Abstract
Purpose:
To investigate the relationship between intraocular pressure (IOP) related patterns recorded with a contact lens sensor (CLS) and blood pressure (BP) patterns in naïve or washed-out primary open angle glaucoma (POAG) patients.
Methods:
20 POAG patients, either naïve or washed-out for 4 weeks, were equipped for 24 hours with a Holter BP recording device (TM-2430, A&D Company Limited, Japan) and with a CLS (SENSIMED Triggerfish®, Sensimed, Switzerland) that detects ocular dimensional changes in the corneoscleral area for the recording of IOP-related patterns. Recording was carried out during an in-hospital stay. Diurnal and nocturnal periods corresponded to patients’ wake and sleep periods as defined by the eye blink frequency on the CLS pattern. Non-/normal BP dippers was defined as a nocturnal reduction in mean arterial pressure (MAP) of ≤10% as compared to diurnal MAP, whereas over-dippers had a nocturnal MAP reduction exceeding 10%. By group mean CLS and MAP patterns were generated. The nocturnal elevation of the IOP related CLS signal was calculated as the difference between mean nocturnal and mean diurnal CLS output. Mean nocturnal CLS increase and MAP decrease were compared for normal dippers versus over-dippers using paired t-tests. Significance level was set to α=0.05.
Results:
Valid BP and CLS patterns were obtained in 5 male and 14 female POAG patients with a mean age of 64.9±9.5 years. Mean Goldmann applanation tonometry IOP was 25.2±5.3 mmHg before the recording session. Mean systolic and diastolic BP at baseline was 134.7±9.0 and 76.1±7.0 mmHg. Nine patients were non-/normal dippers and 12 were over-dippers. BP and CLS patterns were divergent in the nocturnal period. In the combined group of non-/normal dippers mean nocturnal CLS increased by 115±81 mVeq while MAP decreased by 6.5±3.2%. In the over-dippers nocturnal CLS increased by 155±102 mVeq while MAP decrease by 20.1±6.6%. The difference in nocturnal CLS increase between groups was not significant (p=0.382). BP reduction was different between groups (p<0.001).
Conclusions:
Simultaneous recording of BP and IOP related patterns in POAG patients provided evidence of divergent CLS (increase) and MAP (decrease) in the nocturnal period. The high-frequency CLS data provides a possibility to investigate the dynamics of BP vs IOP-related information over time.
Keywords: 568 intraocular pressure •
458 circadian rhythms •
477 contact lens