Blocking Ocular Sympathetic Activity Inhibits Choroidal Neovascularization

Purpose: To investigate how modulating ocular sympathetic activity affects progression of choroidal neovascularization (CNV), a hallmark feature of wet age-related macular degeneration (AMD).Methods: In the first of two studies, Brown Norway rats underwent laser-induced CNV and were assigned to one of the following groups: daily eye drops of artificial tears (n = 10; control group); daily eye drops of the β-adrenoreceptor agonist isoproterenol (n = 10); daily eye drops of the β-adrenoreceptor antagonist propranolol (n = 10); sympathetic internal carotid nerve (ICN) transection 6 weeks prior to laser-induced CNV (n = 10). In the second study, rats underwent laser-induced CNV followed by ICN transection at different time points: immediately after the laser injury (n = 6), 7 days after the laser injury (n = 6), and sham surgery 7 days after the laser injury (n = 6; control group). All animals were euthanized 14 days after laser application. CNV development was quantified with fluorescein angiography and optical coherence tomography (in vivo), as well as lesion volume analysis using 3D confocal reconstruction (postmortem). Angiogenic growth factor protein levels in the choroid were measured with ELISA.Results: In the first study, blocking ocular sympathetic activity through pharmacological or surgical manipulation led to a 75% or 70% reduction in CNV lesion volume versus the control group, respectively (P < 0.001). Stimulating ocular sympathetic activity with isoproterenol also led to a reduction in lesion volume, but only by 27% versus controls (P < 0.05). VEGF protein levels in the choroid were elevated in the three treatment groups (P < 0.01). In the second study, fluorescein angiography and CNV lesion volume analysis indicated that surgically removing the ocular sympathetic supply inhibited progression of laser-induced CNV, regardless of whether ICN transection was performed on the same day or 7 days after the laser injury.Conclusion: Surgical and pharmacological block of ocular sympathetic activity can inhibit progression of CNV in a rat model. Therefore, electrical block of ICN activity could be a potential bioelectronic medicine strategy for treating wet AMD.

Accuracy and Reliability of the Optoelectronic Plethysmography and the Heart Rate Systems for Measuring Breathing Rates Compared with the Spirometer.

Measuring breathing rates without a mouthpiece is of interest in clinical settings. Electrocardiogram devices and, more recently, optoelectronic plethysmography (OEP) methods can estimate breathing rates with only a few electrodes or motion-capture markers placed on the patient. This study estimated and compared the accuracy and reliability of three non-invasive devices: an OEP system with 12 markers, an electrocardiogram device and the conventional spirometer. Using the three devices simultaneously, we recorded 72 six-minute epochs on supine subjects. Our results show that the OEP system has a very low limit of agreement and a bias lower than 0.4% compared with the spirometer, indicating that these devices can be used interchangeably. We observed comparable results for electrocardiogram devices. The OEP system facilitates breathing rate measurements and offers a more complete chest-lung volume analysis that can be easily associated with heart rate analysis without any synchronisation process, for useful features for clinical applications and intensive care.