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Clinical science
Posterior chamber volume does not change significantly during dilation
  1. S Dorairaj1,2,
  2. J M Liebmann1,3,4,
  3. C Tello1,
  4. V H Barocas5,
  5. R Ritch1,6
  1. 1
    Einhorn Clinical Research Center, The New York Eye and Ear Infirmary, New York, USA
  2. 2
    Beth Israel Medical Center, New York, USA
  3. 3
    Department of Ophthalmology, New York University School of Medicine, New York, USA
  4. 4
    Department of Ophthalmology, Manhattan Eye, Ear and Throat Hospital, New York, USA
  5. 5
    Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota, USA
  6. 6
    Department of Ophthalmology, The New York Medical College, Valhalla, New York, USA
  1. Correspondence to Dr V Barocas, Department of Biomedical Engineering, University of Minnesota, 7-105 Nils Hasselmo Hall, 312 Church St SE, Minneapolis, MN 55455, USA; baroc001{at}


Background/aims: To determine whether the volume of the posterior chamber changes during pupillary dilation.

Methods: Eyes with anatomically narrow angles underwent ultrasound biomicroscopy of the posterior chamber and pupillary margin under dark- and light-room conditions to assess changes in posterior chamber anatomy and volume. All examinations were stored as real-time video. A frame-by-frame analysis was performed using a macro written for the ImageJ image-processing software.

Results: Thirteen eyes were assessed. The mean patient age was 63.0 (SD 10.0) years, and the mean refractive error was 1.1 (1.9) dioptres. The horizontal mean pupillary diameter was 2.3 (0.6) mm and 3.5 (0.5) mm under light- and dark-room conditions, respectively (p<10−7, paired t test). The mean posterior chamber volumes were unchanged under light and dark conditions (3.76 (1.09) vs 3.63 (0.78) mm3, p = 0.22, paired t test). Volumes were greater under light conditions in eight eyes and under dark conditions in five eyes.

Conclusions: The volume of the posterior chamber does not change significantly during dilation.

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  • Funding Funding was provided by NIH Grant EY-015795 and the Irving and Elaine Wolbrom Research Fund of the New York Glaucoma Research Institute, New York.

  • Competing interests None.

  • Ethics approval Ethics approval was provided by IRB at NYEEI and UMN.

  • Patient consent Obtained.