September 2016
Volume 57, Issue 12
Open Access
ARVO Annual Meeting Abstract  |   September 2016
A Multicenter Study Assessing Inter-Examiner Agreement of Gonioscopic Shaffer Grading in Patients with Open-Angle Glaucoma and/or Ocular Hypertension
Author Affiliations & Notes
  • Reihab Ahmed
    Allergan plc, Irvine, California, United States
  • Bashir Khan
    Allergan plc, Irvine, California, United States
  • Michelle Chen
    Allergan plc, Irvine, California, United States
  • Michael R Robinson
    Allergan plc, Irvine, California, United States
  • Susan S Lee
    Allergan plc, Irvine, California, United States
  • Footnotes
    Commercial Relationships   Reihab Ahmed, None; Bashir Khan, Allergan plc (E); Michelle Chen, Allergan plc (E); Michael Robinson, Allergan plc (E); Susan Lee, Allergan plc (E)
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science September 2016, Vol.57, 3043. doi:
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    • Get Citation

      Reihab Ahmed, Bashir Khan, Michelle Chen, Michael R Robinson, Susan S Lee; A Multicenter Study Assessing Inter-Examiner Agreement of Gonioscopic Shaffer Grading in Patients with Open-Angle Glaucoma and/or Ocular Hypertension. Invest. Ophthalmol. Vis. Sci. 2016;57(12):3043.

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

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Abstract

Purpose : Shaffer grading is considered the gold standard grading scale used during gonioscopy examination to assess angle opening. This study assessed the inter-examiner agreement between examiners evaluating Shaffer grades during gonioscopy in patients with open-angle glaucoma (OAG) and/or ocular hypertension (OHT).

Methods : This study was performed at 3 glaucoma specialty centers on 100 patients with OAG or OHT. At each site, gonioscopy of the inferior angle of one eye of each patient was performed by two examiners who were masked to each other’s results and Shaffer grades were reported. Cohen’s kappa (weighted)[1], measuring agreement between the pairs of examiners, were determined.

Results : Across all sites, examiners showed a 60% (60/100) agreement in Shaffer grade readings, 37% (37/100) of readings had a difference of 1 grade, and 3% (3/100) had a 2-grade difference. The weighted kappa value indicated moderate inter-examiner agreement (κ = 0.48). Furthermore, inter-examiner agreement at individual sites is shown in Table 1.

Conclusions : The Shaffer grading system is widely used to gonioscopically determine angle width. Our results indicate that there may be variability between examiners across sites when performing Shaffer grading. A more quantitative method for assessing angle width, such as anterior segment optical coherence tomography (AS-OCT), may be considered for improved accuracy.

References
[1] Landis, J., & Koch, G. (1977). The measurement of observer agreement for categorical data. Biometrics 33 (1), 159-174.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

 

Site specific inter-examiner agreement of Shaffer grading for patients with open-angle glaucoma (OAG) and/or ocular hypertension (OHT).

Site specific inter-examiner agreement of Shaffer grading for patients with open-angle glaucoma (OAG) and/or ocular hypertension (OHT).

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