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Axial length variation impacts on superficial retinal vessel density and foveal avascular zone area measurements using optical coherence tomography angiography

Sampson, D.M., Gong, P., An, D., Menghini, M., Hansen, A., Mackey, D.A., Sampson, David and Chen, F.K. (2017) Axial length variation impacts on superficial retinal vessel density and foveal avascular zone area measurements using optical coherence tomography angiography Investigative Ophthalmology and Visual Science, 58 (7). pp. 3065-3072.

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Abstract

Purpose: To evaluate the impact of image magnification correction on superficial retinal vessel density (SRVD) and foveal avascular zone area (FAZA) measurements using optical coherence tomography angiography (OCTA).

Methods: Participants with healthy retinas were recruited for ocular biometry, refraction, and RTVue XR Avanti OCTA imaging with the 3 × 3-mm protocol. The foveal and parafoveal SRVD and FAZA were quantified with custom software before and after correction for magnification error using the Littman and the modified Bennett formulae. Relative changes between corrected and uncorrected SRVD and FAZA were calculated.

Results: Forty subjects were enrolled and the median (range) age of the participants was 30 (18–74) years. The mean (range) spherical equivalent refractive error was −1.65 (−8.00 to +4.88) diopters and mean (range) axial length was 24.42 mm (21.27–28.85). Images from 13 eyes were excluded due to poor image quality leaving 67 for analysis. Relative changes in foveal and parafoveal SRVD and FAZA after correction ranged from −20% to +10%, −3% to +2%, and −20% to +51%, respectively. Image size correction in measurements of foveal SRVD and FAZA was greater than 5% in 51% and 74% of eyes, respectively. In contrast, 100% of eyes had less than 5% correction in measurements of parafoveal SRVD.

Conclusions: Ocular biometry should be performed with OCTA to correct image magnification error induced by axial length variation. We advise caution when interpreting interocular and interindividual comparisons of SRVD and FAZA derived from OCTA without image size correction.

Item Type: Article
Divisions : Faculty of Engineering and Physical Sciences
Faculty of Health and Medical Sciences
Authors :
NameEmailORCID
Sampson, D.M.
Gong, P.
An, D.
Menghini, M.
Hansen, A.
Mackey, D.A.
Sampson, Davidd.sampson@surrey.ac.uk
Chen, F.K.
Date : 2017
DOI : 10.1167/iovs.17-21551
Uncontrolled Keywords : Axial length, Bennett formula, Foveal avascular zone, Littman formula, Magnification error, Normative database, OCTA, Optical coherence tomography angiography, Retina, Retinal disease, Superficial vessel plexus, adult, aged, Article, axial length variation, biometry, blood vessel density, blood vessel parameters, eye fundus, eye refraction, female, foveal avascular zone area, human, image quality, image segmentation, imaging software, male, mathematical analysis, middle aged, normal human, optical coherence tomography angiography, priority journal, refraction error, retina blood vessel, retina fovea, visual acuity, adolescent, capillary, cytology, eye axis length, fluorescence angiography, optical coherence tomography, procedures, reproducibility, retina blood vessel, retina macula lutea, vascularization, young adult, Adolescent, Adult, Aged, Axial Length, Eye, Capillaries, Female, Fluorescein Angiography, Fovea Centralis, Fundus Oculi, Healthy Volunteers, Humans, Macula Lutea, Male, Middle Aged, Reproducibility of Results, Retinal Vessels, Tomography, Optical Coherence, Young Adult
Depositing User : Maria Rodriguez-Marquez
Date Deposited : 04 Jun 2018 08:46
Last Modified : 19 Sep 2018 11:32
URI: http://epubs.surrey.ac.uk/id/eprint/846733

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