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Reliability of rotary prism fusional vergence ranges
D K Penisten1, H W Hofstetter, D A Goss
1College of Optometry, Northeastern State University, Tahlequah, Oklahoma, USA.
Background:
The measurement of fusional vergence ranges is an important clinical test in the assessment of binocular vision status. Fusional vergence ranges are typically measured by recording a patient's reports of blur, break, and recovery to base-in (BI) and base-out (BO) prism. Published reliability data on fusional vergence ranges are very limited.
Methods:
Eight subjects underwent four testing sessions, at which repeated measurements of fusional vergence ranges were taken. Near ranges were tested at the first session only Distance ranges were tested at all four sessions. Intra-examiner standard deviations were calculated for each fusional vergence test result (BI and BO; blur, break, and recovery) for each session. Intra-examiner standard deviations were averaged. These values were used to determine 95% limits of agreement.
Results:
The 95% limits of agreement were between 2 delta and 2.5 delta for the distance BI break and recovery and for the near BI recovery; between 3 and 4 delta for near BI break and near BO break; between 4 and 5 delta for distance BO blur and recovery and for near BI blur; and between 5 and 5.5 delta for distance BO break and near BO blur and recovery.
