***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Background : To compare the effectiveness of subthreshold grid laser treatment ( SGLT ) with infrared micropulse diode laser alone or in combination with intravitreal triamcinolone injection ( SGLT-IVTJ ) for the treatment of macular oedema ( MO ) secondary to branch retinal vein occlusion ( BRVO ) . Methods : Pilot r and omised clinical trial including 24 patients ( 24 eyes ) who were r and omised either to the SGLT ( 13 eyes ) or to SGLT-IVTJ ( 11 eyes ) . Complete ophthalmic examinations , including Early Treatment of Diabetic Retinopathy Study visual acuity , OCT and fluorescein angiography , were performed at the moment of the study entry and at 3-month intervals , with a planned follow-up of 12 months . Main outcome measures were the decrease in mean foveal thickness ( MFT ) on OCT , and the proportion of eyes that gained at least 10 letters ( approximately two or more lines of visual acuity gain ) at the 12-month examination . Secondary outcomes were the decrease in mean total macular volume on OCT , and the timing of MO resolution . Results : The change in MFT from the initial values was statistically significant for the SGLT-IVTJ from the 3-month examination and for the SGLP from the 6-month examination ( p<0.001 ) . At the 12-month evaluation , 10 patients of the SGLT-IVTJ group ( 91 % ) and eight of the SGLT group ( 62 % ) gained at least 10 letters ( two lines ) in visual acuity . The mean number of lines gained was 3.4 and 1.3 in the SGLT-IVTJ and in the SGLT group , respectively . Conclusions : The combined SGLT-IVT treatment of MO secondary to BRVO allows a significant visual acuity improvement , when compared with simple grid laser treatment The Branch Vein Occlusion Study is a multicenter , r and omized controlled clinical trial that was design ed to answer several questions regarding the management of complications of branch vein occlusion . Recently , this study reported the benefit of argon laser photocoagulation for improving visual acuity in certain eyes with macular edema , performing the laser photocoagulation in a " grid " pattern over the area demonstrated as leaking by fluorescein angiography . Comparing treated patients with control patients ( mean follow-up 3.1 years for all study eyes ) , a gain of at least two lines of visual acuity from baseline maintained for two consecutive visits was significantly greater in treated eyes ( P = 0.00049 log rank test ) . Because of this improvement in visual acuity with argon laser photocoagulation , the study recommends laser photocoagulation for patients with macular edema associated with branch vein occlusion who meet the eligibility criteria of the study The objective of this prospect i ve study was to ascertain whether scatter argon laser photocoagulation to the involved sector in major branch retinal vein occlusion and ischemic hemi central retinal vein occlusion ( a ) prevents development of retinal and /or optic disk neovascularization and vitreous hemorrhage , and ( b ) affects visual acuity , visual fields and macular retinal lesions . The study was done in 271 eyes allocated to either treated ( n = 61 eyes ) or untreated ( n = 210 ) groups . In this study , on an average follow-up of 3.6 years , the laser treatment ( 1 ) significantly reduced the risk of development of retinal neovascularization and vitreous hemorrhage , ( 2 ) did not affect the visual acuity and macular retinal lesions , and ( 3 ) produced a significant worsening in the peripheral visual fields compared to the untreated eyes . In view of our findings , we recommend that argon laser photocoagulation treatment should be given only when neovascularization is seen and not otherwise , because in the latter case , its detrimental effects may outweigh its beneficial ones Abstract · 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 aim ed to evaluate prospect ively 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 prospect ively studied during a 24-month period ; eyes were r and omly 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 PURPOSE The study was design ed to evaluate the relative anatomic position of the crossing vessels at the site of occlusion in eyes with branch retinal vein occlusion ( BRVO ) . METHODS Fundus photographs of 106 eyes ( 104 patients ) with recent BRVO from the Eye Disease Case-Control Study were used to examine the relative position of artery and vein at occluded crossings . Three separate comparison groups were formed by identifying corresponding arteriovenous crossings for each occluded crossing in : ( 1 ) the ipsilateral but opposite vessel arcade within eyes affected by BRVO ; ( 2 ) the same quadrant in unaffected eyes of BRVO patients ; and ( 3 ) the same quadrant in eyes of patients without BRVO , matched by age , sex , and race with the BRVO patients . RESULTS The site of obstruction of the branch vein was an arteriovenous crossing in all affected eyes . In 99 % of eyes with BRVO , the artery was located anterior to the vein at the obstructed site . In the three comparison groups , the artery was anterior to the vein in 62 % , 61 % , and 54 % of the crossings , respectively , yielding statistically significant differences for each group of control crossings compared with BRVO crossings ( P < 0.001 ) . CONCLUSION Finding the vein to be consistently between the more rigid artery and the retina at almost all arteriovenous crossings affected by BRVO suggests a possible role for mechanical obstruction in the pathogenesis of BRVO PURPOSE To assess efficacy and safety of intraocular injections of 0.3 mg or 0.5 mg ranibizumab in patients with macular edema following branch retinal vein occlusion ( BRVO ) . DESIGN Prospect i ve , r and omized , sham injection-controlled , double-masked , multicenter clinical trial . PARTICIPANTS A total of 397 patients with macular edema following BRVO . METHODS Eligible patients were r and omized 1:1:1 to receive monthly intraocular injections of 0.3 mg or 0.5 mg of ranibizumab or sham injections . MAIN OUTCOME MEASURES The primary efficacy outcome measure was mean change from baseline best-corrected visual acuity ( BCVA ) letter score at month 6 . Secondary outcomes included other parameters of visual function and central foveal thickness ( CFT ) . RESULTS Mean ( 95 % confidence interval [ CI ] ) change from baseline BCVA letter score at month 6 was 16.6 ( 14.7 - 18.5 ) and 18.3 ( 16.0 - 20.6 ) in the 0.3 mg and 0.5 mg ranibizumab groups and 7.3 ( 5.1 - 9.5 ) in the sham group ( P<0.0001 for each ranibizumab group vs sham ) . The percentage of patients who gained > or = 15 letters in BCVA at month 6 was 55.2 % ( 0.3 mg ) and 61.1 % ( 0.5 mg ) in the ranibizumab groups and 28.8 % in the sham group ( P<0.0001 for each ranibizumab group vs sham ) . At month 6 , significantly more ranibizumab-treated patients ( 0.3 mg , 67.9 % ; 0.5 mg , 64.9 % ) had BCVA of > or = 20/40 compared with sham patients ( 41.7 % ; P<0.0001 for each ranibizumab group vs sham ) ; and CFT had decreased by a mean of 337 microm ( 0.3 mg ) and 345 microm ( 0.5 mg ) in the ranibizumab groups and 158 microm in the sham group ( P<0.0001 for each ranibizumab group vs sham ) . The median percent reduction in excess foveal thickness at month 6 was 97.0 % and 97.6 % in 0.3 mg and 0.5 mg groups and 27.9 % in the sham group . More patients in the sham group ( 54.5 % ) received  rescue grid laser  compared with the 0.3 mg ( 18.7 % ) and 0.5 mg ( 19.8 % ) ranibizumab groups . The safety profile was consistent with previous phase III ranibizumab trials , and no new safety events were identified in patients with BRVO . CONCLUSIONS Intraocular injections of 0.3 mg or 0.5 mg ranibizumab provided rapid , effective treatment for macular edema following BRVO with low rates of ocular and nonocular safety events Purpose To evaluate long-term efficacy of intravitreal bevacizumab ( IVB ) versus combined IVB and macular grid laser photocoagulation for the treatment of macular edema secondary to branch retinal vein occlusion ( BRVO ) . Methods In this prospect i ve study , 18 eyes were r and omized into 2 groups according to treatment : Group 1 ( 9 eyes ) underwent IVB at baseline , at month 1 , and at month 2 ; Group 2 ( 9 eyes ) underwent same IVB protocol combined with macular grid laser photocoagulation .  Macular edema and visual acuity represented the endpoints of the study . IVB reinjections were performed in both groups if recurrent macular edema was diagnosed . Spectral domain optical coherence tomography examination as well as visual acuity examination were performed during follow-up . Statistical evaluation was performed for a matched-pair analysis . Results In Group 1 , median baseline central retinal thickness ( CRT ) decreased from 420 μm ( 95 % confidence interval 355.6 - 484.4 ) to 323 μm ( 261.44 - 384.56 ) at month 12 ( p=0.06 ) ; median baseline BCVA improved from 0.7 logMAR ( 0.54 - 0.86 ) to 0.4 logMAR ( 0.29 - 0.51 ) at month 12 ( p<0.01 ) . In Group 2 , baseline CRT decreased from 386 μm ( 353.91 - 418.09 ) to 238 μm ( 200.58 - 275.42 ) at month 12 ( p<0.01 ) ; median BCVA improved from 0.6 logMAR ( 0.45 - 0.75 ) to 0.2 logMAR ( 0.12 - 0.28 ) at month 12 ( p<0.01 ) . A statistically significant difference ( p=0.03 ) was found regarding the median number of injections ( Group 1 : 4±1.1 ; Group 2 : 3±0.4 ) . Conclusions Both treatment modalities appeared effective to control BRVO-induced macular edema . In the combined-treatment Group , we observed a lower number of reinjections during follow-up , suggesting the efficacy of grid laser photocoagulation to reduce the number of intravitreal injections and maintain short- and long-term results of the therapy PURPOSE To evaluate the outcome of cystoid macular edema ( CME ) treated with intravitreal injections of triamcinolone acetonide ( TA ) , macular laser grid photocoagulation ( MLG ) , or both ( TA+MLG ) . DESIGN Prospect i ve , r and omized , interventional , parallel , three-arm clinical trial . METHODS SETTING Institutional clinical study . PATIENTS Fifty-six patients ( 63 eyes ) affected by diabetic or retinal vein occlusion CME . PROCEDURES Twenty-two eyes received intravitreal injections of 4 mg TA ; 21 eyes underwent MLG ; and 20 eyes received intravitreal injection of 4 mg TA , and after 3 months , MLG . MAIN OUTCOME MEASURES Best-corrected visual acuity ( VA ) , central macular thickness ( CMT ) ( by optical coherence tomography ) , and postoperative complications . RESULTS Mean follow-up was 9 + /- 2 months ( range 6 to 12 months ) . Baseline VA ( logarithm of minimal angle of resolution [ logMAR ] ) and CMT were , respectively , 0.82 + /- 0.19 and 556 + /- 139 microm microns for the TA group , 0.8 
    Output:
    
There was insufficient evidence to support the use of early grid laser or subthreshold laser .
There was insufficient evidence to show a benefit of intravitreal triamcinolone or anti-vascular endothelial growth factor ( VEGF ) over macular grid laser photocoagulation in BRVO .