Grid laser treatment in macular branch retinal vein occlusion

· Background: Macular branch retinal vein occlusion (MBRVO) is a subgroup of branch retinal vein occlusion in which the occlusion is limited to a small venous vessel draining a sector of the macular region. The present study aimed to evaluate prospectively whether grid laser treatment is useful in improving the visual acuity of eyes affected by MBRVO with significant macular edema. · Methods: Ninety-nine patients affected by MBRVO of recent onset were prospectively studied during a 24-month period; eyes were randomly assigned to the control group, the early grid laser treatment group or the delayed grid laser treatment group. Clinical and angiographic features were recorded during the whole follow-up; parameters such as visual acuity and macular edema were carefully evaluated, the latter even by means of stereophotography. · Results: With respect to the baseline mean visual acuity values, a statistically significant improvement was noted at the 3-month follow-up and at the 1-year follow-up . No additional improvement was noted at the 2-year follow-up. No statistically significant difference was found between the treated groups and the control group. · Conclusions: We hypothesize that the abrupt ischemic damage subsequent to MBRVO is the main factor causing the central function impairment. Grid laser treatment is not able to reduce the macular edema more than the natural evolution, and does not improve visual acuity. Received: 25 May 1999 Revised version received: 6 September 1999 Accepted: 14 September 1999     

Retinal branch vein occlusion

Obstruction of a major temporal branch vein, or one of its macular tributaries, presents a significant threat to vision. Visual acuity may be reduced by macular edema or the consequences of retinal neovascularization, and these afflictions frequently become irreversible. Since the complicating macular edema and retinal neovascularization respond, at least in part, to argon laser therapy in some other conditions, some investigators have begun to treat branch vein occlusions with this modality. However, since the pathogenesis and natural history of the disorder have not yet been elucidated by prospective studies, it is not clear whether such treatment is indicated. Clinical and experimental studies are reviewed, and treatment rationale and techniques are discussed. The authors emphasize the need for well-controlled randomized studies to evaluate the natural history of branch vein occlusion and the efficacy of photocoagulation in its treatment.     

The treatment of acute branch vein occlusion by photocoagulation

Twenty-eight eyes with retinal branch vein occlusion were treated by photocoagulation. The clinical posttreatment findings indicated rapid clearing of hemorrhages and exudates. Visual acuity in 12 (43%) eyes improved, in 11 (39%) remained static, and in five (18%) worsened.     

氩激光治疗缺血型视网膜分支静脉阻塞

目的探讨氩激光治疗缺血性视网膜分支静脉阻塞的临床疗效。方法应用美国科以人公司氩激光对经荧光素眼底血管造影（FFA）检查确诊的86例（86只眼）缺血型视网膜分支静脉阻塞进行光凝治疗,3个月后复查FFA。结果86例（86只眼）经视网膜光凝后,视网膜出血Ⅱ度以上吸收73只眼（84．88％）,Ⅳ度吸收10只眼（11．63％）,不变或加重3只眼（3．49％）;黄斑水肿吸收76只眼,占88．37％,不变10只眼,占11．63％;视力增加者69只眼（80．23％）,不变14只眼（16．27％）,下降3只眼（3．49％）。FFA复查渗漏及毛细血管无灌注区消失77只眼（89．53％）。结论视网膜激光光凝治疗能减少缺血型视网膜静脉阻塞引起的新生血管,并能促使黄斑水肿消退,从而不同程度地改善视功能。     

Bilateral branch vein occlusion.

Bilateral branch retinal vein occlusion is a relatively rare occurrence. We report 4 patients who presented with bilateral branch retinal vein occlusion and in each of these cases the fellow eyes were involved within 6 months of the initial episode. The patients were relatively young and all of them had associated essential hypertension. The patients maintained a relatively good visual acuity through a 6-months to 1-year follow-up. This report highlights this rare entity, the associated risk factors and visual prognosis.     

Experimental retinal branch vein occlusion

Experimental retinal branch vein occlusion in monkeys (macaca irus) were produced by yellow wavelength (577nm) dye laser photocoagulation. The clinical sequence was observed in terms of the structural and ultrastructural findings occurring during the natural history of experimental branch vein occlusion, particularly in the early stage. Immediately after the occlusion, venous dilatation and retinal edema and hemorrhage appeared. Extravascular leakage of dye in fluorescein angiography and hemorrhage appeared from small venules at an early stage. Leakage from the larger vessels was observed later. Opening of the intercellular junctional complexes, which signifies breakdown of the blood-retinal barrier was detected by electron microscopy. Subsequently degenerative or necrotic changes in endothelial cells appeared with the formation of intravascular thrombi and extravascular leakage of blood components appeared from these vessels.     

视网膜分支静脉阻塞合并黄斑水肿不同治疗方法的疗效观察

目的　通过对视网膜分支静脉阻塞（ｂｒａｎｃｈｒｅｔｉｎａｌｖｅｉｎｏｃｃｌｕｓｉｏｎ,ＢＲＶＯ）在不同时期进行光凝及光凝联合玻璃体内注射曲安奈德治疗进行比较,探索治疗ＢＲＶＯ合并黄斑水肿更为有效的方法。方法　７５例ＢＲＶＯ患者纳入研究,均为单眼。将所有患者分为５组,Ａ组１４例、病程为３～６个月,Ｂ组１６例、病程＜３个月,以上两组入选后即行黄斑区局部格栅样光凝及颞上象限局部光凝治疗,Ｃ、Ｄ、Ｅ组均为入选后即行玻璃体内注射曲安奈德４ｍｇ,注射后光凝时间分别为２周、４周、６周,每组１５例。对比观察５组治疗前后最佳矫正视力（ｂｅｓｔｃｏｒｒｅｃｔｅｄｖｉｓｕａｌａｃｕｉｔｙ,ＢＣＶＡ）、光学相干断层扫描（ｏｐｔｉｃａｌｃｏｈｅｒｅｎｃｅｔｏｍｏｇｒａｐｈｙ, ＯＣＴ）、多焦视网膜电图（ｍｕｌｔｉｆｏｃａｌｅｌｅｃｔｒｏｒｅｔｉｎｏｇｒａｍ,ｍｆＥＲＧ）结果。结果　ＢＣＶＡ:５组中以Ｃ组ＢＣＶＡ改善最为显著,优于Ａ、Ｂ、Ｄ、Ｅ组（均为Ｐ＜０．０５）。ＯＣＴ结果:Ｃ组最终黄斑中心凹厚度与Ａ、Ｂ、Ｄ、Ｅ组相比,差异均有统计学意义（均为Ｐ＜０．０５）,Ｄ、Ｅ组均明显低于Ａ、Ｂ组（均为Ｐ＜０．０５）。ｍｆＥＲＧ结果:Ｃ、Ｄ、Ｅ各组黄斑区（即１、２环）Ｐ１、Ｎ１波振幅密度分别与Ａ、Ｂ组比较明显增加,差异均有统计学意义（均为Ｐ＜０．０５）。结论　玻璃体内注射曲安奈德联合光凝治疗ＢＲＶＯ效果优于单纯激光治疗,玻璃体内注射曲安奈德２周后行激光光凝治疗效果最佳。     

视网膜分枝静脉阻塞的激光治疗时机选择

目的：分析视网膜分枝静脉阻塞不同发病阶段的激光治疗疗效，为临床治疗时机选择提供依据。方法：按发病时间将患者分为病程短于3个月但长于1个月的A组(20例)及病程大于3个月的B组(29例)，两组采用象限联合后极部格栅样光凝法。记录两组的阻塞部位、激光前后视力、眼部新生血管、黄斑病变的转归及光凝次数和光斑点数。结果：两组在静脉阻塞部位分布、激光次数和光凝点数方面均无显著差异；光凝后两组视力均得到提高，B组基础视力较A组好约1行；B组光凝前眼底新生血管总发病率为51．7％，A组为0；光凝后B组新生血管消退率为80％；光凝后A组和B组黄斑水肿的好转率分别为80％和91．7％。两组均未见明显的并发症。结论：在能保证随访的情况下优先对患者观察，如眼底出现新生血管或出血淡化则予以光凝；如随访不便，在病程1～3个月之间光凝同样是有利和安全的。     

Peripheral retinal non-perfusion and treatment response in branch retinal vein occlusion

AIM: To evaluate the association between the size of peripheral retinal non-perfusion and the number of intravitreal ranibizumab injections in patients with treatment-naive branch retinal vein occlusion (BRVO) and macular edema. METHODS: A total of 53 patients with treatment-naive BRVO and macular edema were included. Each patient underwent a full ophthalmologic examination including optical coherence tomography (OCT) imaging and ultra wide-field fluorescein angiography (UWFA). Monthly intravitreal ranibizumab injections were applied according to the recommendations of the German Ophthalmological Society. Two independent, masked graders quantified the areas of peripheral retinal non-perfusion. RESULTS: Intravitreal injections improved best-corrected visual acuity (BCVA) significantly from 22.23±16.33 Early Treatment of Diabetic Retinopathy Study (ETDRS) letters to 36.23±15.19 letters (P<0.001), and mean central subfield thickness significantly reduced from 387±115 µm to 321±115 µm (P=0.01). Mean number of intravitreal ranibizumab injections was 3.61±1.56. The size of retinal non-perfusion correlated significantly with the number of intravitreal ranibizumab injections (R=0.724, P<0.001). CONCLUSION: Peripheral retinal non-perfusion in patients with BRVO associates significantly with intravitreal ranibizumab injections in patients with BRVO and macular edema.     

Collateral vessels in branch retinal vein occlusion

Experiments show that collaterals that develop and maturate in branch retinal vein occlusion (BRVO) are helpful in the drainage of blood from a blocked area to an adjacent area. Laser treatment on the nonperfusion area can reduce the retinal blood inflow that can impair the formation of collateral vessels. Furthermore, if collaterals were accidentally destroyed by laser photocoagulation, leakage and neovascularization would increase. Forty-five patients with BRVO were reviewed retrospectively. Collateral vessels were noted from angiographic analysis in 27 of 45 (60%) patients. Good visual prognosis was noted in the patients with collaterals. Cases with neovascularization underwent laser treatment. In one case, laser photocoagulation was applied to the collateral vessels accidentally, after which the leakage significantly increased on fluorescein angiography. In conclusion, collateral vessels in BRVO have a favorable effect on visual prognosis. Careful laser treatment is recommended to avoid destroying collaterals in BRVO.     

Pericyte changes in branch retinal vein occlusion

The model of experimental branch vein occlusion (BVO) in the monkey offers the opportunity to examine retinal capillaries under stress. Electron microscopic morphometry was done on 812 capillaries of 13 eyes of cynomolgus monkeys, comparing 579 capillary collaterals of 9 BVO eyes with 233 normal capillaries of 4 control eyes. The tissue underwent the myosin subfragment-1 technique to decorate and quantify bundles of actin filaments in capillary pericytes. The duration of BVO was 2-48 months. Capillary collaterals of BVO eyes had an enlarged caliber, endothelial hyperplasia, and pericyte hypertrophy, but no proportional increase in basement membrane area. Collaterals near the inner plexiform layer (IPL) had a greater wall thickness, pericyte coverage, and actin coverage than collaterals near the outer plexiform layer (OPL). Pericyte hypertrophy was proportionate to caliber increase in OPL vessels and exceeded caliber increase only in IPL vessels. Actin coverage was proportional with the vessel dilation and size of pericyte cytoplasm in all vessels. These findings indicate that capillary collaterals in BVO are not equipped morphologically for an increased regulatory role in microvascular flow beyond their normal function.     

Multifocal electroretinogram in branch retinal vein occlusion

PURPOSE: To describe the response from multifocal electroretinography in branch retinal vein occlusion. DESIGN: Prospective observational case control series. METHODS: Multifocal electroretinography was recorded in 15 patients with temporal branch retinal vein occlusion and 21 control subjects using a visual evoked response imaging system. RESULTS: There were significant differences in mean amplitude (P =.01) and latency (P =.001) between thrombotic and nonthrombotic retina in the same eyes, as well as in patients compared with control subjects. CONCLUSION: Responses from multifocal electroretinography demonstrate retinal dysfunction in branch retinal vein occlusion; additional studies will demonstrate whether multifocal electroretinography has a prognostic value.     

Axial length in branch retinal vein occlusion

To determine the effects of axial length on the development of branch retinal vein occlusion (BRVO), determination of the affected eye, development of surgical complications, and visual prognosis, axial length was measured in 27 eyes each in surgical, non-surgical and control group and in 54 eyes each in occlusion (surgical + non-surgical group), non-affected eye (non-affected eyes of occlusion group), and non-occlusion group (both eyes of the control group). The average axial length was 22.61 mm in surgical, 22.48 mm in non-surgical, 23.09 mm in control, 22.55 mm in occlusion, 22.56 mm in non-affected eye, and 23.11 mm in non-occlusion group. The axial length showed a statistically significant difference between surgical and control group (p = 0.018), between non-surgical and control group (p = 0.002), and between occlusion and non-occlusion group (p < 0.001); however, no statistically significant difference was seen between surgical and non-surgical group, between non-affected eyes of surgical and non-surgical group, and between occlusion and non-affected eye group. Also, in such as BRVO groups as surgical, non-surgical, and occlusion groups, no correlation was present between axial length and degree of visual acuity recovery and final visual acuity. Although the possibility of developing BRVO is higher in those with short axial length, the axial length may have no relationship with the determination of the affected eye, visual prognosis and development of surgical complications.