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Results for “Vision, Entoptic”

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At least 109 records · Page 6Linked to original sources
PubMed2005

Posterior vitreous detachment. How to approach sudden-onset floaters and flashing lights.

Symptomatic PVD is a common age-related problem that in some patients is associated with retinal tear and retinal detachment. Thorough ocular examination of patients with unilateral floaters and photopsias is needed to identify those at greatest risk for vision loss. Patients without retinal pathologic findings on initial examination need to be given careful instructions on what to expect and do should symptoms of retinal tear or detachment occur.

Acute Disease↗
PubMed1981

Historic perspectives. Macular yellow pigment. The first 200 years.

Since 1782 there has been continuing controversy concerning the curious central coloration referred to as "macular yellow," but no cumulative source of information on the subject exists. This paper reviews the research efforts of two centuries to determine the existence, nature, location, and function of a specialized pigment in the foveal region. Using white-light illumination, it is difficult to see a macular yellow spot in the living eye; it is best observed and documented by red-free ophthalmoscopy and blue-light monochromatic photography. Histologic, biochemical, and spectral absorption data suggest that the yellow color is due to a xanthophyllic pigment, lutein, that is distributed in all retinal layers internal to the outer nuclear layer, with greatest concentration in the outer and inner plexiform layers. Clinically absent in newborns, the pigment gradually accumulates from dietary sources and appears to serve both as an optical filter, by absorbing blue light and reducing chromatic aberration, and in a protective capacity, preventing actinic damage. The absorption characteristics of the yellow pigment contribute to the central dark spot seen during fluorescein angiography and to the risk of photocoagulation near the fovea. Its apparent absence in albinos and the reported functional improvement in certain degenerative retinopathies following supplemental xanthophyll administration suggest a possible role in hereditary or acquired maculopathies.

Carotenoids↗
PubMed1977

The diagnosis of amblyopia and strabismus: a programmed approach.

A simplified method of recording and analyzing amblyopic and strabismic examinations is presented. With this new form, the average practitioner is provided with a relatively standardized set of tests in a logical, organized sequence. Programming the patient's responses into meaningful categories facilitates the formation of a differential diagnosis and also provides valuable insight into the eventual outcome of each case.

Adaptation, Ocular↗
PubMed1996

Image formation by the crystalline lens and eye of the rainbow trout.

The image of a distant unresolved point (point image or PI) and modulation transfer function (MTF) of the eye and lens of the trout were recorded with high spatial (0.3 micron) and dynamic (4096 grey levels) resolution for various entrance aperture sizes and focal positions in monochromatic light, and in broadband light simulating sunlight absorbed by a retinal cone pigment. The PI is irregular, with streaks, wisps and speckle, as a result of lens structural irregularity and diffraction of light scattered within the lens and cornea. Maximum diameter of a diffraction-limited aperture area of the eye is about 0.3 mm. Axially spaced multiple foci are caused by irregular and discontinuous zonal spherical aberration. Lens substance dispersion causes strong longitudinal chromatic aberration, resulting in a broadband PI with concentric coloured haloes. Incident linearly polarized light is slightly depolarized in the PI. The nature of the image is discussed relative to lens and cornea structure, optical modelling and vision. Human subjective entoptic phenomena analogous to those observed objectively in the trout are described.

Animals↗
PubMed2000

Scanning laser entoptic perimetry for the screening of macular and peripheral retinal disease.

OBJECTIVE: To determine the effectiveness of scanning laser entoptic perimetry as a noninvasive platform for screening for retinal damage in visually asymptomatic patients within the central 120 degrees (diameter) of vision. DESIGN: A masked study comparing entoptic perimetry with fundus photographs. SETTING: The Shiley Eye Center and the AIDS Ocular Research Unit at the University of California, San Diego. PATIENTS: Fifty-eight patients recruited during ophthalmologic visits for treatment or follow-up of ocular disease. MEASUREMENTS: For each testing session, we compared the presence of a disturbance in the entoptic stimulus with the presence of retinal disease within the central 120 degrees of vision, centered on the fovea. RESULTS: Scanning laser entoptic perimetry has a sensitivity and specificity of more than 90%, a positive predictive value of 100%, and a negative predictive value of 89% for screening retinal lesions within the central 120 degrees diameter of vision. CONCLUSION: Scanning laser entoptic perimetry may be an effective and inexpensive screening test for diagnosing retinal disease in hospitals and community clinics. Arch Ophthalmol. 2000;118:1205-1210

False Positive Reactions↗
PubMed2000

Correlation between static automated and scanning laser entoptic perimetry in normal subjects and glaucoma patients.

OBJECTIVE: To compare the effectiveness of scanning laser entoptic perimetry with static automated perimetry as a noninvasive instrument for screening for glaucomatous damage in visually asymptomatic subjects within the central 60 degrees (diameter) of vision. DESIGN: A masked cross-sectional study comparing entoptic perimetry to achromatic threshold perimetry. PARTICIPANTS: Twenty-three subjects and controls from the Sharp Rees-Stealy Hospital and the Shiley Eye Center at the University of California, San Diego. TESTING: Virtual reality-based entoptic perimetry was compared with achromatic threshold perimetry. MAIN OUTCOME MEASURES: For each testing session, we compared the presence of a disturbance in the entoptic perimetry stimulus with the presence of defects in visual function as measured by Humphrey automated visual field perimetry. RESULTS: Scanning laser entoptic perimetry reasonably estimates the overall visual field loss for moderate-to-severe scotomas as measured by the pattern deviation in standard visual field perimetry. Scanning laser entoptic perimetry has a sensitivity from 27% to 90% and a specificity from 50% to 100% for screening moderate-to-severe visual field defects caused by glaucoma within the central 60 degrees diameter of vision. CONCLUSIONS: Scanning laser entoptic perimetry may be an effective and inexpensive screening test in hospitals and community clinics for diagnosing visual field loss caused by glaucoma.

Cross-Sectional Studies↗
PubMed1982

Preoperative prognostic factors in diabetic pars plana vitrectomy.

The postoperative, six-month visual acuities of 1056 diabetic vitrectomy cases were compared to the following preoperative findings: duration of decreased vision associated with detachments, pupillary responses, iris rubeosis, intraocular tensions, extent of neovascularization, macular status, the ability to recognize entoptic phenomena, bright-flash ERG, and ultrasonography. By comparing these findings to the postoperative visual results, several factors were detected that could be helpful in determining the preoperative prognosis for improved vision. However, major operative complications reduced the incidence of successful visual results from 53% to 22%.

Diabetic Retinopathy↗
PubMed1996

The extraordinarily rapid disappearance of entoptic images.

It has been known for more than 40 years that images fade from perception when they are kept at the same position on the retina by abrogating eye movements. Although aspects of this phenomenon were described earlier, the use of close-fitting contact lenses in the 1950s made possible a series of detailed observations on eye movements and visual continuity. In the intervening decades, many investigators have studied the role of image motion on visual perception. Although several controversies remain, it is clear that images deteriorate and in some cases disappear following stabilization; eye movements are, therefore, essential to sustained exoptic vision. The time course of image degradation has generally been reported to be a few seconds to a minute or more, depending upon the conditions. Here we show that images of entoptic vascular shadows can disappear in less than 80 msec. The rapid vanishing of these images implies an active mechanism of image erasure and creation as the basis of normal visual processing.

Arterioles↗
PubMed1999

[Entoptic phenomena and potential visual acuity].

REVIEW OF PREOPERATIVE EVALUATION OF VISUAL FUNCTION: In the presence of media opacities, the prevision of the potential postoperative visual acuity constitutes often a complicate diagnostic problem. Its solution requires the experience of the ophthalmologist, who should take into account various elements from the patient's visual aggravation progress, the dissociation between far and near vision under mesopic and scotopic conditions, the actual grating acuity and the eventual hand movement and light-perception, as well as, elements from the patient's objective examination, i.e., from the biomicroscopy with direct and indirect illumination through the still transparent media and from the binocular ophthalmoscopy of the fundus. METHODS REVIEWED: Purkinje figure and luminous darting points visualization. POSSIBLE PREDICTIONS: Light induced entoptic imagery, as Purkinje figure and luminous darting points, visualization, helps as a supplementary diagnostic procedure, for the prevision of a low, but socially useful postoperative visual acuity.

Humans↗
PubMed1988

Presurgical prediction of postsurgical visual acuity in patients with media opacities.

Of the estimated 1 million patients each year in the United States who undergo surgery for media opacities, perhaps 5-10% fail to improve because of pre-existing, undiagnosed retinal and/or optic nerve disease. In this paper, the standard presurgical evaluation (case history, visual acuity, refraction, pupillary response testing, biomicroscopy, ophthalmoscopy, tonometry, visual fields and color vision) and the supplementary presurgical evaluation (entoptic phenomena appreciation, ophthalmic ultrasonography, fluorescein angiography, laser interferometry, potential acuity meter, visual evoked potential, electroretinography, contrast sensitivity and hyperacuity measurements) are reviewed.

Cataract↗
PubMed1998

The effect of nimodipine, a centrally active calcium antagonist, on visual function and mascular blood flow in patients with normal-tension glaucoma and control subjects.

PURPOSE: This study was performed to evaluate the effect of nimodipine, a centrally active calcium channel antagonist on automated Humphrey visual fields, Farnsworth-Munsell 100 (FM-100) hue color vision testing, and macular blood flow (blue field entoptic simulation technique) in patients with normal-tension glaucoma (NTG) and control subjects. METHODS: Thirteen patients with NTG and thirteen age- and sex-matched control subjects were studied in a prospective, placebo-controlled, double-masked, crossover protocol. On each of the two study dates, testing was performed at baseline and 90 minutes after administration of either two 30-mg nimodipine capsules or two identical appearing placebo capsules. Blood pressure and pulse were monitored throughout the study. RESULTS: Nimodipine administration resulted in a performance corrected improvement in Humphrey visual field mean deviation (patients with NTG and control subjects), corrected pattern standard deviation (patients with NTG), and macular sensitivity (the average of the foveal threshold and the four most central points of the visual field; patients with NTG). The FM-100 hue error scores significantly decreased after administration of nimodipine in patients with NTG and control subjects compared with baseline. There were no significant differences in baseline leukocyte velocity or density between patients with NTG and control subjects; no significant changes in leukocyte velocity or density were noted after administration of nimodipine in either group. CONCLUSION: Nimodipine caused a significant performance corrected improvement in visual field testing and a significant improvement in color vision. Nimodipine did not alter macular hemodynamics as measured using the blue field entoptic simulation technique, although results were hampered by high variability, particularly in the leukocyte density measurements.

Aged↗