SEARCH · Search PubMed

Results for “EYES”

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.

SourceResearch connectionFrom yearThrough year

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

At least 163 records · Page 9Linked to original sources

PubMed1986

Effects of unilateral frontal eye-field lesions on eye-head coordination in monkey.

We studied the effects of unilateral frontal eye-field (FEF) lesions on eye-head coordination in monkeys that were trained to perform a visual search task. Eye and head movements were recorded with the scleral search coil technique using phase angle detection in a homogeneous electromagnetic field. In the visual search task all three animals showed a neglect for stimuli presented in the field contralateral to the lesion. In two animals the neglect disappeared within 2-3 wk. One animal had a lasting deficit. We found that FEF lesions that are restricted to area 8 cause only temporary deficits in eye and head movements. Up to a week after the lesion the animals had a strong preference to direct gaze and head to the side ipsilateral to the lesion. Animals tracked objects in contralateral space with combined eye and head movements, but failed to do this with the eyes alone. It was found that within a few days after the lesion, eye and head movements in the direction of the target were initiated, but they were inadequate and had long latencies. Within 1 wk latencies had regained preoperative values. Parallel with the recovery on the behavioral task, head movements became more prominent than before the lesion. Four weeks after the lesion, peak velocity of the head movement had increased by a factor of two, whereas the duration showed a twofold decrease compared with head movements before the lesion. No effects were seen on the duration and peak velocity of gaze. After the recovery on the behavioral task had stabilized, a relative neglect in the hemifield contralateral to the lesion could still be demonstrated by simultaneously presenting two stimuli in the left and right visual hemifields. The neglect is not due to a sensory deficit, but to a disorder of programming. The recovery from unilateral neglect after a FEF lesion is the result of a different orienting behavior, in which head movements become more important. It is concluded that the FEF plays an important role in the organization and coordination of eye and head movements and that lesions of this area result in subtle but permanent changes in eye-head coordination.

Animals↗

PubMed2005

Relationship between vision impairment and eye disease to vision-specific quality of life and function in rural India: the Aravind Comprehensive Eye Survey.

PURPOSE: To determine the impact of vision impairment and eye diseases on vision-specific quality of life and visual function in an older population of rural southern India. METHODS: Presenting and best-corrected visual acuity and burden of eye diseases were determined in a population aged 40 years and older, identified through a random cluster sampling strategy from 50 villages of rural south India. A questionnaire validated previously for use in this population was used to ascertain quality of life and visual function. Visual acuity measurements were obtained with illiterate E Early Treatment Diabetic Retinopathy Study (ETDRS) charts. Cataract was graded and defined based on the Lens Opacities Classification System (LOCS) III. Macular degeneration was defined based on the classification system proposed by the International ARM Epidemiologic Study Group. Glaucoma was defined based on results of clinical examinations including optic disc and visual fields. Analyses were performed to explore the relationship of overall and subscale quality-of-life and visual function scores with presenting acuity in the better-seeing eye, specific eye diseases, and demographic variables. RESULTS: Information on quality of life and visual function were available for 5119 (99.4%) of 5150 study subjects. The mean presenting visual acuity in the better eye was 0.76 +/- 0.53 logMAR (logarithm of the minimum angle of resolution) units. Age, education, occupation, presenting acuity in the better eye, and presence of a cataract, glaucoma, or refractive error were independently associated with overall quality-of-life and vision function scores. After adjustment for demographic variables and ocular disease, persons with vision impairment or bilateral blindness based on presenting visual acuity had lower scores across all domains of quality of life and vision function. Scores for subscales of quality-of-life and vision function domains were significantly lower among those with age-related cataract and glaucoma compared with persons without those eye diseases. CONCLUSIONS: Presenting vision in the better eye was associated with quality of life and vision function in this older population of rural south India. Subjects with glaucoma and age-related cataract had an associated decrease in quality of life and vision function, independent of presenting visual acuity in the better eye.

Adult↗

PubMed2003

Impression cytology on conjunctiva and cornea in dry eye patients establishes a correlation between squamous metaplasia and dry eye clinical severity.

PURPOSE: To obtain deeper knowledge of the cellular transition in squamous metaplasia, and to look for a correlation between the clinical grade of severity of dry eye and the grade of squamous metaplasia of the corneal and conjunctival epithelium, studied by impression cytology. METHODS: A total of 143 patients with dry eye disorders of different grades of clinical severity and 33 control subjects of matched age and sex were studied. Symptoms, clinical tests (including Schirmer test, slit-lamp examination, break-up time, rose Bengal staining, vanishing lacunar sulci, and neovascularization), and tear osmolarity were used to establish the diagnosis of dry eye. The subjects were classified into six clinical grades, grade 0 indicating normal and grades 1 to 5 progressively more severe dry eye. Impression cytology specimens were taken from the central cornea and different areas of the conjunctiva of one eye from all patients. A morphologic and morphometric study of the photographs obtained by light microscopy showed cell size, nuclear size, nuclear-cytoplasmic ratio (N:C) in nonsecretory epithelial cells, and density of goblet cells. RESULTS: Morphometric and morphologic studies of the ocular surface cells indicated significant differences, mainly in cell sizes, nuclear alterations, and the N:C ratio, in nonsecretory epithelial cells of the conjunctiva and cornea, and in goblet cell densities from the conjunctiva, between the clinically normal eyes and those with the five grades of clinical severity of dry eye, with different degrees of squamous metaplasia. CONCLUSIONS: A morphologic and morphometric analysis of the ocular surface from patients with dry eye obtained by impression cytology led us to draft a new grading system containing one normal level and five levels of squamous metaplasia. This new grading system is based on a significant decrease in the number of goblet cells with less periodic acid-Schiff-hematoxylin-positive staining, an increase in nonsecretory cell size, more marked cell separation, a lower N:C ratio, and an increase in nuclear alterations. The clinical severity of the dry eye correlates with these alterations.

Adult↗

PubMedDate not supplied

The plasticity of compensatory eye movements in rotatory tests. I. The effect of alertness and eye closure.

Fifteen voluntary subjects with a mean age of 26 years (17-39), participated in two rotatory experiments. The rotatory test used was sinusoidal harmonic acceleration (SHA) test at frequencies of 0.01-0.32 Hz. Compensatory eye movements were measured by means of EOG. Experiment A included rotation in darkness during alerting tasks (day 1), rotation in darkness with no tasks (day 2) and rotation in darkness during alerting tasks (day 3). In the alertness tests, the gain varied between 0.5 and 0.77. Phase values decreased with increasing frequency. The alertness results between days 1 and 3 did not differ in gain or phase. The gain of day 2 (no tasks) displayed significantly reduced gain at all frequencies, and a more pronounced decrease in phase than in the alertness tests. Experiment B comprised testing with eyes open (day 1) and eyes closed (day 2) during alerting tasks. These tests displayed significantly decreased gain at all frequencies with eyes closed compared with eyes open and with more negative phase at 0.08-0.32 Hz with eyes closed. The results indicate a central effect of the alertness level on compensatory eye movements, and the effect of eye closure might be explained by bio-mechanical and possibly even central effects on the eye movements. In low-frequency testing, as short a test time as possible should be used, and due to different alertness levels, the results should be evaluated with great caution.

Acceleration↗

PubMed2001

Eye symptoms and use of eye protection among seasonal and migrant farmworkers.

BACKGROUND: Farmworkers face an array of environmental and workplace hazards that pose risks of eye damage from accidents involving agricultural chemicals and equipment and from exposure to wind, dust, and ultraviolet rays. Eye safety risks are known among industrial and agricultural occupations, yet little is known about the prevalence of eye symptoms and use of eye protection among farmworkers. METHODS: A survey of 197 Latino farmworkers in North Carolina used self-report data to measure workers' prevalence of eye symptoms and eye protection use. RESULTS: Eye pain and redness after working all day in the field were reported by more than 40% of workers. Most (98.4%) reported not wearing sunglasses when working in the fields; reasons included lack of sunglasses and interference with field tasks. CONCLUSIONS: Eye symptoms are prevalent in this population. Failure to use eye protection indicates the need for further education and training of Latino farmworkers and their employers about occupational risks to eyesight.

Adult↗

PubMed1991

[Correction of EOG with eye movement measured by the eye mark recorder system].

The electrooculogram (EOG) is usually necessary for the subject to fixate two targets alternately at a fixed visual angle. However, in the patients with poor vision, it can be difficult to fixate exactly. In such case, the results can be improved by using both the measurement of real eye position and the measurement of EOGs in combination. In this study, we measured subject's eye position simultaneously with the potential changes around his eyes as the subject pursued alternately two on-and-off visual targets which were horizontally placed on the cylindrical screen at a regular visual angle in front of his eyes. The EOG is obtained from those potential changes. If the difference between the target position and the fixating point can be calculated from the net eye movement measured with an eye camera, the error potential can be derived from this difference. Therefore, exact potential changes are obtained by correcting the measured potentials with the above error potentials. The authors were able to confirm that the potential changes were approximately proportional to the amplitude of saccadic eye movements within about 30 degrees in front of the eyes. Therefore, the simultaneous measurement of the potential changes and the eye position enable measurement of EOG without pursuing the targets by transforming the measured potentials into the exact values corresponding to the constant amplitudes of saccades.

Electrooculography↗

PubMed1985

Eye-specific segregation requires neural activity in three-eyed Rana pipiens.

The addition of a third eye primordium to the forebrain region of a Rana pipiens embryo invariably results in the development of a series of periodic, mutually exclusive eye-specific bands in tectal lobes dually innervated by the host and supernumerary fibers. A number of investigators have proposed that such source-specific segregation arises as a compromise between two mechanisms that are normally involved in retinotectal map formation: one which is dependent on cell surface affinities to align the map and produce a rough retinotopy and a second that "fine tunes" the map by stabilizing adjacent terminals from neighboring retinal ganglion cell bodies at the expense of terminals from non-neighboring cells. In this study we have tested the idea that this second "fine-tuning" mechanism is dependent on neural activity by blocking impulse activity in the optic nerves of three-eyed tadpoles. To assess the requirement for activity on the formation of bands, both normal optic nerves of 17 three-eyed tadpoles were crushed intraorbitally. Two weeks after this operation, the supernumerary retinal projection had debanded and spread to cover the entire tectum in a continuous fashion. By 4 weeks, however, the host optic fibers regenerated back to the tecta and began to form segregated stripes with the fibers from the third eye. Six to 7 weeks after the optic nerve crush the periodic pattern of eye-specific segregation characteristic of dually innervated tecta was again pronounced. When activity in all three optic nerves was eliminated with tetrodotoxin (TTX; embedded in a slow release plastic) during the last 3 weeks of this process, the fibers from the two competing eyes failed to segregate and, instead, formed two completely overlapping, continuous projections across the tectal surface. To test for the requirement of activity in the maintenance of segregation, we also subjected three-eyed tadpoles without optic nerve crush to TTX blockade for 2, 3, and 4 weeks. Animals sacrificed at 2 weeks show overlap of the projections in the rostral tectum but distinct interdigitating stripes in other regions of these lobes. After 3 weeks of blockade, segregation of the projections was less distinct in the central tectum as well. After 4 weeks of TTX blockade the terminals from both eyes spread to form continuous overlapping projections throughout the tectum. Examination of well isolated, individual retinal ganglion cell terminal arbors during this period reveals that they occupy a significantly greater area of tectum following the TTX treatment.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗

PubMed1975