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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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Related Experiment Video

Updated: Jun 22, 2026

Dynamic Visual Tests to Identify and Quantify Visual Damage and Repair Following Demyelination in Optic Neuritis Patients
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Visual function in Noonan and LEOPARD syndrome.

P Alfieri1, L Cesarini, G Zampino

  • 1Pediatric Neurology Unit, Catholic University, Rome, Italy.

Neuropediatrics
|July 2, 2009
PubMed
Summary
This summary is machine-generated.

Visual and visuoperceptual deficits are common in Noonan syndrome (NS) and LEOPARD syndrome (LS). This study found frequent abnormalities in ocular movements and stereopsis, suggesting a multifactorial cause.

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Last Updated: Jun 22, 2026

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Area of Science:

  • Ophthalmology
  • Genetics
  • Neuroscience

Background:

  • Noonan syndrome (NS) and LEOPARD syndrome (LS) are genetic disorders.
  • Mutations in PTPN11, SOS1, and RAF1 genes are associated with NS and LS.
  • Visual and visuoperceptual function in these syndromes are not well-characterized.

Purpose of the Study:

  • To assess visual and visuoperceptual function in patients with NS and LS.
  • To identify specific areas of visual impairment.
  • To explore potential genetic and multifactorial etiologies.

Main Methods:

  • Ophthalmological and orthoptic evaluations.
  • Behavioral visual tests including crowding acuity (Cambridge crowding cards) and stereopsis (TNO test).
  • Visuo-motor integration (VMI) test.

Main Results:

  • 83% of patients showed visual function abnormalities.
  • Ocular movements (50%) and stereopsis (79%) were most frequently affected.
  • 33% of patients had visuo-motor integration deficits.

Conclusions:

  • Visual and visuoperceptual abilities are commonly impaired in NS and LS.
  • Abnormalities likely stem from a multifactorial etiology.
  • Further research into the underlying mechanisms is warranted.