Sensory Eye Dominance in Treated Anisometropic Amblyopia

Amblyopia results from inadequate visual experience during the critical period of visual development. Abnormal binocular interactions are believed to play a critical role in amblyopia. These binocular deficits can often be resolved, owing to the residual visual plasticity in amblyopes. In this study, we quantitatively measured the sensory eye dominance in treated anisometropic amblyopes to determine whether they had fully recovered. Fourteen treated anisometropic amblyopes with normal or corrected to normal visual acuity participated, and their sensory eye dominance was assessed by using a binocular phase combination paradigm. We found that the two eyes were unequal in binocular combination in most (11 out of 14) of our treated anisometropic amblyopes, but none of the controls. We concluded that the treated anisometropic amblyopes, even those with a normal range of visual acuity, exhibited abnormal binocular processing. Our results thus suggest that there is potential for improvement in treated anisometropic amblyopes that may further enhance their binocular visual functioning.

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Imbalanced Sensory Eye Dominance of Surgically Aligned Late-onset Acute Acquired Concomitant Esotropes with normal stereopsis

10.21203/rs.3.rs-49517/v1 ◽

2020 ◽

Author(s):

Zhimo Yao ◽

Huanyun Yu ◽

Junxiao Zhang ◽

Bo Chen ◽

Xinping Yu

Keyword(s):

Late Onset ◽

Ocular Dominance ◽

Contrast Ratio ◽

Strabismus Surgery ◽

Control Group ◽

Balance Point ◽

Eye Dominance ◽

Phase Combination ◽

Sensory Eye Dominance ◽

Normal Controls

Abstract Background: Adults with late-onset acute acquired concomitant esotropia (AACE) have chance to develop normal binocular functions including a balanced ocular dominance before the onset of esotropia. For most patients, strabismus surgery re-establishing the ocular alignment indeed effectively restore stereopsis and visual acuity to the normal level. However, it is unclear whether they have already acquired balanced two eyes.Methods: 11 surgically aligned patients with AACE (24.3 ± 1.5 years; mean ± SE) and 14 adults with normal vision (26.1±1.2 years) participated in our experiments. All patients had normal binocularity and stereopsis. Using binocular phase combination paradigm, sensory eye dominance was quantified as the interocular contrast ratio, termed balance point, at which the contribution of each eye to the perception of cyclopean grating were equal.Results: Normal controls had a mean balance point value close to unity (0.95±0.01), while AACE group exhibited evident binocular imbalance (0.76±0.05), which was significantly different from control group (t (10.45) = -3.485, p = 0.006) . The balance point value didn’t depend on the interval from AACE onset to strabismus surgery (r = -0.357, p = 0.281) or the interval from the surgery to examination of sensory eye dominance (r = -0.105, p = 0.759).Conclusions: Although strabismus surgery effectively straightened AACE patients’ ocular alignment and even conferred them normal stereopsis, late-onset AACE patients’ two eyes were still not balanced. These results indicated that binocular imbalance might be a risk factor for adult AACE.

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Visual Experience Is Necessary for Maintenance But Not Development of Receptive Fields in Superior Colliculus

Journal of Neurophysiology ◽

10.1152/jn.00166.2005 ◽

2005 ◽

Vol 94 (3) ◽

pp. 1962-1970 ◽

Cited By ~ 32

Author(s):

M. M. Carrasco ◽

K. A. Razak ◽

S. L. Pallas

Keyword(s):

Superior Colliculus ◽

Critical Period ◽

Visual Experience ◽

Sensory Deprivation ◽

Receptive Fields ◽

Visual Deprivation ◽

Visual Development ◽

Retinotopic Maps ◽

Nmda Receptor Blockade ◽

Dark Rearing

Sensory deprivation is thought to have an adverse effect on visual development and to prolong the critical period for plasticity. Once the animal reaches adulthood, however, synaptic connectivity is understood to be largely stable. We reported previously that N-methyl-d-aspartate (NMDA) receptor blockade in the superior colliculus of the Syrian hamster prevents refinement of receptive fields (RFs) in normal or compressed retinotopic projections, resulting in target neurons with enlarged RFs but normal stimulus tuning. Here we asked whether visually driven activity is necessary for refinement or maintenance of retinotopic maps or if spontaneous activity is sufficient. Animals were deprived of light either in adulthood only or from birth until the time of recording. We found that dark rearing from birth to 2 mo of age had no effect on the timing and extent of RF refinement as assessed with single unit extracellular recordings. Visual deprivation in adulthood also had no effect. Continuous dark rearing from birth into adulthood, however, resulted in a progressive loss of refinement, resulting in enlarged, asymmetric receptive fields and altered surround suppression in adulthood. Thus unlike in visual cortex, early visually driven activity is not necessary for refinement of receptive fields during development, but is required to maintain refined visual projections in adulthood. Because the map can refine normally in the dark, these results argue against a deprivation-induced delay in critical period closure, and suggest instead that early visual deprivation leaves target neurons more vulnerable to deprivation that continues after refinement.

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TrkB Activation During a Critical Period Mimics the Protective Effects of Early Visual Experience on Perception and the Stability of Receptive Fields in Adult Superior Colliculus

10.1101/435784 ◽

2018 ◽

Author(s):

David B. Mudd ◽

Timothy S. Balmer ◽

So Yeon Kim ◽

Noura Machhour ◽

Sarah L. Pallas

Keyword(s):

Visual Acuity ◽

Visual Cortex ◽

Receptive Field ◽

Superior Colliculus ◽

Spontaneous Activity ◽

Signaling Pathway ◽

Critical Period ◽

Visual Experience ◽

Receptive Fields ◽

Trkb Receptors

AbstractDuring a critical period in development, spontaneous and evoked retinal activity shape visual pathways in an adaptive fashion. Interestingly, spontaneous activity is sufficient for spatial refinement of visual receptive fields in superior colliculus (SC) and visual cortex (V1), but early visual experience is necessary to maintain inhibitory synapses and stabilize RFs in adulthood (Carrasco et al. 2005, 2011; Carrasco & Pallas 2006; Balmer & Pallas 2015a). In visual cortex (V1), brain-derived neurotrophic factor (BDNF) and its high affinity receptor TrkB are important for development of visual acuity, inhibition, and regulation of the critical period for ocular dominance plasticity (Hanover et al., 1999; Huang et al., 1999; Gianfranceschi et al., 2003). To examine the generality of this signaling pathway for visual system plasticity, the present study examined the role of TrkB signaling during the critical period for RF refinement in SC. Activating TrkB receptors during the critical period (P33-40) in DR subjects produced normally refined RFs, and blocking TrkB receptors in light-exposed animals resulted in enlarged adult RFs like those in DR animals. We also report here that deprivation- or TrkB blockade-induced RF enlargement in adulthood impaired fear responses to looming overhead stimuli, and negatively impacted visual acuity. Thus, early TrkB activation is both necessary and sufficient to maintain visual RF refinement, robust looming responses, and visual acuity in adulthood. These findings suggest a common signaling pathway exists for the maturation of inhibition between V1 and SC.Significance StatementReceptive field refinement in superior colliculus (SC) differs from more commonly studied examples of critical period plasticity in visual pathways in that it does not require visual experience to occur; rather spontaneous activity is sufficient. Maintenance of refinement beyond puberty requires a brief, early exposure to light in order to stabilize the lateral inhibition that shapes receptive fields. We find that TrkB activation during a critical period can substitute for visual experience in maintaining receptive field refinement into adulthood, and that this maintenance is beneficial to visual survival behaviors. Thus, as in some other types of plasticity, TrkB signaling plays a crucial role in RF refinement.

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Management of Abnormal Visual Developments

10.5772/intechopen.101101 ◽

2021 ◽

Author(s):

Longqian Liu ◽

Xiaohang Chen ◽

Pengfan Chen ◽

Yifan Wu ◽

Jianglan Wang ◽

...

Keyword(s):

Visual Acuity ◽

Visual System ◽

Refractive Error ◽

Visual Function ◽

Visual Experience ◽

External World ◽

Visual Development ◽

Human Beings ◽

Good Visual Acuity ◽

Abnormal Visual

When human beings recognize the external world, more than 80% of the information come from visual function and visual system. Normal visual development and normal binocularity are the fundamental of good visual acuity and visual functions. Any abnormal visual experience would cause abnormality, such as refractive error, strabismus, amblyopia and other diseases. The patients with abnormal visual developments were reported to have abnormal, lonely, and other psycho problems. In this chapter, we will describe the normal developmental of visual function, summarize the abnormal developments and the correction or treatment.

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On the need for a legislative norm for high degrees of hypermetropia in relation to military-combatant services

Kazan medical journal ◽

10.17816/kazmj48446 ◽

1902 ◽

Vol 2 (10) ◽

pp. 567-567

Author(s):

V. F. Velyamovich

Keyword(s):

Visual Acuity ◽

Military Service ◽

Normal Visual Acuity ◽

The Law

As for the current Russian laws on anomalies in the organs of vision that allow or restrict the ability to perform military service, hyperopia, for which the law does not specify a predetermined degree, is completely ignored, compatible with the requirements of military service. Any hyperopia, no matter how high its degree of abnormal refraction, is recognised as extremely suitable for military service, unless it has a normal visual acuity without glasses.

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An Unusual Phenotype in Dutch Patients With Oculocutaneous Albinism Type 4: Evident Hypopigmentation Without Other Ocular Deficits.

10.21203/rs.3.rs-209795/v1 ◽

2021 ◽

Author(s):

Charlotte C Kruijt ◽

Nicoline E Schalij-Delfos ◽

Gerard C de Wit ◽

Ralph F Florijn ◽

Maria M van Genderen

Keyword(s):

Visual Acuity ◽

Visual Pathways ◽

Oculocutaneous Albinism ◽

Novel Mutations ◽

Normal Visual Acuity ◽

Diagnostic Center ◽

Foveal Hypoplasia ◽

Unusual Phenotype ◽

First Time ◽

Dutch Cohort

Abstract Purpose: To describe the phenotype of Dutch patients with oculocutaneous albinism type 4 (OCA4).Patients and Methods: We collected data on pigmentation (skin, hair, and eyes), visual acuity (VA), nystagmus, foveal hypoplasia, chiasmal misrouting, and molecular analyses of nine Dutch OCA4 patients from the Bartiméus Diagnostic Center for complex visual disorders.Results: All patients had severely reduced pigmentation of skin, hair, and eyes with iris transillumination over 360 degrees. Three unrelated OCA4 patients had normal VA, no nystagmus, no foveal hypoplasia, and no misrouting of the visual pathways. Six patients had poor visual acuity (0.6 to 1.0 logMAR), nystagmus, severe foveal hypoplasia and misrouting. We found two novel mutations in the SLC45A2 gene, c.310C>T; p.(Pro104Ser), and c.1368+3_1368+9del p.(?).Discussion: OCA4 patients of this Dutch cohort all had hypopigmentation of skin, hair, and iris translucency. However, patients were either severely affected with regard to visual acuity, foveal hypoplasia, and misrouting, or visually not affected at all. We describe for the first time OCA4 patients with an evident lack of pigmentation, but normal visual acuity, normal foveal development and absence of misrouting. This implies that absence of melanin does not invariably lead to foveal hypoplasia and abnormal routing of the visual pathways.

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