Intra-observer and inter-observer variation of Hertel exophthalmometry.
OBJECTIVE
This study investigated the intra-observer and inter-observer variation of Hertel exophthalmometry.


METHODS
Seventy normal Chinese adults had bilateral exophthalmometry performed by two examiners. The two examiners were masked to the measurement results. One examiner did the measurement twice and the other examiner measured it once; the order was randomised. The same Hertel exophthalmometer was used throughout the study. The Bland-Altman method was used to analyse the intra-observer and inter-observer agreement.


RESULTS
The mean intra-observer and inter-observer agreements on the interorbital distance (IOD) were +/-3.31 mm and +/-6.39 mm, respectively. The intra-observer exophthalmometry difference was -0.01 +/- 0.61 mm for the right eye and 0.09 +/- 0.56 mm for the left eye. Agreements were +/-1.19 mm and +/-1.09 mm for the right and left eyes, respectively. The inter-observer exophthalmometry difference was -0.61 +/- 0.89 mm for the right eye and -0.49 +/- 0.80 mm for the left eye. Agreements were +/-1.74 mm and +/-1.57 mm for the right and left eyes, respectively. There was no significant intra-observer difference but the inter-observer difference was significant on both the IOD and exophthalmometry.


CONCLUSIONS
Good intra-observer agreement was demonstrated using Hertel exophthalmometry. The inter-observer agreement was clinically acceptable.
Lam
Andrew K C
AK
School of Optometry, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong. Andrew.KC.Lam@polyu.edu.hk
Lam
Chun-fai
CF
Leung
Wai-kit
WK
Hung
Pui-kwan
PK
D000328:Adult; D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation*; D005094:Exophthalmos / Q000175:diagnosis* / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D015588:Observer Variation; D015203:Reproducibility of Results; D055815:Young Adult