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Localization and regulation of glucagon receptors in the chick eye and preproglucagon and glucagon receptor expression in the mouse eye.

Myopia is a condition in which the eye is too long for the focal length of cornea and lens. Analysis of the messengers that are released by the retina to control axial eye growth in the animal model of the chicken revealed that glucagon-immunoreactive amacrine cells are involved in the retinal image processing that controls the growth of the sclera. It was found that the amount of retinal glucagon mRNA increased during treatment with positive lenses and pharmacological studies supported the idea that glucagon may act as a stop signal for eye growth. Glucagon exerts its regulatory effects by binding to a single type of glucagon receptor. In this study, we have sequenced the chicken glucagon receptor and compared its DNA and amino acid sequence with the human and mouse homologues. After sequencing about 80% of the receptor, we found a homology between 79.4 and 75.6% on cDNA level. At the protein level, about 73% of the amino acids were identical. Moreover, the cellular localization and regulation of the glucagon receptor in the chick retina was studied. In situ hybridization studies showed that many cells in the ganglion cell layer and inner nuclear layer, and some cells in the outer nuclear layer, express the receptor mRNA. Injection of the glucagon agonist Lys17,18,Glu21-glucagon induced a down-regulation of glucagon receptor mRNA content. Since the mouse would be an attractive mammalian model to study the biochemical and genetic basis of myopia, and because recent studies have demonstrated that form deprivation myopia can be induced, the expression of preproglucagon and glucagon receptor genes were also studied in the mouse retina and were found to be expressed.

Amacrine Cells↗

Eye movements and prospective memory: what the eyes can tell us about prospective memory.

In this study we used eye tracking methodology in combination with multi-element displays to examine the processes underlying event-based prospective memory in a visual search paradigm. In the task individuals searched for a different target stimulus (i.e., a letter) on each trial that could be present or absent, and made prospective responses to the letters D or M. The response accuracy data revealed that target hits were more frequent than prospective hits, and that there was no difference in response time for target and prospective responses. The eye tracking data revealed that both first and total fixation durations increased from distractors (stimuli that were neither targets nor prospective cues) to targets to prospective cues when a target or prospective response was made. These measures also revealed that the presence of a target in the display served to disrupt prospective memory. In addition, prospective memory misses resulted from a combination of failures to fixate the prospective cues and failures to engage in strategic processing of the prospective cues. These data demonstrate the utility of eye tracking methods in examining the processes underlying event-based prospective memory.

Analysis of Variance↗

Femtosecond laser-assisted posterior lamellar keratoplasty: initial studies of surgical technique in eye bank eyes.

OBJECTIVE: To perfect the technique of femtosecond laser-assisted cutting of the lamellar corneal disc in posterior lamellar keratoplasty. DESIGN: Experimental study. METHODS: The femtosecond laser was used to make the posterior corneal lamellar interface and trephine (side) cut in 20 eye bank globes and 9 eye bank corneoscleral buttons. Laser parameters were energy 7.4+/-0.1 microJ (lamellar cut) and 8.7+/-0.1 microJ (trephination cut), spot size 2.4 microm, firing rate 15 kHz, and trephination diameter 6.0 to 8.0 mm. The thicknesses of the excised corneal discs were measured with a digital micrometer and compared with values calculated from the laser treatment parameters and the preoperative ultrasound pachymetric readings. The cut surfaces were examined by light microscopy and scanning electron microscopy. In globes, the corneal disc was removed from the eye after laser treatment through a blade incision in the peripheral cornea. In corneoscleral buttons, the posterior disc was peeled off the cornea with forceps after laser treatment on an artificial anterior chamber device. In simulated transplantation, the excised corneal disc was placed into the posterior stromal bed in 7 globes. RESULTS: The femtosecond laser was successful in making posterior lamellar and trephination cuts in cornea. The cut surfaces were of very good quality with straight, orthogonal edges, albeit with a mild stucco texture of the lamellar stromal surfaces. In 3 globes, the lamellar surface showed shallow concentric ridges. The measured thickness of the excised discs was 55+/-61 microm thicker than the preoperatively predicted values. CONCLUSIONS: These preliminary studies show that the femtosecond laser can make nonmechanical cuts for posterior lamellar keratoplasty with relative ease and reliability, thus facilitating the most technically difficult step in this surgery.

Cornea↗

Risk factors associated with age-related macular degeneration. A case-control study in the age-related eye disease study: Age-Related Eye Disease Study Report Number 3.

OBJECTIVE: To investigate possible risk factors for age-related macular degeneration (AMD) in participants in the Age-Related Eye Disease Study (AREDS). DESIGN: Case-control study. PARTICIPANTS: Of the 4757 persons enrolled in AREDS, 4519 persons aged 60 to 80 years were included in this study. The lesions associated with AMD ranged from absent in both eyes to advanced in one eye. MAIN OUTCOME MEASURES: Stereoscopic color fundus photographs of the macula were used to place participants into one of five groups, based on the frequency and severity of lesions associated with AMD. Participants with fewer than 15 small drusen served as the control group. RESULTS: Staged model building techniques were used to compare each of the four case groups with the control group. Increased age was a consistent finding of all four of the case groups compared with the control group, and all the following associations were age adjusted. Persons with either intermediate drusen, extensive small drusen, or the pigment abnormalities associated with AMD (group 2) were more likely to be female, more likely to have a history of arthritis, and less likely to have a history of angina. Persons with one or more large drusen or extensive intermediate drusen (group 3) were more likely to use hydrochlorothiazide diuretics and more likely to have arthritis. Hypertension, hyperopia, presence of lens opacities, and white race were also found more frequently in this group as well as in persons with neovascular AMD (group 5). Only persons in group 5 were more likely to have an increased body mass index, whereas persons with geographic atrophy (group 4) as well as those in groups 3 and 5 were more likely to have completed fewer years in school or to be smokers. Those with geographic atrophy were also more likely to use thyroid hormones and antacids. CONCLUSIONS: Our findings for smoking and hypertension, which have been noted in previous studies, suggest that two important public health recommendations, the avoidance of smoking and the prevention of hypertension, may reduce the risk of developing AMD. Other associations, such as those for hyperopia, lens opacities, less education, female gender, increased body mass index, and white race, which have been noted in other studies, are also seen in the AREDS population. The increased use of thyroid hormones and antacids in persons with geographic atrophy and the increased likelihood of arthritis or hydrochlorothiazide use in persons with one or more large drusen or extensive intermediate drusen have not been previously reported and need additional investigation.

Aged↗

Neuronal activity in the frontal eye field of the monkey is modulated while attention is focused on to a stimulus in the peripheral visual field, irrespective of eye movement.

We tested the hypothesis that the frontal eye field (FEF) is involved in attention to the peripheral visual field (PVF). Neuronal activity was recorded in the FEF of two monkeys while they were performing three oculomotor tasks. In the visual attention task (VAT), the monkeys released a lever when a test stimulus (TS) presented in the PVF dimmed while they were looking at a central fixation point (FP). In the visual saccade task (VST), the monkeys exhibited saccadic eye movements when the FP was extinguished. In the visual fixation task (VFT), the monkeys released the lever when the FP dimmed. Overall, the activities of 80 FEF neurons were examined. The responses to visual stimuli of 41 of these neurons (51%) were modulated during the VAT. Twenty-five neurons showed pre-saccadic activity. Of these, 13 neurons (52%) exhibited activity modulation during the VAT. Eighteen neurons showed no pre-saccadic activity. Of these, 10 neurons (56%) exhibited activity modulation during the VAT. These results suggest that the FEF is involved in selecting the visual stimuli relevant to performing a task irrespective of eye movements.

Animals↗

Social phobics do not see eye to eye: a visual scanpath study of emotional expression processing.

Clinical observation suggests that social phobia is characterised by eye avoidance in social interaction, reflecting an exaggerated social sensitivity. These reports are consistent with cognitive models of social phobia that emphasize the role of interpersonal processing biases. Yet, these observations have not been verified empirically, nor has the psychophysiological basis of eye avoidance been examined. This is the first study to use an objective psychophysiological marker of visual attention (the visual scanpath) to examine directly how social phobia subjects process interpersonal (facial expression) stimuli. An infra-red corneal reflection technique was used to record visual scanpaths in response to neutral, happy and sad face stimuli in 15 subjects with social phobia, and 15 age and sex-matched normal controls. The social phobia subjects showed an avoidance of facial features, particularly the eyes, but extensive scanning of non-features, compared with the controls. These findings suggest that attentional strategies for the active avoidance of salient facial features are an important marker of interpersonal cues in social phobia. Visual scanpath evidence may, therefore, have important implications for clinical intervention.

Adult↗

Birmingham Eye Trauma Terminology (BETT): terminology and classification of mechanical eye injuries.

Lacking a standardized terminology of eye injury types, it is impossible to fulfill a very basic requirement in medicine: that all communications be unambiguous. Accurate interpretation of published research results, which plays an absolutely crucial role in determining how an individual patient with an eye injury is treated, becomes difficult. This article presents an internationally standardized system that finally allows accurate description of eye injuries of all types.

Alabama↗

Temporal control of glial cell migration in the Drosophila eye requires gilgamesh, hedgehog, and eye specification genes.

In the Drosophila visual system, photoreceptor neurons (R cells) extend axons towards glial cells located at the posterior edge of the eye disc. In gilgamesh (gish) mutants, glial cells invade anterior regions of the eye disc prior to R cell differentiation and R cell axons extend anteriorly along these cells. gish encodes casein kinase Igamma. gish, sine oculis, eyeless, and hedgehog (hh) act in the posterior region of the eye disc to prevent precocious glial cell migration. Targeted expression of Hh in this region rescues the gish phenotype, though the glial cells do not require the canonical Hh signaling pathway to respond. We propose that the spatiotemporal control of glial cell migration plays a critical role in determining the directionality of R cell axon outgrowth.

Animals↗

The Eye Book of Master Peter of Spain--a glimpse of diagnosis and treatment of eye disease in the Middle Ages.

Peter Hispanus, who became Pope John XXI, wrote a book about eye diseases and their treatment in the 13th century. De Oculis was not a scholarly treatise about eye diseases, but a manual intended for general physicians. Nevertheless, Latin copies were made into the 16th century, indicating its influence and importance. We present the first published English translation of De Oculis, based on a synthesis of the medieval Latin manuscripts and a German translation from the 19th century. The sources of Peter's understanding of the causes and treatment of eye diseases were the more scholarly and complete treatises by Greek and Arab writers. Many of the diseases described then cannot be correlated precisely with ophthalmic disorders known to us today because of the limited understanding of anatomy, function and pathophysiology that existed. However, De Oculis provides us with a glimpse of the practice of medicine in the Middle Ages.

Eye Diseases↗

Are eyes windows to a deceiver's soul? Children's use of another's eye gaze cues in a deceptive situation.

Three experiments examined 3- to 5-year-olds' use of eye gaze cues to infer truth in a deceptive situation. Children watched a video of an actor who hid a toy in 1 of 3 cups. In Experiments 1 and 2, the actor claimed ignorance about the toy's location but looked toward 1 of the cups, without (Experiment 1) and with (Experiment 2) head movement. In Experiment 3, the actor provided contradictory verbal and eye gaze clues about the location of the toy. Four- and 5-year-olds correctly used the actor's gaze cues to locate the toy, whereas 3-year-olds failed to do so. Results suggest that by 4 years of age, children begin to understand that eye gaze cues displayed by a deceiver can be informative about the true state of affairs.

Child, Preschool↗

[Consensual inflammatory reaction in chemical eye burn of the rabbit eye].

BACKGROUND: Consensual ocular response has been known to occur following intracranial stimulation of the trigeminal nerve, intracameral injection of prostaglandins and other substances, after paracentesis and contusio bulbi. MATERIAL AND METHOD: We have examined the prostacyclin formation in both eyes after experimental alcali burn (0.25 mo/l NaOH) on 30 rabbits with ELISA over a follow up period of 14 days. RESULTS: After the alcali burn the aqueous prostacyclin level on the right eye is increased from 327 pg/ml aqueous to 27098 pg/ml aqueous, but on the left it stays normally. In conjunctiva and anterior uvea we measured normal amounts of prostacyclin. CONCLUSIONS: We could not find a consensual increase in prostacyclin formation in the anterior part of the fellow eye following alcali burn.

Animals↗

[Eye operation with local anesthesia and protection of the other eye with a watch glass in patients afraid of visual occlusion by surgical drapes].

PATIENTS: We report on 30 patients who were afraid of having their faces fully covered with surgical drapes for the purpose of an eye-operation in local anesthesia. CHOICE: Patients who reported spontaneously of claustrophobia or who showed progressive fear during the routine preoperative preparation were chosen. METHOD: The second eye was protected by means of a watch-glass and covered again with a sterile film together with the eye to be operated upon. RESULTS: In all of these cases operation in local anesthesia was possible, no general anesthesia was needed.

Anxiety↗

An evaluation of the efficacy of a cyclosporine-based dry eye therapy when used with marketed artificial tears as supportive therapy in dry eye.

PURPOSE: To evaluate the efficacy of marketed artificial tears in relieving the signs and symptoms of dry eye when used as supportive therapy to a cyclosporine-based ophthalmic emulsion. METHODS: Sixty-one patients were enrolled in this randomized, investigator-masked, parallel study of 6 months' duration. Eligible patients needed a Schirmer I score without anesthesia of 7 mm or less at day -7 and to answer that they needed artificial tears at least "some of the time." Corneal staining of 3 or more (National Eye Institute grid, 15 points) at day -7 and day 0 in the same eye was also required. Patients were randomized to one of three regimens: Restasis (0.05% cyclosporine) twice per day with Systane used a minimum of once per day (Restasis + Systane); Restasis twice per day with Refresh Tears used a minimum of once per day (Restasis + Refresh); and Systane alone used four times per day. Signs and symptoms were measured at days -7, 0, 7, 14, 28, 42, 120, and 180. RESULTS: A statistical difference was seen in favor of Restasis + Systane versus Restasis + Refresh for corneal staining (P = 0.0048) change from baseline and a trend (P = 0.0725) for increased tear film breakup time at 6 months. There were no differences between treatment groups for Schirmer score, conjunctival staining, or conjunctival injection. Significant differences were seen in favor of Restasis + Systane versus Restasis + Refresh for less ocular burning (P = 0.0210), stinging (P = 0.0314), grittiness (P = 0.0128), and dryness (P = 0.0132). Systane was better than Restasis + Refresh for less burning (P = 0.0288), dryness (P = 0.0480), and scratchiness (P = 0.0294). CONCLUSIONS: Results indicate that the choice of concomitant therapy used with Restasis has significant effects on outcome measures. Both supportive therapies were compatible with Restasis.

Adult↗

Pre-term delivery and the growth of the eye. An oculometric study of eye size around term-time.

Refraction and axial eye dimensions, evaluated by ultrasound measurements, were investigated in 101 pre-term infants and 25 full-term controls. Gestational ages in the pre-term group ranged from 25 to 34 weeks, birth weights from 728 to 2480 g. All were seen in the eye clinic due to risk of developing retinopathy of prematurity. Age at examination was 36-54 weeks (gestational/conceptional) in the pre-terms and 37.3-50 weeks in the term infants. Adjusted to a 40 weeks axial length value (based on an assumed average eye elongation of 0.14 mm per week) the term-values were similar, 17.02 and 17.03 mm in the two groups. Within the premature group, however, the 40-week adjusted axial lengths were shorter, the shorter the gestational age. The study demonstrated more foetal anterior segment proportions, with flatter anterior chambers and thicker, more spheroid lenses in the preterm infants. Probably this explains the early preponderance of myopia in that group, at feature eventually to disappear, and not to be confused with myopia of prematurity. As compared to the full-terms a correlational disturbance by pre-term delivery was further indicated by the absence of the usual correlation between axial length and refractive value.

Anthropometry↗

Effects of frontal eye field and superior colliculus ablations on eye movements.

Two parallel neural pathways are primarily responsible for the control of saccadic eye movements--one mediated through the frontal eye fields and the other through the superior colliculus. When both pathways are disrupted, control of saccadic eye movements is lost. Disruption of either pathway alone produces only subtle deficits.

Animals↗

Eye-specific termination bands in tecta of three-eyed frogs.

An extra eye primordium was implanted into the forebrain region of embryonic Rana pipiens. During development both normal and supernumerary optic tracts terminated within a single, previously uninnervated tectal lobe. Autoradiographic tracing of either the normal or supernumerary eye's projection revealed distinct, eye-specific bands of radioactivity running rostrocaudally through the dually innervated tectum. Interactions among axons of retinal ganglion cells, possibly mediated through tectal neurons, must be invoked to explain this stereotyped disruption of the normally continuous retinal termination pattern.

Animals↗

Prostaglandin F2 alpha-isopropylester eye drops: effects in normal human eyes.

The effects of PGF2 alpha-isopropylester eye drops on intraocular pressure (IOP) and aqueous humour dynamics were investigated in healthy male volunteers. The other eye was treated with vehicle and used as a control. Special attention was also paid to adverse effects. Single and repeated doses were tested. There was a dose related effect on IOP. Significant reductions were observed 4, 8, and 12 hours after application of 1.0, 2.5, or 10 micrograms PGF2 alpha equivalents of the drug. With 10 micrograms the effect lasted 24 hours. An initial tendency towards an increase in IOP was observed for these doses. Repeated doses of 1.0 microgram daily or 0.5 microgram twice daily produced a significant and lasting IOP reduction of about 2 mmHg for 1-2 weeks. Aqueous humour production was not altered, and outflow facility was not significantly changed. There was a dose dependent hyperaemia with a maximum within 2 hours after application. A foreign body sensation, some pain, and photophobia were noted with increasing doses. A slight miosis of 1 mm was seen in three of six eyes treated with 10 micrograms. No signs of intraocular inflammation were recorded, but a slight increase in penetration of fluorescein into the anterior chamber was observed after 16 days of treatment.

Adult↗