Intravitreal injections during COVID-19 outbreak: Real-world experience from an Italian tertiary referral center.

We report our experience during COVID-19 outbreak for intravitreal injections in patients with maculopathy. We proposed a treatment priority levels and timings; the "High" priority level includes all monocular patients; the "Moderate" is assigned to all patients with an active macular neovascularization; the patients affected by diabetic macular edema or retinal vein occlusion belong to the "Low" class. This organization allowed us to treat the most urgent patients although the injections performed had a 91.7% drop compared to the same period of 2019.

Use of Anti-VEGF Drugs in Retinal Vein Occlusions.

Retinal vein occlusion (RVO) is one of the most prevalent causes of visual loss in the Western World. Its pathogenesis is still not completely known. Chronic macular edema and ischemia compromise the functional and anatomical status of the retina. Antivascular endothelial growth factor (anti-VEGF) injections have demonstrated better results than other previous options, including observation or laser therapy. This narrative review aims to analyze the current aspects related to these drugs.

Measuring the precise area of peripheral retinal non-perfusion using ultra-widefield imaging and its correlation with the ischaemic index.

OBJECTIVE: To determine the calculated, anatomically correct, area of retinal non-perfusion and total area of visible retina on ultra-widefield fluorescein angiography (UWF FA) in retinal vein occlusion (RVO) and to compare the corrected measures of non-perfusion with the ischaemic index. METHODS: Uncorrected UWF FA images from 32 patients with RVO were graded manually for capillary non-perfusion, which was calculated as a percentage of the total visible retina (uncorrected ischaemic index). The annotated images were converted using novel stereographic projection software to calculate precise areas of non-perfusion in mm(2), which was compared as a percentage of the total area of visible retina ('corrected non-perfusion percentage') with the ischaemic index. RESULTS: The precise areas of peripheral non-perfusion ranged from 0 mm(2) to 365.4 mm(2) (mean 95.1 mm(2)), while the mean total visible retinal area was 697.0 mm(2). The mean corrected non-perfusion percentage was similar to the uncorrected ischaemic index (13.5% vs 14.8%, p=0.239). The corrected non-perfusion percentage correlated with uncorrected ischaemic index (R=0.978, p<0.001), but the difference in non-perfusion percentage between corrected and uncorrected metrics was as high as 14.8%. CONCLUSIONS: Using stereographic projection software, lesion areas on UWF images can be calculated in anatomically correct physical units (mm(2)). Eyes with RVO show large areas of peripheral retinal non-perfusion.

Reliability of Ischemic Index Grading in Common Retinal Vascular Diseases.

BACKGROUND AND OBJECTIVE: Retinal nonperfusion is closely associated with vision-threatening complications such as neovascularization and macular edema. The purpose of this study is to investigate the reliability of a calculated ischemic index (ISI) by means of intergrader and intragrader agreement on ultrawide-field fluorescein angiography (UWFFA) in common retinal vascular diseases. PATIENTS AND METHODS: Eight trained graders evaluated 15 UWFFA images provided digitally and re-graded on a different day. They included five eyes with diabetic retinopathy (DR), five with branch retinal vein occlusion (BRVO), and five with central retinal vein occlusion (CRVO). To assess intergrader and intragrader agreement and variability among different diseases, the replicate inter- and intragrader standard deviations (SDs) and coefficients of variation (CVs) were calculated. RESULTS: Mean ISI was 46% for images of DR, 26% for images of BRVO, and 61.3% for images of CRVO. Combined intragrader and intergrader replicate SDs were 17.8% for DR, 3.8% for BRVO and 13.0% for CRVO. Combined intragrader and intergrader replicate coefficients of variation were 38.6% (percent of mean ISI) for DR, 14.7% for BRVO, and 21.2% for CRVO. CONCLUSION: Intergrader and intragrader variability was high when assessing DR. This may be due to the chronic nature of DR progression, which can lead to patchy areas of ischemia. Intergrader and intragrader variability was better for CRVO and best for BRVO. This may be due to the acute or subacute nature of retinal vein occlusions.

Fundus changes in branch retinal vein occlusion.

PURPOSE: To investigate systematically the retinal changes in branch retinal vein occlusion (BRVO) and their natural history. METHODS: The study comprised 214 consecutive patients with BRVO (144 major BRVO and 72 macular BRVO eyes) seen within 3 months of onset. Ophthalmic evaluation at initial and follow-up visits included recording visual acuity, visual fields, and detailed anterior segment and fundus examinations and fluorescein fundus angiography. RESULTS: Initially, retinal hemorrhages were moderate to severe in the perifovea and macula in at least 65% in major and 52% in macular BRVO; at the fovea, it was 51% in major and 36% in macular BRVO. Initially, macular edema was more marked in major BRVO than in macular BRVO (P = 0.007). Major BRVO had a significantly higher rate of development of serous macular detachment (P = 0.002), epiretinal membrane (P = 0.008), serous retinal detachment (P = 0.002), perivenous sheathing (P < 0.0001), optic disk pallor (P < 0.0001), and lipid deposit (P < 0.0001) compared with macular BRVO. Retinal and disk neovascularization was seen only in major BRVO. The time to resolution of BRVO was significantly longer for major BRVO compared with macular BRVO (P = 0.0002). CONCLUSION: Major and macular BRVOs are two distinct clinical entities. Initial and final fundus findings in the two types differ markedly.

Intravitreal bevacizumab in acute central/hemicentral retinal vein occlusions: three-year results of a prospective clinical study.

PURPOSE: To prospectively evaluate the effects of intravitreal bevacizumab (IVB, Avastin; Genentech, Inc., San Francisco, CA) injections in patients with acute central/hemicentral retinal vein occlusions (C/HCRVOs) (≤1 month after the occlusion was diagnosed) over the course of 3 years. METHODS: The study included 57 patients with unilateral acute C/HCRVOs. Initially, the treatment for acute C/HCRVO patients consisted of 4 consecutive IVB injections administered off-label at a dose of 2.5 mg per injection, with each injection spaced ∼45 days apart. Thereafter, IVB therapy was flexible, and subsequent injections were administered during scheduled visits whenever a best corrected visual acuity (BCVA) loss of ≥5 Early Treatment Diabetic Retinopathy Study (ETDRS) letters occurred and/or iris/angle neovascularization appeared (regardless of the intraocular pressure level). Changes in the BCVA and foveal thickness (FT), number of IVB injections administered, and incidence of neovascular glaucoma (NVG) were estimated. RESULTS: The increase in the BCVA score at month 36 was 17.15 (ETDRS letters) (P<0.0001) in cases of nonischemic and 26.81 (ETDRS letters) (P<0.01) in cases of ischemic occlusions. At the end of the follow-up, the proportion of BCVA score improvements greater than 15 ETDRS letters was similar in patients with both forms of occlusions (measured in 45.5% of nonischemic and 45.8% of ischemic patients) (P=0.977). There were significant reductions in FT from baseline values to 230±40.50 µm (P=0.0001) in patients with nonischemic occlusions and 270±40.50 µm (P=0.0001) in patients with ischemic forms. There was a significant difference (P<0.03) in the number of IVB injections administered in patients with nonischemic C/HCRVOs (8.7±1.58) compared to patients with ischemic occlusions (9.7±1.78). NVG occurred in 2 cases of ischemic occlusions. CONCLUSIONS: The 3-year IVB therapy provided sustained vision and FT gains in most phakic patients with acute C/HCRVOs, making this treatment option a rational and viable therapeutic strategy. Bevacizumab was more effective in patients with ischemic occlusions who required a significantly higher number of injections.

Baseline characteristics and response to treatment of participants with hemiretinal compared with branch retinal or central retinal vein occlusion in the standard care vs corticosteroid for retinal vein occlusion (SCORE) study: SCORE study report 14.

OBJECTIVE: To compare baseline characteristics and treatment response of participants with hemiretinal vein occlusion (HRVO) with those of participants with branch retinal vein occlusion (BRVO) or central retinal vein occlusion (CRVO) in the Standard Care vs COrticosteroid for REtinal Vein Occlusion (SCORE) Study. METHODS: Eyes were randomized to standard care, 1 mg intravitreal triamcinolone acetonide, or 4 mg intravitreal triamcinolone acetonide. Standard care was observation in the SCORE-CRVO trial and grid photocoagulation in the SCORE-BRVO trial. The HRVO eyes were enrolled in the SCORE-BRVO trial. Baseline characteristics, changes in visual acuity and center point thickness, safety outcomes, and number of treatments were compared among HRVO, BRVO, and CRVO participants. RESULTS: At baseline, HRVO eyes were intermediate between BRVO and CRVO eyes in area of retinal thickening, area of fluorescein leakage, visual acuity, and center point thickness. No differences in visual acuity change from baseline to 1 year were noted between standard care groups for HRVO and BRVO. Within triamcinolone-treated eyes, HRVO eyes did not differ from BRVO eyes in visual acuity change, but HRVO eyes fared better than CRVO eyes. There were no differences in center point thickness change between standard care groups for HRVO and BRVO, nor were there differences across the 3 disease entities for triamcinolone-treated eyes. There were no differences in frequency of protocol treatments and adverse events. CONCLUSIONS: The HRVO participants were similar to BRVO and CRVO participants regarding most demographic characteristics, with fundus findings intermediate between BRVO and CRVO. In the SCORE Study, HRVO was treated as BRVO; HRVO eyes responded to treatment similarly to BRVO eyes, and there was no difference among the 3 disease entities in frequency of protocol treatments and adverse events. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00105027.

Retinal vein occlusion and the optic disk.

PURPOSE: To investigate the effect of cup to disk (C/D) ratio in various types of retinal vein occlusion (RVO) on the severity of retinopathy, visual outcome, and resolution of retinopathy and validity of the concept of the "compartment syndrome" in RVO. METHODS: The study comprised 1,222 consecutive eyes (768 central retinal vein occlusion [CRVO], 183 hemi-CRVO, and 271 branch retinal vein occlusion). Ophthalmic evaluation at initial and follow-up visits included recording visual acuity, visual fields, and detailed anterior segment and fundus examinations and fluorescein fundus angiography. RESULTS: Compared to sex-matched and age-matched normal eyes, C/D ratio ≥0.5 was significantly more common in all CRVOs and hemi-CRVO eyes but not in branch retinal vein occlusion. Retinal hemorrhages were significantly more severe in nonischemic CRVO with C/D ratio ≥0.5 compared to those with no or small cup, but no difference was found in hemi-CRVO and branch RVO. In ischemic CRVO, moderate hemorrhages were more with C/D ≥0.5 but severe hemorrhages were more with no cup. In various types of RVO, there was no significant association of C/D ratio with macular edema, retinopathy resolution, visual acuity, and visual field defect. CONCLUSION: The findings of our study contradict the concept that the "compartment syndrome" plays any role in the prevalence of various types of RVO or in their severity, the resolution of retinopathy, or the visual outcome. This indicates that the advocated procedure of radial optic neurotomy, based on the compartment syndrome, is not a logical treatment for CRVO.

Hemicentral retinal vein occlusion: natural history of visual outcome.

PURPOSE: To investigate the natural history of visual outcome in hemicentral retinal vein occlusion (HCRVO). METHODS: The study comprised 65 consecutive HCRVO patients (67 eyes) seen within 3 months of onset. At first visit, all patients had a detailed ophthalmic and medical history and comprehensive ophthalmic evaluation. Ophthalmic evaluation at initial and follow-up visits included recording visual acuity using the Snellen visual acuity chart, and visual fields with a Goldmann perimeter. Hemicentral retinal vein occlusion was classified into nonischemic (57 eyes) and ischemic (10 eyes) at initial visit. RESULTS: Nonischemic HCRVO involved superior and inferior half of the retina in 39% and 56%, respectively, and in ischemic HCRVO in 50% and 40%, respectively. In nonischemic HCRVO, initial visual acuity was 20/60 or better in 73.7% and minimal to mild visual field loss in 96% and in ischemic HCRVO in 40% and 55.5%, respectively. After resolution of macular edema, in nonischemic HCRVO eyes, cumulative chance of improvement was 50% with 20/70 or worse initial visual acuity, and deterioration in only 6% with 20/60 or better initial visual acuity, and in 5% with minimal to mild visual initial field loss. CONCLUSION: This study suggests a good prognosis in the natural history of visual outcome in nonischemic HCRVO.

[From scientific evidence to clinical practice: treatment regimens for macular edema secondary to retinal vein occlusion]. / De la evidencia cientifica a la practica clinica: pautas de tratamiento del edema macular secundario a oclusion venosa retiniana.

Retinal vein occlusion (RVO) is the second most common cause of retinal vascular disease after diabetic retinopathy. Despite the existence of several possible treatment options, none was entirely satisfactory and many patients suffered irreversible visual loss. As a result of the BRAVO, CRUISE and GENEVA trials, ranibizumab and the intravitreal biodegradable implants of dexamethasone has recently been approved by the US Food and Drug Administration and the European Medicines Agency for the treatment of RVO secondary edema. In this paper we begin by describing the current treatment options for RVO associated macular edema and continue with the description of the treatment regimen with ranibizumab.

Standard Care vs Corticosteroid for Retinal Vein Occlusion (SCORE) Study system for evaluation of stereoscopic color fundus photographs and fluorescein angiograms: SCORE Study Report 9.

OBJECTIVE: To describe the procedures and reproducibility for grading stereoscopic color fundus photographs and fluorescein angiograms of participants in the SCORE Study. METHODS: Standardized stereoscopic fundus photographs and fluorescein angiograms taken at 84 clinical centers were evaluated by graders at a central reading center. Type of retinal vein occlusion (RVO), area of retinal thickening, and area of retinal hemorrhage are evaluated from fundus photographs; area of fluorescein leakage and area of capillary nonperfusion are measured on fluorescein angiography. Temporal reproducibility consisted of annual regrading of a randomly selected dedicated subset of fundus photographs (60 subjects) and fluorescein angiograms (40 subjects) for 3 successive years. Contemporaneous reproducibility involved monthly regrading of a 5% random selection of recently evaluated fundus photographs (n = 73). RESULTS: The intergrader agreement for RVO type and presence of retinal thickening was greater than 90% in the 3 annual regrades. The intraclass correlation (ICC) for area of retinal thickening in the 3 years ranged from 0.39 to 0.64 and for area of retinal hemorrhage, 0.87 to 0.96. The ICC for area of fluorescein leakage ranged from 0.66 to 0.75 and for capillary nonperfusion, 0.94 to 0.97. The contemporaneous reproducibility results were similar to those of temporal reproducibility for all variables except area of retinal thickening (ICC, 0.84). CONCLUSIONS: The fundus photography and fluorescein angiography grading procedures for the SCORE Study are reproducible and can be used for multicenter longitudinal studies of RVO. A systematic temporal drift occurred in evaluating area of retinal thickening.

Plasma thiols and taurine levels in central retinal vein occlusion.

PURPOSE: To determine the plasma levels of the sulfur-containing amino-acids homocysteine, cysteine, cysteinylglycine, glutamylcysteine, glutathione, and taurine in patients with central retinal vein occlusion (CRVO) and in healthy subjects and to ascertain whether there are statistically significant differences between patients and controls. METHODS: Laser-induced fluorescence capillary electrophoresis was used to measure the plasma levels of homocysteine, cysteine, cysteinylglycine, glutamylcysteine, glutathione, and taurine in 29 patients with CRVO and 80 age- and gender-matched control subjects. Wilcoxon or Student's t-test was used, when appropriate, to determine differences between groups. Multivariate logistic regression analysis was used to determine the risks for CRVO. RESULTS: CRVO patients showed significantly higher concentrations of cysteine (p = 0.032) and significantly lower concentrations of cysteinylglycine (p = 0.009) and taurine (p = 0.0002) than controls. Conversely, there were no significant differences in plasma homocysteine, glutamylcysteine, and glutathione between CRVO patients and controls. When categorized by CRVO type (ischemic/non-ischemic), taurine was still lower in both subgroups than in controls, whereas cysteine, cysteinylglycine, as well as homocysteine, were significantly higher only in the ischemic subgroup. In non-ischemic CRVO, cysteinylglycine fell just short of statistical significance (p = 0.06). Logistic regression analysis revealed an odds ratio of 1.02 (95% confidence interval (CI): 1.01-1.04, p = 0.001) for cysteine, 0.79 (95% CI: 0.70-0.89, p = 0.0002) for cysteinylglycine, and 0.94 (95% CI: 0.90-0.97, p = 0.002) for taurine. CONCLUSIONS: Results suggest that reduced plasma levels of cysteinylglycine and taurine may contribute to the pathogenesis of both CRVO types. Furthermore, this study also demonstrated an association between ischemic CRVO and higher concentrations of homocysteine and cysteine.

[Effects of Huoxue Tongmai Lishui method on fundus fluorescein angiography of non-ischemic retinal vein occlusion: a randomized controlled trial].

BACKGROUND: Huoxue Tongmai Lishui method, a traditional Chinese medicine treatment for eliminating water, activating and promoting blood circulation, could inhibit fundus hemorrhage on experimental retinal vein occlusion (RVO) with high obvious effective rate, and improve symptoms in traditional Chinese medicine. The action mechanism may be related to reducing plasma viscosity and non-perfusion area, and the formation of collateral circulation. OBJECTIVE: To explore the therapeutic effects of Huoxue Tongmai Lishui method (Sanxue Mingmu Tablet) on fundus fluorescent angiograph of non-ischemic retinal vein occlusion (RVO). DESIGN, SETTING, PARTICIPANTS AND INTERVENTIONS: Thirty-four patients with non-ischemic RVO in Department of Ophthalmology, the First Affiliated Hospital, Hunan University of Traditional Chinese Medicine from April 2005 to April 2009 were included. All the patients were diagnosed as qi stagnation and blood stasis syndrome or hyperactivity of liver yang syndrome, and they were randomly divided into two groups, with 17 eyes of 17 patients in treatment group treated by Sanxue Mingmu Tablet combined with conventional treatment, and 18 eyes of 17 patients in control group treated by Xueshuantong Tablet combined with conventional treatment. The patients were treated for two months. MAIN OUTCOME MEASURES: Fundus colour photography, and fundus fluorescent angiograph were detected in two groups before and after the treatment. RESULTS: The curative effect of Sanxue Mingmu Tablet was better than that of Xueshuantong Tablet. Huoxue Tongmai Lishui method could significantly shorten the retinal circulation time, reduce the non-perfusion area, decrease the formation of angiogenesis and promote the formation of collateral circulation. CONCLUSION: Huoxue Tongmai Lishui method is an effective traditional Chinese medicine treatment with high obvious effective rate in reducing non-perfusion area and avoiding venous occlusion and formation of collateral circulation.

SCORE Study Report 2: Interobserver agreement between investigator and reading center classification of retinal vein occlusion type.

OBJECTIVE: To evaluate interobserver agreement between investigator and Reading Center classification of retinal vein occlusion. DESIGN: The Standard Care versus COrticosteroid in REtinal Vein Occlusion (SCORE) Study includes 2 multicenter phase 3 randomized clinical trials evaluating the efficacy and safety of intravitreal triamcinolone: one involves participants with central retinal vein occlusion (CRVO) and one for participants with branch retinal vein occlusion (BRVO). Eyes with hemiretinal vein occlusion (HRVO) were classified as BRVO. PARTICIPANTS: A total of 682 SCORE Study participants, including 271 with CRVO and 411 with BRVO. METHODS: Participants were enrolled in each trial on the basis of investigator classification of retinal vein occlusion. Definitions of CRVO, BRVO, and HRVO based on clinical findings were specified in the study protocol. At baseline, 7-field color stereoscopic fundus photographs of the study eye of each participant were forwarded to the University of Wisconsin Fundus Photograph Reading Center (Reading Center) for evaluation. MAIN OUTCOME MEASURES: Percent agreement and kappa statistics comparing investigator and Reading Center classification of retinal vein occlusion type. RESULTS: With HRVO categorized as BRVO (consistent with the SCORE Study design), there was 98.0% agreement between investigator and Reading Center classification (641/654 eyes; kappa = 0.96; 95% confidence interval, 0.94-0.98). Disagreements were fairly evenly divided between classification of an eye as CRVO by the investigator and as BRVO by the Reading Center (7/13 disagreements) and vice versa (6 disagreements). When all 3 disease categories (CRVO, BRVO, and HRVO) were compared, there was 92.2% agreement (603/654; unweighted kappa = 0.86; 95% confidence interval, 0.83-0.90). Most disagreements (38/51, or 74.5%) were between BRVO and HRVO, with 9 between CRVO and BRVO, and 4 between HRVO and CRVO. In univariate analyses, baseline factors significantly associated with disagreement include larger area of capillary loss and black race; black race was the only significant factor in a multivariate analysis. CONCLUSIONS: Investigator and Reading Center agreement was excellent in the SCORE Study; disease classification would have been altered in only 13 eyes (2.0%) had Reading Center eligibility been required. Interobserver agreement was least for classification between BRVO and HRVO.

Branch retinal vein occlusion: classification and treatment.

Branch retinal vein occlusion (BRVO) refers to a heterogeneous group of disorders with different clinical aspects, courses, and probably therapy. Depending on the site of the arteriovenous crossing, we can roughly divide BRVO into 3 main groups: major BRVO, hemispheric retinal vein occlusion, and macular BRVO. Main treatment options include laser treatment, corticosteroid administration, anti-VEGF drugs, and sheathotomy with or without vitrectomy. Laser photocoagulation, as demonstrated by the Branch Vein Occlusion Study, represents the gold standard for the treatment of macular edema and ocular neovascularization following BRVO. The limited functional outcomes achievable by means of laser treatment have prompted researchers to try alternative options, with varying results. The recent introduction of combined therapies for macular edema may provide a superior approach in an attempt to improve and stabilize visual acuity over a long-term follow-up.

Increased serum levels of leptin in retinal vein occlusion.

Retinal vein occlusion is an important cause of visual loss. Several ocular and systemic conditions have been reported for retinal vein occlusion. The pathogenesis of thrombus formation in the retinal vein, which results in retinal vein occlusion, is unclear. The aim of this study was to investigate the correlation between increased serum leptin levels and the occurrence of retinal vein occlusion (RVO). The study group consisted of 40 patients with RVO (58.1 +/- 6 years old; 17 males and 23 females): 15 patients with central RVO, 23 with branch RVO, and 2 with hemispheric RVO. The patients who had any ocular or systemic pathology were not included in the study. The control group consisted of 40 healthy individuals of similar gender, age, date and type of health survey, and geographic region. The blood samples of the RVO patients (n = 40) and controls (n = 40) were obtained antecubitally. Leptin levels were measured by an enzyme-linked immunosorbent assay (ELISA) method, and Student's t-test was used to determine differences between the groups. The mean serum leptin levels were 12.5 +/- 1.64 ng/ml in patients with RVO and 8.4 +/- 1.22 ng/ml in the control subjects; namely, the mean serum leptin levels were significantly higher in the patients with RVO (p < 0.001). These results suggest that leptin may be involved in the pathogenesis of venous thrombosis in the retina probably through its effects on homeostasis of the vessel wall.

Management of central retinal vein occlusion.

The management of central retinal vein occlusion (CRVO) is discussed briefly. Since the prognosis, complications, visual outcome and management of nonischemic and ischemic CRVO are very different, the first essential step in the management of CRVO is to determine which type of CRVO one is dealing with. The various parameters which help to differentiate the two types reliably are described briefly. In this connection, the most important thing to remember is that the conventional, very prevalent use of a 10-disc area of retinal capillary obliteration is an invalid parameter to differentiate ischemic from nonischemic CRVO, or to predict ocular neovascularization (NV). Ocular NV is a complication of ischemic CRVO only. Relevant issues about the natural history of CRVO are summarized; the natural history of the disease must not be mistaken for a beneficial effect of treatment. Various advocated modes of treatment of CRVO and their relative merits are discussed, particularly photocoagulation, which is widely advocated. Controversies with regard to various aspects of CRVO management are examined. Finally, it is noted that apart from routine systemic and hematologic evaluations, the vast majority of patients with CRVO do not need an extensive and expensive workup. In conclusion, in spite of enthusiastic claims of success for various therapies, the reality is that we currently have practically no proven safe and effective treatment for CRVO.

Hematologic abnormalities associated with various types of retinal vein occlusion.

BACKGROUND: The objective of this study was two-fold: (1) to investigate hematologic abnormalities associated with various types of retinal vein occlusion (RVO) and comparison of their prevalence among those various types of RVO; (2) to review the conflicting literature on the subject, to place the information in perspective. METHODS: In patients with various types of RVO seen in our clinic since 1973, we conducted planned prospective studies on the prevalence of: (1) routine hematologic tests (535 patients) and (2) certain special hematologic parameters (platelet aggregation, antithrombin III, and proportional, variant(2) globulin in 110, 81 and 91 patients, respectively). Patients were categorized into six types of RVO, based on defined criteria: non-ischemic and ischemic central RVO (CRVO), non-ischemic and ischemic hemi-CRVO (HCRVO), and major and macular branch RVO (BRVO). The patients had a detailed ophthalmic, systemic and hematologic evaluation. The data were abstracted and analyzed retrospectively from the detailed information originally collected prospectively in the patients' records. For data analysis, patients were divided into young, middle-aged and elderly. Observed prevalence rates of hematologic abnormalities were estimated. Logistic regression, adjusting for age and gender, was used to compare the observed prevalence of hematologic abnormalities among the various types of RVO. RESULTS: No generalizations about the prevalence of hematologic disorders in all six types of RVO are possible. Ischemic CRVO showed a significantly higher prevalence of abnormal hematocrit ( P=0.044), hemoglobin ( P=0.018), and blood urea nitrogen ( P=0.025) than non-ischemic CRVO, while a significantly higher prevalence of abnormal antinuclear antibody (ANA; P=0.049) was seen in non-ischemic CRVO than in ischemic CRVO. There was a significant ( P=0.011) difference in the prevalence of abnormal uric acid among the three main RVO groups (CRVO, HCRVO, BRVO), highest in BRVO and lowest in HCRVO. There was a higher prevalence of abnormal glucose ( P=0.069) and ANA ( P=0.071) in CRVO+HCRVO than in BRVO. Results of special hematologic studies are given. CONCLUSIONS: Our study showed that a variety of hematologic abnormalities may be seen in association with different types of RVO, and any generalization about these disorders applied to all RVO patients may be misleading. The evidence of our study and in the literature indicates that there is no good reason why all patients with RVO should be subjected to extensive, expensive, special hematologic and hypercoagulability investigations, unless, of course, there is some clear indication; the routine, inexpensive hematologic evaluation is usually sufficient for RVO patients. Treatment with anticoagulants or platelet anti-aggregating agents may adversely influence the visual outcome, without any evidence of protective or beneficial effect.