scholarly journals Visual Impairment Caused by Monovision Surgical Design

2021 ◽  
Author(s):  
Humberto Dória Silva ◽  
Rostan Silvestre da Silva ◽  
Eduardo Dória Silva ◽  
Maria Tamires Dória Silva ◽  
Cristiana Pereira Dória ◽  
...  
Keyword(s):  
Visual Field ◽  
Binocular Vision ◽  
Trabecular Meshwork ◽  
Human Vision ◽  
Implantation Technique ◽  
Refractive Errors ◽  
Mobile Mass ◽  
Surgical Implantation ◽  
The Brain ◽  
Continuous Progression

Neurophysiological anatomy of natural binocular vision shows the need to focus with both eyes to jointly produce the two corneas accommodation, correcting, in a compensatory way, the divergences inherent in the two different images, of the same visual field projected in the two distinct spaces, the two retinas. Corneal accommodation is part of the forced convection mechanism for the transfer of mobile mass in the cornea, trabecular meshwork and retina, to inhibit the accumulation of dehydrated intraocular metabolic residue, which can cause refractive errors in the cornea, obstruction of the trabecular meshwork and reduction of the amplitude of the signals produced by the phototransducers and sent to the brain. The IOL monovision surgical implantation technique differs from the physiology of natural binocular vision, which can cause after surgery disorders, described in this chapter, in that it imposes a different adaptation from the neurophysiological anatomy of human vision in addition to favoring the continuous progression of residue accumulation dehydrated intraocular metabolic and stimulate ocular.

Types of refractive errors and methods for their diagnosis

2020 ◽  
pp. 30-36
Author(s):  
Olga Lemzyakova
Keyword(s):  
Optical System ◽  
Contact Lenses ◽  
Vision Impairment ◽  
Refractive Errors ◽  
Vision Correction ◽  
Light Rays ◽  
Different Types ◽  
Almost All ◽  
Degrees Of Severity ◽  
The Brain

Refraction of the eye means its ability to bend (refract) light in its own optical system. In a normal state, which is called emmetropia, light rays passing through the optical system of the eye focus on the retina, from where the impulse is transmitted to the visual cortex of the brain and is analyzed there. A person sees equally well both in the distance and near in this situation. However, very often, refractive errors develop as a result of various types of influences. Myopia, or short-sightedness, occurs when the light rays are focused in front of the retina as a result of passing through the optical system of the eye. In this case, a person will clearly distinguish close objects and have difficulties in seeing distant objects. On the opposite side is development of farsightedness (hypermetropia), in which the focusing of light rays occurs behind the retina — such a person sees distant objects clearly, but outlines of closer objects are out of focus. Near vision impairment in old age is a natural process called presbyopia, it develops due to the lens thickening. Both myopia and hypermetropia can have different degrees of severity. The variant, when different refractive errors are observed in different eyes, is called anisometropia. In the same case, if different types of refraction are observed in the same eye, it is astigmatism, and most often it is a congenital pathology. Almost all of the above mentioned refractive errors require correction with spectacles or use of contact lenses. Recently, people are increasingly resorting to the methods of surgical vision correction.

scholarly journals Epidemiological Findings of Refractive Errors and Amblyopia among the Schoolchildren in Hatta Region of the United Arab Emirates

2021 ◽  
pp. 1-7
Author(s):  
Salam Chettian Kandi ◽  
Hayat Ahmad Khan
Keyword(s):  
Visual Acuity ◽  
Visual Field ◽  
United Arab Emirates ◽  
Refractive Error ◽  
Screening Program ◽  
Low Vision ◽  
Refractive Errors ◽  
Vision Screening ◽  
Screening Programs ◽  
School Based

<b><i>Introduction:</i></b> Uncorrected refractive errors and amblyopia pose a major problem affecting schoolchildren. We had previously observed that many schoolchildren in the Hatta region presented to the ophthalmology clinic with uncorrected refractive errors and amblyopia, which led us to undertake this research. As per the WHO, the term “visual impairment” can be “low vision” or “blindness.” Based on the presenting vision, “low vision” is defined for children who have vision of &#x3c;6/18 to 3/60 or having visual field loss to &#x3c;20° in the better-seeing eye. Children defined to have “blindness” have presenting vision of &#x3c;3/60 or corresponding visual field of &#x3c;10°. <b><i>Purpose:</i></b> To estimate the magnitude of uncorrected refractive errors and amblyopia among the schoolchildren aged 6–19 years and to assess the efficacy of school-based refractive error screening programs in the Hatta region of the United Arab Emirates. <b><i>Methods:</i></b> An epidemiological, cross-sectional, descriptive study was conducted on the entire student population studying in the government schools of the region. Those who failed the Snellen visual acuity chart test and those who were wearing spectacles were evaluated comprehensively by the researcher in the Department of Ophthalmology of the Hatta Hospital. Data were entered in the Refractive Error Study in School Children (RESC) eye examination form recommended by the WHO, and were later transferred to Excel sheets and analyzed by SPSS. <b><i>Results:</i></b> 1,591 students were screened and evaluated from the end of 2016 to mid-2017. About 21.37% (<i>n</i> = 340) had impaired vision with 20.9% (<i>n</i> = 333) refractive errors, of which 58% were uncorrected. Among the refractive error group, 19% (64 subjects) had amblyopia (4% of total students). The incidence of low vision was 9.5% and blindness was 0.38%. Low vision was found to be 9.5% and blindness 0.38%, taking in to account presenting visual acuity rather than best-corrected visual acuity for defining low vision and blindness. <b><i>Conclusion:</i></b> A significant number of students were detected to have uncorrected refractive errors among the vision impaired group (59%, <i>n</i> = 197) despite a school-based vision screening program in place. Seventy-eight percent of the amblyopia cases (<i>n</i> = 50) were found to be in the 11–19 years age group. Noncompliance with optical corrections was the reason for the high number of cases. A rigorous vision screening program and refractive services, complimented with awareness among parents and teachers, are recommended.

scholarly journals Ocular, Neurologic and Systemic Findings of the Cases with Optic Nerve Hypoplasia

2016 ◽  
Vol 10 (1) ◽  
pp. 5-11 ◽  
Author(s):  
Eyyup Karahan ◽  
Ayse Tulin Berk
Keyword(s):  
Optic Nerve ◽  
Chart Review ◽  
Retrospective Chart Review ◽  
Optic Nerve Hypoplasia ◽  
Refractive Errors ◽  
Poor Vision ◽  
The Relationship ◽  
The Brain ◽  
Ocular Signs ◽  
Neurologic Findings

Aim: To describe the associated ocular, neurologic, and systemic findings in a population of children with optic nerve hypoplasia (ONH) and to evaluate the relationship between ocular signs and neurologic findings. Method: A retrospective chart review of 53 patients with the diagnosis of ONH seen between December 1998 and September 2012 was performed. All neurodevelopmental anomalies, neuroradiologic findings, endocrinologic and systemic findings were recorded. Poor vision was defined as the visual acuity poorer than logMAR 1.0 or inadequate central steady maintained fixation. Results: Thirty (56.6%) of the 53 children with ONH were boys. Mean age at presentation was 56.2±46.8 months (range; 3 months to 18 years). Poor vision defined for the purpose of this study was found in 47.2% of 53 patients. Thirty-three (62.3%) children had nystagmus. Thirty-four (64.2%) children had strabismus. Thirteen (38.2%) of those with strabismus had esotropia, 20 (58.8%) had exotropia. The total number of the children with neurodevelopmental deficit was 22 (41.5%) in our study. Conclusion: The vision of young children with ONH should be monitored at least annually, and any refractive errors should be treated. Neuroimaging of the brain and endocrinologic evaluation is necessary in all cases with ONH.

Will brain tissue grafts become an important therapy to restore visual function in cerebrally blind patients?

1995 ◽  
Vol 18 (1) ◽  
pp. 74-74
Author(s):  
Reinhard Werth
Keyword(s):  
Visual Field ◽  
Brain Tissue ◽  
Visual Function ◽  
Visual Field Loss ◽  
Embryonic Brain ◽  
Cerebral Lesions ◽  
Tissue Grafts ◽  
The Brain ◽  
Neuropsychological Methods ◽  
Blind Patients

AbstractGrafting embryonic brain tissue into the brain of patients with visual field loss due to cerebral lesions may become a method to restore visual function. This method is not without risk, however, and will only be considered in cases of complete blindness after bilateral occipital lesions, when other, risk-free neuropsychological methods fail.

scholarly journals Low-frequency electroencephalogram oscillations govern left-eye lateralization during anti-predatory responses in the music frog

2020 ◽  
Vol 223 (21) ◽  
pp. jeb232637
Author(s):  
Jiangyan Shen ◽  
Ke Fang ◽  
Ping Liu ◽  
Yanzhu Fan ◽  
Jing Yang ◽  
...  
Keyword(s):  
Visual Field ◽  
Left Visual Field ◽  
Right Hemisphere ◽  
Brain Area ◽  
Power Spectra ◽  
Low Frequency ◽  
The Right ◽  
Electroencephalogram Eeg ◽  
The Brain ◽  
Steady Velocity

ABSTRACTVisual lateralization is widespread for prey and anti-predation in numerous taxa. However, it is still unknown how the brain governs this asymmetry. In this study, we conducted behavioral and electrophysiological experiments to evaluate anti-predatory behaviors and dynamic brain activities in Emei music frogs (Nidirana daunchina), to explore the potential eye bias for anti-predation and the underlying neural mechanisms. To do this, predator stimuli (a model snake head and a leaf as a control) were moved around the subjects in clockwise and anti-clockwise directions at steady velocity. We counted the number of anti-predatory responses and measured electroencephalogram (EEG) power spectra for each band and brain area (telencephalon, diencephalon and mesencephalon). Our results showed that (1) no significant eye preferences could be found for the control (leaf); however, the laterality index was significantly lower than zero when the predator stimulus was moved anti-clockwise, suggesting that left-eye advantage exists in this species for anti-predation; (2) compared with no stimulus in the visual field, the power spectra of delta and alpha bands were significantly greater when the predator stimulus was moved into the left visual field anti-clockwise; and, (3) generally, the power spectra of each band in the right-hemisphere for the left visual field were higher than those in the left counterpart. These results support that the left eye mediates the monitoring of a predator in music frogs and lower-frequency EEG oscillations govern this visual lateralization.

A 9L Gliosarcoma Transplantation Model for Studying Adoptive Immunotherapy into the Brains of Conscious Rats

1992 ◽  
Vol 1 (4) ◽  
pp. 307-312 ◽  
Author(s):  
Monika Fleshner ◽  
Linda R. Watkins ◽  
Joan M. Redd ◽  
Carol A Kruse ◽  
Donald Bellgrau
Keyword(s):  
Adoptive Immunotherapy ◽  
Effector Cells ◽  
9L Gliosarcoma ◽  
Conventional Animal ◽  
Rat Strain ◽  
Surgical Implantation ◽  
Conscious Animals ◽  
The Brain ◽  
Transplantation Model

A rat model for brain tumor immunotherapy is described that closely mimics the type of treatment that could be administered to humans. It involves surgical implantation of a permanent cannula in the brain, through which tumor cells and various effector cells and/or cytokines can be injected. The advantage of this system over more conventional animal surgical procedures is that conscious animals can be treated multiple times while avoiding morbidity and mortality associated with reoperative procedures. Using this system to study adoptive immunotherapy for brain tumors, we provide evidence that the 9L gliosarcoma tumor from the Fischer rat strain can be reduced or destroyed in situ following adoptive immunotherapy with specifically activated cytotoxic T lymphocytes.

Effect of uncorrected refractive errors upon central visual field testing

1993 ◽  
Vol 13 (4) ◽  
pp. 339-343 ◽  
Author(s):  
David B. Henson ◽  
Ellen J. Morris
Keyword(s):  
Visual Field ◽  
Field Testing ◽  
Refractive Errors ◽  
Visual Field Testing ◽  
Central Visual Field

Landing Reaction of Musca domestica, IV: A. Monocular and Binocular Vision; B. Relationships between Landing and Optomotor Reactions

1973 ◽  
Vol 28 (9-10) ◽  
pp. 579-592 ◽  
Author(s):  
Cloe Taddei-Ferretti ◽  
Antonio Fernandez Perez de Talens
Keyword(s):  
Visual Field ◽  
Musca Domestica ◽  
Binocular Vision ◽  
Lateral Displacement ◽  
Double Vision ◽  
Single Vision ◽  
Monocular Stimulation

Abstract 1. The behaviours of monocular and binocular flies are compared with respect to the landing reaction. It is found that landing reaction is elicited through different mechanisms by stimulating the zones of single or of double vision: Monocular stimulation in the field of single vision evokes reactions with both ipsilateral and contralateral leg s; monocular stimulation in the field of double vision evokes reaction only with the ipsilateral legs. 2. T he relationships between landing and optomotor reactions are analyzed. It is found that, a. W hen the fly is not free to turn itself, it may react to a lateral displacement in the visual field (optomotor stimulus) with a landing reaction ; b. The threshold for landing evoked by an expansion in the visual field (landing stimulus) is much low er than the threshold for landing evoked by a lateral displacement; c. A horizontal lateral displacement in the visual field of an eye is adequate to evoke the landing reaction only if it is perceived in the direction from the front to the back of the eye; d. W hen the fly is free to turn itself, it can present both landing and opto­motor reactions to a optomotor stimulus; e. W hen the fly is fixed at a point, landing reaction can be evoked also by an escape stimulus.

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