June 2020
Volume 61, Issue 7
Free
ARVO Annual Meeting Abstract  |   June 2020
Assessment of glaucomatous defects within the macula using two different circular perimetric stimuli.
Author Affiliations & Notes
  • Muhammed Alluwimi
    College of Applied Medical Sciences, Optometry Department, Qassim University, Qassim, Saudi Arabia
  • William H Swanson
    School of Optometry, Indiana University, Bloomington, Indiana, United States
  • Footnotes
    Commercial Relationships   Muhammed Alluwimi, None; William Swanson, None
  • Footnotes
    Support  NIH R01EY024542
Investigative Ophthalmology & Visual Science June 2020, Vol.61, 3890. doi:
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      Muhammed Alluwimi, William H Swanson; Assessment of glaucomatous defects within the macula using two different circular perimetric stimuli.. Invest. Ophthalmol. Vis. Sci. 2020;61(7):3890.

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

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Abstract

Purpose : Perimetric testing is used to assess glaucomatous defects; and most often uses Goldmann circular stimuli with sharp edges. Studies have reported that within 10° of fixation the Goldmann size III stimulus is larger than the critical area; therefore perimetric defects will on average be less deep. Our lab authored a study showing that, at the nasal visual field (temporal raphe), a Gaussian blob stimulus with blurred edges and 0.5° standard deviation (SD) yielded deeper defects than a circular stimulus of similar size (Goldmann size V). In the current study, we tested the hypothesis that within 10° of fixation, a smaller stimulus with blurred edges (Gaussian blob with SD of 0.25°) would yield deeper defects than Goldmann stimulus size III.

Methods : Fifteen patients with perimetric glaucomatous defect at the macula were recruited (ages 61 to 81 years). All patients were tested, one eye for each, with the size III stimulus and a Gaussian blob stimulus with SD of 0.25°, using the 68 10-2 locations. Total deviation (TD) was computed as difference from means for age-similar controls. To assess agreement on defect depth for the two stimuli, Bland-Altman analysis was used. Similar ranges were obtained for both sets of TD, by defining a floor (lowest TD) at − 1.3 log unit and a ceiling (highest TD) at + 0.3 log unit.

Results : Bland-Altman analysis found a mean difference of 0.09 log unit in depth of defect for the size III stimulus versus the Gaussian blob stimulus. Linear regression of difference versus mean found a small but statistically significant increase in the difference for deeper defects (r = 0.15, p <0.001), with 95% limits of agreement of ±0.61 log unit. Perimetric defects, on average, were increasingly deeper for the size III stimulus.

Conclusions : We found that, within 10° fixation, the size III stimulus on average yielded deeper perimetric defects than a similar-size Gaussian blob stimulus. This is inconsistent with a prior finding using larger stimuli in the nasal visual field. We infer that the prior finding may be limited to larger stimuli.

This is a 2020 ARVO Annual Meeting abstract.

 

Bland-Altman analysis for the total deviation (TD) values for the size III and Gaussian stimuli. X-axis represents the average of the TD values for the two stimuli while y-axis represents the difference between them. The solid line indicates mean difference, while the dashed lines indicate the 95% limits of agreement.

Bland-Altman analysis for the total deviation (TD) values for the size III and Gaussian stimuli. X-axis represents the average of the TD values for the two stimuli while y-axis represents the difference between them. The solid line indicates mean difference, while the dashed lines indicate the 95% limits of agreement.

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