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Optimal number and orientation of anterior segment OCT images to measure ocular biometric parameters in angle closure eyes: the Chinese American Eye Study
  1. Jing Shan1,
  2. Anmol Pardeshi1,2,
  3. Xuejuan Jiang1,
  4. Grace M Richter1,
  5. Roberta McKean-Cowdin1,2,
  6. Rohit Varma3,
  7. Benjamin Y Xu1
  1. 1Department of Ophthalmology, University of Southern California, Los Angeles, California, USA
  2. 2Department of Preventive Medicine, University of Southern California, Los Angeles, California, USA
  3. 3Southern California Eye Institute, CHA Hollywood Presbyterian Medical Center, Los Angeles, CA, USA
  1. Correspondence to Dr Benjamin Y Xu, Department of Ophthalmology, University of Southern California, Los Angeles, CA 90033, USA; Benjamin.Xu{at}


Purpose To assess the optimal number and orientation of anterior segment optical coherence tomography (AS-OCT) images for accurately measuring ocular biometric parameters in angle closure eyes.

Methods Subjects with angle closure, defined as >3 quadrants of non-visible pigmented trabecular meshwork on static gonioscopy, were selected from the Chinese American Eye Study. Mean angle opening distance (AOD500) was calculated using four images (0°−180°, 45°−225°, 90°−270° and 135°−315° meridians) from one eye per subject. Ten eyes from each quartile of AOD500 measurements were randomly selected for detailed 32-image analysis of 10 biometric parameters, including AOD500, iris curvature (IC), anterior chamber depth (ACD), lens vault (LV), and anterior chamber area (ACA). Mean and range of measurements from 1, 2, 4, 8 or 16 images were compared with 32-image values for all parameters.

Results 40 out of 335 eyes with angle closure were selected for 32-image analysis. Deviation from the 32-image mean was between 0.44% and 19.31% with one image, decreasing to 0.08% to 4.21% with two images for all parameters. Deviation from the 32-image range of measurements was between 54.67% to 88.94% with one image, decreasing to <7.00% with eight images for all parameters except ACD and ACA. Orienting the first image analysed along the 25°−205° meridian better approximated the range of measurements when four or fewer images were analysed.

Conclusions Sectoral anatomical variations in angle closure eyes are easily misrepresented based on current AS-OCT imaging conventions. A revised multi-image approach can better capture the mean and range of biometric measurements.

  • angle
  • anterior chamber
  • diagnostic tests/investigation
  • glaucoma
  • imaging

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  • Contributors BYX and GMC designed the presented study. XJ, RM-C, and RV collected data. AP, BYX, and JS analysed the data. All authors contributed to the final manuscript. BYX acts as guarantor of the study.

  • Funding This work was supported by the National Eye Institute K23 EY029763; the American Glaucoma Society Young Clinician Scientist Research Award; and Research to Prevent Blindness unrestricted grant to the Department of Ophthalmology; and UCSF Initiative for Digital Transformation in Computational Biology & Health.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.

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