Twelve hour reproducibility of choroidal blood flow parameters in healthy subjects

Abstract

Aims/background: To investigate the reproducibility and potential diurnal variation of choroidal blood flow parameters in healthy subjects over a period of 12 hours. Methods: The choroidal blood flow parameters of 16 healthy non-smoking subjects were measured at five time points during the day (8:00, 11:00, 14:00, 17:00, and 20:00). Outcome parameters were pulsatile ocular blood flow as assessed by pneumotonometry, fundus pulsation amplitude as assessed by laser interferometry, blood velocities in the opthalmic and posterior ciliary arteries as assessed by colour Doppler imaging, and choroidal blood flow, volume, and velocity as assessed by fundus camera based laser Doppler flowmetry. The coefficient of variation and the maximum change from baseline in an individual were calculated for each outcome parameter. Results: None of the techniques used found a diurnal variation in choroidal blood flow. Coefficients of variation were within 2.9% and 13.6% for all outcome parameters. The maximum change from baseline in an individual was much higher, ranging from 11.2% to 58.8%. Conclusions: These data indicate that in healthy subjects the selected techniques provide adequate reproducibility to be used in clinical studies. Variability may, however, be considerably higher in older subjects or subjects with ocular disease. The higher individual differences in flow parameter readings limit the use of the techniques in clinical practice. To overcome problems with measurement validity, a clinical trial should include as many choroidal blood flow outcome parameters as possible to check for consistency.

Volumetric colour Doppler imaging: a useful tool for the determination of ocular blood flow in glaucoma patients?

“…Experience of the investigators and internal quality control is important because it is known that CDI in general is a subjective measurement. 17 In our laboratory, we reach acceptable reproducibility of the CDI measurements by maximal standardization of the CDI procedure. 18 Compared to previous reports, the diameter of the OA as well as that of the CRA appears to be slightly overestimated.…”

Effect of Aging on Nocturnal Blood Flow in the Optic Nerve Head and Macula in Healthy Human Eyes

“…[9][10][11][12][13] Previous studies showed that variations in ocular blood flow throughout the diurnal/ wake period were not significant in both younger and older adults. 20,31 One study suggested that ocular blood flow in the optic nerve head decreased at the end of the diurnal/wake period in younger adults. 32 In the present study, we extended the measurement times into the nocturnal/sleep period.…”

Evaluation of choroidal thickness using enhanced depth imaging by spectral-domain optical coherence tomography in patients with pseudoexfoliation syndrome

“…Therefore, a precise clinical evaluation of choroidal morphology should be important for understanding the pathogenesis of many retinal and choroidal diseases. 16,17 To date, SD-OCT featuring high resolution and scanning speeds has allowed the choroid to be assessed in vivo. 12 N2: choroidal thickness at 1000 μm nasal to the fovea; N1: choroidal thickness at 500 μm nasal to the fovea; F: choroidal thickness at fovea; T1: choroidal thickness at 500 μm temporal to the fovea; T2: choroidal thickness at 1000 μm temporal to the fovea; T3: choroidal thickness at 1500 μm temporal to the fovea.…”