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The Spatial And Temporal Characteristics Of Blur Adaptation

Subramanian, Vidhya

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2009, Doctor of Philosophy, Ohio State University, Vision Science.
The reduction in visual resolution due to visual blur is a common experience, especially when individuals requiring eyewear remove their spectacles or contact lenses. However,studies have shown that when one looks continually at a visual acuity chart through blur, the smallest letters that one can read at first are not as small as the letters that one can read several minutes later. This improvement in sensitivity following a period of exposure to blur is referred to as blur adaptation. The purpose of this dissertation is to evaluate the temporal and spatial aspects of blur adaptation. Ten subjects were enrolled in each of the three visual acuity studies. The temporal characteristics were assessed, firstly, by varying the initial blur exposure duration (0min, 1min, 5min and 15min exposures) to a natural scene image. Visual acuity measured using a short 1.5min and a long 10min computer-based letter presentations, using Bailey-Lovie optotypes, was the outcome measure. Secondly, the influence of varying letter exposure durations was tested using three letter presentation times (2sec, 4sec and 15sec exposure per letter). The spatial characteristics of adaptation were assessed by adapting to a blurred natural scene, visual acuity chart, and different sets of alphabets presented in large and small sizes. A fourth study, carried out on one subject, looked at the effects of blur adaptation on the contrast sensitivity function. It was seen that visual acuity was not influenced by the four initial blur exposure durations to the natural scene. Also, adaptation to stimuli with various spatial characteristics like a natural scene, acuity chart, and letters of varying sizes did not result in different acuity scores. However, there was a significant influence of test letter presentation duration. Acuity was better with long acuity presentation times compared to short presentation times. The acuity score from the 15sec per letter presentation was better than those from 2sec per letter and 4sec per letter presentations. Interestingly, blur adaptation did not significantly influence contrast sensitivity. Thus this work suggests that blur adaptation is not driven by spatial features but may be due to temporal summation effects.
Donald Mutti, OD, PhD (Advisor)
Delwin Lindsey, PhD (Committee Member)
Thomas Raasch, OD, PhD (Committee Member)
Mathew Allen, VetMB, PhD (Committee Member)
136 p.

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Citations

  • Subramanian, V. (2009). The Spatial And Temporal Characteristics Of Blur Adaptation [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1230923311

    APA Style (7th edition)

  • Subramanian, Vidhya. The Spatial And Temporal Characteristics Of Blur Adaptation. 2009. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1230923311.

    MLA Style (8th edition)

  • Subramanian, Vidhya. "The Spatial And Temporal Characteristics Of Blur Adaptation." Doctoral dissertation, Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1230923311

    Chicago Manual of Style (17th edition)