The effect of flammer-syndrome on retinal venous pressure

BMC Ophthalmology The effect of flammer-syndrome on retinal venous pressure Lei Fang 0 1 Michael Baertschi 0 Maneli Mozaffarieh 0 0 Department of Ophthalmology, University of Basel , Mittlere Strasse 91, 4031 Basel , Switzerland 1 Department of Biomedicine, University of Basel , Basel , Switzerland Background: The purpose of the study was to measure the retinal venous pressure (RVP) in the eyes of primary open-angle glaucoma (POAG) patients and healthy subjects with and without a Flammer-Syndrome (FS). Methods: RVP was measured in the following four groups of patients and age- and sex-matched healthy controls: (a) 15 patients with a POAG and a FS (POAG/FS+); (b) 15 patients with a POAG but without a FS (POAG/FS-); (c) 14 healthy subjects with a FS (healthy/FS+) and (d) 16 healthy subjects without a FS (healthy/FS-). RVP was measured in all participants bilaterally by means of contact lens ophthalmodynamometry. Ophthalmodynamometry is done by applying increasing pressure on the eye via a contact lens. The minimum force required to induce a venous pulsation is called ophthalmodynamometric force (ODF). The RVP is defined and calculated as the sum of ODF and intraocular pressure (IOP) [RVP = ODF + IOP]. Results: The participants with a FS (whether patients with POAG or healthy subjects), had a significantly higher RVP compared to subjects without a FS (p = 0.0103). Patients with a POAG and FS (POAG/FS+) had a significantly higher RVP compared to patients without a FS (POAG/FS) (p = 0.0301). There was a notable trend for a higher RVP in the healthy/FS + group compared to the healthy/FS group, which did not reach statistical significance (p = 0.0898). Conclusions: RVP is higher in subjects with a FS, particularly in glaucoma patients. The causal relationship needs to be further evaluated. - Background Disturbances of ocular blood flow are involved in many ophthalmic diseases and are therefore of utmost clinical relevance [1-5]. There are various causes for blood flow disturbances, such as diseased blood vessels [6] or mechanical compression of the vessel wall [7]. However, some organs are not well perfused, despite anatomically healthy blood vessels, when the regulation of blood flow is not adapted to the needs of the tissue [8]. Such a vascular dysregulation implies either inappropriate vasoconstrictions (vasospasms) or an insufficient vasodilation (more or less than is required) [9]. Dysregulation can be secondary in nature, as in multiple sclerosis [10], wherein the high level of Endothelin-1 reduces ocular blood flow OBF. Dysregulation can also be primary in nature (primary vascular dysregulation or PVD) [9], meaning that it can occur without any underlying disease and caused by an inborn tendency to respond differently to various stimuli, such as cold temperatures or mechanical or emotional stress. The combination of PVD with a cluster of additional vascular and non-vascular signs and symptoms is what is known today as the Flammer-Syndrome [11,12]. The eye is one of the best-perfused organs in the body. One factor influencing this process is the ocular perfusion pressure (OPP) [13-17]. OPP is the difference between systemic blood pressure and the RVP. In the eye, arterial pressure is assumed to be 2/3 of the brachial arterial pressure. The RVP is assumed equal to the IOP. The latter assumption is not always true in glaucoma patients [18-21]. As summarized in the literature reviews, glaucoma patients often concomitantly suffer from a FS [22,23]. One of the clinical observations that we made in patients with a FS was that they often had dilated retinal veins, which is why we hypothesized that RVP may be higher in FS than in non-FS subjects. We therefore set out to measure RVP in glaucoma patients and healthy subjects with and without a FS. Methods Patients with POAG were recruited from the University Eye Clinic, Basel, between January 2011 and December 2012. Healthy volunteers, age- and sex-matched to the POAG patients, were recruited in our outpatient department. The control subjects did not have any relevant eye disease and attended our outpatient department for various reasons, including prescriptions for eyeglasses, dry eye symptoms and regular ophthalmic check-up examinations. Ethical approval was obtained from the local medical ethics committee of Basel City (Ethik Kommission Beider Basel or EKBB) to measure RVP in healthy controls who gave oral consent to take part in the study (Reference Number 272/11). No ethical approval was required to measure RVP in glaucoma patients as RVP measurements are always taken in all glaucoma patients at the Department of Ophthalmology of the University of Basel. For inclusion, the patients with POAG met the following criteria: (1) glaucomatous visual fields or glaucomatous optic nerve cupping and (2) the absence of alternative causes of optic neuropathy. FS was defined as being present if it was detected in the patient history and confirmed by the dynamic retinal vessel analyser (DVA). Cases in which the patient history and DVA results were contradictory were excluded from the study. Evaluation of patient history for FS FS is defined as present (FS+) in the patient history if the subjects answer three of the following six questions with Yes, and it is defined as absent (FS-) if the subjects answer less than three questions with Yes: 1) Do you suffer from cold hands or feet even in summer [24]?; 2) Do you have trouble falling asleep, especially when you are cold [25]?; 3) Are you seldom thirsty, and do you have to remind yourself to drink enough [26]?; 4) Do you suffer from migraine attacks [27]?; 5) Do you have low blood pressure [28]?; 6) Do you identify smells better than others [29]? Evaluation of DVA results for FS The results of DVA were considered positive for FS (pathological) if the reaction of the arteries in both eyes was reduced in response to flickering light. Cases in which the patient history and DVA results were contradictory were excluded from the study. The following groups of subjects were compared: (1) POAG patients with a FS (POAG/FS+); (2) POAG patients without a FS (POAG/FS); (3) healthy controls with a FS (healthy/FS+) and (4) healthy controls without a FS (healthy/FS). Table 1 presents the demographic data of the different groups of subjects. Table 2 lists the local and systemic treatment regimens of the POAG patients. For all patients and controls, RVP was measured in both eyes by ophthalmodynamometry (Meditron GmbH, Table 1 Demographic and baseline characteristics of the four groups of participants Age Mean (SD) 67.0 (8.7) IOP Mean (SD) 10.6 (1.5) 13.33 (2.55) 11.71 (1.33) Patients with POAG and FS: POAG/FS +. Patients with POAG but without FS: POAG/FS . Healthy subjects with FS: Healthy/FS + . Healthy subjects without FS: Healthy/FS . Vlklingen, Germany). This device consists of a conventional Goldmann contact lens fitted with a pressure sensor at its outer margin where the Goldmann cont (...truncated)