Please use this identifier to cite or link to this item:
Title: Technical note : how many readings are required for an acceptable accuracy in pulsatile ocular blood flow assessment?
Authors: Yu, BSY
Lam, AKC 
Keywords: Accuracy
Intraocular pressure
Pulsatile ocular blood flow
Issue Date: 2007
Publisher: Wiley-Blackwell
Source: Ophthalmic and physiological optics, 2007, v. 27, no. 2, p. 213-219 How to cite?
Journal: Ophthalmic and physiological optics 
Abstract: Purpose:  Pulsatile ocular blood flow (POBF) assessment aids the diagnosis of ocular diseases with defective ocular haemodynamics, such as glaucoma. Although each successful POBF measure given by the instrument represents five ‘repeatable’ pulses, there has been no study verifying how repeatable they are. There is also no report on the minimal number of measurements for an acceptable accuracy.
Methods:  Forty-three healthy young subjects were recruited and each subject had five consecutive POBF measurements obtained from one randomly selected eye. The coefficient of variation was calculated from the raw data of the five ‘repeatable’ pulses. The average from five consecutive measurements was considered as the standard for comparison with the first, average of the first two, the first three and the first four measurements. The 95% limits of agreement were determined using the Bland and Altman approach.
Results:  The coefficient of variation was greater than the manufacturer's claim of within 10%. The mean (±S.D.) POBF calculated from five consecutive measures was 732.5 ± 243.2 μL min−1. The mean (±S.D.) difference between the standard POBF and the first, average of the first two, the first three and the first four measurements was (in μL min−1): 12.5 ± 59.8, 7.8 ± 42.1, 9.6 ± 32.5 and 3.7 ± 19.6 respectively. The corresponding 95% limits of agreement were (in μL min−1): ±117.2, ±82.6, ±63.8 and ±38.4 respectively.
Conclusions:  As the five ‘repeatable’ pulses were not as repeatable as the manufacturer claims, practitioners should not rely on one single POBF measure. An average of three consecutive measurements will be adequate to detect the minimum reported difference in POBF between glaucoma and normal patients.
ISSN: 0275-5408
EISSN: 1475-1313
DOI: 10.1111/j.1475-1313.2006.00463.x
Appears in Collections:Journal/Magazine Article

View full-text via PolyU eLinks SFX Query
Show full item record


Last Week
Last month
Citations as of Nov 14, 2018


Last Week
Last month
Citations as of Nov 9, 2018

Page view(s)

Last Week
Last month
Citations as of Nov 12, 2018

Google ScholarTM



Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.