Plasma homocysteine levels in patients with normal tension glaucoma.

PURPOSE: To investigate whether there is an association of elevated plasma levels of homocysteine (Hcy) and normal tension glaucoma (NTG). PATIENTS AND METHODS: Plasma levels of Hcy (fluorescence polarization immunoassay), vitamin B6 (high-performance liquid chromatography), vitamin B12, and folate levels (immunoassay) were determined in 42 patients with NTG and in 42 age-matched and sex-matched controls. RESULTS: No significant difference regarding Hcy (NTG: 10.95 µmol/L±2.65; controls: 11.29 µmol/L±2.76) (P=0.639), vitamin B6 (NTG: 14.45 ng/mL±12.89; controls: 13.57 ng/mL±10.41) (P=0.629), vitamin B12 (NTG: 387.73 pg/mL±282.04; controls: 423.27 pg/mL±188.85) (P=0.052) and folate (NTG: 9.45ng/mL±3.42; controls: 10.82 ng/mL±4.48) (P=0.181) levels were found between both groups. CONCLUSIONS: An association of elevated Hcy levels and NTG was not found and therefore a role of Hcy as a modifiable risk factor in the pathogenesis of NTG seems unlikely.

Wall-to-lumen ratio of retinal arterioles and arteriole-to-venule ratio of retinal vessels in patients with cerebrovascular damage.

PURPOSE: There is evidence that generalized retinal arteriolar narrowing, which can be measured by the arteriole-to-venule ratio (AVR) of retinal vessels, predicts cerebrovascular events. The wall-to-lumen ratio (WLR) and wall cross-sectional area (WCSA) of retinal arterioles reflect structural arteriolar parameters. The primary objective was to test the association between WLR and AVR in a distinct cohort of patients with cerebrovascular damage. METHODS: In this cross-sectional study, 23 patients (57.5 +/- 9.4 years) with acute transitory ischemic attack or lacunar cerebral infarct were compared with two age-matched control groups: 83 subjects with essential hypertension (53.7 +/- 5.5 years) and 16 normotensive subjects (52.2 +/- 8.3 years). Retinal arteriolar parameters (WLR, WTH, and WCSA) were assessed in vivo with scanning laser Doppler flowmetry (SLDF). AVR and a qualitative evaluation of retinal vessels were obtained from digital retinal color photographs. The intima-media thickness (IMT) of the carotid artery was measured. RESULTS: WLR (0.44 +/- 0.1 vs. 0.34 +/- 0.1 vs. 0.30 +/- 0.1, P < 0.001) and carotid IMT (P < 0.05) were significantly greater in the cerebrovascular event group compared with normotensive subjects. WLR and WCSA were significantly higher in the cerebrovascular event group compared with subjects with mild arterial hypertension. AVR was similar in all three study groups (0.75 +/- 0.07 vs. 0.74 +/- 0.07 vs. 0.78 +/- 0.1, P = 0.18). CONCLUSIONS: The increase in WLR and WCSA of retinal arterioles, as well as in IMT in patients with cerebrovascular damage suggests vascular hypertrophy in the microvascular and macrovascular bed. The lack of association between AVR of retinal vessels and WLR of retinal arterioles may point to different stages of cerebrovascular disease and/or different pathophysiological changes in the arteriolar wall.

Correlation between local glaucomatous visual field defects and loss of nerve fiber layer thickness measured with polarimetry and spectral domain OCT.

PURPOSE: To study the correlation between local perimetric field defects and glaucoma-induced thickness reduction of the nerve layer measured in the peripapillary area with scanning laser polarimetry (SLP) and spectral domain optical coherence tomography (SOCT) and to compare the results with those of a theoretical model. METHODS: The thickness of the retinal nerve fiber layer was determined in 32 sectors (11.25 degrees each) by using SLP with variable cornea compensation (GDxVCC; Laser Diagnostics, San Diego, CA) and the newly introduced high-resolution SOCT (Spectralis; Heidelberg Engineering, Heidelberg, Germany). Eighty-eight healthy subjects served as control subjects, to determine the thickness deviation in patients with glaucoma. The relationship between glaucomatous nerve fiber reduction and visual field losses was calculated in six nerve fiber bundle-related areas. Sixty-four patients at different stages of open-angle glaucoma and 26 patients with ocular hypertension underwent perimetry (Octopus G1; Haag-Streit, Köniz, Switzerland) and measurements with the two morphometric techniques. RESULTS: Sector-shaped analyses between local perimetric losses and reduction of the retinal nerve fiber layer thickness showed a significant association for corresponding areas except for the central visual field in SLP. Correlation coefficients were highest in the area of the nasal inferior visual field (SOCT, -0.81; SLP, -0.57). A linear model describes the association between structural and functional damage. CONCLUSIONS: Localized perimetric defects can be explained by reduced nerve fiber layer thickness. The data indicate that the present SOCT is useful for determining the functional-structural relationship in peripapillary areas and that association between perimetric defects and corresponding nerve fiber losses is stronger for SOCT than for the present SLP. (ClinicalTrials.gov number, NCT00494923.).

Increased wall:lumen ratio of retinal arterioles in male patients with a history of a cerebrovascular event.

Arterial hypertension is a major risk factor for stroke, and retinal vessels can be regarded as a mirror of the cerebral vasculature. Whether vascular remodeling of retinal arterioles with ageing and hypertension plays a role in cerebrovascular risk stratification has not yet been adequately addressed. In study 1, retinal arteriolar structure was assessed in 182 normotensive volunteers and 117 patients with essential hypertension. In study 2, we compared retinal arteriolar structure among 74 normotensive volunteers, 47 patients with treated essential hypertension, and 18 subjects with a history of a cerebrovascular event. Retinal arteriolar structure was assessed using scanning laser Doppler flowmetry and automatic full-field perfusion imaging analysis. In study 1, wall:lumen ratio of retinal arterioles revealed a significant correlation with age (r=0.198; P=0.001). In study 2, wall:lumen ratio was highest in patients with a history of a cerebrovascular event compared with treated hypertensive and normotensive subjects (0.46+/-0.08, 0.36+/-0.14, and 0.35+/-0.12; P=0.007). When the treated group with hypertension was divided into 2 subgroups according to the quality of blood pressure control, patients with poor blood pressure control showed higher wall:lumen ratio than subjects with good blood pressure control (0.40+/-0.13 versus 0.31+/-0.13; P=0.025). Thus, assessment of wall:lumen ratio of retinal arterioles emerged as an attractive tool to identify treated patients with hypertension with increased cerebrovascular risk.

Morphometric age-related evaluation of small retinal vessels by scanning laser Doppler flowmetry: determination of a vessel wall index.

BACKGROUND: Measurement of the retinal vessel wall thickness may contribute to the diagnosis of microvascular diseases. We present a methodical approach to calculate these alterations and to determine age-related differences. METHODS: One hundred fifty-three subjects without eye or internal diseases (mean age +/- SD, 47.6 +/- 14.9 years) underwent measurement of the retinal temporal superior artery and vein by scanning laser Doppler flowmetry (Heidelberg retina flowmeter). We calculated the difference between the diameter of reflectivity and the Doppler signal (Delta[VD-FD]/2) and determined a "vessel wall index" (VWI) by normalization of Delta(VD-FD)/2 for age and vessel diameter. RESULTS: Delta(VD-FD)/2 correlated with vessel diameter (artery, r = +0.60, P < 0.001; vein, r = +0.49, P<0.001) and age (artery, r = +0.19, P = 0.02; vein, r = +0.27, P = 0.001) but not with sex, if controlled for the other variables each. The venous, but not the arterial, vessel diameter correlated with age (r = +0.18, P = 0.02), if controlled for sex. The relative statistical weight of these empirical contributions to the variation observed in Delta(VD-FD)/2 was 36.5% (P < 0.001, artery) and 21.7% (P< 0.001, vein), and that of age was 3.6% (P = 0.02, artery) and 7.3% (P = 0.001, vein). The limit value of VWI to pathologic changes (80th percentile) was 1.25 microm/y (artery) and 1.31 microm/y (vein). Delta(VD-FD)/2 normalized for vessel diameter correlated with the 10-year categories of age (artery, r = +0.196, P = 0.017; vein, r = +0.250, P = 0.002). CONCLUSION: In a group of subjects aged 21 years to 70 years, we detected an increase of Delta(VD-FD)/2 in the retinal temporal superior artery and vein with age.