June 2013
Volume 54, Issue 15
Free
ARVO Annual Meeting Abstract  |   June 2013
Tonic Accommodation Correlates with Accommodative Amplitude-Scaled Facility Test for Symptomatic Graduate Students
Author Affiliations & Notes
  • Chunming Liu
    Optometry, Western University of Health Sciences College of Optometry, Pomona, CA
  • Chris Chase
    Optometry, Western University of Health Sciences College of Optometry, Pomona, CA
  • Stefanie Drew
    California State University, Northridge, Northridge, CA
  • Efrain Castellanos
    Optometry, Western University of Health Sciences College of Optometry, Pomona, CA
  • Amy Escobar
    Optometry, Western University of Health Sciences College of Optometry, Pomona, CA
  • Eric Borsting
    Southern California College of Optometry, Fullerton, CA
  • Lawrence Stark
    Southern California College of Optometry, Fullerton, CA
  • Footnotes
    Commercial Relationships Chunming Liu, None; Chris Chase, None; Stefanie Drew, None; Efrain Castellanos, None; Amy Escobar, None; Eric Borsting, None; Lawrence Stark, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science June 2013, Vol.54, 4259. doi:https://doi.org/
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      Chunming Liu, Chris Chase, Stefanie Drew, Efrain Castellanos, Amy Escobar, Eric Borsting, Lawrence Stark; Tonic Accommodation Correlates with Accommodative Amplitude-Scaled Facility Test for Symptomatic Graduate Students. Invest. Ophthalmol. Vis. Sci. 2013;54(15):4259. doi: https://doi.org/.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract
 
Purpose
 

Among standard clinical measures of binocular function, the accommodative amplitude-scaled facility (AsFac) test is the most sensitive for predicting visual discomfort symptoms. The AsFac test may be a better correlate due to its individual adjustment of the accommodative stimulus (AS) based on amplitude. Another factor that could affect stimulus demand is tonic accommodation (TA). Higher TA could put the accommodation resting state closer to the target demand, effectively reducing the AS. This study examined the relationship between AsFac test and TA in symptomatic and asymptomatic graduate students.

 
Methods
 

Visual symptoms were assessed by the Convergence Insufficiency Symptom Survey (CISS). Based on the CISS adult cut-off score of 21, the sample was divided into High (N=22) and Low (N=17) symptom groups. Assessment of binocular function was made using standard clinical procedures. TA was recorded for 2 min after 5 min of dark adaptation. From the AsFac test with the plus lens, a TA-corrected AS was calculated based on testing distance, lens power, and TA with the formula: [(100/distance in cm) - lens power - TA].

 
Results
 

Among all clinical measures, including accommodative amplitude/facility, and vergence facility (3BI/12BO), only the binocular AsFac test showed a statistically significant correlation with TA (r=0.48, p=0.004). A positive correlation was found in the high symptom group (Y=6.989+2.812*X; R2=0.435; p=0.001), but not in the low symptom group (Y=13.948+0.961*X; R2=0.169; p=0.145) (Fig 1). A similar group effect was also found in the relationship between TA-corrected AS and AsFac. A statistically significant negative correlation only existed in the high symptom group (Y=14.330-1.184*X; R2=0.336; p=0.006), not in the low symptom group (Y=16.496-0.697*X; R2=0.064; p=0.406) (Fig 2).

 
Conclusions
 

Our results suggest a possible link between AsFac test and the tonic accommodative adaptation state in graduate students with significant visual discomfort. The sensitivity of the test for predicting symptom might rely, at least partly, on this correlation. TA might be utilized as compensatory mechanism for reducing AS demand at near for this population. With lowered demand, subjects would be more efficient at performing a facility test.

 
 
Fig 1. Regression plot for TA and AsFac test
 
Fig 1. Regression plot for TA and AsFac test
 
 
Fig 2. Regression plot for TA-corrected AS and AsFac test
 
Fig 2. Regression plot for TA-corrected AS and AsFac test
 
Keywords: 404 accommodation • 434 binocular vision/stereopsis  
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