Pulse waveform analysis on temporal changes in ocular blood flow due to caffeine intake : a comparative study between habitual and non-habitual groups

• Main Authors: Aishah Ismail, Bhatti, Mehwish S., Faye, Ibrahima, Lu, Cheng Kai, Laude, Augustinus, Tang, Tong Boon
• Other Authors: Lee Kong Chian School of Medicine (LKCMedicine)
• Format: Article
• Language: English
• Published: 2020
• Subjects: Science::Medicine; Pulse Waveform; Laser Speckle Flowgraphy
• Online Access: https://hdl.handle.net/10356/143144
• Institution: Nanyang Technological University

Purpose To evaluate and compare the temporal changes in pulse waveform parameters of ocular blood flow (OBF) between nonhabitual and habitual groups due to caffeine intake. Method This study was conducted on 19 healthy subjects (non-habitual 8; habitual 11), non-smoking and between 21 and 30 years of age. Using laser speckle flowgraphy (LSFG), three areas of optical nerve head were analyzed which are vessel, tissue, and overall, each with ten pulse waveform parameters, namely mean blur rate (MBR), fluctuation, skew, blowout score (BOS), blowout time (BOT), rising rate, falling rate, flow acceleration index (FAI), acceleration time index (ATI), and resistive index (RI). Two-way mixed ANOVA was used to determine the difference between every two groups where p < 0.05 is considered significant. Result There were significant differences between the two groups in several ocular pulse waveform parameters, namely MBR (overall, vessel, tissue), BOT (overall), rising rate (overall), and falling rate (vessel), all with p < 0.05. In addition, the ocular pulse waveform parameters, i.e., MBR (overall), skew (tissue), and BOT (tissue) showed significant temporal changes within the nonhabitual group, but not within the habitual group. The temporal changes in parameters MBR (vessel, tissue), skew (overall, vessel), BOT (overall, vessel), rising rate (overall), falling rate (overall, vessel), and FAI (tissue) were significant for both groups (habitual and non-habitual) in response to caffeine intake. Conclusion The experiment results demonstrated caffeine does modulate OBF significantly and response differently in nonhabitual and habitual groups. Among all ten parameters, MBR and BOT were identified as the suitable biomarkers to differentiate between the two groups.