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Related Experiment Videos

Asthenopia and the dark focus of accommodation

T Miwa1, T Tokoro

  • 1Department of Ophthalmology, Tsuchiura Kyodo General Hospital, Japan.

Optometry and Vision Science : Official Publication of the American Academy of Optometry
|June 1, 1994
PubMed
Summary

Asthenopia, or eye strain, is linked to lower tonic accommodation. This study found that individuals with daily eye strain had a reduced dark focus of accommodation compared to those without symptoms.

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Area of Science:

  • Ophthalmology
  • Vision Science
  • Neuroscience

Background:

  • Asthenopia, characterized by daily eye strain despite corrected refractive error, affects a significant portion of the population.
  • The underlying mechanisms of asthenopia remain incompletely understood, necessitating further investigation into visual system function.
  • Tonic accommodation, the resting state of the eye's focusing system, is a potential factor influencing visual comfort.

Purpose of the Study:

  • To investigate the relationship between asthenopia and the dark focus of accommodation.
  • To compare the dark focus of accommodation in individuals with and without symptomatic asthenopia.
  • To determine if tonic accommodation levels differ between symptomatic and asymptomatic groups.

Main Methods:

  • A comparative study involving 54 symptomatic and 56 asymptomatic subjects, matched for age and refractive error.

Related Experiment Videos

  • Measurement of refractive error in bright light (Non-Cyclo R), dark conditions (Dark R), and after cycloplegia (Cyclo R) using an autorefractometer.
  • Calculation of dark focus of accommodation (DFcus) by comparing dark refractive state to both non-cycloplegic and cycloplegic refractive errors.

    • Main Results:

    • Symptomatic subjects exhibited a significantly smaller dark focus of accommodation (DFcus) compared to asymptomatic controls.
    • Both DFcus (Cyclo R) and DFcus (Non-Cyclo R) were reduced in the asthenopic group.
    • These findings suggest a lower level of tonic accommodation in individuals experiencing asthenopia.

    Conclusions:

    • Asthenopia is associated with a diminished dark focus of accommodation.
    • A low level of tonic accommodation, rather than a high level, appears to be a contributing factor to asthenopia.
    • Further research into tonic accommodation could lead to improved management strategies for eye strain.