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Related Concept Videos

Photoreceptors and Visual Pathways01:22

Photoreceptors and Visual Pathways

At the molecular level, visual signals trigger transformations in photopigment molecules, resulting in changes in the photoreceptor cell's membrane potential. The photon's energy level is denoted by its wavelength, with each specific wavelength of visible light associated with a distinct color. The spectral range of visible light, classified as electromagnetic radiation, spans from 380 to 720 nm. Electromagnetic radiation wavelengths exceeding 720 nm fall under the infrared category, whereas...
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Focusing of Light in the Eye

Light rays enter the eye through the cornea, a transparent dome-shaped tissue that is the eye's outermost layer. The cornea bends or refracts, light rays traveling to the pupil. The shape of the cornea determines how much of the light is bent and whether the image will be focused correctly on the retina at the back of the eye. Once the light has passed through both refraction layers, it converges into a single focal point onto a small area. This is where photoreceptors start transforming...
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The eye is a spherical, hollow structure composed of three tissue layers. The outer layer — the fibrous tunic, comprises the sclera — a white structure — and the cornea, which is transparent. The sclera encompasses some of the ocular surface, most of which is not visible. However, the 'white of the eye' is distinctively visible in humans compared to other species. The cornea, a clear covering at the front of the eye, enables light penetration. The eye's middle layer, the vascular tunic,...
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DefinitionDiabetic retinopathy is a microvascular complication of diabetes affecting the retinal blood vessels.Risk FactorsDiabetic retinopathy is present in almost all individuals with type 1 diabetes and more than 60% of those with type 2 diabetes after two decades of disease.The risk increases with poor glycemic control, hypertension, dyslipidemia, smoking, pregnancy, and puberty.Although cataracts and glaucoma are also more frequent in people with diabetes, retinopathy remains the leading...
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Meiosis I

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Why do children with down syndrome have subnormal vision?

Gail V Morton1

  • 1Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, Wisconsin 53705, USA. gmorton@uwhealth.org

The American Orthoptic Journal
|August 23, 2011
PubMed
Summary
This summary is machine-generated.

Individuals with Down syndrome often experience subnormal vision, with common factors including nystagmus, refractive errors, and accommodative insufficiency. Visual acuity typically ranges from 20/40 or worse, necessitating further investigation into visual development.

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Area of Science:

  • Ophthalmology
  • Genetics
  • Developmental Biology

Background:

  • Down syndrome is associated with a high prevalence of visual impairments, affecting both ocular structures and neural pathways.
  • Subnormal vision in Down syndrome presents a complex challenge due to variations in visual acuity and potential underlying causes.

Discussion:

  • Nystagmus and significant refractive errors are frequently observed but do not invariably lead to poor vision.
  • Accommodative insufficiency is a common finding, particularly impacting near vision capabilities.
  • Standardized methodologies for vision studies are challenging due to variability in refractive error assessment and correction.

Key Insights:

  • Visual acuity in individuals with Down syndrome typically measures 20/40 or worse, with considerable individual variation.
  • Ocular and neurological differences are characteristic in Down syndrome compared to age-matched controls.
  • Dynamic retinoscopy reveals frequent accommodative insufficiency, suggesting bifocals as a potential management strategy.

Outlook:

  • Further research is needed to elucidate the precise mechanisms behind visual impairments in Down syndrome.
  • Development of standardized vision testing protocols is crucial for accurate diagnosis and monitoring.
  • Early identification and intervention, including the potential use of bifocals, may improve visual outcomes for children with Down syndrome.