Ua 767

Standard anthropometric measures of height and weight were recorded to determine body mass index (BMI = weight/height²). Systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) were measured using an automatic Blood Pressure monitor (UA-767; A&D Instruments Ltd., Abingdon UK) [13 (link)] to determine mean arterial pressure (MAP = 2/3 DBP + 1/3 SBP) [14 (link)]. Intraocular pressure (IOP) readings were obtained using non-contact tonometry (Pulsair; Keeler Ltd., Winsor, UK).

Standard anthropometric measures of height and weight were recorded to determine body mass index (BMI = weight/height). Systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) were measured using an automatic Blood Pressure monitor (UA-767; A&D Instruments Ltd., Wokingham, UK) to determine mean arterial pressure (MAP = 2/3 DBP + 1/3 SBP) [24 (link)]. Eye opening and motor and verbal responses were assessed to all patients to objectively measure their level of consciousness using Glasgow Coma Score (GCS) [25 (link)].

During exercise, heart rate (HR), stroke volume (SV) and cardiac output (Q̇) were measured continuously using impedance cardiology (PhysioFlow^®, Manatec Biomedical, France) (Charloux et al., 2000 (link); Richard et al., 2001 (link)). The theoretical basis for determining cardiac output from this method and its validity during rest and exercise has been described previously (Charloux et al., 2000 (link); Lepretre et al., 2004 (link)), and has been validated against the direct Fick method (Richard et al., 2001 (link)). Two sets of electrodes (Skintact FS-50, Leonhard Lang Gmbh, Austria) – one transmitting, one sensing – were applied above the supra-clavicular fossa at the left base of the neck, and along the xiphoid process. Another two electrodes were used to monitor a single electrocardiographic signal (ECG; CM5 position). Blood pressure was assessed (Digital blood pressure monitor, UA-767, A&D Instruments Ltd., United Kingdom) as part of standard calibration process for the PhysioFlow^® prior to the exercise test. During the experimental trials (Figure 1), HR, SV, and Q̇ data were sampled at 5-s intervals, with the average for each interval determined during moderate and high loads. The coefficient of variation of cardiac output measures during peak exercise using this method has been reported as 3.4–3.6% (Hsu et al., 2006 (link)).

The study followed the guidelines of the Declaration of Helsinki and was approved by the Aston Optometry and Audiology Research Ethics Committee. All participants gave written informed consent prior to inclusion in the study. We included 45 arbitrarily selected eyes (25 left and 20 right eyes) of 45 healthy participants (age range: 21 – 62 years). Twelve subjects were of South Asian (SA) background and thirty-three of Caucasian (CA) origin. All participants initially underwent non-contact tonometry (Pulsair, Keeler, UK) followed by pupil dilation using one drop of Tropicamide 1 % (Bausch & Lomb, UK). After a minimum of 15–20 min acclimatisation in a temperature controlled room (21 ± 2 °C) systemic blood pressure and heart rate was measured using a digital sphygmomanometer (UA-767, A&D Instruments Ltd., UK).