eye was found to be 246 ft/sec. CONCLUSION: Due to the nearly identical size and anatomy of the human eye to the pig eyes used in this study, it is felt that 246 ft/sec is a reasonable approximation of the velocity needed to penetrate the human eye.

Animals↗
PubMed1996

Viscous carbomer eye drops in patients with dry eyes. Efficacy and safety. A randomized, open, cross-over, multicentre study.

The efficacy and safety of a new carbomer containing ocular gel was compared to a commonly used 1.4% polyvinyl alcohol-based (PVA) offificial tear preparation. Sixty-one patients with symptoms and signs of dry eyes were treated with each preparation separately for two weeks in a multicentre, randomized, open cross-over study. A statistically significant difference in favour of the new viscous carbomer eye drops compared to the PVA preparation was achieved in reducing the symptom of 'dryness', the total symptom score and in prolonging the break-up time. During the carbomer eye drops period the mean daily frequency of application was 3.92 compared to 4.64 for the PVA eye drops period (p = 0.02). Twenty-three patients (38%) reported adverse events only while using the carbomer gel and 5 (8%) only while using the PVA eye drops (p < 0.001). 'Blurred vision' was the most common adverse event reported. The present carbomer containing ocular gel may offer advantages in the treatment of dry eyes.

Acrylates↗
PubMed1992

Diagnostic tests for dry eye disease in normals and dry eye patients with and without Sjögren's syndrome.

In order to compare the diagnostic tests for dry eye disease and the results of conjunctival impression cytology, we examined three groups of eyes: 146 eyes of normal controls, 108 eyes of keratoconjunctivitis sicca (KCS) patients without Sjögren's syndrome (SS) and 102 eyes of patients with SS. The clinical tests (break-up time, Schirmer test, Rose Bengal staining) and conjunctival impression cytology specimens from the superior part of the bulbar conjunctiva were evaluated from all the eyes. Our results showed that the patients with KCS without SS have abnormal lacrimal tests (p < 0.001) without changes in impression cytology [nucleo/cytoplasmic ratio (N/C), p > 0.1]. The patients with KCS and SS have also abnormal lacrimal tests (p < 0.01), and their epithelial cells presented squamous metaplasia (N/C, p < 0.001). The goblet cell number remained unchanged in the three groups (p > 0.1).

Adolescent↗