Effect of arteriovenous sheathotomy on retinal blood flow and macular edema in patients with 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.

Deterioration of Retinal Blood Flow Parameters in Branch Retinal Vein Occlusion Measured by Doppler Optical Coherence Tomography Flowmeter

Background: Doppler optical coherence tomography (DOCT) flowmeter can be used to measure retinal blood flow (RBF) parameters, including vessel diameter, blood velocity, and the absolute value of RBF within 2.0 s. We investigated the RBF parameters in eyes with branch retinal vein occlusion (BRVO) using a DOCT flowmeter. Methods: Seventeen patients with unilateral BRVO were enrolled. All subjects underwent comprehensive ophthalmologic examinations. The RBF parameters were assessed from three veins, i.e., (1) an occluded vein, (2) a non-occluded vein in the BRVO eyes, and (3) an equivalent (superior or inferior) vein in the fellow eye (non-affected vein), using prototype DOCT flowmeter (Topcon, Tokyo, Japan). Moreover, the correlation between RBF parameters and the best corrected visual acuity (BCVA) was examined. We investigated the correlation between (1) the RBF parameters and the time from the initial visit, (2) the RBF parameters and the time from the last injection, and (3) the RBF parameters and the number of anti-vascular endothelial growth factor injections (VEGF). Results: The diameter of the occluded vein (95.9 ± 24.7 µm) was smaller than that of the non-occluded vein (127.9 ± 23.7 µm) and that of the healthy veins (116.4 ± 13.9 µm). The RBF was lower in the occluded veins (4.7 ± 3.7 µL/min) than that in the non-occluded veins (10.3 ± 5.1 µL/min; p < 0.01) and in the fellow eyes (8.6 ± 4.0 µL/min; p = 0.013). In contrast, the blood velocity was not significantly different among the three types of veins. BCVA was correlated with the diameter of the occluded vein (ρ = 0.711, p = 0.001) but not with the RBF and blood velocity. The time from the initial visit, the time from the last injection, and the total number of anti-VEGF injections were not associated with any RBF parameters on the occluded vein. Conclusions: The RBF was significantly lower in the occluded veins than that in the other veins, and the diameter of the occluded vein was significantly smaller than that of the other veins in patients with BRVO. However, neither the time from the initial visit, nor the time from the last injection, nor the number of anti-VEGF injections were correlated with the RBF parameters on the occluded vein.

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.

Branch retinal vein occlusion and vitreovascular traction: a preliminary spectral domain OCT case-control study

OBJECTIVE

Branch retinal vein occlusion (BRVO) typically occurs at an arteriovenous (AV) crossing site. Although the pathogenesis is unclear, vitreovascular traction might have a significant role in some BRVO cases. The purpose of present study was to determine the incidence of vitreoretinal traction at the obstruction site in patients diagnosed with BRVO.

METHODS

In this prospective observational case–control study, 32 consecutive BRVO patients were studied with spectral-domain optical coherence tomography (SD-OCT) to detect the presence of vitreovascular traction or vitreous adherence at the occlusion site.

RESULTS

SD-OCT directed to the occlusion site revealed a vitreovascular traction at this point in eight eyes (25 %). Fourteen eyes (43.75 %) were associated with an adherence of posterior hyaloids without signs of retinal traction, whereas ten eyes (31.25 %) had neither vitreoretinal adherence nor vitreous traction. Regarding either the same vessel segment of the fellow eye, none of the cases revealed vitreovascular traction in the correspondent AV crossing site; 12 cases (37.5 %) presented vitreoretinal adherence; and the remaining 20 cases (62.5 %) showed neither traction nor adhesion. Thus, vitreovascular traction in the occlusion site was significantly associated with BRVO (p = 0.024, chi-squared test). B-scan ultrasonography showed that the posterior vitreous cortex remains more frequently attached in eyes with BRVO compared to unaffected fellow eyes (p = 0.041, chi-squared test).

CONCLUSIONS

A common firm vitreous adhesion at the obstruction site is reported herein, pointing out the possible role of vitreovascular traction in the etiology of some cases of BRVO. Likewise, although not all BRVO cases can be explained by this pathogenic mechanism, an attached posterior vitreous cortex might be a cofactor in the origin of this entity.

Branch retinal vein occlusion: treatment modalities: an update of the literature

BACKGROUND

Retinal vein occlusion is the second most common retinal vascular disorder after diabetic retinopathy and is considered to be an important cause of visual loss. In this review, our purpose is to update the literature about the treatment alternatives for branch retinal vein occlusion.

METHODS

Eligible papers were identified by a comprehensive literature search of PubMed, using the terms "branch retinal vein occlusion," "therapy," "intervention," "treatment," "vitrectomy," "sheathotomy," "laser," "anti-VEGF," "pegaptanib," "bevacizumab," "ranibizumab," "triamcinolone," "dexamethasone," "corticosteroids," "non-steroids," "diclofenac," "hemodilution," "fibrinolysis," "tPA," and "BRVO." Additional papers were also selected from reference lists of papers identified by the electronic database search.

RESULTS

Treatment modalities were analyzed.

CONCLUSIONS

There are several treatment modalities for branch retinal vein occlusion and specifically for its complications, such as macular edema, vitreous hemorrhage, retinal neovascularization, and retinal detachment, including anti-aggregative therapy and fibrinolysis, isovolemic hemodilution, vitrectomy with or without sheathotomy, peripheral scatter and macular grid retinal laser therapy, non-steroid agents, intravitreal steroids, and intravitreal anti-vascular endothelial growth factors (anti-VEGFs).

Morphologic and functional changes in retinal vessels associated with branch retinal vein occlusion

OBJECTIVE

To study the morphologic and functional changes in retinal veins of eyes affected with branch retinal vein occlusion (BRVO) by thin sectioning with optical coherence tomography (OCT).

DESIGN

Prospective, observational, cross-sectional study.

PARTICIPANTS

Twenty-five consecutive patients (25 eyes) with acute BRVO.

METHODS

Major retinal veins, arteries, and arteriovenous (A/V) crossing were examined by sequential thin sectioning by Spectralis HRA+OCT (Heidelberg Engineering, Heidelberg, Germany). The retinal blood flow was mimicked in vitro and scanned with Spectralis HRA+OCT.

MAIN OUTCOME MEASURES

Morphologic characteristics of normal and BRVO-affected retinal vessels seen in OCT sections.

RESULTS

Cross-sectional OCT images revealed physiologic retinal vessels as oval configurations with 4 distinctive hyperreflectivities in a line. The vessel walls showed the innermost and outermost hyperreflectivity, and the blood flow showed internal paired hyperreflectivities with an hourglass shape. No eye with disturbed blood flow due to BRVO showed this internal hyperreflectivity pattern. In vitro, OCT sections of the blood within the glass tube without flow showed homogeneous reflectivities. Increased blood flow velocity resulted in the development of heterogeneous internal reflectivity and hourglass-shaped hyperreflectivities. In all eyes with acute BRVO, sequential sectioning with OCT visualized 3-dimensional vascular architecture and the intravascular conditions at the A/V crossing. At the affected A/V crossing, arterial overcrossing was seen in 17 eyes and venous overcrossing was seen in 8 eyes. In eyes with arterial overcrossing, the retinal vein seemed to run deep under the artery at the A/V crossing, and the venous lumen often appeared to be preserved even at the A/V crossing. In all eyes with venous overcrossing, the retinal vein appeared to be compressed and choked between the internal limiting membrane and the arterial wall at the A/V crossing. Optical coherence tomography sectioning showed intravenous thrombi in 21 eyes, and the thrombi were detected downstream of the A/V crossing in all the cases. The detection of thrombus was significantly associated with ischemic pattern in BRVO (P=0.036).

CONCLUSIONS

In eyes with BRVO, sequential thin sections with OCT visualized 3-dimensional retinal vasculature. The present OCT findings suggest that BRVO may occur by 2 different mechanisms, depending on the relative anatomic positions of the crossing vessels.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Retinal vascular changes following intravitreal ranibizumab injections for neovascular AMD over a 1-year period

PURPOSE

To assess retinal vascular calibre changes in eyes with neovascular age-related macular degeneration (AMD), treated with intravitreal anti-vascular endothelial growth factor agents, over a 1-year period and compare any such changes to untreated fellow eyes.

METHODS

Treatment naïve patients with neovascular AMD received three consecutive intravitreal injections of ranibizumab, followed by a pro re nata dosing regimen up to 1 year, with the aim of maintaining a 'fluid-free' macula. Retinal arteriolar and venular calibre was measured from digital fundus photographs at baseline and at three monthly intervals to 1 year, and summarised as central retinal artery equivalent (CRAE) and central retinal venular equivalent (CRVE), respectively.

RESULTS

A total of 53 injected eyes and 41 fellow, non-injected eyes were analysed. At baseline, there were no differences in retinal vascular calibre between injected and non-injected eyes (mean CRAE (SD) 144.93 (14.07) vs 145.74 (13.10) μm, P=0.80 and mean CRVE (SD) 216.23 (25.93) vs 219.91 (22.82) μm, P=0.53). Over a 12-month period, retinal venular calibre dilatation occurred in injected eyes (mean CRVE change +5.71 (14.71) μm, P=0.007), with no change in retinal arterioles, +0.69 (14.71) μm, P=0.68. In non-injected eyes, arteriolar narrowing occurred as a whole, mean CRAE change -4.20 (7.00) μm, P=0.001, over 12 months, with a trend for narrowing in venules, -2.16 (11.56) μm, P=0.28. In injected eyes, after controlling for covariates, the changes in CRVE over 12 months mirrored improvements in macular thickness, -0.06 (-0.005, -0.11) μm, P=0.04, and visual acuity, +9.66 (-0.30, +19.32) μm, P=0.06.

CONCLUSION

Intravitreal ranibizumab significantly dilated retinal venules after a 1-year period.

Feasibility study on retinal vascular bypass surgery in isolated arterially perfused caprine eye model

PURPOSE

To investigate the feasibility of bypassing occluded segments of retinal venous main vessels in isolated, arterially perfused caprine eyes via the closed-sky vitrectomy approach using keratoprosthesis.

METHODS

Isolated caprine eyes were used in this study. For each eye, the retinal vessel was perfused by Krebs solution via ophthalmic artery, and pars plana vitrectomy was performed using temporary keratoprosthesis. All retinal micro-vascular maneuvers were performed in a closed-sky eyeball. The main retinal vein was blocked by endodiathermy at the site of the vessel's first branching. Two openings, several millimeters apart, were created by vascular punctures in both the main vein and its branch vein wall straddling the induced occluded segment. Catheterization was achieved using a flexible polyimide tube, with each end inserted into the vessel wall opening. A sealed connection between the vessel and the tube was obtained by endodiathermy. Bypass of the occluded retinal vein segment was thus achieved, and the patency of this vascular bypass was confirmed by intravascular staining.

RESULTS

Puncturing, catheterization, and endodiathermy were viable by closed-sky approach using keratoprosthesis. Bypassing of the occluded retinal main vein segment was accomplished with the combination of these maneuvers. Good results were obtained in 23 of 38 (60%) caprine eyes.

CONCLUSIONS

This study demonstrated that bypassing the occluded segment of retinal main vein can be successfully performed in a closed-sky eyeball model of isolated, arterially perfused caprine eye. This early work indicated that the more advanced retinal vascular bypass surgery in in vivo eye may be feasible in the future.

Visual acuity and multifocal electroretinographic changes after arteriovenous crossing sheathotomy for macular edema associated with branch retinal vein occlusion

PURPOSE

To evaluate the influence of arteriovenous (AV) sheathotomy on retinal function with central multifocal electroretinography (mfERG) in eyes with macular edema secondary to branch retinal vein occlusion (BRVO).

METHODS

Fifteen patients (15 eyes) who underwent AV sheathotomy for macular edema secondary to BRVO were included in the study. Best-corrected visual acuity and mfERG responses from the most central seven hexagons were analyzed before and 6 months after the operation.

RESULTS

The mean preoperative Early Treatment Diabetic Retinopathy Study (ETDRS) score +/- SD was 34.1 +/- 12.7 letters (Snellen equivalent, 20/50) and significantly improved up to 40.5 +/- 10.9 letters (Snellen equivalent, 20/40) at 6 months after AV sheathotomy (P = 0.027, Wilcoxon signed rank test). The mean preoperative P1 amplitude +/- SD of the most central 7 hexagons was 39.30 +/- 10.86 nV/deg(2) for the affected eye versus 47.72 +/- 6.67 nV/deg(2) for the normal fellow (control) eye (P = 0.013, Mann-Whitney U test) and significantly increased up to 50.71 +/- 15.58 nV/deg at 6 months after the operation (P = 0.014, Wilcoxon signed rank test). Significant correlations between preoperative and postoperative ETDRS score and preoperative P1 amplitude were present (r = 0.929, P < 0.001; r = 0.768, P = 0.001; respectively [Spearman correlation]).

CONCLUSIONS

AV sheathotomy improved macular function and anatomical outcome as measured by ETDRS score and mfERG responses in patients with macular edema due to BRVO.

Branch retinal vein occlusion: pathogenesis, visual prognosis, and treatment modalities

In branch retinal vein occlusion (BRVO), abnormal arteriovenous crossing with vein compression, degenerative changes of the vessel wall and abnormal hematological factors constitute the primary mechanism of vessel occlusion. In general, BRVO has a good prognosis: 50-60% of eyes are reported to have a final visual acuity (VA) of 20/40 or better even without treatment. One important prognostic factor for final VA appears to be the initial VA. Grid laser photocoagulation is an established treatment for macular edema in a particular group of patients with BRVO, while promising results for this condition are shown by intravitreal application of steroids or new vascular endothelial growth factor inhibitors. Vitrectomy with or without arteriovenous sheathotomy combined with removal of the internal limiting membrane may improve vision in eyes with macular edema which are unresponsive to or ineligible for laser treatment.

Association between integrity of foveal photoreceptor layer and visual acuity in branch retinal vein occlusion

AIM

To study the correlation between integrity of the photoreceptor layer after resolution of macular oedema (MO) associated with branch retinal vein occlusion (BRVO) and final visual acuity (VA), and to determine prognostic factors for visual outcome.

METHODS

We retrospectively studied 46 eyes from 46 patients with resolved MO secondary to BRVO, the foveal thickness of which was less than 250 microm at final observation. We assessed the status of the third high reflectance band (HRB) in the fovea using optical coherence tomography (OCT) at final observation, and studied OCT images taken at the initial visit in the hope of identifying a factor that would be prognostic of visual outcome.

RESULTS

No differences were found in initial VA or in foveal thickness between eyes with or without complete third HRB at final observation. However, final VA in eyes without a complete HRB was significantly poorer (p<0.002). Additionally, initial status of the third HRB in the parafoveal area of unaffected retina was associated with final VA; lack of visualisation of the third HRB at 500 microm (p = 0.0104) or 1000 microm (p = 0.0167) from the fovea on initial OCT images was associated with poor visual recovery after resolution of the MO.

CONCLUSION

Integrity of the photoreceptor layer in the fovea is associated with VA in resolved MO, and status of the third HRB before treatment might be predictive of visual outcome.

Long-term outcomes of vitrectomy with or without arteriovenous sheathotomy in branch retinal vein occlusion

PURPOSE

To evaluate the long-term effect of vitrectomy with or without arteriovenous sheathotomy for macular edema secondary to branch retinal vein occlusion (BRVO).

METHODS

The study was a prospective, randomized, comparative, interventional case series of 36 patients (36 eyes) who underwent pars plana vitrectomy with or without arteriovenous sheathotomy for macular edema due to BRVO of <or=8 weeks' duration of symptoms. Eighteen eyes with arteriovenous sheathotomy (sheathotomy group) were compared with 18 eyes without sheathotomy (vitrectomy group). Main outcomes measures were best-corrected visual acuity and central foveal thickness as evaluated by optical coherence tomography.

RESULTS

Baseline demographic characteristics of the groups were similar. Postoperative follow-up period ranged from 12 months to 45 months (31 months). Median best-corrected visual acuity significantly improved from 0.4 at baseline to 1.0 at the final visit in both groups, and there was no significant difference in best-corrected visual acuity at any postoperative period between the groups. Of 16 patients with duration of symptoms of <4 weeks, those with arteriovenous sheathotomy had a tendency toward better visual outcomes than those without arteriovenous sheathotomy (P = 0.064). The central foveal thickness also significantly decreased after surgery in both groups, but the differences were not significant for the two groups at each time point. No patients had severe intraoperative and/or postoperative complications.

CONCLUSIONS

Our findings suggest that vitrectomy with or without arteriovenous sheathotomy may improve the long-term functional and tomographic outcomes for patients with macular edema secondary to BRVO. Although additional arteriovenous sheathotomy did not lead to a distinct functional benefit in this series, early surgical intervention may result in better visual outcomes.

Evaluation of arteriovenous crossing sheathotomy for decompression of branch retinal vein occlusion

PURPOSE

To report the effects of arteriovenous adventitial sheathotomy on anatomical and functional improvements in patients with macular oedema due to branch retinal vein occlusion (BRVO).

METHODS

Pars plana vitrectomy and arteriovenous sheathotomy was performed on 11 patients with BRVO who had vision loss due to macular oedema. Ten patients with macular oedema due to BRVO and who have been treated with grid laser photocoagulation were included in the control group. The measurement of visual acuity with ETDRS chart was taken preoperatively and at 1, 3, 6, and 9 months follow-up in the study group and at 1, 3, 6, and 9 months after grid laser in the control group.

RESULTS

The mean preoperative logMAR visual acuity was 0.84+/-0.3 in the surgical group and 1.06+/-0.4 in the control group. The postoperative mean logMAR visual acuity was 0.41+/-0.2, 0.40+/-0.2, 0.40+/-0.3, and 0.36+/-0.3 at 1, 3, 6, and 9 months follow-up, respectively. In the control group the postlaser mean logMAR visual acuity was 0.92+/-0.3, 0.87+/-0.4, 0.85+/-0.3, and 0.82+/-0.3 at 1, 3, 6, and 9 months follow-up, respectively. The improvements of visual acuity in both groups were statistically significant when compared to pretreatment (P=0.003 and P=0.007 at 9 months in the study and control group, respectively).

CONCLUSION

Arteriovenous sheathotomy for decompression of BRVO in patients who have vision loss due to macular oedema was safe and effective for anatomical and functional improvement and resulted in significantly better visual outcomes than a matched control group of laser-treated eyes.

Retinal blood flow and macular edema after radial optic neurotomy for central retinal vein occlusion

PURPOSE

To determine the effect of radial optic neurotomy (RON) on retinal blood flow (RBF) and macular edema in eyes with a central retinal vein occlusion.

DESIGN

Prospective interventional study.

METHODS

Seven eyes of seven patients with central retinal vein occlusion underwent RON and vitrectomy and were followed for at least 6 months. The RBF was calculated from dye dilution curves of video fluorescein angiograms. The foveal thickness was determined by optical coherence tomography.

RESULTS

At 1 week after surgery, the RBF was significantly reduced from 28.5 +/- 5.4 to 21.1 +/- 6.6 pixel(2)/s (P < .01). At 6 months after surgery, the RBF (26.0 +/- 7.7 pixel(2)/s) was not significantly different from the preoperative RBF, although chorioretinal anastomoses were found in all seven eyes. The foveal thickness was significantly decreased from 711 +/- 271 to 488 +/- 182 mum (P = .03). The postoperative visual acuity was better than the preoperative visual acuity by two or more lines in three out of seven eyes, and was worse in two eyes.

CONCLUSIONS

Neither RON nor chorioretinal anastomoses improved the RBF but macular edema was improved. These findings suggest that removal of the vitreous could reduce macular edema as in diabetic macular edema. However, we cannot exclude the possibility that the changes represent the natural course of this disease.