[Phenomenology and Clinical Relevance of the Flammer Syndrome]. / Phänomenologie und klinische Bedeutung des Flammer-Syndroms.

The Flammer syndrome (FS) describes the phenotype of people with a predisposition for an altered reaction of the blood vessels to stimuli like coldness, emotional stress or high altitude. Frequent symptoms are: cold hands and/or feet, low blood pressure, prolonged sleep onset time, reduced feeling of thirst, increased sensitivity to odour, pain, vibration and certain drugs. SF subjects are often ambitious and successful but also perfectionistic and sometimes brooding. Frequent signs are: altered gene expression, prolonged blood flow cessation in nailfold capillaroscopy after cold provocation, reduced autoregulation of ocular blood flow, and reduced vasodilation after stimulation with flickering light. Retinal venous pressure is on the average higher and retinal astrocytes are more often activated. FS occurs more often in females than in males, in thin than in obese subjects, in young than in old people, in graduates than in blue collar workers, in subjects with indoor than outdoor jobs. Associated diseases are: normal tension glaucoma, occlusion of ocular vessels, retinitis pigmentosa, multiple sclerosis, tinnitus or even sudden hearing loss.

Unexpected Effect of Calcium Channel Blockers on the Optic Nerve Compartment Syndrome.

BACKGROUND: The optic nerve compartment syndrome is a pathological condition in which cerebrospinal fluid of the subarachnoid space surrounding the optic nerve is partly or totally segregated from the cerebrospinal fluid of the intracranial subarachnoid space, leading - inter alia - to an increase in the diameter of the optic nerve sheath. The pathogenesis of this condition remains unclear. We have observed clinically that optic nerve compartment syndrome often occurs in normal tension glaucoma patients with Flammer syndrome. To treat Flammer syndrome, some glaucoma patients received a low dose of a calcium channel blocker and we analysed whether this treatment also had an effect on the optic nerve compartment syndrome. PATIENTS AND METHODS: We retrospectively analysed the data of 10 eyes of seven patients suffering from a combination of primary open angle glaucoma, optic nerve compartment syndrome, and Flammer syndrome. We included subjects who had eye socket echography before and after a few months of therapy with a calcium channel blocker. THERAPY AND RESULTS: All patients received a low dose of a calcium channel blocker (nifedipine or amlodipine) to treat Flammer syndrome. As expected, the symptoms of Flammer syndrome were mitigated. To our surprise, the optic nerve compartment syndrome also improved in eight of the 10 eyes (80 %), but remained unchanged in the remainder. CONCLUSIONS: To some extent, the optic nerve compartment syndrome is related to the combination of primary open angle glaucoma and Flammer syndrome. On the basis of our results, we hypothesise that treatment of Flammer syndrome may also improve the optic nerve compartment syndrome.

The effect of hypoxia on intra-ocular, mean arterial, retinal venous and ocular perfusion pressures.

INTRODUCTION: High altitude hypoxia is linked to decreased blood oxygen saturation with a related increase of Endothelin-1 (ET-1) blood plasma levels. As a consequence of such elevated ET-1 levels, alterations of retinal venous and ocular perfusion pressures are suspected. PURPOSE: To measure the effect of hypoxia on intra-ocular pressure, mean arterial pressure, retinal venous pressure and to calculate ocular perfusion pressure. METHOD: An experimental, prospective cohort study with 33 healthy subjects was conducted in which the subjects were confronted with long-term (days) environmental hypoxia at high altitudes. Mean arterial pressure, arterial blood oxygen saturation, intra-ocular pressure, retinal venous and ocular perfusion pressure were measured at 300 m/1'000 ft (baseline), 4200 m/13'800 ft and 6000 m/19'700 ft above sea level. RESULTS: Arterial oxygen saturation (-13.06% ± 4.69, p = < 0.001; -23.46% ± 5.7,p = < 0.001), retinal venous pressure (+7.16 m Hg±8.2, p = < 0.001;+9.9 mm Hg±8.5, p = < 0.001) and ocular perfusion pressure (-8.49 mm Hg±10.6, p = < 0.001; -6.02 mm hg±11.2, p = 0.006) changed significantly from baseline at both high altitude of 4200 and 6000 m. Intra-ocular pressure did not change significantly at all altitudes (+1.16 mm Hg±4.5, p = 0.227; +0.84 mm Hg±4.8, p = 0.286) and mean arterial pressure changed significantly only at an altitude of 6000 m (+3,8 mm Hg±21.1, p = 0.005) from baseline. CONCLUSION: As hypoxia increases with higher altitude, arterial oxygen saturation and ocular perfusion pressure decreased, retinal venous pressure increased, intra-ocular pressure remains stable and mean arterial pressure was elevated only at 6000 m.

Analysis of risk factors for long-term glaucomatous damage development.

PURPOSE: The aim of this study was to analyze predictors of long-term glaucoma progression. PATIENTS AND METHODS: We followed 17 primary open angle glaucoma patients (POAG) and 25 ocular hypertensives (OHT) over three years, with regular follow-up examinations of both eyes every 6 months. Glaucoma damage was quantified by optical coherence tomography (retinal nerve fiber layer - OCT RNFL) and by perimetry. Corneal and hand temperature (infrared thermometer), corneal hysteresis, pachymetry and ocular pulse amplitude (OPA) readings were taken at baseline, and applanatory intraocular pressure and retinal vessel analysis recordings were made at baseline and follow-up visits. Forward-stepwise multiple regression analysis was performed. RESULTS: With OCT-RNFL progression as the dependent variable, the model selected initial diagnosis (OHT less probable of progressing), baseline RNFL thickness, retinal arterial and venous diameter and arterial flicker response as significant damage predictors. For visual field damage progression, these were: corneal temperature, OPA, initial diagnosis and venous flicker response (all p<0.05). CONCLUSION: Initial damage and vascular factors are strong predictors of future glaucoma progression.

Retinal venous pressure in the non-affected eye of patients with retinal vein occlusions.

BACKGROUND: To measure the retinal venous pressure (RVP) in both eyes of patients with unilateral central retinal vein occlusions and to compare these values to controls. METHODS: The study included 31 patients with unilateral central retinal vein occlusions (CRVO) and 31 controls who were matched by age, sex, and systemic disease. RVP was measured in all patients bilaterally by means of contact lens ophthalmodynamometry, and the RVP measurements of the affected and unaffected eyes of patients were compared to the RVPs of controls. Ophthalmodynamometry is done by applying an 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 RVP group means ± SD were as follows: patient's affected eyes (45.0 ± 11.6 mmHg), patient's unaffected eyes (38.0 ± 11.1 mmHg) ,and (17.7 ± 6.7 mmHg) in the eyes of controls. The values of RVP, even in the patients unaffected eyes, were significantly higher than in the eyes of controls (P < 0.001). CONCLUSIONS: In patients with CRVO, the RVP is increased in both the affected as well as in the unaffected contralateral eye.

[Analysis of retinal vein motion in glaucoma patients]. / Analyse der Venenbewegungen in der Netzhaut von Glaukompatienten.

BACKGROUND: Analysis of retinal vein amplitude in eyes of glaucoma patients. PATIENTS AND METHODS: Motion of retinal veins was captured by Retinal Vessel Analyzer in duration of 30 seconds. Inferotemporal vein segments of 500 micrometers length in the immediate vicinity of, as well as away from the optic disc were chosen. Time behavior of the average segment diameter was analyzed by the self made software: dominating frequency (heart rate) was determined by Fourier analysis, and based on this an average pulse form was produced. Difference between the highest and lowest diameter point was the subject of analysis in 25 eyes of 25 glaucoma patients and 25 age-sex-matched healthy controls. RESULTS: Pulse amplitude of retinal veins in healthy eyes was higher than in glaucoma patients: in the optic disc vicinity the pulse amplitude relative to baseline was 2.6 ± 2.1% in control eyes and 1.4 ± 0.8% in glaucoma eyes (t-test, p = 0.009). Away from the disc, it was 1.7 ± 1.0% and 1.1 ± 0.5% respectively (p = 0.01). CONCLUSIONS: Retinal veins in glaucoma eyes demonstrate lower pulse amplitudes than healthy eyes, indicating disturbance in venous outflow and increased intraluminal venous pressure.

[Value of non-IOP lowering therapy for glaucoma]. / Stellenwert der "nicht Augendruck senkenden Glaukomtherapie"

It is well established that an IOP reduction improves, on average, the prognosis of all types of glaucoma. It is also known, however, that even an ideal IOP does not stop progression in all patients. The insight into the pathogenesis of glaucomatous damage leads to new therapeutic approaches. Whilst most of these new avenues of treatment are still in the experimental phase, others, such as magnesium, Ginkgo, salt and fludrocortisone are already used by some physicians. Blood pressure dips can be avoided by intake of salt or fludrocortisone. Vascular regulation can be improved either locally by carbonic anhydrase inhibitors or systemically with magnesium or with low doses of calcium channel blockers. A number of other food ingredients such as polyphenolic flavonoids occurring in tea, coffee, dark chocolate or red wine and anthocyanosides found in bilberries have potential antioxidative effects. The oxidative stress at the level of the mitochondria can be reduced by Ginkgo biloba. Experimentally, glaucomatous optic neuropathy can be prevented by inhibition of astrocyte activation, either by blockage of epidermal growth factor receptor or by counteracting endothelin. Glaucomatous optic neuropathy can also be prevented by nitric oxide-2 synthase inhibition. Inhibition of matrix metalloproteinase-9 inhibits apoptosis of retinal ganglion cells and tissue remodelling. Up-regulation of heat shock proteins protects the retinal ganglion cells and the optic nerve head.

Retinal neurovascular coupling in patients with glaucoma and ocular hypertension and its association with the level of glaucomatous damage.

PURPOSE: To analyze neurovascular coupling in the retina of untreated primary open-angle glaucoma (POAG) and ocular hypertension (OHT) patients. PATIENTS AND METHODS: Maximal vessel dilation in response to flicker light was analyzed with Retinal Vessel Analyzer (RVA) in temporal superior/inferior arterioles and veins in 51 POAG patients, 46 OHT and 59 control subjects. RVA parameters were compared between groups, between contralateral POAG eyes, and correlated to intraocular pressure, visual field mean defect and retinal nerve fiber layer thickness. RESULTS: POAG eyes demonstrated generally smaller response of all vessels to flicker light than the other two groups (ANOVA p=0.026; mean arterial flicker response in percent of baseline, averaged superior and inferior was 3.48 ± 2.22 % for controls , 2.35 ± 2.06 % for POAG patients , and 2.97 ± 2.35 % for OHT patients; corresponding values for venules were 3.88 ± 1.98 %, 2.89 ± 1.72 %, 3.45 ± 2.77 %). There was no difference in flicker response between the eye with more and less advanced damage in each patient of the POAG group (ANOVA p=0.79). Correlation of flicker response to intraocular pressure (IOP) was borderline at best, correlations to the level of glaucomatous damage were not significant. Correlation of flicker response of superior and inferior vessels of the same eye was significant for the arteries (Pearson r=0.23, p=0.004), as well as venules (r=0.52, p<0.001). CONCLUSION: General vessel response to flicker light was decreased in POAG patients, compared to normal controls and OHT patients. In contrast to significant correlation between the two contralateral eyes of the flicker response itself, only its borderline correlation to IOP was seen. There was no correlation to the level of damage, altogether indicating a systemic dysregulation phenomenon. GRANTS: Swiss National Foundation Grant 3200B0-113685, Velux Stiftung Grant, Freie Akademische Gesellschaft (FAG) Grant, Pfizer Inc. Grant CLINICAL TRIAL REGISTRATION REFERENCE NUMBER: ClinicalTrials.gov NCT00430209.

Detection of retinal glial cell activation in glaucoma by time domain optical coherence tomography.

BACKGROUND: Activated retinal astrocytes and Müller cells (ARAM) have been found in glaucoma patients. This study investigated whether presumed ARAM can be detected by optical coherence tomography (OCT), and assessed their relationship to the retinal nerve fiber layer (RNFL) thickness. PATIENTS AND METHODS: Single-center observational study involving 35 age-matched healthy controls and 19 patients with primary open-angle glaucoma (POAG) between 45 - 82 years of age. Presumed ARAM was defined as patchy, discrete glittering but transparent changes of the macula. The retina was documented by red-free photography to assess distribution of ARAM, and compared to the RNFL thickness measured around the fovea by OCT. A linear mixed effects model was used to detect a difference between eyes with ARAM versus eyes without ARAM. RESULTS: ARAM was not found in healthy subjects. The mean RNFL around the fovea was not significantly thicker in healthy controls (34.01 SD ± 22.24) than in POAG patients with ARAM (30.86 microns SD ± 15.09; p = 0.36) or without ARAM (33.19 microns SD ± 19.87; p = 0.46). Furthermore, the median RNFL thickness was similar to the control group (29 microns) but slightly thinner in POAG patients (each 27 microns with ARAM and without ARAM). In a subgroup analysis of POAG patients with ARAM, the within subject standard deviation of RNFL was significantly lower in areas with ARAM (SD 10.12) than in areas without ARAM (SD 17.30) (p < 0.001). CONCLUSIONS: Although the mean and median RNFL thickness was comparable between the groups, the variability of the RNFL thickness was significantly lower in areas with ARAM than in areas without ARAM suggesting that ARAM may mask RNFL loss in POAG patients.

Ginkgo biloba: an adjuvant therapy for progressive normal and high tension glaucoma.

Gingko biloba has been used for hundreds of years to treat various disorders such as asthma, vertigo, fatigue and, tinnitus or circulatory problems. Two of the main extracts are EGb761 and LI 1370. Most pharmacological, toxicological and clinical studies have focused on the neuroprotective value of these two main extracts. Neuroprotection is a rapidly expanding area of research. This area is of particular interest due to the fact that it represents a new avenue of therapy for a frustrating disease that may progress despite optimal treatment. One such disease is glaucoma.Glaucoma leads to the loss of retinal ganglion cells and their axons but also to tissue remodelling which involves both the optic nerve head and the retina. In the retina the astrocytes get activated. In addition, the optic nerve gets thinner and the cells of the lateral geniculate ganglion disappear partially. On average, ocular blood flow (OBF) is reduced in glaucoma patients in various tissues of the eye. Increased intraocular pressure (IOP) is a major risk factor for glaucomatous damage. Nevertheless, there is little doubt that other risk factors besides IOP are involved. One such risk factor is a primary vascular dysregulation (PVD) occurring in patients with a disturbed autoregulation, another risk factor is oxidative stress.

Dynamics of retinal vessel response to flicker light in glaucoma patients and ocular hypertensives.

PURPOSE: To analyze dynamics of retinal vessel dilation response to flicker light in patients with glaucoma and ocular hypertension. PATIENTS AND METHODS: Response to flicker light was measured in retinal vessels by means of Retinal Vessel Analyzer. After the baseline 50 seconds long diameter recording of inferior and superior temporal artery and vein, three flicker stimulations of 20 seconds duration was applied, with a 80 seconds break in between. Area under the curve of the vessel diameter (AUC) was compared during 3 flicker periods in the open angle glaucoma patients group (POAG, n = 47) and ocular hypertensives (OHT, n = 46) and age-matched healthy controls (n = 56) RESULTS: POAG eyes demonstrated smaller response of all vessels to flicker light in general than the other two groups (p = 0.0008), but the response dynamics was significantly different between the groups (p = 0.038), showing in three flicker periods a delayed increasing response in the POAG and OHT groups, and remaining stable in healthy subjects. CONCLUSION: General vessel response to flicker light was decreased in POAG patients despite the slow improvement in repeated flicker stimulation, indicating an altered response pattern.

Relationship between peripheral blood flow in extremities and choroidal circulation.

BACKGROUND: The aim of this study was to explore the relationship between subjectively estimated and objectively measured finger temperature on the one, and choroidal blood flow on the other side. PATIENTS AND METHODS: We measured submacular choroidal blood flow (CBF) in 73 healthy subjects. Based on the history of cold hands and feet, they were divided in three groups, reporting "never", "sometimes" and "always" having cold extremities. As an objective measure of finger temperature, it was recorded at the fingertips with an infrared thermometer (IRT). Analysis of variance for CBF based on the group selection and with blood and intraocular pressures as covariates was performed, as well as the correlation between CBF and IRT. RESULTS: There were 37 subjects in the group with "never" cold extremities, 20 in the group with "sometimes", and 16 subjects in the group with "always" cold extremities. Average age was 44.2 ± 12.9 years. CBF was 11.5 ± 7.3 AU (arbitrary units), 13.6 ± 6.1 AU and 14.3 ± 4.6 AU in the three groups, respectively. The ANOVA p-value was 0.04. Pearson's R for correlation between CBF and IRT was - 0.51, p < 0.001. CONCLUSION: Subjectively and objectively, colder extremities are associated with higher CBF, possibly due to the redistribution of blood flow.

Olfactory function in primary open-angle glaucoma patients.

PURPOSE: The aim of this study was to assess the olfactory function of primary open-angle glaucoma patients. PATIENTS AND METHODS: We analyzed odour threshold, identification, and discrimination in 30 primary open-angle glaucoma patients and 30 age- and gender-matched healthy control subjects. The "Sniffin' Sticks" test battery was applied sequentially on both sides, scores of two nostrils were averaged and means were compared with Mann-Whitney U-test between the groups. RESULTS: Scores for odour threshold were 5.9 +/- 2.2 and 7.4 +/- 2.1 in glaucoma and control group, respectively (p = 0.01), for odour discrimination 10.5 +/- 2.0 and 10.8 +/- 1.6 (p = 0.65), and for odour identification 11.8 +/- 2.1 and 10.6 +/- 1.6 (p = 0.008). Comparing within glaucoma group between those with (n = 18) and without history (n = 12) of cold hands and feet, the former had significantly better odour threshold scores, 6.6 +/- 1.5, than the latter, 4.8 +/- 2.6 (p = 0.036); no difference in other two olfactory modalities were detected. CONCLUSION: Changes of olfactory function have been described in neurodegenerations such as Alzheimer and Parkinson diseases. Complex alterations of olfactory performance seem to be present in POAG patients as well.

Volumetric blood flow measurement in the ophthalmic artery using colour Doppler.

BACKGROUND: Herewith we present a new method for measurement of the volumetric blood flow in absolute units in the ophthalmic artery. PATIENTS AND METHODS: A Philips EnVisor HD ultrasound unit with a 12 - 3 MHz linear transducer was used to measure flow in the ophthalmic artery in 8 healthy young subjects. The transducer was mounted on a custom-made holder which enabled precise and reproducible positioning in 3 axes as well as in rotation angle. Blood flow velocity and vessel diameter were measured during 10 consecutive heartbeats. The measurements were ECG-gated. Blood vessel diameter and blood flow velocity were calculated in an average heartbeat cycle. Hence blood volume over time within a heartbeat cycle as well as blood flow in mL/min were determined. Simultaneously, cardiovascular parameters have been recorded by Finapres. Short time reproducibility (5 measurements on day 1) and long time reproducibility (5 days once daily) as well as interindividual coefficient of variation were evaluated. RESULTS: Average blood flow in the ophthalmic artery in all measurements was 39.7 mL/min. The short-term intraindividual coefficient of variation was 24.1 +/- 9.2 %, the long-term coefficient 32.0 +/- 13.8 %. Interindividual coefficient of variation was 32.8 %. CONCLUSIONS: Our method allows volumetric blood flow measurements in the ophthalmic artery in absolute units, reproducible to a limited extent.

Retinal vessels in patients with multiple sclerosis: baseline diameter and response to flicker light stimulation.

BACKGROUND: Transparency of ocular media enables the precise quantitative analysis of vessels of retina, a neuronal tissue which can be affected by multiple sclerosis (MS). PATIENTS AND METHODS: Eyes with no history of optic neuritis (non-ON eyes) of 21 patients with MS were examined with Retinal Vessel Analyzer. Segments of vessels of 500 microm length were measured proximal and distal from the optic disc and compared to those of 21 age- and gender-matched controls. Baseline diameters and peak response to flicker light stimulation of retinal vessels were analyzed. RESULTS: MS eyes had thinner arterioles (p = 0.02) and thicker venules (p = 0.008) than controls: arterioles 111 +/- 14 microm (proximal), 99 +/- 11 microm (distal) in MS eyes and 121 +/- 15 and 107 +/- 9 in controls, respectively. Values for venules were 157 +/- 18 and 136 +/- 20 (MS); 147 +/- 15 and 119 +/- 20 (controls). Peak response was higher in MS eyes than in controls for arterioles (p = 0.007), but comparable for venules (p = 0.35). CONCLUSION: Narrower arterioles and wider venules might be a consequence of subclinical swelling of optic nerve axons in eyes with negative history of ON in MS patients.

Rigidity of retinal vessels in patients with multiple sclerosis.

PURPOSE: The aim of this study was to analyze pulse wave propagation in the ocular circulation by assessing the phase delay between retinal arterioles and venules and calculating the pulse delay between the retinal and choroidal circulations in MS patients and in control subjects. SUBJECTS AND METHODS: Twenty patients with multiple sclerosis (38.3 +/- 6.2 years) and twenty healthy subjects (37.4 +/- 15.2 years) were examined with the Retinal Vessel Analyzer. In addition, an average peripapillary RNFL (retinal nerve fiber layer) thickness was measured by means of ocular coherence tomography in MS patients. The phase delay between the arteriole and venule pulsations was assessed at three sites: in the close retinal vicinity of the disc, 1 - 2 disc diameters and 3 - 4 disc diameters away from the disc. Assuming that venules are counterphased to the choroidal circulation, a choroid-to-retina pulse delay was calculated. RESULTS: The choroid-to-retina pulse delay was 0.26 +/- 0.11, 0.27 +/- 0.13 and 0.34 +/- 0.15 sec in eyes with history of optic neuritis (ON-eyes); in eyes of MS patients without such a history (non-ON eyes) the corresponding values were 0.27 +/- 0.14, 0.29 +/- 0.11 and 0.30 +/- 0.15 sec, and in control eyes 0.32 +/- 0.19, 0.38 +/- 0.16 and 0.45 +/- 0.20 sec, respectively, at three sites centrifugal from the disc. The choroid-to-retina pulse delay was significantly longer in healthy control eyes than both in ON eyes (p = 0.012) and non-ON eyes of MS patients (p = 0.004). The interocular difference of the choroid-to-retina pulse delay and OCT RNFL thickness showed a significant correlation in MS patients (Pearson r = 0.54, p = 0.015; Spearman R = 0.66, p = 0.0016). CONCLUSION: Patients with multiple sclerosis seem to demonstrate an increased rigidity of the retinal vessels. The interocular difference in retinal vessel rigidity was significantly correlated with the interocular difference in RNFL thickness in MS patients.

Macula-off retinal detachment--a matter of time?

BACKGROUND: The aim of this study was to determine the influence of the lag time between macular detachment and surgical intervention on post-operative visual acuity gain in patients with rhegmatogenous macula-off retinal detachment. PATIENTS AND METHODS: We retrospectively evaluated the medical records of 62 consecutive patients having undergone scleral buckling surgery for rhegmatogenous macula-off retinal detachment. The correlation of gender, age, refraction, number of retinal breaks, development of cataract during follow-up, pre-operative visual acuity and timing of surgical intervention with final visual acuity and post-operative visual acuity gain were determined. Mean follow-up time was 12.7 months. RESULTS: A correlation with final visual acuity was found for pre-operative visual acuity and lag between the beginning of symptoms and surgical intervention. A correlation with visual acuity gain was found only for timing of surgical procedure. When divided into subgroups operated after 0, 1-3, 4-6, or 7-9 days, respectively, visual recovery was better the earlier the patients underwent surgical repair. Compared to surgery at day 0, statistical significance was found only for patients operated 4 or more days after the occurrence of symptoms. CONCLUSION: The first three days seem to represent a relatively safe period during which surgery for macula-off retinal detachment may be postponed without compromising the patient's visual prognosis.

[Response of retinal vessel diameter to flicker-light in vasospastics compared to healthy controls]. / Flickerlichtprovokation bei Vasospastikern verglichen mit gesunden Kontrollpersonen.

BACKGROUND: Vascular dysregulation is considered to be a risk factor in several ophthalmic diseases. The purpose of this study was to evaluate the reaction of retinal vessels to flicker light in otherwise healthy subjects with a vasospastic propensity. PATIENTS AND METHODS: Thirty healthy Caucasians, aged between 18-35 years were recruited for this study and grouped into vasospastics, based on a history of frequent cold hands, even in summer, with concordant findings in nailfold capillary microscopy, or as controls, if such a history was absent. The reaction of the retinal vascular diameter to flicker light was observed in a distance of two to three discs diameters away from the optic nerve head with the retinal vessel analyser. Three phases of flicker light of twenty seconds followed by baseline light phases of eighty seconds were recorded. The maximal vasodilatory amplitude of each flicker phase was determined and the results averaged. RESULTS: The maximal average dilatory amplitude at the arterial side reached (mean +/- SD) 2.9 +/- 1.7 % and 4.8 +/- 2.6 % of the baseline amplitude respectively in vasospastic subjects and in healthy controls (t = 2.34; p = 0.025). The reaction at the venous side was statistically comparable in both groups. CONCLUSIONS: Otherwise healthy, vasospastic subject disclosed an altered reaction of the retinal vasculature to flicker light in this study.