April 2014
Volume 55, Issue 13
Free
ARVO Annual Meeting Abstract  |   April 2014
Influence Of Selected Retinal Vessel Length On Dynamic Vessel Analyzer Output
Author Affiliations & Notes
  • Angelos Kalitzeos
    Optometry and Vision Sciences, Aston University, Birmingham, United Kingdom
  • Rebekka Heitmar
    Optometry and Vision Sciences, Aston University, Birmingham, United Kingdom
  • Footnotes
    Commercial Relationships Angelos Kalitzeos, None; Rebekka Heitmar, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science April 2014, Vol.55, 236. doi:
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      Angelos Kalitzeos, Rebekka Heitmar; Influence Of Selected Retinal Vessel Length On Dynamic Vessel Analyzer Output. Invest. Ophthalmol. Vis. Sci. 2014;55(13):236.

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

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Abstract

Purpose: To assess the impact of retinal vessel length on continuous retinal diameter measurements, when applying flicker light provocation in healthy subjects using the DVA (Dynamic Vessel Analyzer).

Methods: The DVA is a commercially available unit which is capable of recording vessel diameter fluctuations as a function of time and location with high temporal and spatial resolution. We obtained retinal vessel diameter responses of eleven healthy subjects (one arterial and one venular segment, 1-2 disk diameters away of the optic nerve head) following intraocular pressure and systemic blood pressure measurements. The diameter measurements were recorded during a 350 seconds period consisting of 50 seconds baseline followed by three cycles of 20 seconds flicker light provocation (12.5 Hz) and 80 seconds recovery time. All vessel segments were analysed twice: firstly by including the maximum length as selected (limited only by each individual's angio-architecture) and secondly by analysing a truncated, standardized length of 240 MU. For each vessel length analysis, the vessel diameter output (in Measuring Units (MU), with 1 MU corresponding to 1 μm for the Gullstrand's normal eye) was plotted against time (in seconds). A second-by-second subtraction of the retinal vessel diameter recordings, during flicker stimulation between the long and the short segments per subject, followed. If vessel length had no impact, the subtraction between the two plots would yield values equal to 0 MU.

Results: The long versus short selected vessel segments yielded unequal diameter recordings: across subjects, arterial segments differed on average (± standard deviation) by 5.4 MU (± 1.8 MU) and venular segments by 7.5 MU (± 5.4 MU) across the full recording duration.

Conclusions: Retinal vessel reactivity recordings by means of flicker provocation as obtained with the DVA are influenced by the length of the vessel selected. Hence, vessel diameters recorded should be truncated to the same length for group comparisons to avoid this influence as it could potentially lead to falsely augmented or attenuated results.

Keywords: 688 retina • 550 imaging/image analysis: clinical  
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