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At least 343 records · Page 19Linked to original sources

Large optic discs in large eyes, small optic discs in small eyes.

The optic disc area, varying interindividually by a factor of 1:7, is correlated with the count of the retinal ganglion cell axons and photoreceptors. This study evaluated whether the variations in the disc size are additionally correlated with those of the coronary diameters of the globe. Fifty-three normal human donor eyes with a mean age of 54.2 +/- 19.6 years were included in the study. After performing a 16-mm corneoscleral trephination, the globes were fixed and the horizontal and vertical diameters of the globes were measured. We cut the globes into meridional slices sticking together at the posterior fundus region. The areas of the whole retina and the optic disc were planimetrically evaluated on photographs with a millimeter scale aligned. We found that the horizontal and vertical diameters of the globe were correlated with the optic disc size and the retinal surface area. Eyes with long horizontal and vertical diameters had a larger optic disc and a larger retinal surface area than eyes with short diameters. The results suggest the combination of large optic discs in large eyes and of small optic discs in small eyes. Taking into account the relatively low correlation coefficients of 0.3 and 0.4, the study also suggests the existence of other not-evaluated factors influencing the occurrence of large optic discs. The results go along with the reported association between a large optic disc area and a large cornea size.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Flattening of central corneal curvature with intrastromal corneal rings of increasing thickness: an eye-bank eye study.

Intrastromal Corneal Rings (ICRs) have been demonstrated to flatten human corneas when implanted into peripheral intrastromal corneal channels. To study the flattening effect, ICRs of increasing thickness, 0.26, 0.31, 0.36, 0.41, and 0.46 mm, were placed into oversized (approximately 70% depth) intrastromal channels in 38 eye-bank eyes. Each of 33 eyes received one ICR; the mean change in dioptric data was obtained for four meridians using an intraoperative photokeratoscope. Intrastromal corneal rings of increasing thickness resulted in corneal flattening of 3.8 +/- 1.1, 4.9 +/- 0.6, 5.2 +/- 1.1, 5.3 +/- 1.9, and 7.3 +/- 1.6 diopters, respectively, for keratoscope mire 2. One of each size ICR was placed into one of five additional eye-bank eyes; the degree of flattening measured by laser holographic interferometry was 1.8, 2.9, 5.5, 4.7, and 10.1 diopters, respectively, for the central 6 mm corneal zone. These results indicate that the ICR provides a fairly linear flattening relationship over the range of thicknesses tested. Additionally, laser holographic interferometry wave unit maps of preoperative and postoperative corneas demonstrated that the ICR tends to preserve positive corneal asphericity if present preoperatively.

Anthropometry↗

Tensile strength of lens capsules in eye-bank eyes.

PURPOSE: To measure the tensile strength of the anterior and posterior lens capsules in eye-bank eyes and study the tensile strength of capsules dehydrated with hypertonic glucose solution. SETTING: Tongren Hospital, Beijing, China. METHODS: The in situ anterior and posterior capsules of 35 eye-bank eyes (Group 1) donated by healthy men aged 20 to 40 years (mean 27.1 years) were measured with a biomembrane strength device. Sixteen eyes (Group 2), from donors aged 20 to 37 years (mean 27.0 years) and similar to those in Group 1, were measured in the same way after the anterior and posterior capsules were exposed to glucose 50% solution for 15 minutes. RESULTS: In Group 1, anterior and posterior capsule strength was 6.269 +/- 1.118 and 3.755 +/- 0.835 g, respectively (P < .01), and the correlation between the tensile strength of the anterior and posterior capsules was statistically significant (r = .94; P < .001). In Group 2, the strength of the capsules increased to 9.024 +/- 0.586 and 4.424 +/- 0.761 g, respectively, a finding that was statistically significantly different from that in Group 1 (P < .01 and .05, respectively. CONCLUSION: The tensile strength of the anterior capsule was stronger than that of the posterior capsule under the experimental conditions. Glucose 50% solution has the potential to increase the tensile strength of anterior and posterior capsules.

Adult↗

Transient expression of the Drosophila melanogaster cinnabar gene rescues eye color in the white eye (WE) strain of Aedes aegypti.

The lack of eye pigment in the Aedes aegypti WE (white eye) colony was confirmed to be due to a mutation in the kynurenine hydroxylase gene, which catalyzes one of the steps in the metabolic synthesis of ommochrome eye pigments. Partial restoration of eye color (orange to red phenotype) in pupae and adults occurred in both sexes when first or second instar larvae were reared in water containing 3-hydroxykynurenine, the metabolic product of the enzyme kynurenine hydroxylase. No eye color restoration was observed when larvae were reared in water containing kynurenine sulfate, the precursor of 3-hydroxykynurenine in the ommochrome synthesis pathway. In addition, a plasmid clone containing the wild type Drosophila melanogaster gene encoding kynurenine hydroxylase, cinnabar (cn), was also able to complement the kynurenine hydroxylase mutation when it was injected into embryos of the A. aegypti WE strain. The ability to complement this A. aegypti mutant with the transiently expressed D. melanogaster cinnabar gene supports the value of this gene as a transformation reporter for use with A. aegypti WE and possibly other Diptera with null mutations in the kynurenine hydroxylase gene.

Aedes↗

Apparent movement, eye movements and phoria when two eyes alternate in viewing a stimulus.

Three experiments were conducted to test the hypothesis that the apparent movement of a stimulus when the two eyes are alternately occluded can be explained by phoria and Hering's principles of visual direction. In experiments 1 and 2, the direction of apparent movement, eye position, and eye movements were measured when eye movements did and did not occur. In experiment 3, the magnitude of apparent movement and the extent of phoria were comapred. Results from the experiments 1 and 2 indicated that the direction of apparent movement could be predicted from the direction of phoria, in conjunction with Hering's principles, and was not contingent on eye movements. In experiment 3, a high positive correlation (r = 0.95) between the magnitude of apparent movement and the extent of phoria was obtained.

Eye Movements↗

Clinical evaluation of an HP-guar gellable lubricant eye drop for the relief of dryness of the eye.

PURPOSE: To evaluate the efficacy of a new lubricant eye drop containing polyethylene glycol 400 and propylene glycol demulcents with hydroxypropyl-guar as a gelling agent (Test Product) to a system with carboxymethylcellulose (Control Product) for reducing dry eye signs and symptoms. METHODS: Eighty-seven dry eye volunteers were enrolled at seven sites for this six-week, concurrently controlled, double-masked clinical study. RESULTS: The Test Product significantly reduced conjunctival staining (p = 0.025) and temporal corneal staining (p = 0.024) compared to the Control. The Test Product also significantly reduced symptoms of dryness in the morning and evening, compared to the Control (p = 0.015 and p = 0.023, respectively). Subjects in the Test treatment group reported lower frequencies of foreign body sensation and felt their eyes were "refreshed longer" compared to those in the Control group (p = 0.033 and p = 0.037, respectively). CONCLUSIONS: The Test Product was more effective at reducing both the signs and symptoms of dry eye compared to the carboxymethylcellulose containing Control.

Carboxymethylcellulose Sodium↗

ECEM (eye closure eye movements): integrating aspects of EMDR with hypnosis for treatment of trauma.

The paper addresses distinctions between hypnotic interventions and Eye Movement Desensitizing and Reprocessing (EMDR) and discusses their effect on persons who have symptoms of Posttraumatic Stress Disorder (PTSD). Eye movements in hypnosis and EMDR are considered in terms of the different ways they may affect responses in treatment. A treatment intervention within hypnosis called ECEM (Eye Closure, Eye Movements) is described. ECEM can be used for patients with histories of trauma who did not benefit adequately from either interventions in hypnosis or the EMDR treatment protocol used separately. In ECEM the eye movement variable of EMDR is integrated within a hypnosis protocol to enhance benefits of hypnosis and reduce certain risks of EMDR.

Adult↗

Novel ENU-induced eye mutations in the mouse: models for human eye disease.

We have carried out a genome-wide screen for novel N-ethyl-N-nitrosourea-induced mutations that give rise to eye and vision abnormalities in the mouse and have identified 25 inherited phenotypes that affect all parts of the eye. A combination of genetic mapping, complementation and molecular analysis revealed that 14 of these are mutations in genes previously identified to play a role in eye pathophysiology, namely Pax6, Mitf, Egfr and Pde6b. Many of the others are located in genomic regions lacking candidate genes and these define new loci. Four of the mutants display a similar phenotype of dilated pupils but do not appear to be allelic, and at least two of these are embryonic lethal when homozygous. This collection of eye mutations will be valuable for understanding gene function, for dissecting protein function and as models of human eye disease.

Alkylating Agents↗

The immune response and the eye. TCR alpha-chain related molecules regulate the systemic immunity to antigen presented in the eye.

Injection of antigen into the anterior chamber (AC) of the eye results in the induction of immune deviation in which antibody production is activated and delayed-type hypersensitivity (DTH) is inhibited. This system is termed anterior chamber associated immune deviation (ACAID) and the model is used to examine certain aspects of the immunologic privilege of the eye. Recent studies have established that following antigen presentation in the eye, an 'ACAID-inducing' signal is produced that directly enters the blood. This signal then homes to the spleen where T cells that down-regulate DTH are activated. For many antigens this 'ACAID signal' is a soluble protein released within 2 days of AC injection. Although the presence of this molecule (or molecules) has been described using several antigens, the exact nature of the soluble mediator has escaped characterization. We have further explored the nature of this signal using HSV-1-induced immune deviation. Our results show the soluble 'signal' was released by T cells that encounter antigen in the ocular microenvironment. This mediator was antigen specific, contained TCR alpha-chain (but not the TCR beta-chain) determinants and had an apparent molecular weight of 46 kDa. These results show that the release of soluble TCR alpha-chain from sites of T cell interaction within the microenvironment of the eye can regulate systemic immune responses. These results have implications for the control of immune response that might be damaging to organs such as the eye.

Animals↗

Eyes first! Eye processing develops before face processing in children.

Faces and eyes are critical social stimuli which adults process with ease, but how this expertise develops is not yet understood. Neural changes associated with face and eye processing were investigated developmentally using ERPs (N170), in 128 subjects (4-15 year olds and adults). Stimuli included upright faces to assess configural processing, eyes and inverted faces to assess feature-based processing. N170 was present in the youngest children with similar patterns of face sensitivity seen in adults. Development of N170 to upright faces continued until adulthood, suggesting slow maturation of configural processing. In contrast, N170 was shorter latency and much larger to eyes than faces in children and was mature by 11 years, suggesting the early presence of an eye detector, with a rapid maturational course.

Adolescent↗

Investigation of corneal effect of different types of artificial tears in a simulated dry eye condition using a novel porcine dry eye model (pDEM).

PURPOSE: To use a novel porcine dry eye model (pDEM) to study the effect of various artificial tears on corneal abrasion and epithelial cell death under severe "dry eye" conditions. METHODS: A 60-second lacrimation-blink interval, which simulates a severe dry eye condition, was set up with our novel pDEM. The corneal protective effect of lubricating the eye for 4 hours with Dulbecco phosphate-buffered saline (DPBS, as control; n = 20) and with 3 types of commercially available artificial tears (n = 17 for each) that contained different lubricating agents was studied. Effect was determined in terms of the change in fluorescein staining grade (on a 0-4 point scale with 0.5 increments) of the cornea and the number of dead cells (by trypan blue staining) on the corneal surface. RESULTS: Median increase in fluorescein grading (median) in corneas treated for 4 hours with artificial tears containing sodium hyaluronate or hydroxypropyl methylcellulose was significantly (P < 0.002) smaller than with artificial tears containing balanced saline with an unknown demulcent or the DPBS control. The numbers of dead epithelial cells in the central corneas lubricated with artificial tears containing sodium hyaluronate or hydroxypropyl methylcellulose (229 +/- 71 and 221 +/- 65 [SD], respectively) were also significantly (P < 0.005) smaller than those in the corneas of eyes lubricated with artificial tears containing balanced saline with an unknown demulcent or DPBS alone (328 +/- 106 and 341 +/- 113, respectively). CONCLUSION: Results show that artificial tears containing sodium hyaluronate or hydroxypropyl methylcellulose as lubricating agents give enhanced corneal protection against desiccation and show the use of this novel pDEM model in evaluating corneal protection from desiccation.

Animals↗

Survey of eye practitioners' attitudes towards diagnostic tests and therapies for dry eye disease.

BACKGROUND: There is a wide variation in the use of diagnostic tests for dry eye disease. The purpose of this study was to survey the attitudes of eye practitioners towards both tests and therapies available for dry eye disease. METHOD: An anonymous, web-based questionnaire was used, containing both quantitative and qualitative sections. RESULTS: Thirty-eight respondents, evenly distributed in experience, confirmed the wide variation of diagnostic tests in use. History and staining techniques were significantly preferred to tests of tear flow (P < 0.05). 'Evidence' was the most valued test characteristic, and was regarded as significantly more important than 'comfort' or 'cost' (P < 0.003). However, 'evidence' was not valued significantly higher than 'ease of use' or 'time taken to perform'. Overall, there was poor satisfaction with diagnostic and therapeutic options in dry eye, for both quantitative and qualitative measures. CONCLUSION: This is the first qualitative study of attitudes towards dry eye disease. Attitudes towards the adequacy of diagnostic tests vary considerably. As evidence supporting a diagnostic test's validity is the most highly valued test characteristic, a systematic review of the topic is justified.

Attitude of Health Personnel↗

Efficacy of corneal eye shields in protecting patients' eyes from laser irradiation.

BACKGROUND: The continuing development of new types and applications of lasers has appeared to surpass the development of specific eye protection for these lasers. There are a variety of eye shields on the market, but few are specifically designed for laser protection. OBJECTIVE: Our purpose was to test a variety of eye shields by two parameters, light transmission and temperature rise, and to determine from these measurements the most protective shield for patients. METHODS: We tested four plastic shields, one metal shield, and two sets of tanning goggles for temperature rise and light transmission when irradiated with a beam from a flashlamp-pumped, pulsed-dye laser. RESULTS: The temperature rise at the surface of the shield opposite the laser impacts was no more than 0.2 degree C in any case. White light was transmitted at significant levels through several of the shields, but yellow light transmittance was noted only through the green eye shield. CONCLUSION: Our measurements indicate that all except the green shield appeared safe from transmission of the 585-nm radiant energy. However, the optimal laser eye shield, in our opinion, would be a composite of several different shields' characteristics.

Color↗

Limulus lateral eye: properties of receptor units in the unexcised eye.

Single receptor units in the compound eye of the horseshoe crab were illuminated, and their impulse discharges were recorded without removing the eye from the animal. The receptors were spontaneously active in darkness and responded without saturation over a light intensity range of 10(10) to 1. When the eye was excised, the receptors did not discharge in darkness and had an intensity range of 10(5) to 1, as is usually found. Experiments show that these and other differences result from cutting off the blood supply to the eye when it is excised. In addition, the range and shape of the intensity characteristic suggest that more than one receptor mechanism encodes light intensity in this eye.

Action Potentials↗

Eye dominance columns from an isogenic double-nasal frog eye.

Removing the posterior (temporal) two-thirds of the Xenopus eye bud produces a remaining fragment, which becomes round and grows to a normal adult size eye. Electrophysiological and anatomical analyses showed that each of the two halves of this eye projected across the entire optic tectum in mirror image (double-nasal) fashion, and that fibers from each half-eye sorted out to form eye dominance stripes on the tectum. That both halves of the mirror-symmetric map were derived from only one animal, and from only one side of the head, rules out global markers such as right versus left and histocompatibility differences as causing the formation of these stripes.

Animals↗

Squash ball to eye ball: the likelihood of squash players incurring an eye injury.

The records of the 118 patients treated as Southampton Eye Hospital during 1978-9 for injuries incurred while playing squash, badminton, tennis, table tennis, cricket, and football show that for squash the main cause of eye injury was the player being hit by the ball. Severe eye injuries--those requiring treatment as an inpatient--were rare but much more frequent than such injuries in other sports. Less serious injuries--those requiring treatment as an outpatient--were also rare, with a frequency comparable with that of similar injuries in football and badminton. Squash players are most unlikely to incur an eye injury, but should this occur it has far-reaching consequences both in the short and the long term. Each individual player must weigh these chances and consequences against the possible inconvenience of using some form of eye protection.

Adult↗

Sensitivity and specificity of photography and direct ophthalmoscopy in screening for sight threatening eye disease: the Liverpool Diabetic Eye Study.

OBJECTIVE: To evaluate different methods for community based screening for sight threatening diabetic eye disease. DESIGN: Prospective study. SETTING: Mobile screening unit visiting inner city community clinics; hospital assessment clinic (tertiary centre). SUBJECTS: 395 diabetic patients registered with four general practices in an inner city location. INTERVENTIONS: Community based photography with mydriasis and direct ophthalmoscopy through dilated pupils by an experienced ophthalmologist, both compared with reference standard of slit lamp biomicroscopy by a consultant specialist in medical retinal disease. MAIN OUTCOME MEASURES: Sensitivity and specificity of screening method and prevalence of sight threatening diabetic eye disease (moderate preproliferative retinopathy, circinate maculopathy, exudate within 1 disc diameter of fixation, other diabetes related eye disease). RESULTS: 358 subjects underwent photography, 326 attended hospital clinic for ophthalmoscopy, and six were ungradable on photographs and biomicroscopy, leaving 320 for analysis. Of these 295 (91%) attended clinic within four months of photography. Sensitivity of detection of eye disease by photography was 89% (95% confidence interval 80% to 98%), significantly better than for direct ophthalmoscopy (65% (51% to 79%)). Analysis of patients with false negative results indicated possible improvement of photographic sensitivity to 93% by addition of stereoscopic macular pair photographs. Specificity of detection of sight threatening eye disease was 86% (82% to 90%) for photography and 97% (95% to 99%) for direct ophthalmoscopy. CONCLUSIONS: Since high sensitivity is essential for an effective screening programme, a photographic method should be considered as preferred option in national, community based screening programmes. Even in the hands of an experienced ophthalmologist, direct ophthalmoscopy is limited by weaknesses inherent to the instrument.

Ambulatory Care↗

[Evaluation of the cut quality of Masyk microkeratome in obtaining corneal flap from human eyes of an eye bank].

PURPOSE: To evaluate the cut quality of Masyk microkeratome in obtaining a corneal flap from human eyes of Eye Banks. METHODS: Prospective study with 20 human eyes from Eye Banks. All flaps were programmed to obtain 160 microm thickness and 9.5 mm diameter. The thicknesses were calculated with P55 pachymeter (Paradigm, USA), and diameter with compass. RESULTS: No complications were observed during the use of the microkeratome. The central corneal thickness average was 160.34+/-5.10 microm and range from 149 to 181 microm. The vertical diameter average was 9.64+/-0.16 mm and range from 9.30 to 9.85 mm. CONCLUSION: Masyk microkeratome showed to be effective for obtention of corneal flap with appropriate thickness and diameter from human corneas of Eye Banks.

Corneal Stroma↗