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At least 199 records · Page 11Linked to original sources
PubMedDate not supplied

Corneal asphericity in eye bank eyes implanted with the intrastromal corneal ring.

OBJECTIVE: To evaluate the effects of the intrastromal corneal ring, a device developed to reduce myopia, on corneal asphericity in a large set of eye bank eyes. METHODS: Forty-one deturgesced eye bank eyes were implanted with intrastromal corneal rings of five different thicknesses, ranging from 0.25 mm to 0.45 mm. Corneal asphericity, before and after implantation, was examined using two different metrologies. Corneal asphericity profiles were produced from dioptric power data collected from videokeratography. To statistically assess the corneal asphericity differences between exam times for each intrastromal corneal ring thickness, dependent sample confidence intervals (95%) were calculated for the mean differences between preoperative and postoperative measures for each topographic diameter zone. Laser holographic interferometry was used to inspect corneal asphericity in one eye bank eye case study for four intrastromal corneal ring sizes. Wave unit map and geometric zonal spot ray tracing analyses derived from laser holographic interferometry topography were surveyed. RESULTS: Videokeratographic analysis suggested that preoperative corneal shape was prolate, i.e., flattened from central to paracentral cornea. Corneal shape became more prolate with intrastromal corneal ring implantation for all intrastromal corneal ring thicknesses. Laser holographic interferometry demonstrated that prolate asphericity was preserved with the intrastromal corneal ring sizes tested and that optical collection efficiency of the cornea was not diminished. CONCLUSION: Using two different measurement techniques, this eye bank eye study demonstrated that intrastromal corneal rings maintain prolate corneal asphericity.

Cornea↗
PubMedDate not supplied

[Blood-eye barrier in the acute period of experimental severe alkaline burn of the eye by injection of deoxyglucose into the central vein].

The permeability of the blood-eye barrier for 14C-labeled deoxyglucose injected intravenously was studied on a model of severe experimental eye burn in 12 rabbits (24 eyes). The barrier permeability was evaluated by the content of radioactive material in the burnt eye humor in comparison with intact eye. Analysis of radiometric data showed a significant difference in the content of 14C in damaged and intact eyes. The permeability of the blood-eye barrier was increased in the damaged eye, this permeability depending on the concentration of the agent in the blood.

Acute Disease↗
PubMed2005

The "third eye"-- a new concept of trans-differentiation of pineal gland into median eye in amphibian tadpoles of Bufo melanostictus.

Median third eye was found to develop from transplanted pineal gland of external gill stage tadpoles in the recipient 5 toe stage tadpoles of Bufo melanostictus. Pineal gland along with a bit part of brain tissue of the donor external gill stage tadpole was cut out and transplanted into a pit made between two lateral eyes of 5 toe stage recipient tadpoles. Half of the operated tadpoles were treated with vitamin A (15 IU/ml.) for 15 days. Median "third eye" was found to develop in the both untreated and vitamin A treated tadpoles. However, vitamin A increased the percentage of the development of median eyes. Morphological and histological study revealed that newly transformed median eyes were similar to that of normal functional eyes. A stalk like structure developed which connects the median eye to the brain. The median third eye could not develop when pineal gland of 5 toe stage mature tadpole was transplanted into the tadpole of the same age.

Animals↗
PubMedDate not supplied

Geometric adjustments to account for eye eccentricity in processing horizontal and vertical eye and head movement data.

Neglecting the eccentric position of the eyes in the head can lead to erroneous interpretation of ocular motor data, particularly for near targets. We discuss the geometric effects that eye eccentricity has on the processing of target-directed eye and head movement data, and we highlight two approaches to processing and interpreting such data. The first approach involves determining the true position of the target with respect to the location of the eyes in space for evaluating the efficacy of gaze, and it allows calculation of retinal error directly from measured eye, head, and target data. The second approach effectively eliminates eye eccentricity effects by adjusting measured eye movement data to yield equivalent responses relative to a specified reference location (such as the center of head rotation). This latter technique can be used to standardize measured eye movement signals, enabling waveforms collected under different experimental conditions to be directly compared, both with the measured target signals and with each other. Mathematical relationships describing these approaches are presented for horizontal and vertical rotations, for both tangential and circumferential display screens, and efforts are made to describe the sensitivity of parameter variations on the calculated results.

Eye Movements↗
PubMedDate not supplied

Characteristics and causes of penetrating eye injuries reported to the National Eye Trauma System Registry, 1985-91.

Ocular trauma is one of the most important preventable causes of visual impairment. The National Eye Trauma System was developed to provide optimal clinical care for severe ocular injuries, to foster research on eye injury, and to increase awareness of ocular trauma as a public health problem. From 1985 through 1991, the National Eye Trauma System Registry collected data on 2,939 cases of penetrating eye injury reported by ophthalmologists at 48 collaborating eye trauma centers in 28 States and Washington, DC. Eighty-three percent of the cases involved men; the median age of the patients was 27 years, ranging from 1 to 92 years of age. Seventy-seven percent of the injuries were unintentional, 22 percent were the result of assault, and 1 percent were self-inflicted. In 62 percent of the cases studied, the injured person's initial best corrected visual acuity in the injured eye was the ability to perceive hand motion, or worse. The settings in which the injuries occurred included the home (28 percent), the worksite (21 percent), at recreation (11 percent), and in transportation (8 percent). At the time of the injury, 1.5 percent of the injured persons were wearing safety glasses and 2.9 percent were wearing nonsafety glasses. There was evidence of definite or possible alcohol use by at least 24 percent of the injured persons and illicit drug use by 8 percent. The most frequent types of tissue damage included corneal or scleral laceration, traumatic cataract, intraocular foreign body, vitreous hemorrhage, and prolapse of intraocular tissue. Analyses of the causes and characteristics of ocular injuries reported to the National Eye Trauma System Registry will help identify high risk settings for such injuries. Results will be used to develop and implement interventions that will reduce the incidence of eye trauma.

Adolescent↗
PubMed1986

Characteristics of eye velocity storage during periods of suppression and reversal of eye velocity in monkeys.

An eye velocity storage mechanism has been postulated in the vestibulo-optokinetic system to account for the prolongation of vestibular nystagmus (VN) and the occurrence of optokinetic after-nystagmus (OKAN). Presentation of a subject-stationary full-field surround during VN and OKAN (= full-field fixation) rapidly reduces activity related to eye velocity of the storage mechanism. If the subject-stationary full-field surround is presented for short periods during VN or OKAN, nystagmus resumes when the animal is again in darkness, but at a lesser velocity than would be predicted from a control response. This reduction in peak eye velocity after fixation reflects a decrease in activity of the storage mechanism due to full-field fixation. This decrease in activity occurs with a shorter time constant compared to that in control trials, it has been called "dumping". We demonstrate that a subject-stationary small target light presented during VN or OKAN (= target fixation) also reduces activity of the storage mechanism with a time constant slightly greater than that for full-field fixation, but still considerably smaller than that in control trials. In 3 monkeys the time constant of discharge was reduced during the post-rotatory period from 20 s in control trials to 4.6 s by fixation of a single target light and to 2.9 s by fixation of a full-field. The time constant of discharge was reduced during OKAN from 13.2 s in control trials to 3.8 s by target fixation and to 2.6 s by full-field fixation. We report a second experimental paradigm with which the dynamics of visual-vestibular interaction involving the eye velocity storage mechanism is analysed by means of transient step responses. In this paradigm eye velocity due to activation of the storage mechanism (OKAN) is forced to reverse by a short exposure to a full-field moving in the opposite direction of the slow phases of nystagmus. Short periods of eye velocity reversal did not reduce activity of the storage mechanism more rapidly than fixation, i.e. suppression of eye velocity alone. Fixation of a full-field or of a single target light during vestibular or optokinetic stimulation reduces peak nystagmus velocity after stimulation when monkeys are in darkness. Suppression of OKN by target fixation during full-field stimulation reduces the initial eye velocity of OKAN to 15-20% compared to the OKAN velocity when OKN is allowed to occur.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

Two-eyed versus one-eyed salamanders: does binocularity enhance the optically evoked skin blanching reactions of Ambystoma larvae?

A wide variety of visual functions show increases attributable to binocularity, and the question pursued here was whether a second eye enhances the visually stimulated skin blanching reaction of the larval salamander. Dermal melanin spots (produced by the aggregations of melanosomes within dermal melanophores and which contract or expand to lighten or darken the skin) were measured in eyeless (controls), one-eyed and two-eyed Ambystoma punctatum larvae after chronic adaptation of the subjects to a white background (i.e., stimulus conditions for maximum blanching). The eyeless subjects showed no blanching (thus remained dark) in white cups, and they exhibited melanin spots 7 or 8 times the size of those of the other two groups. All one-eyed or two-eyed subjects exhibited blanching reactions; planometric comparison revealed a significantly larger melanin spot area for one-eyed than for two-eyed animals; i.e., the binocular condition permitted greater contraction of the pigment spots than did the monocular condition. Analytical data compared favorably with independently ascertained pigmentation indices. The results indicate that a second eye quantitatively elevates the blanching maximum of a larval salamander.

Ambystoma↗
PubMed1985

Red nucleus lesions impair acquisition of the classically conditioned nictitating membrane response but not eye-to-eye savings or unconditioned response amplitude.

Following a single electrocoagulating RF lesion aimed at left red nucleus, rabbits received classical conditioning of the nictitating membrane (NM) response. A tone was the conditioned stimulus (CS) and electrostimulation of the eye was the unconditioned stimulus (US). The US was applied to the right eye during the initial phase of training. It was then switched to the left eye to assess transfer of learning and ultimately switched back to the right eye. NM responses were recorded simultaneously from both eyes during each phase of training. Consistent with reports implicating a cerebellar-rubro circuit in this behavior, RN lesions disrupted acquisition of CRs in the eye contralateral to the lesion. Animals with disrupted NM CRs of the right eye resembled controls in showing transfer of conditioning to the left eye. CR-disrupting lesions did not affect UR amplitude.

Animals↗
PubMed1997

Refractive outcome of radial keratotomy: does the result of the first eye predict outcome in the second eye?

PURPOSE: To present a method of quantifying variability in the outcome of a refractive surgical procedure using the SD of the difference between achieved and expected refractive changes. We used this method to determine whether the refractive outcome of radial keratotomy in a first eye is predictive of outcome in the second eye. METHODS: We retrospectively identified patients who underwent eight-incision radial keratotomy in the first eye from February 1993 through April 1994, with follow-up refraction 2.5 to 5 months postoperatively. This group consisted of 129 eyes of 81 patients. Thirty-nine patients had bilateral surgery with appropriate follow-up. Achieved refractive change was analyzed by multivariate linear and nonlinear regression to yield an expected refractive change for each eye based on patient age and optical zone size. RESULTS: Residuals, defined as the difference between the achieved and expected refractive change, were normally distributed. The SD of the residuals was 0.68 diopter and was independent of the expected correction. The prediction of second-eye refractive change was not significantly improved by incorporating the residual from the first eye into the regression prediction. CONCLUSIONS: The SD of the difference between the achieved and expected refractive change is an appropriate measure of the variability in refractive outcome following a refractive surgical procedure. Surgeons who perform bilateral simultaneous radial keratotomy do not sacrifice refractive accuracy in the second eye.

Adult↗
PubMed2003

Longitudinal rates of annual eye examinations of persons with diabetes and chronic eye diseases.

OBJECTIVE: To assess the rate of annual eye examinations over time among older Americans with diabetes and chronic eye diseases. DESIGN: Longitudinal analysis of Medicare claims data. PARTICIPANTS: Random sample of Medicare beneficiaries aged 65 years or older. METHODS: Beneficiaries were followed between 1991 and 1999, unless mortality or enrollment in a health maintenance organization for > 6 months in a given 12-month period intervened. All claims data (both physician and facility) during this time were analyzed for the presence of International Classification of Diseases 9 codes consistent with 1 of the 3 study conditions and the performance of eye examinations. MAIN OUTCOME MEASURES: Claims submitted by optometrists, ophthalmologists, or other providers of eye care for subjects with diabetes, glaucoma, or age-related macular degeneration (ARMD). Rates were calculated on the basis of a 15-month time window for annual examinations rather than for 12 months to allow for less than full compliance with the guidelines for various reasons (e.g., bad weather). RESULTS: Among those with diabetes in this population, 50% to 60% had annual eye examinations in a 15-month period. Of those followed for at least 75 months after diagnosis, about three quarters had one or more 15-month gaps between visits. For subjects diagnosed with glaucoma, most visit rates were in the 70% to 90% range per 15-month period. The percentage of subjects with at least one 15-month period with no visits was considerably lower than for diabetes. The patterns for those with ARMD were in between those for diabetes and glaucoma. Over a nine-year period, only slightly over half of persons with at least one of the study conditions complied with practice guidelines. CONCLUSIONS: Annual eye examinations for persons diagnosed with diabetes, glaucoma, and ARMD are important for detecting potentially treatable vision loss among those already diagnosed with these conditions. Currently, actual rates of eye examinations for persons diagnosed with the study conditions fall far short of recommended rates. As such, approaches to enhancing longitudinal follow-up of those already in the eye care system are needed.

Aged↗
PubMed2003

A noninvasive eye fixation and computer-aided eye monitoring system for linear accelerator-based stereotactic radiotherapy of uveal melanoma.

PURPOSE: To introduce a noninvasive eye fixation and computer-aided eye monitoring system for linear accelerator-based stereotactic radiotherapy for uveal melanoma. METHODS AND MATERIALS: At the Department of Radiotherapy and Radiobiology, University of Vienna, stereotactic radiotherapy is offered to patients with uveal melanoma considered unsuitable for (106)Ru brachytherapy or local resection. For the present feasibility study, 8 patients were carefully selected according to their ability to fixate a small light source with the diseased eye and whether they had a rather small head to meet the limited geometric space available. A polymethyl methacrylate tube was attached to a stereotactic mask system in craniocaudal orientation supporting a 45 degrees mirror, which was placed in front of the diseased eye. At the other end of the tube, the patient was given a small fixation light, and a small camera was positioned beneath, which was shielded for use during MRI. A computer interface calculated and visualized the spatial difference of the actual and a given reference pupil position, which was defined before CT scanning, during the MRI sequences, and during treatment delivery at the linear accelerator. RESULTS: The described system can be attached to a conventional stereotactic mask system with minor modifications. Because of the large distance between the eye and the fixation light, the optical fixation system was well tolerated by all patients, and a stable position of the eye was obtained. The camera system can be used during CT and MRI without interference. Absorption of the 6-MV photon beam by the mirror and the polymethyl methacrylate tube was negligible. The computer interface designed to determine the pupil position uses an image-processing algorithm that correlates a template of the reference image with the actual image of the eye. Provided sufficient illumination of the pupil, the correlation function showed a pronounced minimum at the reference position. The precision of the algorithm was tested by phantom measurements. For a given 1 mm or 2 mm displacement, the interface reported a mean shift of 0.96 +/- 0.18 mm or 2.07 +/- 0.11 mm, respectively. CONCLUSION: The results of this study demonstrated the feasibility of a new optical fixation system for linear accelerator-based stereotaxis. The artifact-free application of the camera system during image acquisition and irradiation and the use of the computer interface, which automatically monitored eye movements with submillimeter precision, provided large improvements compared with existing techniques. Given well-defined interruption criteria and accelerated image processing, the described system has a high potential to perform automatically gated treatment beam delivery in the near future.

Humans↗
PubMed1998

The effects of frontal eye field and dorsomedial frontal cortex lesions on visually guided eye movements.

In the frontal lobe of primates, two areas play a role in visually guided eye movements: the frontal eye fields (FEF) and the medial eye fields (MEF) in dorsomedial frontal cortex. Previously, FEF lesions have revealed only mild deficits in saccadic eye movements that recovered rapidly. Deficits in eye movements after MEF ablation have not been shown. We report the effects of ablating these areas singly or in combination, using tests in which animals were trained to make saccadic eye movements to paired or multiple targets presented at various temporal asynchronies. FEF lesions produced large and long-lasting deficits on both tasks. Sequences of eye movements made to successively presented targets were also impaired. Much smaller deficits were observed after MEF lesions. Our findings indicate a major, long-lasting loss in temporal ordering and processing speed for visually guided saccadic eye movement generation after FEF lesions and a significant but smaller and shorter-lasting loss after MEF lesions.

Animals↗
PubMed2005

Accuracy of GDx variable corneal compensation polarization measurements in normal human eyes: effect of accommodation, cycloplegia, focus, pupil size, and eye selection on reproducibility.

PURPOSE: To evaluate the reproducibility of variable corneal compensation (VCC) and the effect of accommodation, cycloplegia, eye selection, focus, and pupil size on this measurement of polarization. METHODS: Using a GDx scanning laser polarimeter, multiple measurements of the VCC were obtained from each eye of 33 healthy, young adults under differing conditions. Pupil size and refraction were independently measured with a pupillometer and an autorefractometer. The effects of eye, instrument focus, pupil diameter, cycloplegia, and accommodation were statistically assessed. RESULTS: The reproducibility of a single retardation measurement and its axis, as determined by the standard deviations (SD) of repeated measurements, is +/-1.58 nm and 2.10 degrees , respectively. There is a difference in retardation between right and left eyes, of 5.26+/-9 nm, P=0.002. Increasing pupil size increases retardation. Cycloplegia or defocusing decreases retardation, and pharmacologically induced accommodation has no effect on retardation. CONCLUSIONS: The retardation and its axis are highly reproducible measurements when the pupil is of physiologic size and the GDx is properly focused. There is a consistent difference in VCC retardation between the paired right and left eyes. This difference may reflect equipment-induced measurement artefact and/or an anatomic asymmetry between the paired eyes of the subjects studied. Clinicians should be cautious when comparing interocular VCC measurements between paired right and left eyes and using data pooled from both eyes for age-adjusted, normalized standards.

Accommodation, Ocular↗
PubMed1989

[The retinal nerve fiber layer in normal eyes and in glaucoma. I. Semiquantitative data of 398 eyes with glaucoma].

Atrophy of the optic nerve is associated with changes of the retinal fiber layer (RNFL). Using red-free photographs the authors examined the RNFL of 398 eyes with chronic primary open-angle glaucoma and compared it with the RNFL of 234 normal eyes. The glaucoma group was divided into five stages and the fundus into four sectors. Differences between the normal and glaucoma eyes were: (1) The sequence of the sectors, with regard to the best visibility of the retinal nerve fiber bundles, was changed. In the normal eyes the nerve fiber bundles were most often best visible in the inferior temporal sector, followed by the superior temporal sector, the temporal horizontal area and finally the nasal region. In the glaucoma group the nerve fiber bundles were significantly more often best detectable in the superior temporal sector and the temporal horizontal area. (2) The degree of visibility of the retinal nerve fibers decreased significantly with increasing glaucoma stage. (3) Localized defects were seen in 15% of the eyes with glaucoma and none of the normal eyes. The specificity of this qualitative parameter was, therefore, 100%. The defects were found most often in the superior and inferior temporal regions. These differences between normal and glaucomatous eyes were also significant for the first glaucoma stage of this study. The localization of the foveola below the optic disk center (0.53 +/- 0.34 mm in the glaucoma group and 0.55 +/- 0.29 mm in the normal eyes) was not significantly different.

Adolescent↗
PubMed2006

Further analysis of the human spontaneous eye blink rate by a cluster analysis-based approach to categorize individuals with 'normal' versus 'frequent' eye blink activity.

PURPOSE: To further analyze the possible causes of variability in spontaneous eye blink activity in apparently healthy humans. METHODS: One hundred men, aged between 23 and 57 years and with no significant eye disease, were questioned on the number of ocular symptoms they experienced (one, two, three, and so forth). Five-minute video recordings were made of the eyes in primary gaze and in silence between 11:00 and 17:00 hours. The spontaneous eye blink rate (SEBR) and palpebral aperture features were assessed from the video recordings. The central corneal threshold touch sensitivity was then assessed with a Cochet-Bonnet aesthesiometer. RESULTS: The average SEBR was 13.8 +/- 9.7 blinks per minute (range, 2.8-48 blinks per minute), but the distribution was heterogeneous and skewed to higher values. The SEBR was not obviously dependent on the time of day that the recordings were made, on the number of mild symptoms that the subjects reported, or on the central corneal sensitivity (P> or =0.6). Analysis of SEBR in relation to age showed a possible weak association (P=0.082, r = 0.175), but SEBR showed absolutely no correlation with palpebral aperture height (P=0.546). A hierarchic cluster analysis clearly resolved the distribution of SEBR values into two distinct groups (P<0.001, F ratio = 222). CONCLUSIONS: Spontaneous eye blink activity can be rather different between healthy individuals, even under a single experimental condition. These differences do not appear to be caused by the time of day, mild symptoms, corneal sensitivity, age, or palpebral aperture features. In line with previous metaanalyses, it is therefore proposed that individuals could be grouped as to whether they have "normal" eye blink activity or be classified as having "frequent" eye blink activity. The latter group would include those who had an SEBR greater than 20 blinks per minute when assessed in primary eye gaze and in silence.

Adult↗
PubMed2004

Keratoconus in Asian eyes at a tertiary eye care facility.

BACKGROUND: The purpose of this study was to assess the demographic variables, age at diagnosis, keratometry and slitlamp signs in keratoconus. METHODS: Thirty-one patients with 61 keratoconic eyes were selected provided they met one of two criteria: 1. They had an irregular corneal surface, Vogt's striae, Fleischer's ring or apical sub-epithelial corneal scarring characteristic of keratoconus; 2. Corneal topography revealed an average simulated keratometry of more than 45.2 D, central corneal power higher than 47.2 D or infero-superior asymmetry greater than 1.4 D. The main outcome measures were demographic variables, age at diagnosis, disease severity on keratometry and biomicroscopic signs. RESULTS: The patients' mean age at presentation was 20.2 +/- 6.4 years. Based on average keratometry values, 67.2 per cent of eyes had severe and 32.8 per cent had moderate keratoconus. Eyes with severe keratoconus presented at a younger average age (18.8 +/- 5.35 years) than moderate keratoconus (23.69 +/- 8.07 years). Thirty-eight eyes (92.5 per cent) with severe and 13 eyes (65 per cent) with moderate keratoconus demonstrated biomicroscopic signs of keratoconus. Twenty eyes (32.7 per cent) demonstrated apical sub-epithelial cornea scarring and 95 per cent of these eyes had severe keratoconus. CONCLUSIONS: The majority of keratoconic eyes in Asian-Indian patients demonstrate the severe stage of the disease by the second decade.

Adolescent↗
PubMed1989

The relationship between eye-winking tics, frequent eye-blinking and blepharospasm.

A family is reported in which three generations were affected with eye-winking tics and/or blepharospasm. The proband developed eye-winking tics in childhood and then developed excessive blinking progressing to blepharospasm by the age of 21 years. His mother presented with Meige's syndrome and spasmodic torticollis at the age of 59 years; his uncle had blinked excessively from his early forties. His eldest son developed an eye-winking tic with facial grimacing at the age of 8 years, and in another son, a self-limiting period of eye-blinking occurred at the age of 4 years. The recovery cycle of the blink reflex was abnormal in all three generations. Three other children with eye-winking tics have a parent or close relative with frequent eye-blinking or blepharospasm. Five patients with adult-onset blepharospasm or Meige's syndrome are also described who had excessive eye-blinking dating back to childhood. It is suggested that eye-winking tics, frequent blinking and blepharospasm may share common pathophysiological mechanisms; the clinical expression may be age-related.

Adolescent↗
PubMed1993

Smooth eye movements elicited by microstimulation in the primate frontal eye field.

1. We electrically stimulated the macaque monkey's frontal eye field (FEF) region to localize and to analyze the smooth pursuit eye movement representation. Rhesus monkeys were trained to fixate stationary spots of light, and trains of stimulation (usually 250-500 ms at 10-100 microA) were applied while the fixation targets remained lit and stationary. This paradigm was used in a total of 485 electrode penetrations through the arcuate sulcus region of six hemispheres in three adult monkeys. Smooth eye movements (SEMs), clearly distinct from saccades, were elicited at 86 sites in 53 of these penetrations. These SEMs had an average peak velocity of 11 degrees/s and an average latency of 39 ms. 2. The initial acceleration and peak velocity of elicited SEMs increased with stimulation intensity at any given site. On the other hand, SEM direction was characteristic of a given stimulation site and did not vary with stimulation intensity. These findings indicate that SEM amplitude is coded by the intensity of neural activity, and SEM direction is coded by the location of this activity within the cortex ("rate" vs. "place" codes). 3. SEMs elicited in the presence of a stationary fixation target (closed-loop conditions) typically reached a plateau velocity early in the stimulation and maintained that velocity throughout most of the stimulation train. However, when retinal slip was eliminated by artificially stabilizing the fixation target on the fovea (open-loop conditions), the electrical stimulation caused the eye to accelerate for longer periods and to attain higher velocities than in the closed-loop condition. Eye velocities obtained at the same site in open- and closed-loop conditions diverged from one another approximately 100 ms after SEM onset, consistent with the visual latency of the pursuit system. These findings suggest that the FEF primarily conveys an eye acceleration signal, rather than an eye velocity goal, to the pursuit system, and that this signal can be affected by visual retinal errors before effecting the smooth eye movements. 4. SEMs were elicited from a small portion of the arcuate fundus and neighboring posterior bank lying directly posterior to the principal sulcus. Functionally, this SEM region was surrounded by the saccadic FEF and by somatic premotor cortex. 5. Even though ipsilateral, contralateral, and vertical SEMs were elicited, the distribution of SEM directions was skewed toward ipsilateral movements. This tendency was more pronounced for sites in the arcuate fundus, whereas SEMs elicited from the posterior arcuate bank were often directed contralaterally and vertically.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗