Blood-retina barrier in acute retinal branch vein occlusion

The role of lipid peroxidation in epithelial-mesenchymal transition of retinal pigment epithelial cells

Epithelial-Mesenchymal Transition (EMT) of retinal pigment epithelial (RPE) cells is recognized as pivotal in various retinal diseases. Previous studies have suggested a reciprocal regulation between reactive oxygen species (ROS) and EMT, though the involvement of peroxidized lipids or the effects of reducing them has remained unclear. The present study disclosed that EMT of ARPE-19 cells induced by TGF-β2 and TNF-α involves increased lipid peroxidation, and Ferrostatin-1 (Fer-1), a lipophilic antioxidative agent, successfully inhibited the increase in lipid peroxidation. Fer-1 suppressed the formation of EMT-associated fibrotic deposits, while EMT induction or Fer-1 treatment did not influence the cell viability or proliferation. Functionally, Fer-1 impeded EMT-driven cell migration and reduction in transepithelial electrical resistance. It demonstrated regulatory prowess by downregulating the mesenchymal marker fibronectin, upregulating the epithelial marker ZO-1, and inhibiting the EMT-associated transcriptional factor ZEB1. Additionally, VEGF, a major pathogenic cytokine in various retinal diseases, is also upregulated during EMT, and Fer-1 significantly mitigated the effect. The present study disclosed the involvement of lipid peroxidation in EMT of RPE cells, and suggests the suppression of lipid peroxidation may be a potential therapeutic target in retinal diseases in which EMT is implicated.

Novel pharmaceuticals for the management of retinal vein occlusion and linked disorders

INTRODUCTION

Retinal vein occlusion (RVO) is the second leading cause of blindness from retinal vascular disease behind diabetic retinopathy. Anti-vascular endothelial growth factor (VEGF) and glucocorticoid therapy are the cornerstones of pharmaceutical treatment for RVO. There is considerable interest in developing new pharmaceuticals in and out of these two classes to reduce costs, lower injection burden, and treat the occlusion itself, rather than the complications.

AREAS COVERED

In this review, we discuss novel pharmaceuticals for the treatment of RVO outside of current standard of care. We performed a comprehensive literature search encompassing pharmaceuticals that have recently been approved or have shown promising results in early clinical trials or animal models.

EXPERT OPINION

Anti-VEGF therapy remains the most efficacious treatment for RVO with a very favorable side effect profile. New biosimilars reduce costs while maintaining efficacy. Novel glucocorticoids may be a useful therapy in patients for whom anti-VEGF therapy has failed, or as an adjunct. Pharmaceuticals in other drug classes, particularly those with neuroprotective or regenerative properties, as well as those geared toward treating the occlusion itself, represent exciting options for early RVO therapy, but are likely years away from clinical relevance.

Cytokines and Pathogenesis of Central Retinal Vein Occlusion

Central retinal vein occlusion (CRVO) causes macular edema and subsequent vision loss and is common in people with diseases such as arteriosclerosis and hypertension. Various treatments for CRVO-associated macular edema have been trialed, including laser photocoagulation, with unsatisfactory results. However, when the important pathogenic role of vascular endothelial growth factor (VEGF) in macular edema was identified, the treatment of CRVO was revolutionized by anti-VEGF therapy. However, despite the success of intraocular injection of anti-VEGF agents in many patients with CRVO, some patients continue to suffer from refractory or recurring edema. In addition, the expression of inflammatory cytokines increases over time, causing more severe inflammation and a condition that is increasingly resistant to anti-VEGF therapy. This indicates that the pathogenesis of macular edema in CRVO is more complex than originally thought and may involve factors or cytokines associated with inflammation and ischemia other than VEGF. CRVO is also associated with leukocyte abnormalities and a gradual reduction in retinal blood flow velocity, which increase the likelihood of it developing from the nonischemic type into the more severe ischemic type; in turn, this results in excessive VEGF expression and subsequent neovascular glaucoma. Here, we review the role of different factors and cytokines involved in CRVO pathogenesis and propose a mechanism that holds promise for the development of novel therapies.

Correlation between macular edema recurrence and macular capillary network destruction in branch retinal vein occlusion

BACKGROUND

The aim of this study was to evaluate the correlation between changes in the macular capillary network and macular edema (ME) recurrence with branch retinal vein occlusion (BRVO) using swept-source optical coherence tomography angiography (SS-OCTA).

METHODS

We reviewed the data for 43 patients with treatment-naïve ME associated with BRVO. Patients who received intravitreal bevacizumab injection were divided into two groups based on ME recurrence at 6 months after edema resolution. The perifoveal capillary morphology and the macular capillary vessel density (VD) were retrospectively analyzed using en face SS-OCTA after ME resolution.

RESULTS

The perifoveal capillary ring loss in the superficial capillary plexus (SCP) and deep capillary plexus (DCP) was more common in the ME recurrence group (n = 22) than in the no ME recurrence group (p = 0.047 and p = 0.002). Relative to the findings in the no ME recurrence groups, the destruction of the perifoveal capillary ring was more severe in the DCP (30.0° vs 87.3°, p = 0.001) than in the SCP (17.3° vs 69.5°, p = 0.006) in the ME recurrence group. The hemi-VD disparity between the affected and the unaffected areas in the SCP and DCP showed significant differences (p = 0.031 and p = 0.017), while macular VD showed no differences between the groups.

CONCLUSIONS

Destruction of the perifoveal capillary ring and hemi-VD disparity could be related to ME recurrence in BRVO. Therefore, these factors may be helpful in predicting ME recurrence.

Topical Triamcinolone Acetonide-Loaded Liposomes as Primary Therapy for Macular Edema Secondary to Branch Retinal Vein Occlusion: A Pilot Study

Purpose: To explore safety and therapeutic efficacy of a topical ophthalmic triamcinolone acetonide-loaded liposome formulation (TA-LF) as primary therapy in patients with macular edema (ME) secondary to branch retinal vein occlusion (BRVO). Methods: Twelve eyes of 12 patients with ME secondary to BRVO were exposed to a topical instillation of 1 drop of TA-LF (TA 0.2%) 6 times a day for 12 weeks to evaluate safety and efficacy. Best corrected visual acuity (BCVA) intraocular pressure (IOP), slit lamp examination, and central foveal thickness (CFT) were analyzed at every visit. In addition, the morphology of TA-LF was analyzed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results: Patients presented a significant improvement of BCVA and CFT without significant IOP modification (P = 0.94). Treated eyes showed BCVA improvement from 40 ± 12.05 to 64.83 ± 15.97 letters and CFT reduction from 682.91 ± 278.60 to 271.58 ± 57.66 μm after 12 weeks of TA-LF therapy (P < 0.001). No adverse events, including IOP rising, were registered. SEM analysis of liposomal formulations showed that liposome (LP) size depends on its concentration. As the concentration of TA increased, the average size of LPs and the number of larger particles increased as well. TEM study displayed that LP formulation efficiently solubilizes TA crystals in nanoparticles and encapsulates them. Conclusion: LPs can function as nanocarriers of TA and they could be used as topical ophthalmic primary therapy instead of intravitreal drugs in patients with ME secondary to BRVO.

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.

Ranibizumab in macular oedema secondary to branch retinal vein occlusion - 24 months of treatment

PURPOSE

To retrospectively evaluate the efficacy and safety of ranibizumab treatment for macular edema (ME) secondary to branch retina vein occlusion (BRVO) after 24 months.

MATERIALS AND METHODS

This study included 39 eyes of 39 patients with ME associated with BRVO treated at the Ophthalmology Department of Faculty Hospital in Hradec Kralove. The average age of included patiens was 69,3 years, the mean duration of symptoms before treament was 5,4 months, the mean baseline visual acuity (VA) was 54,6 ETDRS (Early Treatment Diabetic Retinopathy Study) letters, the mean baseline central retinal thickness (CRT) was 544,9 µm. At 64,1% patients a retinal laserphotocoagulation was performed before intravitreal ranibizumab. After one year, the study was discontinued by 17 patiens, the remaining 22 patients were observed for 24 months. Initially, there were 3 doses of intravitreal ranibizumab administered in monthly intervals, further injections were applied according to PRN (pro re nata) regiment. Patients were examined at baseline and then at 3, 6, 9, 12 and 24 months from initiation of the treatment. In this study, the effect of ranibizumab on functional and morphological parameters of the affected eye was monitored, the safety of this treatment was also evaluated. During the follow-up, a statistically significant improvement in VA was achieved in every visit in comparison to baseline parameters, the mean VA gain at the 3 month visit was 12,1 ETDRS letters (p.

The Effect of Dexamethasone Intravitreal Implant on Retinal Nerve Fiber Layer in Patients Diagnosed with Branch Retinal Vein Occlusion

PURPOSE

To evaluate the effect of a single dose of intravitreal dexamethasone (DEX) implant on retinal nerve fiber layer (RNFL) thickness in patients with branch retinal vein occlusion (BRVO) in a 6-month period.

MATERIALS AND METHODS

This retrospective observational study included the patients with BRVO who received intravitreal DEX implant and whose assessment included the baseline RNFL thickness measurements. The data of 26 eyes of 24 patients were retrospectively analyzed. Spectral domain optic coherence tomography was used to measure peripapillary RNFL thickness in six regional subfields. Intraocular pressure (IOP) values at each visit were recorded. The data of single dose DEX implant during 6 months were assessed.

RESULTS

The mean preoperative and postoperative 6th month nasal RNFL values were 85.4 ± 23.0 μm and 82.1 ± 17.6 μm, respectively, and the difference between the measurements was not statistically significant (p = 0.372). There was a slight decrease in the mean RNFL values postoperatively compared to the baseline values in all quadrants except supero-temporal quadrant; however, none of them reached statistically significant level (p > 0.05). The mean IOP values before and 6 months after implantation were 15.7 ± 2.9 mmHg and 16.5 ± 4.2 mmHg, respectively. The difference between the 6th month IOP values and baseline IOP values was not statistically significant (p = 0.236).

CONCLUSION

Intravitreal DEX implant seems to have no adverse effect on RNFL thickness in BRVO patients in a 6-month period.

New Developments in the Classification, Pathogenesis, Risk Factors, Natural History, and Treatment of Branch Retinal Vein Occlusion

For years, branch retinal vein occlusion is still a controversial disease in many aspects. An increasing amount of data is available regarding classification, pathogenesis, risk factors, natural history, and therapy of branch retinal vein occlusion. Some of the conclusions may even change our impression of branch retinal vein occlusion. It will be beneficial for our doctors to get a deeper understanding of this disease and improve the treatment skills. The aims of this review is to collect the information above and report new ideas especially from the past a few years.

Combination therapy of intravitreal bevacizumab with single simultaneous posterior subtenon triamcinolone acetonide for macular edema due to branch retinal vein occlusion

PurposeTo evaluate efficacy and safety of combination therapy of intravitreal bevacizumab (IVB) with single simultaneous posterior subtenon triamcinolone acetonide (STA) for treatment of macular edema (ME) secondary to branch retinal vein occlusion (BRVO).MethodsThis was a prospective, randomized, interventional comparative study conducted in 45 eyes with ME secondary to BRVO who were treated primarily with IVB 1.25 mg (23 eyes, IVB group) or combination therapy of IVB 1.25 mg with a single simultaneous STA 40 mg (18 eyes, IVB/STA group). Reinjections were performed with IVB if optical coherence tomography (OCT) showed recurrent ME associated with decreased visual acuity. The main outcome measurement was the number of additional IVB injections, and changes of best-corrected visual acuity (BCVA) and central macular thickness (CMT) during a 6-month follow-up period were compared.ResultsBCVA showed significant improvement in two groups at 6 months. In addition, CMT showed significant decrease in two groups at 6 months. No significant differences in the change of BCVA and CMT at 6 months after injection (P=0.973, P=0.639) were observed between the two groups. A statistically significant difference was found regarding the number of additional IVB injections (IVB group 0.96±0.83; IVB/STA group 0.44±0.70, P=0.034).ConclusionAlthough combination therapy of IVB with a single simultaneous STA for treatment of ME secondary to BRVO did not affect the visual outcomes compared with IVB monotherapy, it had a benefit of reducing the number of additional IVB injections.

The role of inflammation in the pathogenesis of macular edema secondary to retinal vascular diseases

Macular edema (ME) is a nonspecific sign of numerous retinal vascular diseases. This paper is an updated overview about the role of inflammatory processes in the genesis of both diabetic macular edema (DME) and ME secondary to retinal vein occlusion (RVO). We focus on the inflammatory mediators implicated, the effect of the different intravitreal therapies, the recruitment of leukocytes mediated by adhesion molecules, and the role of retinal Müller glial (RMG) cells.

Correlation between vascular endothelial growth factor and nonperfused areas in macular edema secondary to branch retinal vein occlusion

Purpose

To determine the role of vascular endothelial growth factor (VEGF) in macular edema secondary to branch retinal vein occlusion (BRVO).

Patients and methods

Aqueous humor samples were collected from 52 eyes with macular edema secondary to BRVO before intravitreal drug injections and from 62 control eyes with cataract. VEGF was measured using an enzyme-linked immunosorbent assay. Fluorescein angiography showed capillary nonperfused areas (NPAs). Macular edema was evaluated by optical coherence tomography as the central retinal thickness.

Results

The mean aqueous VEGF levels in eyes with BRVO and control eyes with cataract were, respectively, 290.5 pg/mL ± 294.9 pg/mL (range 81.9 pg/mL–1567.3 pg/mL) and 118.0 pg/mL ± 50.1 pg/mL (range 24.6 pg/mL–241.1 pg/mL), which differed significantly (P < 0.0001). The mean VEGF level in eyes with BRVO without apparent NPA was 171.4 pg/mL ± 52.5 pg/mL (range 90.9 pg/mL–299.9 pg/mL), which was significantly higher than controls (P = 0.001). VEGF levels were correlated positively with the size of NPA (P = 0.0002) but not with the central retinal thickness.

Conclusion

The aqueous VEGF concentration in patients with macular edema secondary to BRVO increased significantly and was correlated significantly with the size of NPA. Aqueous VEGF increased even in eyes without apparent NPA.

Extrafoveal changes following intravitreal bevacizumab injections for macular edema secondary to branch retinal vein occlusion: an mfERG and OCT study

PURPOSE

To evaluate the functional and structural changes of extrafoveal macula after intravitreal bevacizumab (IVB) injection in patients with macular edema due to branch retinal vein occlusion (BRVO) using multifocal electroretinogram (mfERG) and optical coherence tomography (OCT).

METHODS

A total of 19 eyes of 19 patients with macular edema due to BRVO received three consecutive IVB injections with a 6-week interval. Spectral domain optical coherence tomography (SD-OCT), mfERG, and fluorescein angiography (FA) were performed at baseline. The macular area was divided into four quadrants (Q1-Q4) based on FA. The mean retinal thickness (MRT) and mfERG parameters in each of the four quadrants were measured at baseline and 4 weeks after the third injection.

RESULTS

The MRT in the four quadrants improved significantly after IVB injections (p < 0.01 for Q1 and Q2, p < 0.05 for Q3 and Q4) compared to baseline. The significant improvements in mfERG responses were seen in Q1 and Q2. In Q1, there were 68 and 56% improvement in N1 and P1 amplitude, respectively (p < 0.01). N1 and P1 amplitude in Q2 increased significantly by 43 and 46%, respectively, compared to baseline (p < 0.05). The MRT and P1 amplitude were significantly correlated at baseline in Q1 and Q2, but no significant correlations were found after three IVB injections.

CONCLUSIONS

The injection of IVB improved functional and structural outcomes in the primarily affected half of the extrafoveal macula effectively. The measurements of structural and functional changes using mfERG and OCT may be appropriate for monitoring the effects of IVB injection in BRVO patients.

Chemokines in aqueous humour before and after intravitreal triamcinolone acetonide in eyes with macular oedema associated with branch retinal vein occlusion

PURPOSE

To determine the aqueous humour levels of chemokines before and after an intravitreal injection of triamcinolone acetonide (IVTA) in eyes with macular oedema associated with a branch retinal vein occlusion (ME-BRVO).

DESIGN

  Single-centre, prospective, consecutive interventional case series.

PARTICIPANTS

Seventeen eyes of 17 consecutive patients with ME-BRVO who underwent IVTA were studied. Seven eyes without retinal vascular disease served as control.

INTERVENTION

All patients with ME-BRVO underwent IVTA.

MAIN OUTCOME MEASURES

The optical coherence tomographically determined foveal thickness (FT) and the aqueous humour levels of inflammatory chemokines of the C-C subfamily, including eotaxin, monocyte chemotactic protein-1 (MCP-1), macrophage inflammatory protein-1α (MIP-1α), β (MIP-1β), and RANTES was determined before the IVTA (baseline) and at 1 week after the IVTA.

RESULTS

At the baseline, only MCP-1 and MIP-1β were detected in the aqueous, and MIP-1β was significantly higher in eyes with a ME-BRVO than in controls (p = 0.004). The level of both of these chemokines was not correlated with the FT (p = 0.654 and p = 0.608, respectively). One week after IVTA, the FT was significantly decreased (p < 0.001), and the levels of MCP-1 and MIP-1β were also significantly reduced (p < 0.001 and p = 0.044, respectively). The decrease in the FT was correlated with the decrease in only MIP-1β (r = 0.58, p = 0.020).

CONCLUSIONS

Alterations of the aqueous level of MIP-1β reflect the improvement of the macular oedema after IVTA in eyes with ME-BRVO. This indicates that the steroid-dependent ME-BRVO was closely related with the level of MIP-1β.

Pars plana vitrectomy and internal limiting membrane peeling for macular edema secondary to retinal vein occlusion

Purpose:

To evaluate the effects of vitrectomy and internal limiting membrane peeling for treatment of macular edema secondary to retinal vein occlusion (RVO).

Methods:

Nine cases of visual loss due to macular edema caused by central retinal vein occlusion or branch retinal vein occlusion underwent pars plana vitrectomy with removal of the preretinal hyaloid, peeling of the internal limiting membrane stained with indocyanine green dye, air–fluid exchange, and postoperative prone positioning. Best-corrected visual acuity (BCVA) and central foveal thickness by optical coherence tomography were measured pre- and postoperatively then compared to assess the outcome of surgery.

Results:

In all cases intraretinal blood and retinal thickening diminished within 2 months of surgery. Visual acuity improved in all of the central retinal vein occlusion cases and 3/6 branch retinal vein occlusion cases. The decrease in macular thickness was statistically significant (mean postoperative macular thickness 361 ± 61.1 versus mean preoperative macular thickness 563.9 ± 90.0, P = 0.001, t-test). The improvement in BCVA was not statistically significant (mean preoperative BCVA in LogMAR 1.23 ± 0.29 versus mean postoperative BCVA in LogMAR 1.06 ± 0.49, P = 0.09, t-test).

Conclusion:

In eyes with macular edema secondary to RVO, pars plana vitrectomy with internal limiting membrane peeling can resolve macular edema, but the improvement in BCVA was not statistically significant in this study.

Levels of VEGF but not VEGF(165b) are increased in the vitreous of patients with retinal vein occlusion

PURPOSE

To determine the concentration of the pro-angiogenic vascular endothelial growth factor VEGF(165) (VEGF) and the anti-angiogenic VEGF(165b) in vitreous samples of patients with branch retinal vein occlusion (BRVO) and central retinal vein occlusion (CRVO) in comparison to patients without retinal occlusive disease.

DESIGN

Experimental laboratory investigation.

METHODS

Vitreous samples were collected from patients undergoing surgery for arteriovenous dissection after BRVO, radial optic neurotomy after CRVO in the occlusion group, or macular pucker or macular hole in the control group. Concentrations of VEGF and VEGF(165b) were determined by ELISA and an ELISA-type antibody microarray.

RESULTS

Average vitreal concentration of VEGF was 8.6 ng/mL in the CRVO group and 2.0 ng/mL in the BRVO group as compared to 0.26 ng/mL in the control group. Average vitreal concentration of VEGF(165b) was 27 pg/mL in the CRVO group, 42 pg/mL in the BRVO group, and 49 pg/mL in the control group. In patients with CRVO and BRVO, the angiogenic balance was shifted towards angiogenic stimulation.

CONCLUSION

The severity of RVO from BRVO to CRVO correlates with an increase of VEGF and the decrease of VEGF(165b), indicating a pro-angiogenic shift. Altering the ratio of VEGF(165b)/VEGF(165) might be a feasible approach for treating retinal occlusive diseases.

Multifocal electroretinogram in retinal vein occlusion

PURPOSE

To determine the effects of retinal vein occlusion (RVO) on multifocal electroretinogram (MF-ERG) parameters, to correlate MF-ERG and standard electroretinogram (ERG) and to correlate MF-ERG with findings of optical coherence tomography (OCT) in cases of RVO.

METHODS

Both eyes of 50 patients with RVO and 50 eyes of 25 normal subjects were examined using MF-ERG, standard ERG, fluorescein angiography and OCT. The latency in millisecond (ms) and response density in nanovolt (nv/degenerations) were measured for each of four quadrant areas and central area. OCT was used to measure the foveal retinal thickness. Fluorescein angiography was used to measure retinal ischemia.

RESULTS

Central retinal vein occlusion (CRVO) markedly affected all parameters of MF-ERG. In pathological quadrants in branch retinal vein occlusion, the response densities of MF-ERG were decreased and latencies of p-wave were prolonged. The MF-ERG responses obtained from eyes with RVO were significantly different (P > 0.05) from derived from the fellow eyes. The amplitude of MF-ERG were abnormal in 40 eyes and implicit times were delayed in 48 eyes compared with normal subjects. While 30 Hz flicker implicit were abnormal in only 24 eyes with RVO. Implicit times were prolonged in eyes with macular ischemia than in eyes without ischemia. There were significant correlation between foveal retinal thickness measured by OCT and P response density MF-ERG in cases of retinal vein occlusion.

CONCLUSION

MF-ERG is more susceptible than standard ERG to eye changes of RVO due to the multiple frequencies of stimulation used to record MF-ERG response. MF-ERG could be sensitive indicator of underlying disease affecting the retinal in eyes with RVO. MF-ERG is useful for detecting local retinal dysfunction in patients with RVO and sensitive to morphological changes and functional disorders induced by RVO.

Visual prognosis and vitreous cytokine levels after arteriovenous sheathotomy in branch retinal vein occlusion associated with macular oedema

PURPOSE

To investigate the relationship between vitreous levels of cytokines, including interleukin-6 (IL-6) and vascular endothelial growth factor (VEGF), and visual prognosis after pars plana vitrectomy (PPV) with arteriovenous sheathotomy in patients with branch retinal vein occlusion (BRVO) associated with macular oedema.

METHODS

We studied 60 patients with logMAR visual acuity (VA) scores of < 0.3 and visual impairment secondary to BRVO-associated macular oedema. All patients underwent PPV with arteriovenous sheathotomy. At the time of PPV, vitreous samples were collected from the operated eye and vitreous levels of VEGF and IL-6 were measured. Best corrected VA (BCVA) (using a logMAR chart) and foveal thickness (FT) (using optical coherence tomography) were monitored for up to 6 months after PPV.

RESULTS

Both BCVA and FT significantly improved after PPV. According to multiple regression analysis, both the improvement in BCVA and decrease in FT were closely related to the vitreous level of IL-6 but not to that of VEGF. The vitreous level of VEGF was strongly correlated with duration of BRVO.

CONCLUSIONS

Both improvement in BCVA and decrease in FT were observed after PPV in BRVO patients with macular oedema. Interestingly, these visual prognoses strongly correlate with the vitreous level of IL-6, whereas the duration of BRVO strongly correlates with the vitreous level of VEGF.

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.

Multifocal electroretinography and fluorescein angiography in retinal vein occlusion

PURPOSE

To interpret the responses of multifocal electroretinography (mfERG) of the central macula in retinal vein occlusion and correlate them with findings of fluorescein angiography, optical coherence tomography (OCT), and visual acuity.

METHODS

In a prospective observational case series, 25 patients with branch or hemiretinal vein occlusion were examined by means of mfERG, fluorescein angiography, OCT, and visual acuity.

RESULTS

In eyes with macular ischemia shown by fluorescein angiography, the implicit time was significantly longer than that in eyes without macular ischemia (P = 0.006; Mann-Whitney test). The amplitudes in the first-order kernel responses in the ischemic eyes were more reduced (P = 0.04; Mann-Whitney test), and the amplitudes in the central macula correlated well with visual acuity (P = 0.006; Pearson correlation). There was no significant correlation between the degree of retinal thickening as measured by OCT and the mfERG responses, although there was a trend toward reduced amplitudes in the maculae with central retinal thickening (P = 0.08; Pearson correlation).

CONCLUSION

Macular ischemia as measured by fluorescein angiography correlates well with the prolonged implicit time on the first-order kernel response in mfERG, but no significant correlation was detected between the responses of mfERG and the OCT findings. Further investigations will demonstrate if this can be used as a prognostic instrument in the selection of patients, who will most likely benefit from future treatments.

Intravitreal levels of vascular endothelial growth factor and interleukin-6 are correlated with macular edema in branch retinal vein occlusion

BACKGROUND

To investigate whether vascular endothelial growth factor (VEGF) or interleukin-6 (IL-6) contributes to the pathogenesis of macular edema in eyes with branch retinal vein occlusion (BRVO), the correlations between these factors were investigated.

METHODS

We studied 25 patients suffering from macular edema with BRVO and 14 patients with nonischemic ocular disease (control group). The degree of retinal ischemia was evaluated in terms of the area of capillary nonperfusion using Scion Images, and the severity of macular edema was examined using optical coherence tomography. Vitreous fluid samples were obtained at the time of vitreoretinal surgery, and VEGF and IL-6 levels in the vitreous fluid and plasma were determined by means of enzyme-linked immunosorbent assays.

RESULTS

Vitreous fluid levels of VEGF and IL-6 were significantly elevated in patients with BRVO compared with control patients (P = 0.0011 and P < 0.0001, respectively). Also, the vitreous level of VEGF was significantly correlated with that of IL-6 (P = 0.0012), and vitreous levels of VEGF and IL-6 were correlated with the size of the BRVO nonperfusion area (P < 0.0001 and P = 0.0033, respectively). Furthermore, vitreous levels of VEGF and IL-6 were correlated with the severity of macular edema (P = 0.0008 and P = 0.0191, respectively) and the severity of macular edema of BRVO was significantly correlated with the size of the BRVO nonperfusion area (P=0.0044).

CONCLUSIONS

The levels of VEGF and IL-6 are increased in patients with macular edema with BRVO and are significantly correlated with the size of the nonperfusion area and the severity of macular edema. Therefore, they may play a role in macular edema with BRVO.

Pathogenesis of macular edema with branch retinal vein occlusion and intraocular levels of vascular endothelial growth factor and interleukin-6

PURPOSE

To determine whether correlations between vascular endothelial growth factor (VEGF) or interleukin-6 (IL-6) contribute to the pathogenesis of macular edema in eyes of patients with branch retinal vein occlusion (BRVO).

DESIGN

Retrospective case-control study.

METHODS

Nineteen patients with macular edema with BRVO and seven patients with non-ischemic ocular disease (control group) were studied. The degree of retinal ischemia was evaluated in terms of the area of capillary non-perfusion, and the severity of macular edema was examined by optical coherence tomography. Aqueous humor samples were obtained at the time of combined vitrectomy and cataract surgery, and VEGF and IL-6 levels in aqueous humor and plasma were determined by enzyme-linked immunosorbent assay.

RESULTS

Aqueous levels of VEGF (351 +/- 273 pg/ml) and IL-6 (7.10 +/- 6.51 pg/ml) were significantly elevated in patients with BRVO compared with the control patients (119 +/- 38.7 pg/ml and 2.27 +/- 1.11 pg/ml, respectively) (P = .0017 and P = .0052, respectively). Aqueous level of VEGF was significantly correlated with that of IL-6 (P = .0396), and aqueous levels of VEGF and IL-6 were correlated with the size of the BRVO non-perfused area (P < .0001 and P = .0331, respectively). Aqueous level of VEGF was correlated with the severity of macular edema (P = .0306).

CONCLUSIONS

VEGF and IL-6 may be involved in the pathogenesis of macular edema with BRVO. The increase in these cytokines might be used as a unique index of BRVO, through which we can determine the severity of the ischemic condition as being in a quiescent state or an exacerbation of macular edema.

Quantitative evaluation for blood-retinal barrier breakdown in experimental retinal vein occlusion produced by photodynamic thrombosis using a new photosensitizer

Purpose. To establish a rat model of retinal vein occlusion (RVO), we applied photodynamic thrombosis using a new photosensitizer. By measuring the breakdown of the blood-retinal barrier (BRB), we evaluated the model quantitatively. We also investigated how hypertension and retinal pigment epithelium (RPE) influence the breakdown of BRB after RVO. Methods. We modified a slit lamp biomicroscope for photodynamic thrombosis. The light source was changed from white light to argon laser, which made it possible to perform fluorescein angiography (FAG) simultaneously during photodynamic thrombosis. We irradiated with a continuous diode laser to occlude three retinal veins in a rat after PAD-S31 injection. The breakdown of BRB was quantitated by measuring extravasated Evans blue dye in albino and pigmented rats. We compared hypertensive rats (SHR) to normotensive rats (WKY) and sodium iodate-treated rats to normal rats. Results. High photosensitivity of PAD-S31 made it possible to occlude any retinal veins within 120 seconds at a low dose of 10 mg/kg without retinal thermal burn at the occlusion site. Simultaneous FAG enabled us to observe the formation of thrombus during diode laser irradiation. Our measured value of intraretinal Evans blue correlated with the range of serous retinal detachment. Both albino and pigmented rats demonstrated stable and constant values of Evans blue. SHR recovered from the breakdown of BRB after venous occlusion more slowly than WKY. Sodium iodate-treated rats had smaller breakdowns of BRB and recovered earlier than normal rats. Conclusions. In this study, we established the stable and constant rat model of RVO efficiently by using a new photosensitizer. Our simultaneous FAG method was considered to have an advantage of several potential clinical applications. Our rat model of RVO allows us to study factors associated with the recovery from damage by RVO.