June 2017
Volume 58, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2017
Steeper iris conicity is related to a shallower anterior chamber but not to higher intraocular pressure – The Gutenberg Health Study
Author Affiliations & Notes
  • Alexander Karl-Georg Schuster
    Department of Ophthalmology, Mainz University Medical Center, Mainz, Germany
  • Norbert Pfeiffer
    Department of Ophthalmology, Mainz University Medical Center, Mainz, Germany
  • Stefan Nickels
    Department of Ophthalmology, Mainz University Medical Center, Mainz, Germany
  • Andreas Schulz
    Preventive Cardiology and Preventive Medicine, Center for Cardiology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
  • Philipp S Wild
    Preventive Cardiology and Preventive Medicine, Center for Cardiology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
    DZHK (German Center for Cardiovascular Research), partner site Rhine-Main, Mainz, Germany
  • Maria Blettner
    Department of Biomedical Statistics, Mainz, Germany
  • Karl J Lackner
    Institute for Clinical Chemistry and Laboratory Medicine, Mainz, Germany
  • Manfred E Beutel
    Department of Psychosomatic Medicine and Psychotherapy, Mainz, Germany
  • Thomas Münzel
    Center for Cardiology, Mainz, Germany
  • Urs Vossmerbaeumer
    Department of Ophthalmology, Mainz University Medical Center, Mainz, Germany
  • Footnotes
    Commercial Relationships   Alexander Schuster, None; Norbert Pfeiffer, None; Stefan Nickels, None; Andreas Schulz, None; Philipp Wild, None; Maria Blettner, None; Karl Lackner, None; Manfred Beutel, None; Thomas Münzel, None; Urs Vossmerbaeumer, None
  • Footnotes
    Support  None.
Investigative Ophthalmology & Visual Science June 2017, Vol.58, 4806. doi:
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      Alexander Karl-Georg Schuster, Norbert Pfeiffer, Stefan Nickels, Andreas Schulz, Philipp S Wild, Maria Blettner, Karl J Lackner, Manfred E Beutel, Thomas Münzel, Urs Vossmerbaeumer; Steeper iris conicity is related to a shallower anterior chamber but not to higher intraocular pressure – The Gutenberg Health Study. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4806.

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

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Abstract

Purpose : The geometry of the iris plays an important role in the regulation of outflow of aqueous humor. The iris geometry can be described by its relative position in the anterior chamber (steepness of the iris cone: iris conicity) and its bowing (iris convexity). Scheimpflug imaging allows quantitative analysis of the anterior segment including iris conicity. We report the population-based distribution of iris conicity, investigate associated factors and test the hypothesis whether pseudophakia allows the iris to sink back.

Methods : A population-based cross-sectional study was carried out in Germany. A comprehensive ophthalmological examination including refraction, biometry and Scheimpflug imaging was performed. Automated measurement of the iris conicity was performed. Analyses were carried out to determine independently associated systemic and ocular factors for iris conicity using a generalized estimating equation model in phakic eyes. In addition, pseudophakic and phakic eyes were compared.

Results : 3708 subjects (48% female) with a mean age of 58.7+/-10.4 years were included. The mean iris conicity was 8.28° +/- 3.29° (right eyes) and 8.51° +/- 3.27° (left eyes). Statistical analysis revealed an association between steeper iris conicity and younger age, shallower anterior chamber depth, thicker human lens and higher corneal power. Body height, body weight, refraction, axial length, central corneal thickness, pupil diameter and intraocular pressure were not associated. Pseudophakia resulted in a 5.82° flatter iris conicity.

Conclusions : Associations indicate a relationship between iris conicity with lens thickness and anterior chamber depth, all risk factors known for angle closure. No association was seen with intraocular pressure indicating that the steepness of the iris does not affect regulation of the intraocular pressure in eyes without angle closure. In pseudophakic eyes, iris conicity approaches 0°, showing that cataract surgery flattens the iris position. This supports the approach of removing the lens in an eye prone to angle closure glaucoma to create a wider anterior chamber angle and to lower the risk for angle-closure.

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

 

Illustration of iris conicity measurement. The iris surface is approximated by a linear slope (orange line). Iris conicity is the angle alpha between this slope and the plane through the opposite anterior chamber angles (yellow line).

Illustration of iris conicity measurement. The iris surface is approximated by a linear slope (orange line). Iris conicity is the angle alpha between this slope and the plane through the opposite anterior chamber angles (yellow line).

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