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 NCT0043020

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 50seconds long diameter recording of inferior and superior temporal artery and vein, three flicker stimulations of 20seconds duration was applied, with a 80seconds 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 patter

Relationship between peripheral blood flow in extremities and choroidal circulation

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

Relation of body mass index and blood pressure to subjective and objective acral temperature

BACKGROUND: Vascular dysregulation, indicated by a positive history of cold extremities, has been postulated as a risk factor for a number of ocular diseases. In order to further characterize the phenotype of vasospastic persons, we tested the association between cold extremities, body mass index (BMI) and blood pressure (BP) in a cohort of healthy subjects. PATIENTS AND METHODS: Questionnaire data were collected from one hundred and seventeen 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. BP was measured sphygmomanometrically and as an objective measure of finger temperature, it was recorded at the fingertips with an infrared thermometer (IRT). Two-way analysis of variance with gender as one, and group selection as the second factor was performed separately for BMI and mean BP. The correlation of finger temperature with BMI and BP was analyzed by the Pearson regression. RESULTS: Gender distribution was male/female = 41/16, 13/21 and 4/22, for the three groups, respectively, and average age 45.8 +/- 13.0 years. For BMI, factor groups was highly significant (p = 0.0012) with both genders behaving comparably (interaction p = 0.18). For BP the corresponding p values were: factor group p = 0.026, interaction p = 0.89. Correlation coefficients between IRT and BMI were 0.34 (p = 0.0002) and between IRT and BP 0.24 (p = 0.009). CONCLUSION: A statistical significant association is present in healthy subjects between body mass index and blood pressure on one, and cold extremities on the other side, defined subjectively as well as measured objectively. This relationship is gender-independent

Olfactory function in primary open-angle glaucoma patients

The aim of this study was to assess the olfactory function of primary open-angle glaucoma patients

Resting energy expenditure in vasospastic subjects and its potential relevance in glaucoma

BACKGROUND: Peripheral vasospastic syndrome is frequently encountered in normal tension glaucoma patients. We tested the hypothesis as to whether peripheral vascular spastic tendency is due to an attempt to preserve body heat in subjects with reduced resting energy expenditure. PATIENTS AND METHODS: Twenty healthy non-smoking female individuals were enrolled into the study. Subjects were classified as having vasospasm (10 subjects) if they related a clear history of frequent cold hands, and as normal subjects (10 subjects) if they denied such a history. Sample size calculation was based on a power of 80 % to find a difference of 20 %. Resting energy expenditure (REE) was assessed by indirect calorimetry and corrected for fat-free mass (FFM), which was assessed by bioelectric impedance analysis. RESULTS: REE was 1198 +/- 155 kilocalories (kcal) in vasospastics and 1169 +/- 122 in controls (Mann-Whitney U-test: p = 0.62). FFM was 39.6 +/- 3.3 kg in vasospastics and 41.1 +/- 2.3 kg in controls (Mann-Whitney U-test: p = 0.16). REE adjusted for FFM was 30.2 +/- 2.5 kcal/kg in vasospastics and 28.4 +/- 2.3 kcal/kg in controls (Mann-Whitney U-test: p = 0.08). CONCLUSIONS: Peripheral vasospastic syndrome seems not to be a secondary response to insufficient resting energy expenditure. The results of the present study rather indicate an opposite tendency which deserves further investigation

Pattern of macular thickness changes measured by ocular coherence tomography in patients with multiple sclerosis

BACKGROUND: An analysis of the pattern of retinal thickness changes in macula in patients with multiple sclerosis (MS) was performed. PATIENTS AND METHODS: In fifteen patients with MS retinal thickness measurements in the central (fovea plus inner macular ring) and peripheral (outer ring) macula obtained by ocular coherence tomography (OCT-3 device) were compared to those of 15 age-matched healthy controls. RESULTS: Eyes of MS patients had on the average a thinner macula (241.8 +/- 20.6 micrometers) than control eyes (252.0 +/- 16.4, p value 0.038). Significant segmental differences occurred in the central macula (p = 0.013). Eight eyes with a positive history of optic neuritis (ON) had on average a thinner macula (226.8 +/- 14.0) than eyes of MS patients without a history of ON (non-ON eyes: 247.3 +/- 20.1, p value 0.01). The only measure significantly different between non-ON and control eyes was the ratio between the central and peripheral macular thickness (p = 0.017). Average macular thickness in non-ON eyes, unlike control eyes (r = - 0.63, p = 0.0002), did not correlate with age (r = 0.01, p = 0.97), however, it did show a borderline correlation with disease duration (r = - 0.41, p = 0.056). CONCLUSIONS: Preferential thinning in the central relative to the peripheral macular region is present in eyes of patients with MS. The macular thickness pattern is likely due to the histological distribution of nerve fibre layer and retinal ganglion cell in the macular area and seems to be particularly informative of neurodegeneration in the eyes of MS patients without a history of optic neuritis

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

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