April 2011
Volume 52, Issue 14
ARVO Annual Meeting Abstract  |   April 2011
Effect Of Scan Beam Entry Position On Measurements Of Optic Nerve Parameters Using Spectral-domain Optical Coherence Tomography
Author Affiliations & Notes
  • Kunliang Qiu
    JSIEC, Shantou, China
  • Mingzhi Zhang
    Ophthalmology, Joint Shantou International Eye Center, Shantou, China
  • Christopher K. Leung
    3/F, University Eye Center, Hong Kong Eye Hospital, Hong Kong, Hong Kong
  • Dennis S C. Lam
    Chinese Univ Hong Kong Eye Hosp, Kowloon, Hong Kong
  • Footnotes
    Commercial Relationships  Kunliang Qiu, None; Mingzhi Zhang, None; Christopher K. Leung, None; Dennis S C. Lam, None
  • Footnotes
    Support  JSIEC Grant 09-013
Investigative Ophthalmology & Visual Science April 2011, Vol.52, 171. doi:
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      Kunliang Qiu, Mingzhi Zhang, Christopher K. Leung, Dennis S C. Lam; Effect Of Scan Beam Entry Position On Measurements Of Optic Nerve Parameters Using Spectral-domain Optical Coherence Tomography. Invest. Ophthalmol. Vis. Sci. 2011;52(14):171.

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

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To evaluate the effect of the entry position of the scan beam on measurements of optic nerve parameters by using spectral-domain optical coherence tomography (OCT).


16 eyes from 16 normal subjects were scanned by the Optic disc cube 200x200 protocol of a spectral-domain Cirrus HD-OCT (Carl Zeiss Meditec, Inc., Dublin, CA) under dilated pupils (pupil diameter no less than 7mm). For each eye, the entry position of the scan beam through the dilated pupil was varied horizontally. Parapapillary RNFL thickness, disc area and rim area from 3 different scan beam locations (temporal, central and nasal, respectively) were recorded and compared.


The mean age was 22 ± 1.5 years. Significant differences in RNFL thicknesses were found among different scan locations (e.g average RNFL thickness for temporal, central and nasal scanning were 92.9 ± 7.4um, 97.0 ± 8.0um, and 101.0 ± 6.8um, respectively, all with p<0.001). No significant difference was detected for disc area (temporal, 1.76 ± 0.35mm2; central, 1.75 ± 0.35 mm2; nasal, 1.75 ± 0.36 mm2; all with p>0.05) and rim area (temporal, 1.26 ± 0.15 mm2; central, 1.24 ± 0.17 mm2; nasal, 1.27 ± 0.14 mm2; all with p>0.05) from different scan locations.


Measurement of RNFL thickness but not optic disc parameters was significantly affected by the entry position of the scan beam of Cirrus HD-OCT. Caution should be exercised in interpreting the results of RNFL measurement from different scan beam entry position during longitudinal assessment. Obtaining RNFL measurement at similar scan beam entry position is recommended.  

Keywords: nerve fiber layer • optic nerve 

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