Macular microcirculation in hypertensive patients with and without branch retinal vein occlusion

Fatty acid-binding protein 4 is an independent factor in the pathogenesis of retinal vein occlusion

The main objective of current study was to identify the fatty acid-binding protein 4 (FABP4) expressed in both adipocytes and macrophages in vitreous fluid from patients with retinal vein occlusion (RVO). Patients with RVO (n = 14, CRVO; central RVO n = 5, BRVO; branch RVO n = 9) and non-RVO (macular hole or epiretinal membrane, n = 18) were surgically treated by a 25 or 27G vitrectomy. Undiluted vitreous fluid samples obtained as the result of surgery were subjected to enzyme-linked immunosorbent assays to measure the levels of FABP4 and vascular endothelial growth factor A (VEGFA).Data including ocular blood flow by laser speckle flow graphy (LSFG), height and weight, systemic blood pressures and several blood biochemistry values were collected. Among the LSFG mean blur rate (MBR) values of the optic nerve head (ONH) at baseline, MA (MBR of all area), MV (MBR of the vascular area), and MV-MT (MBR of the tissue area) were significantly decreased in patients with CRVO. The levels of V-FABP4 and V-VEGFA were relatively or significantly (P< 0.05) higher in the BRVO or CRVO patients compared to the non-RVO patients, respectively. A positive correlation (r = 0.36, P = 0.045) or a negative correlation (r = -0.51, P = 0.006) was observed between Log V-FABP4 and Log V-VEGF, or Log V-FABP4 and MV-MT at post-operative 1-week, respectively. Furthermore, neither of these factors were affected with respect to sex, body mass index and several clinical parameters that were collected, except that a positive correlation was observed for Log V-FABP4 with blood urea nitrogen. Stepwise multivariable regression analyses indicated that MV-MT at post-operative 1week was independently associated with Log V-FABP4 after adjustment for age and gender, and gender and Log V-FABP4 were independently associated with Log V-VEGFA after adjustment for age. The findings reported herein suggest that an independent factor, FABP4 may be synergistically involved in the pathogenesis of RVO with VEGFA.

Altered Retinal Hemodynamics and Mean Circulation Time in Spontaneously Hypertensive Rats

Purpose

Although it is known that the retinal arteriolar vasculature is constricted in hypertension, the details of retinal hemodynamics and perfusion of the retinal circulation have yet to be adequately characterized.

Methods

Male and female spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) controls were anesthetized before measurements of mean arterial blood pressure and preparation for intravital microscopy of the retinal microcirculation. Retinal vascular velocities were measured with the use of fluorescent microspheres, and diameters and mean circulation times were measured after the infusion of fluorescent dextran. Arteriolar and venular shear rates were calculated from the ratio of velocity to diameter.

Results

In the retinas of SHR, velocities were elevated (compared with control WKY) in arterioles, but not in venules. Both arteriolar and venular diameters were significantly smaller in SHR versus WKY, with substantial increases in shear rates. Despite a tendency toward lower retinal blood flow rates, the mean circulation time through the SHR retina was much faster than can be explained by the measured arteriolar and venular velocities.

Conclusions

The pattern of hypertension-induced increases in blood velocity, dissipating from the arteriolar to venular side of the retinal circulation, indicates a potential transfer of the extra kinetic energy through the vasculature. The combination of elevated velocities through narrower retinal arterioles resulted in a markedly higher level of wall shear rate that may induce changes in the vessel wall. Finally, significantly more rapid transits through the hypertensive retina could be a result of altered blood flow distribution.

Retinal oximetry in branch retinal vein occlusion

PURPOSE

To measure retinal oxygen saturation (SO₂ ) in eyes with branch retinal vein occlusion (BRVO).

METHODS

Retinal oximetry was performed using the Oxymap T1 retinal oximeter in 50 eyes (50 patients) with resolved BRVO. SO₂ was calculated in each major retinal artery and vein in four quadrants. The superior or inferior hemisphere with BRVO was categorized as the affected hemisphere and the other as the unaffected hemisphere.

RESULTS

Oxymap T1 allowed us to measure SO₂ in major retinal vessels. Both arterial and venous SO₂ in the affected hemisphere were significantly higher than those in the unaffected hemisphere. However, there was no significant difference in arteriovenous (A-V) difference in SO₂ between the affected and unaffected hemispheres. Of the 50 included eyes, 32 had non-ischemic BRVO and 18 had ischemic BRVO. In the affected hemisphere, arterial SO₂ was significantly higher in ischemic BRVO (106.9 ± 8.8%) than in non-ischemic BRVO (101.3 ± 9.2%, p = 0.044). There were no significant differences in venous SO₂ between non-ischemic and ischemic BRVO. Consequently, the A-V difference in SO₂ was significantly higher in ischemic BRVO (51.9 ± 13.9%) than in non-ischemic BRVO (43.4 ± 11.5%, p = 0.028). In multiple regression analysis, the type of perfusion (non-ischemic or ischemic) had associations with arterial SO₂ (β = 0.365, p = 0.013) and with A-V differences in SO₂ in the affected hemisphere (β = 0.406, p = 0.006).

CONCLUSION

In ischemic BRVO, arterial SO₂ and the A-V difference in SO₂ in the affected hemisphere were significantly higher than in non-ischemic BRVO.

Characteristics of Somatic Status and Individual Biochemical Markers in Patients with Retinal Vein Occlusion

Retinal vein occlusion is one of the most severe vascular lesions of the organ of vision, usually accompanied by somatic pathology.

The aim of the study was to study the somatic status and individual biochemical markers in patients with retinal vein occlusion and comparison in groups opposing the effectiveness of anti-VEGF therapy.

Methods. 84 patients with macular edema were examined on the background of retinal vein occlusion, who underwent intravitreal injections of an angiogenesis inhibitor for therapeutic purposes. Further, depending on the effectiveness of treatment, the patients were divided into 2 groups, in which a retrospective comparative analysis of somatic status and laboratory data was performed.

Results. It was shown that patients with occlusion of the retinal veins have significant impairments in terms of somatic status, blood biochemical parameters and coagulogram. Moreover, there is a direct relationship between the severity of somatic changes and ocular manifestations of the disease. The data obtained reflect a clear tendency in patients with occlusion of the retinal veins to a high risk of cardiovascular complications, including occlusive lesions. In patients with an insufficient treatment effect, a more severe course of arterial hypertension with an increased risk of stratification was detected.

Conclusion. The somatic status and laboratory parameters of patients with retinal vein occlusion are significantly different from the norm, which must be taken into account in the prognosis of the course of an ophthalmologic disease.

Cytokines and the Pathogenesis of Macular Edema in Branch Retinal Vein Occlusion

Branch retinal vein occlusion (BRVO) is a very common retinal vascular problem in patients with lifestyle-related diseases, such as hypertension and arteriosclerosis. In patients with BRVO, development of macular edema is the main cause of visual impairment. BRVO is still a controversial condition in many respects. Over the years, various methods such as laser photocoagulation have been tried to treat macular edema associated with BRVO, but the results were not satisfactory. After vascular endothelial growth factor (VEGF) was found to have an important role in the pathogenesis of macular edema in BRVO patients, treatment of this condition was revolutionized by development of anti-VEGF therapy. Although macular edema improves dramatically following intraocular injection of anti-VEGF agents, repeated recurrence and resistance of edema is a major problem in some BRVO patients. This suggests that factors or cytokines other than VEGF may be associated with inflammation and retinal hypoxia in BRVO and that the pathogenesis of macular edema is complicated. The present review assesses the role of various factors and cytokines in the pathogenesis of macular edema associated with BRVO. We present a mechanism that is not only plausible but should also be useful for developing new therapeutic strategies.

Visual field changes after vitrectomy with internal limiting membrane peeling for epiretinal membrane or macular hole in glaucomatous eyes

Purpose

To investigate visual field changes after vitrectomy for macular diseases in glaucomatous eyes.

Methods

A retrospective review of 54 eyes from 54 patients with glaucoma, who underwent vitrectomy for epiretinal membrane (ERM; 42 eyes) or macular hole (MH; 12 eyes). Standard automated perimetry (Humphrey visual field 24–2 program) was performed and analyzed preoperatively and twice postoperatively (1^st and 2nd sessions; 4.7 ± 2.5, 10.3 ± 3.7 months after surgery, respectively). Postoperative visual field sensitivity at each test point was compared with the preoperative value. Longitudinal changes in mean visual field sensitivity (MVFS) of the 12 test points within 10° eccentricity (center) and the remaining test points (periphery), best-corrected visual acuity (BCVA), intraocular pressure (IOP), and ganglion cell complex (GCC) thickness, and the association of factors with changes in central or peripheral MVFS over time were analyzed using linear mixed-effects models. In addition, 45 eyes from 45 patients without glaucoma who underwent vitrectomy for epiretinal membrane (ERM; 34 eyes) or macular hole (MH; 11 eyes) were similarly examined and statistically analyzed (control group).

Results

In glaucomatous eyes, visual field test points changed significantly and reproducibly; two points deteriorated only at the center and twelve points improved only at the periphery. Central MVFS decreased (p = 0.03), whereas peripheral MVFS increased postoperatively (p = 0.010). In the control group, no visual field test points showed deterioration, and central MVFS did not change significantly after vitrectomy. BCVA improved, GCC thickness decreased, and IOP did not change postoperatively in both groups. The linear mixed-effects models identified older age, systemic hypertension, longer axial length, and preoperative medication scores of ≥2 as risk factors for central MVFS deterioration in glaucomatous eyes.

Conclusions

Visual field sensitivity within 10° eccentricity may deteriorate after vitrectomy for ERM or MH in glaucomatous eyes.

RISK OF RETINAL VEIN OCCLUSION IN PATIENTS WITH PSORIASIS: A Population-Based Cohort Study

PURPOSE

To investigate the risk of developing retinal vein occlusion (RVO) in patients with psoriasis.

METHODS

In this retrospective population-based cohort study, 30,198 patients with psoriasis (Psoriasis((+)) group) and 30,198 controls without psoriasis (Psoriasis((−)) group) between 2001 and 2006 from the Taiwan National Health Insurance Research Database were selected.

RESULTS

The incidence of RVO was 1.46 times higher in the Psoriasis((+)) group than in the Psoriasis((−)) group (3.61 vs. 2.47/10,000 person-years) (adjusted hazard ratio = 1.50; 95% confidence interval = 1.07-2.10) calculated using Cox proportional hazard regression. Age was an independent risk factor for RVO (adjusted hazard ratio: 11.9 for patients 65 years or older vs. 1.00 for those 0-49 years old). In the 65 years or older Psoriasis((+)) group, the incidence of developing RVO was 1.97 times higher (95% confidence interval = 1.19-3.26) than in the 65 years or older Psoriasis((−)) group. In Psoriasis((+)) women, the incidence of developing RVO was 1.82 times higher (95% = 1.05-3.14) than in Psoriasis((−)) women. For the subgroup with comorbid hypertension, the incidence of developing RVO was 2.07 times higher (95% confidence interval = 1.22-3.50) in the Psoriasis((+)) group than in the Psoriasis((−)) group.

CONCLUSION

Psoriasis was significantly associated with a higher risk of developing RVO.

Retinal oximetry

ABSTRACT.:

PURPOSE

Malfunction of retinal blood flow or oxygenation is believed to be involved in various diseases. Among them are retinal vessel occlusions, diabetic retinopathy and glaucoma. Reliable, non-invasive technology for retinal oxygen measurements has been scarce and most of the knowledge on retinal oxygenation comes from animal studies. This thesis describes human retinal oximetry, performed with novel retinal oximetry technology. The thesis describes studies on retinal vessel oxygen saturation in (1) light and dark in healthy volunteers, (2) central retinal vein occlusion, (3) branch retinal vein occlusion, (4) central retinal artery occlusion, (5) diabetic retinopathy, (6) patients undergoing glaucoma surgery and (7) patients taking glaucoma medication.

METHODS

The retinal oximeter (Oxymap ehf., Reykjavik, Iceland) is based on a fundus camera. An attached image splitter allows the simultaneous capture of four images of the same area of the fundus. Two images are used for further analysis, one acquired with 586 nm light and one with 605 nm light. Light absorbance of retinal vessels is sensitive to oxygen saturation at 605 nm but not at 586 nm. Measurement of reflected light at these wavelengths allows estimation of oxygen saturation in the main retinal vessels. This is performed with custom-made analysis software.

RESULTS

LIGHT AND DARK: After 30 min in the dark, oxygen saturation in retinal arterioles of healthy volunteers was 92 ± 4% (mean ± SD, n = 15). After 5 min in 80 cd/m(2) light, the arteriolar saturation was 89 ± 5%. The decrease was statistically significant (p = 0.008). The corresponding values for retinal venules were 60 ± 5% in the dark and 55 ± 10% in the light (p = 0.020). Similar results were found after alternating 5 min periods of darkness and light. In a second experiment (n = 19), a significant decrease in retinal vessel oxygen saturation was found in 100 cd/m(2) light compared with darkness but 1 and 10 cd/m(2) light had no significant effect. CENTRAL RETINAL VEIN OCCLUSION: In patients with central retinal vein occlusion, the mean saturation in affected retinal venules was 49 ± 12%, while the mean value for venules in the fellow eye was 65 ± 6% (mean ± SD, p = 0.003, n = 8). The retinal arteriolar saturation was the same in affected (99 ± 3%) and the unaffected (99 ± 6%) eyes. The venous oxygen saturation showed much variation between affected eyes. BRANCH RETINAL VEIN OCCLUSION: Median oxygen saturation in venules affected by branch retinal vein occlusion was 59% (range, 12-93%, n = 22), while it was 63% (23-80%) in unaffected venules in the affected eye and 55% (39-80%) in venules in the fellow eye. The difference was not statistically significant (p > 0.05). There was a significant difference between affected arterioles (median 101%; range, 89-115%) and unaffected arterioles (95%, 85-104%) in the affected eye (p < 0.05, n = 18). CENTRAL RETINAL ARTERY OCCLUSION: In a patient with a day's history of central retinal artery occlusion due to temporal arteritis, the mean arteriolar saturation was 71 ± 9% and 63 ± 9% in the venules. One month later, after treatment with prednisolone, the mean arteriolar saturation was 100 ± 4% and the venous saturation 54 ± 5%. DIABETIC RETINOPATHY: When compared with healthy volunteers (n = 31), patients with all categories of diabetic retinopathy had on average 7-10 percentage points higher saturation in retinal arterioles (p < 0.05 for all categories, n = 6-8 in each category). In venules, the saturation was 8-12 percentage points higher (p < 0.05 for all categories). GLAUCOMA SURGERY: Oxygen saturation in retinal arterioles increased by 2 percentage points on average (p = 0.046, n = 19) with surgery, which lowered intraocular pressure from 23 ± 7 mmHg (mean ± SD) to 10 ± 4 mmHg (p < 0.0001). No other significant changes were found (p ≥ 0.35). DORZOLAMIDE: A significant reduction of 3 percentage points was found in arterioles (p < 0.01) and venules (p < 0.05) when patients with glaucoma or ocular hypertension changed from dorzolamide-timolol combination eye drops to timolol alone (n = 6). No change was found in patients, who started on timolol and switched to the combination therapy (p > 0.05, n = 7).

CONCLUSIONS

Dual wavelength oximetry can be used to non-invasively measure retinal vessel oxygen saturation in health and disease. The results indicate that retinal vessel oxygen saturation is (1) increased in the dark, (2) lower in venules affected by central retinal vein occlusions, (3) variable in branch retinal vein occlusion, (4) lower in retinal arterioles in central retinal artery occlusion, (5) increased in diabetic retinopathy, (6-7) mildly affected by glaucoma surgery or dorzolamide.

Oxygen saturation in branch retinal vein occlusion

PURPOSE

The aim of this study was to test whether oxygen saturation in retinal blood vessels is affected by branch retinal vein occlusion (BRVO).

METHODS

The spectrophotometric retinal oximeter is based on a fundus camera. It simultaneously captures images of the retina at 586 and 605 nm and calculates optical density (absorbance) of retinal vessels at both wavelengths. The ratio of the two optical densities is approximately linearly related to haemoglobin oxygen saturation. Relative oxygen saturation was measured in retinal blood vessels in 24 patients with BRVO. Friedman's test and Dunn's post test were used for statistical analyses.

RESULTS

  Oxygen saturation in occluded venules ranged from 12% to 93%. The median oxygen saturation was 59% (range 12-93%, n = 22) in affected retinal venules, 63% (23-80%) in unaffected venules in the BRVO eye and 55% (39-80%) in venules in the fellow eye (p = 0.66). Corresponding values for arterioles were 101% (89-115%, n = 18), 95% (85-104%) (p < 0.05) and 98% (84-109%).

CONCLUSIONS

Venular saturation in BRVO is highly variable between patients. Hypoxia is seen in some eyes but not in others. This may reflect variable severity of disease, degree of occlusion, recanalization, collateral circulation, tissue atrophy, arteriovenous diffusion or vitreal transport of oxygen.

Influence of macular microcirculation and retinal thickness on visual acuity in patients with branch retinal vein occlusion and macular edema

PURPOSE

To investigate perifoveal capillary blood flow velocity and retinal thickness at the central fovea in patients with branch retinal vein occlusion (BRVO) and macular edema and to assess their relation with visual acuity and visual prognosis.

METHODS

Eighteen patients with BRVO and 16 healthy volunteers were compared. Perifoveal capillary blood flow velocity was measured on fluorescein angiograms with a scanning laser ophthalmoscope by the tracing method. Retinal thickness was measured at the central fovea by optical coherence tomography. Best-corrected visual acuity (BCVA) was determined.

RESULTS

BCVA differed significantly between patients and controls (P < 0.0001). Among patients, BCVA was negatively correlated with perifoveal capillary blood flow velocity by univariate analysis (r = -0.7916, P < 0.0001), and positively correlated with retinal thickness at the central fovea (r = 0.8970, P < 0.0001). Multivariate analysis showed that retinal thickness at the central fovea was the only independent determinant of BCVA (P < 0.0001).

CONCLUSIONS

In patients with BRVO, BCVA was more strongly influenced by retinal thickness at the central fovea than by perifoveal capillary blood flow velocity.

Retinal vein occlusions: The potential impact of a dysregulation of the retinal veins

A retinal vein occlusion (RVO) is a sight threatening disease. It can be divided into central vein occlusion and branch retinal vein occlusion. The pathogenesis of the condition remains to be solved. Mechanical compression of the vessel wall or thrombotic occlusion of the vessel lumen, sometimes combined with rheological disorders, are often assumed pathomechanisms. Accordingly, the therapy relies either on mechanical decompression, lyses of thrombi or improvement of rheology. A number of observations however, such as the relationship of RVO to atherosclerotic risk factors, spontaneous reversibility particularly in young patients, rest flow observed in angiography, occlusion despite anticoagulation or thrombocytopenia and finally the positive effect of anti-VEGF therapy are not explained by the present pathogenetic concept. As a new concept we propose a local venous constriction induced by vasoconstrictive molecules diffusing from neighbouring diseased arteries and/or from other neighbouring (hypoxic) tissues. Recognizing these postulated conditions might lead to an earlier identification of impending vein occlusions as well as to a treatment more tailored to the risk factor constellation of the particular patient.

Long-term study of vascular perfusion effects following arteriovenous sheathotomy for branch retinal vein occlusion

PURPOSE

To evaluate the perfusion effects and long-term visual outcome of pars plana vitrectomy (PPV) combined with arteriovenous sheathotomy (AVS) with or without triamcinolone for nonischaemic branch retinal vein occlusion (NI-BRVO).

METHODS

Prospective, interventional case series of eight patients with NI-BRVO and haemorrhagic macular oedema. Patients underwent PPV and AVS (n = 5), or PPV, AVS and intravitreal triamcinolone (IVT, n = 3). A masked grading technique assessed fundus photographs and fluorescein angiography (FFA) following surgery. Scanning laser ophthalmoscopy/optical coherence tomography (SLO/OCT) evaluated macular oedema and outer retinal architecture. Main outcomes examined included visual acuity (VA), retinal reperfusion, collateral vessel regression, vascular dilatation, cystoid macular oedema (CMO), and ocular neovascularization.

RESULTS

Seven of eight patients underwent uncomplicated surgery, with increased intraretinal perfusion and reduced engorgement of distal retinal veins. The mean pre-logMAR VA was 0.8 (SD 0.17) and did not improve significantly after surgery (post-logMAR 0.6, SD 0.38; p = 0.11, paired t-test). SLO/OCT showed persistent CMO in four patients, and subfoveal thinning of the photoreceptor layer. Collateral vessels disappeared at the blockage site post-AVS in 7/8 eyes, and this was associated with improved retinal perfusion. Six of eight patients developed epiretinal membrane. No patients developed ocular neovascularization. The average follow-up was 34.5 months.

CONCLUSIONS

PPV with AVS is a safe procedure, and adjunctive IVT had no additional effects on vascular perfusion. Successful decompressive surgery was followed by disappearance of collateral vessels at the BRVO blockage site and was a clinical marker for intravascular reperfusion. Long-term epiretinal gliosis and subfoveal photoreceptor atrophy limited functional and visual recovery.

Association between macular microcirculation and soluble intercellular adhesion molecule-1 in patients with macular edema and retinal vein occlusion

BACKGROUND

In patients who have macular edema secondary to retinal vein occlusion, the role of vasoactive molecules such as growth factors and the influence of molecules related to leukocyte adhesion need to be investigated further.

METHODS

A prospective study was performed to investigate the relations between perifoveal capillary blood flow velocity and the vitreous levels of vascular endothelial growth factor (VEGF) and soluble intercellular adhesion molecule-1 (sICAM-1) in patients with macular edema and retinal vein occlusion. Undiluted vitreous specimens were obtained from 11 eyes of 11 patients with macular edema (nine had branch retinal vein occlusion and two had central retinal vein occlusion). VEGF and sICAM-1 levels were measured by enzyme-linked immunoabsorbent assay. Before vitreous sampling, perifoveal capillary blood flow velocity was measured by fluorescein angiography with a scanning laser ophthalmoscope and the tracing method. The relations between perifoveal capillary blood flow velocity and the vitreous levels of VEGF and sICAM-1 were investigated.

RESULTS

There was a significant correlation between perifoveal capillary blood flow velocity and the vitreous level of sICAM-1 (rho = -0.7303, p = 0.03). In contrast, there was no significant association between blood flow velocity and the vitreous level of VEGF (rho = -0.1458, p = 0.67).

CONCLUSIONS

The vitreous level of sICAM-1 is associated with perifoveal capillary blood flow velocity in patients who have retinal vein occlusion and macular edema.