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Role of Accommodation in Clinical Measures of Proximal Vergence

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2019, Master of Science, Ohio State University, Vision Science.
Proximal vergence is the subtype of vergence that is stimulated by visual cues other than blur and disparity. There are two major clinical methods to assess proximal vergence. In one of these methods, termed the AC/A differencing method, proximal vergence is determined by calculating the difference in vergence change from the far-near AC/A method and the vergence change from the gradient AC/A method (equated for the accommodative demand). In the other method, termed the +2.50D method, the change in vergence posture between distance viewing and near viewing through a +2.50D lens is calculated. In assessing these values, it is typically assumed that response accommodation matched the change in accommodative demand from distance to near, which would be 2.50D for a 40cm near viewing distance. However, individuals often do not alter their accommodation by the amount of the accommodative demand. Therefore, proximal values calculated using accommodative responses might vary from proximal values that are calculated using the accommodative demand. The purpose of the present research is to determine the extent to which response accommodation could influence these methods of assessing proximal vergence, in order to better understand how proximal vergence is measured and therefore to better understand the relationship between proximal vergence and the other vergence subtypes in future studies. Thirteen subjects were recruited, ages 22-37, who underwent a battery of measurements consisting of interpupillary distance, visual acuity, stereoacuity, accommodative amplitudes, step vergence ranges, distance heterophoria, and near heterophoria using various refractive lenses. A Grand Seiko WR5100K autorefractor measured accommodation. Accommodative data revealed high accommodative lags in many subjects, which influenced response AC/A ratios and response proximal vergence results. Proximal vergence was then calculated in four distinct ways, two based on stimulus measurements and two taking response accommodation into consideration. Statistical analysis using t-tests showed no statistically significant difference between any of these proximal vergence calculations after using the Bonferonni correction (p>0.0083 for all comparisons). Additionally, no statistically significant relationship between measures of fusional vergence and measures for proximal vergence were found (p>0.05) using linear regression analysis. In conclusion, this study found that all four clinical methods, using stimulus and response measurements, yielded similar values.
Nicklaus Fogt (Advisor)
Catherine McDaniel (Committee Member)
Donald Mutti (Committee Member)
55 p.

Recommended Citations

Citations

  • Fenton, R. (2019). Role of Accommodation in Clinical Measures of Proximal Vergence [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555572551774614

    APA Style (7th edition)

  • Fenton, Rachel. Role of Accommodation in Clinical Measures of Proximal Vergence. 2019. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1555572551774614.

    MLA Style (8th edition)

  • Fenton, Rachel. "Role of Accommodation in Clinical Measures of Proximal Vergence." Master's thesis, Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555572551774614

    Chicago Manual of Style (17th edition)