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At least 433 records · Page 24Linked to original sources
PubMed1986

Inspection time as mental speed in mildly mentally retarded adults: analysis of eye gaze, eye movement, and orientation.

The effect of eye movements away from a target on accuracy of visual discrimination was examined. In Experiment I inspection time was measured for 10 mildly mentally retarded and 10 nonretarded adults under two conditions, with each trial initiated by the subject or under experimental control. Retarded subjects did not gain any advantage from controlling trial onset. Video records of eye movements revealed that retarded subjects glanced off-target more than did nonretarded controls, but this was not sufficient to explain appreciably slower inspection time of the retarded group. Experiment 2 supported this conclusion; the same subjects completed a letter-discrimination task with direction of gaze monitored automatically. Although retarded subjects' eye gaze was more scattered early during a trial, gaze was appropriately directed by the time that the target appeared. Results from both experiments supported the hypothesis that speed of central, perceptual processing is slower among retarded persons, over and above the influence of distractibility. Results from three experiments in Part II were consistent with this interpretation. Experiment 3 was designed to eradicate trials among retarded subjects in which gaze was not properly directed, but results showed that too few such events occurred to influence accuracy. Experiment 4 demonstrated that the preparatory procedure in the previous studies resulted in efficient eye gaze among retarded subjects. Experiment 5 confirmed that lower discriminative accuracy among 10 retarded adults (compared with 10 nonretarded controls) was not due to less-efficient orientation prior to discrimination.

Adolescent↗
PubMed1983

Na,K-ATPase in simulated eye bank and cryoextracted rabbit lenses, and human eye bank lenses and cataracts.

In the rabbit, cryoextraction of the lens and subsequent storage in Tyrode's solution did not alter the Na,K-ATPase activity from that determined in immediately excised rabbit lenses. Similarly, the procedures employed with the rabbit eye to simulate collection and storage of normal human eyes (eye banking) had no effect upon the Na,K-ATPase activity of the lens. These results permitted the investigation of human lenses with the knowledge that measured Na,K-ATPase activity had not been altered grossly by any manipulation procedures. Analysis of Na,K-ATPase activity in 44 eye bank lenses, 14 primary nuclear cataracts, 11 primary cortical cataracts, 18 primary posterior subcapsular cataracts, and 31 mixed cataracts revealed no significant difference in the enzyme activity between these groups. Similarly, there was no correlation between electrolyte levels and Na,K-ATPase in a further 18 mixed cataracts. It is concluded that, despite an often pronounced electrolyte imbalance, human cataract can develop without significant alteration in Na,K-ATPase activity.

Adenosine Triphosphatases↗
PubMed1980

The eye margin and compound-eye development in the cockroach: evidence against recruitment.

The compound eye of the cockroach nymph grows from stadium to stadium by the addition of new ommatidia to the growing edge of the eye. By a series of transplant operations on Periplaneta americana and from SEM studies on Gromphadorhina portentosa it is shown that the proliferating region of the eye margin is a budding zone. There is no recruitment of larval head-capsule epidermis into the eye.

Animals↗
PubMed1994

Blindness in different types of eye disease. A study based on the records of the Department of Eye Diseases in the Medical University, Plovdiv for the period 1982-1991.

Between 1982 and 1991, inclusive, a total of 13718 patients were treated in the Department of Eye Diseases in Plovdiv University of Medicine. Cataract patients formed the most numerous group (19.71%), followed by those with diseases of the retina (9.53%), glaucoma (7.95%), uveitis (4.9%), diseases of the cornea (3.86%), malignant tumors of the eyelids and the eyeball (2.29%) and diseases of the optic nerve (1.54%). Of these 13718 patients, 1727 (12.58%) had monocular and binocular vision below 0.08. The patients with visual acuity from 0 to 0.03 were 1330 (9.69%). Nosologically, they were distributed as follows: glacoma-422 (3.07%), eye traumas-281 (2.04%), diseases of the retina-270 (1.96%), diseases of the cornea-89 (0.64%), cataract-80 (0.58%), uveitis-77 (0.56%), malignant tumors of the eyelids and the eyeball-66 (0.48%), and diseases of the optic nerve-45 (0.32%). Glaucoma was found to be the most common cause of blindness among the patients treated in the Department of Eye Diseases, followed by eye traumas and disease of the retina. The importance of the vascular factor in inducing blindness is undeniably great. It is the underlying cause of the open-angle glaucoma, the diseases of the retina and the optic nerve.

Blindness↗
PubMedDate not supplied

Mobile eye units in the fight against eye disease in East Africa.

1. Trachoma is one of the leading causes of blindness in Kenya, but it may be prevented in the early stages by tetracycline ointment. Mobile eye units (MEUs) provide the means by which technicians travel to remote villages. 2. Ophthalmic clinical officers travel to remote areas, providing examinations, diagnoses, ointments, eye medications, and lectures on eye care. In addition, villagers are trained in basic health and hygiene to help prevent many eye disorders. 3. Once the MEUs are purchased, continuing funds are needed to keep them running and to supply them with gasoline.

Eye Diseases↗
PubMed1994

Sulfated proteoglycans in the lamina cribrosa of normal monkey eyes and monkey eyes with laser-induced glaucoma.

The distribution of the sulfated proteoglycans in the lamina cribrosa of normal monkey eyes and monkey eyes with laser-induced glaucoma were analysed by electron microscopy after cuprolinic blue dye binding. Three types of cuprolinic blue-positive filaments, CB-1, CB-2 and CB-3, were identified in the laminar beams of normal monkey eyes. CB-1 and CB-2 were both small filaments representing chondroitin and dermatan sulfate proteoglycan copolymers. The former lined up perpendicularly to the long axis of collagen fibrils, whereas the latter ran axially parallel to collagen fibrils. The large CB-3 filaments, representing chondrotin sulfate proteoglycans, were located around collagen bundles or in loose spaces within the beams. In addition, small CB-4 filaments or punctate structures representing heparan sulfate proteoglycans were found aligned on the basal laminae of blood vessels and glial cells. In the glaucomatous eyes, accumulation and enlargement of collagen-associated proteoglycan filaments were seen, accompanied by the destruction of collagenous beams. Accumulation of chondroitin sulfate proteoglycans was most evident. Prominent filamentous heparan sulfate/heparin proteoglycans were also noted in thickened astrocytic and vascular basal laminae. These may be alterations secondary to the destruction of collagen bundles. They may also represent cellular responses related to intraocular pressure elevation.

Animals↗
PubMed1993

Stereoscopic cooperation between the fovea of one eye and the periphery of the other eye at large disparities. Implications for anomalous retinal correspondence in strabismus.

In normal human observers we searched for the largest amount of visual disparity that can still provide depth information; we compared (1) crossed and uncrossed disparities and (2) symmetrical and asymmetrical locations of disparate stimuli. A pair of 3 degrees discs projected for 100 ms served as targets. Symmetrical stimuli were projected on temporal or nasal retinal loci in both eyes; asymmetrical stimuli were projected on the fovea of one eye and on the nasal or temporal periphery of the other eye. Thresholds were determined using a two-alternative forced choice procedure. Subjects had to distinguish binocular disparate images from monocular double images of identical angular separation. Among six subjects, crossed disparities were recognized by one up to 6 degrees, by three up to 9 degrees, by one up to 18 degrees, and by one up to 21 degrees. Uncrossed disparities were recognized by two at 3 degrees, by two up to 6 degrees and by two up to 9 degrees. Hence, crossed disparities could be recognized up to higher angles than uncrossed. No consistent difference was found between symmetrical and asymmetrical stimuli. Stimuli with crossed disparity appeared smaller and with uncrossed disparity larger than monocular stimuli of the same objective size, suggesting that the size-constancy mechanism operates when disparity stimuli are presented as briefly as 100 ms, i.e., without simultaneous vergence eye movements. We speculate that the far-reaching interocular connections demonstrated in normal subjects might also be utilized in the case of strabismus: these interocular connections could form the basis for anomalous retinal correspondence.

Adult↗
PubMed2006

A model that integrates eye velocity commands to keep track of smooth eye displacements.

Past results have reported conflicting findings on the oculomotor system's ability to keep track of smooth eye movements in darkness. Whereas some results indicate that saccades cannot compensate for smooth eye displacements, others report that memory-guided saccades during smooth pursuit are spatially correct. Recently, it was shown that the amount of time before the saccade made a difference: short-latency saccades were retinotopically coded, whereas long-latency saccades were spatially coded. Here, we propose a model of the saccadic system that can explain the available experimental data. The novel part of this model consists of a delayed integration of efferent smooth eye velocity commands. Two alternative physiologically realistic neural mechanisms for this integration stage are proposed. Model simulations accurately reproduced prior findings. Thus, this model reconciles the earlier contradictory reports from the literature about compensation for smooth eye movements before saccades because it involves a slow integration process.

Animals↗
PubMed2006

Implanting a clear intraocular lens in one eye and a yellow lens in the other eye: a case series.

PURPOSE: To describe the color vision disturbance reported by patients in whom a clear intraocular lens (IOL) was implanted in one eye and a yellow-tinted (blue-light-absorbing) IOL in the other eye. DESIGN: Retrospective interventional case series. METHODS: Data recorded included demographic information, dates of surgery, IOL model and power (manufacturer is the same for all lenses), best-corrected visual acuity, and subjective visual complaints. RESULTS: Four of five patients had no spontaneous color vision complaints. When these patients were informed of the unintended mismatch, all remarked that they could perceive a color vision difference, but that it was not bothersome. One of the five patients reported "beige" vision. None of the patients wanted an IOL exchange. CONCLUSION: Many patients can tolerate the color vision imbalance that results when a clear IOL is implanted in one eye and a yellow-tinted IOL is implanted in the other eye.

Aged↗
PubMed2004

Assessment of the Pascal dynamic contour tonometer in monitoring intraocular pressure in unoperated eyes and eyes after LASIK.

PURPOSE: To assess the performance of the Pascal dynamic contour tonometer (PDCT) (Swiss Microtechnology AG) by comparing it to Goldmann applanation tonometry (GAT) and noncontact air tonometry (NCT) before and after laser in situ keratomileusis (LASIK). SETTING: Vlemma Eye Institute, Athens, Greece. METHODS: Intraocular pressure was measured in 118 eyes before and 1 and 4 weeks after LASIK using GAT, NCT, and the PDCT, which allows direct, digital, transcorneal measurement of intraocular pressure. RESULTS: Preoperatively, central corneal thickness (CCT) correlated with GAT and NCT measurements but not with PDCT measurements. After LASIK, the mean reduction in CCT ranged from -3.0 to -171.0 microm (median 78 microm). The mean GAT measurement dropped by -4.9 mm Hg +/- 2.7 (SD) at 1 week and was -5.4 +/- 3.0 mm Hg at 4 weeks. Similar drops were observed in NCT measurements. The observed post-LASIK changes in GAT and NCT IOP measurements were not directly proportional to the change in CCT, refractive error, or mean keratometric readings. The preoperative and postoperative PDCT measurements did not differ significantly. CONCLUSIONS: The structural corneal changes induced by LASIK appeared to influence GAT and NCT measurements but not PDCT measurements. Therefore, PDCT may be better suited for monitoring IOP in unoperated eyes and in eyes that have had LASIK.

Adult↗
PubMed1993

Lesions of the frontal eye field impair pursuit eye movements, but preserve the predictions driving them.

Visually guided eye movements are driven by a mix of current signals (e.g. visual motion) and prior experience (predictive strategies). Previously, large ablations of the frontal eye field (FEF) impaired visually guided smooth pursuit. This study examined if the pursuit decrement could be laid to a selective loss in predictive signals. Normal monkeys demonstrated some of the same predictive eye movements documented in humans. They pursued periodic visual targets with near-zero phase lag. When such targets suddenly disappeared, the monkeys continued smooth pursuit without visual guidance for several reaction times. These epochs of 'blind pursuit' achieved a peak velocity proportional to the prior target frequency just experienced by the monkey. With predictable step-ramp targets smooth eye movements sometimes preceded target motion (anticipatory pursuit). Reaction time to begin pursuit was influenced by the target velocity of prior trials. Small unilateral ablations of 'low threshold' FEF showed smooth pursuit if the fundus of the arcuate sulcus was thoroughly removed. On the step-ramp targets the slowing was evident in both the initial 100 ms and subsequent portions of pursuit. During sine pursuit blind epochs were more slowed by surgery than were visually guided epochs of pursuit. Ipsilateral anticipatory pursuit was abolished in one subject, but not in the other subject with pursuit deficits. Otherwise, pursuit after surgery continued to display the influence of predictive strategies. The average phase lag of periodic pursuit remained much less than the pursuit system's reaction time. Blind epochs persisted after the periodic target disappeared, albeit with a lower peak velocity. Reaction time to begin pursuit of step-ramp targets remained a function of the monkey's experience on prior trials. It is argued that the FEF pursuit deficits do not reflect the loss of visual motion signals or the loss of some 'cognitive' signal such as a prediction about the target's motion, but rather can be explained as a motor deficit.

Animals↗
PubMed1999

Prevalence of diabetic eye disease in an inner city population: the Liverpool Diabetic Eye Study.

PURPOSE: To measure the population prevalence of diabetic eye disease in an inner city setting. METHODS: As part of a systematic screening programme all adult diabetic patients in four general practices were invited to attend for slit-lamp biomicroscopy by a retinal specialist. Data on non-attenders were available from community-based photography. RESULTS: Of 395 diabetic patients identified, 326 attended biomicroscopy with photographic data available on a further 31, giving a 90% compliance rate. Point prevalence of diabetes in the target population was 12.4/ 1000. Demographic data included: mean age 60 years (range 13-92 years); type of control: type I 49, type II insulin-requiring (IR) 40, type II non-insulin-requiring (NIR) 268. Prevalences were as follows: any retinopathy: of all diabetic patients 33.6%, type I 36.7%, type II IR 45.0%, type II NIR 31.3%; proliferative/ advanced: all 1.1%, type I 2.0%, type II IR 0, type II NIR 1.1%; clinically significant macular oedema: all 6.4%, type I 2.3%, type II IR 16.2%, type II NIR 5.7%. The percentage of patients with retinopathy requiring follow-up by an opthalmologist was 4.5%, and 9.2% had macular exudates within 1 disc diameter of fixation or significant circinate maculopathy. Sight-threatening diabetic eye disease (STED) was found in 13.4%. A visual acuity of < or = 6/24 in the better eye occurred in 12 (3.4%) patients and of < or = 6/60 in the better eye in 3 (0.8%). CONCLUSIONS: Compared with previous population studies, prevalences appear to have declined in type I, but remain high in type II diabetic patients and especially in those requiring insulin.

Adolescent↗
PubMed2006

Comparison of amplitude of apparent accommodation in pseudophakic eyes with that of normal accommodation in phakic eyes in various age groups.

PURPOSE: To compare the amplitude of apparent accommodation in eyes with monofocal intraocular lenses with that of normal accommodation in the phakic fellow eyes in various age groups. PATIENTS AND METHODS: In all, 130 eyes of 130 patients scheduled to undergo cataract surgery, and 130 fellow eyes that had little cataract and good visual acuity of 20/33 or better were studied. The following groups were studied: in their 40s and younger (n = 20) or in their 50s (n = 30), 60s (n = 30), 70s (n = 30), and 80s (n = 20). Using an accommodometer (Kowa HS-9E), the accommodative amplitude was measured at 1 month after surgery. RESULTS: In the patients in their 40s and younger or in their 50s, the amplitude of apparent accommodation was significantly less than that of normal accommodation; no significant difference was observed in the patients in their 60s, 70s, or 80s. The incidence of patients in whom the amplitude of apparent accommodation was more than that of normal accommodation was greater in the patients in their 60s, 70s, and 80s than in the patients in their 40s and younger and in their 50s. CONCLUSION: The amplitude of apparent accommodation is virtually equivalent to that of normal accommodation in patients older than 60 years of age.

Accommodation, Ocular↗
PubMed2006

Training the adult amblyopic eye with "perceptual learning" after vision loss in the non-amblyopic eye.

We recently reported acuity development in the amblyopic eye of a 60-year-old patient after loss of vision in her non-amblyopic eye. Here, we focus on the training that we implemented, based on new insights from psychophysical procedures aiming at functional visual improvement of adults ("perceptual learning"). We alternately used the following procedures: grating acuity (Teller-Cards); contrast sensitivity (Vistech-Charts); two spatial localization tests (vertical alignment, pointing); and labyrinth patterns for a eye-hand coordination exercise. One month without intervention was followed by six months of training and two blocks of pleoptic treatment. Clinical parameters were assessed monthly. Besides acuity gain, we observed enhanced grating resolution and contrast sensitivity, decreased alignment distortions, pointing shifts, mainly after pleoptics, and more efficient labyrinth tracing. A questionnaire reflected the patient's perception of the changes. These data confirm the plasticity of the adult amblyopic system, be it spontaneous due to the loss of the non-amblyopic eye or caused by the intervention or both. Further experience is necessary to isolate the role of the intervention. Our results also underline the limitation of adult plasticity, emphasizing the importance of early diagnosis and treatment of amblyopia.

Amblyopia↗
PubMed1996

Centration and fixation of posterior chamber intraocular lenses in eyes with pseudoexfoliation syndrome. An analysis of explanted autopsy eyes.

Pseudoexfoliation syndrome is an important risk factor in cataract surgery. We examined decentration of posterior chamber intraocular lenses in a series of 24 autopsy eyes with pseudoexfoliation syndrome that had undergone cataract surgery and intraocular lens implantation. The results were compared to a control group of 25 normal autopsy eyes that matched the pseudoexfoliation collection for age distribution, implant duration and further anatomical parameters. The mean lens decentration in all pseudoexfoliation eyes (0.75 +/- 0.38 mm) was significantly higher than in the control group (0.40 +/- 0.29 mm) (p = 0.0008). Analysis of subgroups with symmetrical bag/bag fixated intraocular lenses showed a significantly higher decentration in the pseudoexfoliation group (p = 0.04). The main reason for decentration was a decentration of the entire capsular bag in pseudoexfoliative eyes (p = 0.001), which was related to zonular weakness and damage. The results indicate that in patients with pseudoexfoliation syndrome alternative fixation sites, like sulcus or transscleral fixation, should also be considered.

Aged↗
PubMed1998

Draize eye scores and eye irritation thresholds in man can be combined into one QSAR.

Draize eye scores (DES) of 37 pure organic liquids have been converted into scores for the corresponding vapors, DES/P0, where P0 is the liquid vapor pressure in atmospheres at 298 K. It is shown that there is a constant difference of 6.7 between values of log(DES/P0) and log (1/EIT), where EIT is the eye irritation threshold in parts per million (ppm, by volume) of eight vapors for human subjects. The 37 log(DES/P0) values can be combined with log(1/EIT) values for 17 vapors into one quantitative structure-activity relationship (QSAR) for sensory potency (SP) using our general solvation equation, [formula: see text] where R2 is an excess molar refraction, pi 2H is the compound polarizability/dipolarity, sigma alpha 2H and sigma beta 2H are the compound hydrogen-bond acidity and basicity, and L16 is the gas-hexadecane partition coefficient at 298 K. n is the number of data points, r the correlation coefficient, SD the standard deviation, and F the F-statistic. LogSP is then either [log(DES/P0) - 0.66] or log (1/EIT), confirming the result for the eight common compounds. It is suggested that the equation can be used to predict eye irritancy of organic vapors and pure liquids. It is further suggested that for the compounds in the data set, the main process in eye irritation is transfer of the compound from the vapor or pure liquid to a biological phase, and a number of chemical properties of the biological phase have been mapped out through the equation. These properties are consistent with corresponding properties for a number of organic liquid phases.

Animals↗
PubMed1981

Early removal of one eye reduces normally occurring cell death in the remaining eye.

During normal development of the hamster eye, there is a substantial loss of cells from the retinal ganglion cell layer in the first two postnatal weeks. If one eye is lost at birth, this cell death is reduced in the remaining eye. This may account for the increased ipsilateral projection from this eye to the thalamus and midbrain observed in these animals.

Animals↗
PubMed1981

Microbial flora of in-use, display eye shadow testers and bacterial challenges of unused eye shadows.

We surveyed 15 different brands of eye shadow on display for customer use in different retail stores for microbial contamination. This was the first reported microbial surveillance of in-use eye shadow display testers in retail establishments. Cultures were obtained at each retail store. Sterile dacron swabs were rolled and rubbed over the entire used surface of each shadow, and each inoculum was streaked onto the surfaces of blood agar plates. Of the 1,345 individual samples obtained, 67% were contaminated with one or more species of microorganisms representing the genera Staphylococcus, Micrococcus, Corynebacterium, Acinetobacter, Bacillus, and Moraxella. We also purchased two different brands of water-miscible eye shadows in replicate unit containers. Each brand was challenged separately with a few hundred to several thousand colony-forming units of Staphylococcus aureus, Pseudomonas aeruginosa, or Acinetobacter calcoaceticus. Both brands permitted growth of P. aeruginosa but not growth of S. aureus. A. calcoaceticus was inhibited after inoculation into one brand. With the other brand, the inoculum of Acinetobacter multiplied in one of the two different lots tested. This experimental challenge procedure can serve as a useful model system for studying the behavior of microbes in eye shadows and similar matrices.

Acinetobacter↗