June 2017
Volume 58, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2017
Individual Variation in Accommodative Change of the Iris Profile among Young Adults
Author Affiliations & Notes
  • Ji C He
    New England College of Optometry, Boston, Massachusetts, United States
  • Footnotes
    Commercial Relationships   Ji He, None
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science June 2017, Vol.58, 2090. doi:
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      Ji C He; Individual Variation in Accommodative Change of the Iris Profile among Young Adults. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2090.

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

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Abstract

Purpose : The function of accommodation is to change refractive power of the eye for near vision, but meanwhile, it also changes intraocular pressure (IOP) in the anterior chamber due to a forward movement of the anterior lens surface. For pigmentary glaucoma patients, accommodation causes iris to be bowed, and the iris bowing was attributed to a pressure reversal between the anterior and posterior chambers. The purpose of this study was to measure accommodative change of the iris profile for normal young adults in order to better understand dynamics of the aqueous humor in the normal eyes.

Methods : Accommodations from 0D to 6D in a step of 2D were induced and measured in the right eyes of 16 young adults (age ranged 22 to 27 years) by using a customized anterior segment OCT system, and the accommodative changes in the lens shape and refractive power have been previously reported in ARVO 2014 and 2015. In this study, the OCT images were re-processed with a customized MatLab program by outlining the posterior profile of the iris after correcting refractive distortion with a customized ray tracing procedure. A 2nd order polynomial function was used to fit the iris profile, and the coefficients were derived to assess slope and curvature of the iris profile.

Results : For all subjects, mean slope coefficient of posterior iris profile was 0.177±0.155 at 0D and changed to -0.012±0.119 at 6D accommodation. The mean curvature coefficient was changed from 0.035±0.027 in convex shape at 0D to -0.036±0.022 in concave shape at 6D accommodation. The difference of curvature coefficient between the 0D and 6D changed substantially from subject to subject, with a minimum of -0.005 and a maximum of -0.128. The accommodative change of curvature coefficient was not significantly correlated to accommodative change of ACD.

Conclusions : There is a substantial variation in accommodative change of the iris profile among young adults, and the iris bowing is not associated with the amount of forward movement of the anterior lens surface. The results suggest that accommodative change of iris profile might be associated with fluid dynamics of the anterior chamber, and the test of iris change during accommodation could be an interesting method in clinical practice to assess risk factor of glaucoma.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

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