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PubMedDate not supplied

Modulation of mean eye position during vestibular induced eye movements of the rhesus monkey.

Vestibular induced nystagmus in the dark was measured during sinusoidal rotational stimulation in three male monkeys using electrooculography. A periodic modulation of mean eye position was observed. This periodic modulation was quantified by least squares fitting through the nystagmus a sinusoid whose frequency was the same as that of the stimulus. The magnitude and the phase of the best fitting sinusoid were used to determine gain and phase delay at various combinations of stimulus amplitudes and frequency. Results indicate that the mean eye position in the alert animals is predominantly modulated in the direction of the fast component of nystagmus. The magnitude of this modulation of mean eye position is independent of the amplitude of the stimulus. The phase relationship of this modulation is dependent on the frequency of stimulation. In drowsy animals, the modulation of mean eye position is predominantly in the direction of the slow component of nystagmus. We conclude that the modulation of mean eye position during vestibular induced nystagmus operates as an automatic gain control system which is sensitive to the animal's level of alertness. The quantitative data in this report are useful in refining current models of vestibular nystagmus.

Animals↗
PubMed2001

Conjunctival histologic findings of dry eye and non-dry eye contact lens wearing subjects.

PURPOSE: To determine if contact lens wearers with dry eye (DE CL) have greater histological and inflammatory conjunctival epithelial changes compared to non-dry eye contact lens wearers (CL). METHODS: Fifty-eight myopic subjects were recruited for the study: DE CL group (N=27), CL group (N=11), and control group (N=20). Contact lens groups were matched for proportions of rigid gas permeable (RGP) lenses, disposables, and conventional soft contact lenses. Dry eye was defined by McMonnies dry eye symptom survey score of > or =14, fluorescein break up time (FBUT) of <10 seconds, and the presence of rose bengal staining. Ocular surface samples were taken using conjunctival impression cytology to determine nucleo-cytoplasm ratio, goblet cell density (GCD), and expression of conjunctival antigens to HLA DR and CD23. RESULTS: HLA DR and CD23 expression were significantly greater for the DE CL group compared to the CL group (P=0.0122 and P=0.0072, respectively). The CL group had a significant reduction in GCD (P=0.0001), and greater expression of ocular surface antigens to HLA DR (P=0.04) and CD23 (P=0.04) compared to the control group. CONCLUSIONS: The results of this study support the view that mechanical influences are responsible for the conjunctival squamous metaplasia changes in contact lens wear. Dry eye in contact lens wear is associated with allergic and immune mediated inflammatory processes.

Adult↗
PubMedDate not supplied

[Fluorescence angiography of the anterior eye segment in the evaluation of impaired microcirculation within the diagnosis of severity of eye burns].

We used fluorescence angiography to study the vascular microcirculation in the anterior eye segment of 14 patients with severe eye bums. The severity of eye burns is not only related with an impaired blood circulation in the conjunctiva, it also depends on a microcirculation status of episcleral vessels. Different degrees of permeability of fluorescein through the conjunctival or episcleral vessels make it possible to specify circulation disorders in both cases. Whether the impaired microcirculation in the anterior eye segment is transient or not can be established through a second fluorescence angiography made during days 7-8 from the burn trauma. The severity of eye burn depends directly on the sizes of ischemic regions of the sclera.

Adult↗
PubMed1977

[Visual imagery and eye movements: effects of projective size of image on eye movements (author's transl)].

The effects of size of image on eye movements were explored. Eye movements of 18 subjects were recorded by the corneal reflection method. The subjects imagined various objects within an indicated circle of concentric circles presented externally. As the result, two types of the subjects were observed. They were as follows: (a) The majority moved their eyes within the projective angle under the 10 degrees condition and the 30 degrees condition whereas they scarcely showed eye movements under the 1 degrees condition. Asked whether a property of the stimulus belonged to the image, over 60% of the subjects, under the 30 degrees condition, showed a saccade to the proper projected part which might be considered as scanning. (b) Some subjects hardly moved their eyes under any of the conditions.

Adolescent↗
PubMed1996

Searching eye movement, smooth pursuit eye movement and schizophrenia.

OBJECTIVE: To detect whether the smooth pursuit eye movement (SPEM) and searching eye movement (SEM) could be considered as a biological marker of schizophrenia, and used as a tool in helping diagnosis of schizophrenia. METHODS: 88 schizophrenics, 77 patients with mood disorders, 32 with "neurosis", and 74 normal healthy controls were examined for SPEM and SEM individually. The authors verified the results in all the first-visit 150 outpatients in March 1993 by comparing the examination results with the clinical diagnoses after a 6-month follow-up. RESULTS: Significant differences were found in the number of eye fixation (NEF) and total eye scanning length (TESL) of SEM between schizophrenics and normal controls or patients with other disorders. Less NEF and shorter TESL could be helpful in differential diagnosis, and the agreement rate, Kappa coefficient was 0.62. No significant differences were found in SPEM in this investigation between non-medicated schizophrenics and normal controls. CONCLUSION: Searching eye movement (SEM) might be considered as a biological marker of schizophrenia and might be used as a supplementary tool in its diagnosis.

Adult↗
PubMed1997

Airbag-induced eye injuries: experiments with in situ cadaver eyes.

In an attempt to investigate eye injuries from airbags, a set of experiments was performed that involved the deployment of several types of airbags onto thirteen unembalmed, previously frozen cadaver heads. The airbags differed in the material, coating, presence of a tether, and folding pattern, and were deployed via a pneumatic deployment system. The eyes were impacted in situ after being repressureized with saline injected through a 30-gauge needle. Injury determination was achieved by ophthalmic ultrasound imaging, staining with fluorescein dye, and dissection. All twenty-six eyes revealed detached retinas, as shown by the ultrasound, before impact as a result of decaying tissue and the freezing process. High speed video and film were used to capture the events. The impact velocities of the airbags were recorded from the digitized film at the first contact location with the eye and ranged from 30 m/s to 66 m/s. Eyeglasses were placed on four of the specimens, and the presence of eyeglasses seemed to provide protection to the eye because of the lack of contact between the airbag and ocular region. Minimal ocular damage was recorded for all experiments.

Air Bags↗
PubMed2005

Visual and vergence eye movement-related responses of pursuit neurons in the caudal frontal eye fields to motion-in-depth stimuli.

The caudal parts of the frontal eye fields (FEF) contain smooth-pursuit related neurons. Previous studies show that most FEF pursuit neurons carry visual signals in relation to frontal spot motion and discharge before the initiation of smooth-pursuit. It has also been demonstrated that most FEF pursuit neurons discharge during vergence tracking. Accurate vergence tracking requires information about target motion-in-depth. To further understand the role of the FEF in vergence tracking and to determine whether FEF pursuit neurons carry visual information about target motion-in-depth, we examined visual and vergence eye movement-related responses of FEF pursuit neurons to sinusoidal spot motion-in-depth. During vergence tracking, most FEF pursuit neurons exhibited both vergence eye position and velocity sensitivity. Phase shifts (re target velocity) of most neurons remained virtually constant up to 1.5 Hz. About half of FEF pursuit neurons exhibited visual responses to spot motion-in-depth. The preferred directions for visual responses of most neurons were similar to those during vergence tracking. Visual responses of most of these neurons exhibited sensitivity to the velocity of spot motion-in-depth. Phase shifts of most of the responding neurons remained virtually constant up to 2.0 Hz. Neurons that exhibited visual responses in-depth were mostly separate from neurons that showed visual responses in the frontal plane. To further examine whether FEF pursuit neurons could participate in initiation of vergence tracking, we examined latencies of neuronal responses with respect to vergence eye movements induced by step target motion-in-depth. About half of FEF pursuit neurons discharged before the onset of vergence eye movements with lead times longer than 20 ms. These results together with previous observations suggest that the caudal FEF carries visual signals appropriate to be converted into motor commands for pursuit in depth and frontal plane.

Action Potentials↗
PubMed2002

[Dynamic aberrometry during accommodation of phakic eyes and eyes with potentially accommodative intraocular lenses].

Since the introduction of potentially accommodative intraocular lenses (IOLs), it was hard to perform an objective evaluation of the accommodative amplitude in pseudophakic eyes. Laser interferometric measurements were performed to evaluate anterior chamber depth changes, which provides information on the functionality of potentially accommodative IOLs. By means of wavefront analysis, the dynamic behaviour of potentially accommodative IOLs can be determined. All measurements in this study were performed using a Hartmann-Shack aberrometer at a frequency of 7 Hz. Six to 8 weeks after implantation of potentially accommodative IOLs (CrystaLens AT-45, C&C Vision, 1CU, Humanoptics), 43 eyes were investigated using this dynamic wavefront analysis. Patients focussed at a distance target for 10 s, followed by focussing at a near target for 10 s and then again at a distance target for a further 10 s. During these 30 s, a total of 200 single measurements were performed. The same measurements were also conducted in healthy eyes of young persons as well as in eyes after implantation of standard IOLs for comparative purposes. The dynamic course of changes in low-order aberrations (defocus, astigmatism) as well as high-order (e.g., fourth-order spherical aberration) were analysed. Dynamic wavefront analysis allowed objective and observer-independent measurement of changes in accommodation in phakic and pseudophakic eyes. Dynamic aberrometry is capable of objectively quantifying the effect of any surgical option for the treatment of presbyopia. We recommend use of this technology in addition to the common psychophysical examinations to attain objective information on the efficacy of the treatment modality used.

Accommodation, Ocular↗
PubMed1990

Binocular motion rivalry in macaque monkeys: eye dominance and tracking eye movements.

When the two eyes are exposed to markedly different patterns, perception becomes unstable, falling into oscillations, so that the image of one eye is seen first and then that from the other. With large stimuli the alternation is piecemeal, whilst when small stimuli are used the whole pattern alternates in unison. The purpose of this study was to determine whether a reliable, objective indicator of the perceptual state during binocular rivalry could be developed in the nonhuman primate. Monkeys (Macaca mulatta) were trained to discriminate direction of motion when presented with vertically drifting gratings moving in opposite directions in the two eyes. A high correlation was found between the direction of the slow phase of the optokinetic nystagmus (OKN) elicited by the drifting gratings during rivalry and the direction of motion reported by the monkey even though the gain of the OKN was reduced during rivalry, and the latency was longer. Behavioral eye dominance during rivalry varied significantly over time, between individuals and as a function of interocular contrast differences. Since the direction of tracking eye movements can be used to reliably monitor perceptual state during binocular motion rivalry, the opportunity exists in nonhuman primates to study the neurophysiological mechanisms underlying motion perception during the perceptually ambiguous condition of binocular rivalry.

Animals↗
PubMed1981

Fellow eyes of eyes with macular holes.

We studied the fellow eyes of eyes with macular holes by fundus photography, fluorescein angiography, and central visual field testing. Eight of 37 fellow eyes (22%) observed for a minimum of 36 months developed macular holes. Fellow eyes initially classified as normal developed fewer macular holes than fellow eyes with initial pigment epithelial defects or cystic formation.

Female↗
PubMed2002

Prediction of improved vision in the amblyopic eye after visual loss in the non-amblyopic eye.

Amblyopia arises from abnormal visual experiences in early childhood. Improved function of the amblyopic eye after visual loss in the non-amblyopic eye could be a model for residual neural plasticity. We aimed to establish the likelihood of, and predictive factors for, this improvement in function. We identified 254 individuals aged 11 years or older with unilateral amblyopia who were visually impaired after loss of vision in their non-amblyopic eye but had no other disorder affecting their amblyopic eye. 25 (10%) of 254 people had improved visual acuity in their amblyopic eye. These findings suggest there is some plasticity in the visual system of a few visually mature individuals with amblyopia, which warrants further study. Children should remain the focus of detection and treatment.

Adolescent↗
PubMed2006

[Visual improvement of an amblyopic eye in an adult patient after visual loss in the non-amblyopic eye].

BACKGROUND: The sensitive period for a successful amblyopia treatment is limited to the age of 11 to 13 years. HISTORY AND SIGNS: We present a 60-year-old patient with complete visual loss on his dominant eye after retinal arterial occlusion. The fellow eye had a known severe amblyopia with a corrected visual acuity of 0.1. THERAPY AND OUTCOME: After retinoscopy the patient received a full correction for his amblyopic eye and the vision increased to 0.25. After three months follow-up visual acuity was 0.5 for single optotypes. CONCLUSIONS: Even in adulthood a attempt at full correction of an amblyopic eye after loss of vision in the dominant eye should be performed for optimising the quality of life.

Amblyopia↗
PubMed2000

Immunobiology of xenogeneic cornea grafts in mouse eyes. II. Immunogenicity of xenogeneic cornea tissue grafts implanted in anterior chamber of mouse eyes.

BACKGROUND: Xenogeneic corneal fragments (guinea pig) are highly resistant to immune rejection in the anterior chamber of mouse eyes. Because guinea pigs and mice are discordant (i.e., mouse serum normally contains guinea pig reactive xenoantibodies), we wished to determine the extent to which xenogeneic corneal fragments placed intraocularly in normal and specifically sensitized mice activated xenoreactive T and B cells. METHODS: Guinea pig corneas, deprived surgically of epithelium, were cut into fragments and inserted into the anterior chamber of eyes of BALB/c mice, adjacent to the central cornea of the recipient. Antibody (immunoglobulin [Ig]M, IgG) and delayed type hypersensitivity (DTH) immune responses of recipient mice to guinea pig xenoantigens were assessed. The fate of xenogeneic cornea implants was assessed in mice immunized systemically to guinea pig antigens. RESULTS: Guinea pig spleen cells and corneal fragments implanted s.c. induced within 2 weeks of immunization both DTH and IgG antibodies to guinea pig xenoantigens. By contrast, xenogeneic corneal fragments implanted in the anterior chamber of mouse eyes evoked no change in recipient humoral immune status and induced mild guinea pig-specific DTH only after 5 weeks. Presensitization of mice to guinea pig xenoantigens failed to increase the proportion of grafts that were regarded as rejected, but the onset of rejection in failed grafts occurred earlier than in unsensitized recipients. Active systemic immunization of mice bearing intracameral guinea pig corneal fragments failed to curtail the grafts' survival. Guinea pig corneal fragments implanted in the anterior chamber of normal mice failed to induce anterior chamber-associated immune deviation. CONCLUSIONS: Xenogeneic corneal fragments implanted in the anterior chamber of eyes of normal mice display strikingly reduced immunogenicity, and an inability to induce anterior chamber-associated immune deviation. These properties are discussed in terms of the vulnerability of guinea pig corneal tissue to immune rejection within the eye.

Animals↗
PubMed1992

Double-blind group comparative study of 2% nedocromil sodium eye drops with 2% sodium cromoglycate and placebo eye drops in the treatment of seasonal allergic conjunctivitis.

A 4 week, multicentre, double-blind, double dummy, placebo controlled group comparative study was carried out during the birch pollen season to compare the efficacy and tolerability of 2% nedocromil sodium eye drops (twice daily) and 2% sodium cromoglycate eye drops (four times daily). Participants with a history of seasonal allergic conjunctivitis (SAC) were randomized to receive nedocromil sodium (60), sodium cromoglycate (61) or placebo (64). Clinical assessment of SAC showed improvement with both active treatments compared to placebo but symptomatology was low and only changes in photophobia and grittiness reached significance (P < 0.05). Patient diaries showed significant control of itching by both active treatments, compared to placebo, with no differences between the active preparations. Patients' opinions indicated a marked placebo effect: 73% of this group reported full or moderate control of symptoms, compared with 75% in sodium cromoglycate and 80% in the nedocromil sodium group. Unusual symptoms were most common (27 patients) with nedocromil sodium eye drops: P < 0.05 vs. placebo (15 patients). There were no serious adverse events. Nedocromil sodium eye drops (b.d.) and sodium cromoglycate eye drops (q.i.d.) were both considered clinically more effective than placebo in controlling symptoms of SAC due to birch pollen.

Adult↗
PubMed1982

Pterygium, the dominant eye and the habit of closing one eye in sunlight.

Based on findings in 21 patients with pterygium and 22 normal controls a theory is proposed that pterygium develops initially in the dominant eye. In 13 patients with unilateral pterygium the disorder in 13 was located in the dominant eye. The visual response to intense sunlight of the 21 control subjects confirmed the clinical observation that the non-dominant eye is closed and the dominant eye held open in people facing the sun. These results might explain why pterygium usually occurs first in the dominant eye. A genetic pre-disposition for the disorder is likely.

Adult↗
PubMed1996

Visually guided saccade versus eye-hand reach: contrasting neuronal activity in the cortical supplementary and frontal eye fields.

1. We studied neuronal activity in the supplementary eye field (SEF) and frontal eye field (FEF) of a monkey during performance of a conditional motor task that required capturing of a target either with a saccadic eye movement (the saccade-only condition) or with an eye-hand reach (the saccade-and-reach condition), according to visual instructions. 2. Among 106 SEF neurons that showed presaccadic activity, more than one-half of them (54%) were active preferentially under the saccade-only condition (n = 12) or under the saccade-and-reach condition (n = 45), while the remaining 49 neurons were equally active in both conditions. 3. By contrast, most (97%) of the 109 neurons in the FEF exhibited approximately equal activity in relation to saccades under the two conditions. 4. The present results suggest the possibility that SEF neurons, at least in part, are involved in signaling whether the motor task is oculomotor or combined eye-arm movements, whereas FEF neurons are mostly related to oculomotor control.

Animals↗
PubMedDate not supplied

Differences between regressive eyes and non-regressive eyes after LASIK for myopia in the time course of corneal changes assessed with the Orbscan.

The aim of this study was to compare regressive eyes with non-regressive eyes after laser in situ keratomileusis (LASIK) for myopia with regard to the time course of biomechanical changes of the cornea and to evaluate the possible roles of these changes in refractive regression following surgery. 15 eyes of 9 patients with refractive regression and 15 eyes of 11 patients with no refractive regression after LASIK for myopia were enrolled in this study. The time courses of central corneal thickness (CCT) and anterior/posterior corneal curvature radiuses (CCR) were measured with Orbscan slit scanning before and 1 week, 1 month and 3 months after LASIK for myopia. The regressive and non-regressive eyes had similar time courses of CCT before and after LASIK, whereas the 2 groups differed in the time courses of corneal shifting movements. In the regression group, the posterior CCR after LASIK was relatively stable (all p > 0.05). By contrast, in the non-regression group, the postoperative posterior CCR at week 1 had a significantly steeper curvature than that at month 3 (p = 0.000). The anterior CCR in the regression group at week 1 had a significantly flatter curvature than that at month 3 (p = 0.002) postoperatively. In contrast, there was no significant change of anterior CCR postoperatively (all p > 0.05) in the non-regression group. Taken together, these data suggest that refractive regression after LASIK might be mainly induced by corneal protrusion rather than central corneal thickening.

Adult↗
PubMed2004

Localization of collagen XVIII and the endostatin portion of collagen XVIII in aged human control eyes and eyes with age-related macular degeneration.

PURPOSE: Endostatin, a C-terminal fragment of collagen XVIII (coll XVIII) formed by proteolysis, specifically inhibits endothelial cell migration and proliferation in vitro and potently inhibits angiogenesis and tumor growth in vivo. The purpose of this study was to examine the immunolocalization of endostatin and coll XVIII in the retina and choroid of human donor tissue sections from aged control donor eyes and to determine whether the localization or relative levels are changed in age-related macular degeneration (AMD). METHODS: Ocular tissues were obtained from six aged control donors (age range, 75-86 years; mean age, 80.5 years) without evidence or history of chorioretinal disease and from nine donors with AMD (age range, 74-105 years; mean age, 88.6 years). Tissues were cryopreserved, and streptavidin alkaline phosphatase immunohistochemistry was performed with goat anti-human and mouse anti-human endostatin antibodies and rabbit anti-mouse coll XVIII. Blood vessels were identified with mouse anti-human CD-34 antibody in adjacent sections. Pigment in RPE and choroidal melanocytes was bleached. Three independent observers scored the immunohistochemical reaction product. RESULTS: In aged control eyes, coll XVIII and endostatin (the endostatin portion of coll XVIII) immunoreactivity was observed in large retinal blood vessels and in capillaries in some individuals, but the internal limiting membrane (ILM) had the most intense retinal immunostaining. There was no significant difference in immunoreactivity to both antibodies in retinal blood vessels in aged control eyes. In the choroid, endostatin and coll XVIII were localized to blood vessels, Bruch's membrane, and RPE basal lamina. AMD retina and choroid had a similar pattern and intensity of coll XVIII immunostaining, as observed in control eyes but reaction product was more diffuse in the choroid. Endostatin immunoreactivity was significantly higher in ILM (P = 0.037) in AMD retina and significantly lower in the choriocapillaris, Bruch's membrane, and RPE basal lamina of AMD choroids (P < 0.05) and completely negative in some areas of AMD choroids. CONCLUSIONS: These data suggest that reduced levels of the endostatin portion of coll XVIII in Bruch's membrane, RPE basal lamina, intercapillary septa, and choriocapillaris in eyes with AMD may be permissive for choroidal neovascularization.

Aged↗