Natural History of Central Retinal Vein Occlusion: An Evidence-Based Systematic Review

Purpose To explore the risk factors for central retinal vein occlusion (CRVO) by comparing a large sample of patients with healthy controls. Materials and Methods Multi-center case-control study. The study group includes patients affected by central retinal vein occlusion, confirmed angiographically, aged 50 years old or above (Group A). The control group includes healthy subjects without an history of retinal vein occlusion (Group B). Outcome measures: age, gender, active smoking, presence of uncontrolled arterial hypertension (uHTN), presence of the following comorbidities: diabetes mellitus type II (DMII), chronic liver disease (CLD), chronic kidney disease (CKD), thyroid disease (TD), systemic lupus erythematosus (SLE), hyperhomocystenemia (HHcy), dyslipidemia (DLip), carotid artery disease (CAD), glaucoma, atrial fibrillation (AF), migraine headache (MH), chronic obstructive pulmonary disease (COPD), obstructive sleep apnea syndrome (OSAS), history of myocardial infarction (MI). Odds-ratios were calculated with logistic regression analysis. Results A total of 203 patients (Group A) and 339 controls (Group B). Statistically-significant differences were found for the following variables: age (OR: 1.109 [1.081–1.138], p < .001), active smoking (OR: 2.048 [1.210- 3.466], p < .008), DMII (OR: 4.533 [2.097–9.803], p < .001), HHcy (OR: 4.507 [2.477–10.001 ], p < .001), DLip (OR: 2.255 [1.352–3.762], p = .002), CAD (OR: 6.632 [2.944- 14.942], p < .001), glaucoma (OR: 4.656 [2.031–10.673], < .001), OSAS (OR: 1.744 [1.023–2.975], < .041), uHTN (OR: 3.656 [2.247–5.949], < .001). No statistically-significant differences were found for the other variables. Conclusions Older age, active smoking, as well as presence of DMII, HHcy, DLip, CAD, glaucoma, OSAS, and uHTN, all increase the risk for CRVO. A comprehensive assessment of patients with CRVO is paramount. Adequate control of all the aforementioned risk factors is likely of great significance in reducing the incidence of CRVO among the general population, and it likely plays an important role in improving the prognosis following the occlusive event.

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The Use of the PFA-100® and Thromboelastograph in Assessing Haemostasis and Drug Efficacy in Essential Thrombocythemia.

Blood ◽

10.1182/blood.v106.11.4959.4959 ◽

2005 ◽

Vol 106 (11) ◽

pp. 4959-4959

Author(s):

Betty Y.Y. Cheung ◽

Kiran Parmar ◽

Ghasem Yadegarfar ◽

Beverley J. Hunt ◽

Claire N. Harrison

Keyword(s):

Platelet Count ◽

Retinal Vein Occlusion ◽

Essential Thrombocythemia ◽

Central Retinal Vein Occlusion ◽

Clot Strength ◽

Vein Occlusion ◽

Increased Risk ◽

History Of ◽

Digital Ischaemia ◽

Central Retinal Vein

Abstract Introduction. Essential thrombocythemia (ET) is associated with an increased risk of thrombosis. Many patients are treated with anti-platelet agents and/or cytoreductive therapy in order to minimise the risk but some still develop thrombotic events. The PFA-100® is an effective near-patient platelet function analyser and the Thromboelastograph (TEG®) Haemostasis Analyser assesses global haemostasis in whole blood. The usefulness of these technologies has not been fully evaluated in ET. Patients and Methods. We compared results from the PFA-100® and TEG® in 25 ET patients and 19 controls. Overall the ET patients comprised 18 females and 7 males, their median age was 55 yrs, median platelet count 423x109/l. Twenty-two were on anti-platelet therapy (21 on 75mg aspirin, 1 on aspirin and clopidogrel). Seventeen patients were receiving cytoreductive therapy (10 hydroxyurea, 2 a-interferon, 4 busulphan and 1 busulphan with anagrelide). Eight patients had previous thrombosis (4 transient ischaemic attacks, 1 stroke, 1 central retinal vein occlusion, 2 multiple events [1 stroke, erythromelalgia and digital ischaemia; 1 central retinal vein occlusion and digital ischaemia]) and 2 had haemorrhagic events. Results. All had normal INR, APTT and fibrinogen levels. Using the PFA-100®, Collagen/ADP closure times were prolonged in 15 (60%) patients compared to normal controls, suggesting platelet dysfunction, which included both patients with previous bleeding episodes. Twenty (91%) patients on aspirin had prolonged Collagen/Epinephrine closure times but for 2 (9%) patients these were within the normal range indicating aspirin-resistance. Both these patients had a history of thrombosis whilst on aspirin alone. Using TEG®, ET patients when compared to controls, took longer to initiate and to reach maximal clot strength (significantly longer R and K times, p=0.001, p=0.012 respectively and smaller angle, p=0.01) but the developed clot had a higher tensile strength (larger MA, p=0.024). There was a positive correlation between fibrinogen levels and MA (r=0.54, p=0.006) as well as APTT with R time (r=0.437, p= 0.029). There was no correlation between platelet count or prior history of thrombosis with any PFA-100® or TEG® variables. Conclusion. Low-dose aspirin had biochemical efficacy as assessed by PFA-100® Collagen/Epinephrine closure times in most but not all ET patients. Further studies are necessary to assess whether Collagen/ADP times can identify those at risk of bleeding. In ET, the TEG® demonstrates slower formation but a higher tensile clot strength than controls. Larger studies are needed to fully evaluate these findings and their clinical relevance.

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