***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 
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    Input: BACKGROUND To compare the long-term effect of dalteparin in the prevention of neovascularization of iris in recent-onset central retinal vein occlusion with that of aspirin . METHODS A r and omized controlled clinical trial was conducted on patients with central retinal vein occlusion of less than 30 days duration . Patients in the dalteparin group received subcutaneous dalteparin 100 IU/kg twice a day for 10 days , and then 100 IU/kg once a day for another ten days . In the aspirin group the patients received 100 mg aspirin daily throughout the study . RESULTS Forty seven patients were enrolled , 24 in the dalteparin group and 23 in the aspirin group , and were followed up for one year . One ( 4.1 % ) of the 24 patients in dalteparin group , and 9 ( 39.1 % ) of 23 patients in aspirin group developed iris neovascularization . the difference was significant ( P=0.0001 ) . The visual outcomes of the two groups were compared , and a significant difference was found ( P=0.016 ) . CONCLUSION Patients treated with dalteparin within 30 days of the onset of central retinal vein occlusion were less likely to develop neovascularization of iris . There was also a significant difference in the visual acuity between two groups Forty patients with central retinal vein occlusion were allocated at r and om either to a treatment group given streptokinase followed by anticoagulatns or to a control group given no specific treatment . The two groups , which were each of 20 patients , were broadly similar in respect of clinical and laboratory values and similar in their initial visual acuity . At follow-up ( " final " vision ) the visual acuity in the treated group was significantly better than in the untreated group . Only one treated patient developed thrombotic glaucoma compared with four controls . Streptokinase may , however , have been responsible for vitreous haemorrhage ( and permanent loss of vision ) in three patients and hence probably has only a limited role in the treatment of central retinal vein occlusion INTRODUCTION Retinal vein occlusion ( RVO ) is a common cause of unilateral visual loss . Evidence based treatment recommendations for patients with RVO can not be made because of the lack of adequate clinical trials . To compare the efficacy and safety of aspirin and of a low molecular weight heparin , parnaparin , in the treatment of RVO . MATERIAL S AND METHODS In a multicenter , r and omized , double blind , controlled trial eligible patients with a delay between symptoms onset and objective diagnosis of less than 15 days were r and omized to aspirin 100 mg/day for 3 months or to a fixed daily dose of parnaparin , 12.800 IU for 7 days followed by 6.400 IU for a total of 3 months . Primary end-point of the study was the incidence of functional worsening of the eye with RVO at 6 months , as assessed by fluorescein angiography , visual acuity , and visual field . Study end-points were adjudicated by an independent committee . RESULTS Sixty-seven patients were enrolled in the study and 58 of them ( 28 treated with parnaparin , 30 with aspirin ) were evaluable for the analysis . Baseline characteristics were well balanced between groups . Functional worsening was adjudicated in 20.7 % of patients treated with parnaparin and in 59.4 % of patients treated with ASA ( p=0.002 ) . Recurrent RVO was diagnosed in 3 patients , all treated with ASA ( p = n.s . ) . Bleeding rates were similar between the two groups . CONCLUSIONS Parnaparin appears to be more effective than aspirin in preventing functional worsening in patients with RVO . The results of this study need to be confirmed in a larger clinical trial BACKGROUND Retinal vein occlusion is the second most common vascular disease of retina after diabetic retinopathy , affecting 1.6 % of the population above the age of 40 . The aim of this study was to compare the effect of dalteparin and aspirin in patients with recent-onset branch retinal vein occlusion . METHODS A r and omized clinical trial was conducted on patients with branch retinal vein occlusion of less than 30 days ' duration . Ophthalmic , systemic , and hematologic evaluations were made . Visual acuity was measured with Early Treatment Diabetic Retinopathy Study chart . Patients in the dalteparin group received subcutaneous dalteparin 100 IU/kg twice daily for 10 days , then 100 IU/kg once daily for another 10 days while the patients in the aspirin group were given aspirin 100 mg daily throughout the study . RESULTS Seventy-eight patients were enrolled , 37 in the dalteparin and 41 in the aspirin group . The patients were followed for six months . The visual outcomes of the two groups were compared . Although dalteparin improved mean visual acuity slightly more than aspirin , no statistically significant differences were found between the groups at one ( P=0.37 ) , two ( P=0.16 ) , three ( P=0.11 ) , or six ( P=0.13 ) months . Resolution of macular edema and development of new vessels made no statistically significant difference between the groups [ ( P=0.08 ) and ( P=0.49 ) , respectively ] . CONCLUSION In recent-onset branch retinal vein occlusion , no significant difference was found in the final visual acuity between the patients treated by dalteparin or aspirin . A further study with larger sample size is recommended PURPOSE To investigate systemic diseases associated with various types of retinal vein occlusion . METHODS We investigated prospect ively in 1090 consecutive patients with retinal vein occlusion , almost all Caucasian ( consistent with the racial pattern here ) , the prevalence of associated systemic disorders before or at the onset of various types of retinal vein occlusion . The patients were categorized into six types of retinal vein occlusion based on defined criteria : nonischemic and ischemic central retinal vein occlusion , nonischemic and ischemic hemi- central retinal vein occlusion , and major and macular branch retinal vein occlusion . The patients had a detailed ophthalmic and systemic evaluation according to our protocol . For data analysis , patients were divided into three age groups : young ( younger than 45 years ) , middle-aged ( 45 to 64 years ) , and elderly ( 65 years or older ) . The observed prevalence rates of major systemic diseases were compared among central retinal vein occlusion , hemi- central retinal vein occlusion , and branch retinal vein occlusion using a polytomous logistic regression analysis adjusting for gender and age . Logistic regression adjusting for age and gender was also used to compare the observed prevalence of systemic disease between nonischemic and ischemic in central retinal vein occlusion and hemi- central retinal vein occlusion and between major and macular branch retinal vein occlusion . These observed prevalence rates were also compared with those expected in a gender-matched and age-matched control population from estimates from the US National Center for Health Statistics . RESULTS There was a significantly higher prevalence of arterial hypertension in branch retinal vein occlusion compared with central retinal vein occlusion ( P < .0001 ) and hemi- central retinal vein occlusion ( P = .028 ) . Branch retinal vein occlusion also had a significantly higher prevalence of peripheral vascular disease ( P = .0002 ) , venous disease ( P = .011 ) , peptic ulcer ( P = .031 ) , and other gastrointestinal disease ( P < .0001 ) compared with central retinal vein occlusion . The proportion of patients with branch retinal vein occlusion with cerebrovascular disease was also significantly ( P = .049 ) greater than that of the combined group of patients with central retinal vein occlusion and patients with hemi- central retinal vein occlusion . There was no significant difference in prevalence of any systemic disease between central retinal vein occlusion and hemi- central retinal vein occlusion . A significantly greater prevalence of arterial hypertension ( P = .025 ) and diabetes mellitus ( P = .011 ) was present in the ischemic central retinal vein occlusion compared with the nonischemic central retinal vein occlusion . Similarly , arterial hypertension ( P = .0002 ) and ischemic heart disease ( P = .048 ) were more prevalent in major branch retinal vein occlusion than in macular branch retinal vein occlusion . Relative to the US white control population , the combined group of patients with central retinal vein occlusion and patients with hemi- central retinal vein occlusion had a higher prevalence of arterial hypertension ( P < .0001 ) , peptic ulcer ( P < .0001 ) , diabetes mellitus ( in ischemic type only , P < .0001 ) , and thyroid disorder ( P < .0001 ) . The patients with branch retinal vein occlusion showed a greater prevalence of arterial hypertension ( P < or = .005 ) , cerebrovascular disease ( P = .007 ) , chronic obstructive pulmonary disease ( P = .012 ) , peptic ulcer ( P < .0001 ) , diabetes ( in young only , P = .0005 ) , and thyroid disorder ( P = .003 ) compared with the US white control population . CONCLUSIONS The findings of our study revealed that a variety of systemic disorders may be present in association with different types of retinal vein occlusion and in different age groups , and that their relative prevalence differs significantly , so that the common practice of generalizing about these disorders for the entire group of patients with retinal vein occlusion can be misleading . The presence of a particular associated systemic disease does not necessarily imply a cause- and -effect relationship with that type of retinal vein occlusion ; the particular disease may or may not be one of the risk factors in a multifactorial scenario predisposing an eye to develop a particular type of retinal vein occlusion . Based on our study , we think that apart from a routine medical evaluation , an extensive and expensive workup for systemic diseases is unwarranted in the vast majority of patients with retinal vein occlusion BACKGROUND The present study assessed the therapeutic effects of dalteparin in patients who had recent onset central retinal vein occlusion ( CRVO ) as compared with those of acetylsalicylic acid ( ASA ) . METHODS Patients with recent onset of CRVO were r and omly assigned to receive dalteparin subcutaneously every day for 20 days or ASA daily for the same period . Complete ophthalmic examinations were conducted at baseline and at each follow-up interval : 1 week and 1 , 2 , 3 , 4 , and 6 months later . Best-corrected visual acuity was assessed by an investigator blind to the treatment group . RESULTS The mean 6-month change in logMAR visual acuity for dalteparin-treated patients was an increase of 5.5 letters ( Early Treatment Diabetic Retinopathy Study chart ) ( -0.11 [ SD 0.71 ] logMAR ) and for ASA-treated patients was a decrease of 14 letters ( + 0.28 [ SD 0.79 ] logMAR ) , representing a significant difference between the 2 groups ( p = 0.016 ) . One patient in the dalteparin group and 14 in the ASA group showed iris neovascularization ( NVI ) ( 2.1 % vs. 30.4 % , p = 0.0001 ) . INTERPRETATION Dalteparin was found to be superior to ASA in terms of improving visual acuity and preventing NVI over the first 6 months of treatment . Similar studies are recommended of other newer types of anticoagulants , especially those that could be used orally Purpose : To investigate the efficacy of intravenous thrombolysis with low-dose recombinant tissue plasminogen activator ( rt-PA ) in recent-onset central retinal vein occlusion ( CRVO ) or branch retinal vein occlusion . Methods : This was a prospect i ve , r and omized , controlled multicenter trial in patients with CRVO or branch retinal vein occlusion , best-corrected visual acuity ≤20/50 , and onset of symptoms within 11 days before treatment . In each group , patients were r and omized to either hemodilution or thrombolysis with 50 mg of rt-PA with concomitant intravenous heparinization . The primary clinical outcome measure was improvement in best-corrected visual acuity from baseline at 1 year . Results : Fifty-two subjects were enrolled in the study . Patients with CRVO ( n = 41 ) who were treated with rt-PA exhibited a significant improvement in best-corrected visual acuity compared with those who received hemodilution ( P < 0.0001 ) . At 1-year follow-up , the proportion of eyes with CRVO achieving an improvement in visual acuity of three or more lines was 45 % after treatment with rt-PA and 21 % after hemodilution therapy . The median final best-corrected visual acuity among CRVO patients given rt-PA was 20/60 ( light perception , 20/15 ) compared with 20/400 ( light perception , 20/20 ) in the hemodilution group . There were no significant differences among patients with branch retinal vein occlusion ( n = 11 ) . We observed no serious adverse events . No significant differences were found regarding the development of ocular ne 
    Output:
    
The present systematic review suggests that antithrombotic therapy , in particular LMWH , may be part of the therapeutic armamentarium for patients with recent onset RVO .