[False paraprotein-induced hypoglycemia in the measurement of glucose by the hexokinase method]. / Fausse hypoglycémie induite par les paraprotéines lors de la mesure du glucose par la méthode de l'hexokinase.

A 67 years old woman with a Waldenström disease was admitted in the intensive care unit for dyspnea and fever. During hospitalization, episodes of undetectable glycemia were observed without any hypoglycemia symptoms. Plasma glucose was determined with the hexokinase method (recommended). From this observation, a literature review on PubMed was performed to investigate similar cases. In patients with protides in excess (e.g. immunoproliferative syndrome), absorption measurements could be disrupted by the precipitation of excess protein (IgM in most cases). Other parameters could be affected: bilirubin, phosphate, HDL cholesterol, GGT, CRP and calcemia. In our case, the main difficulty was to identify the cause of the interference and then correct it. Using a series of dilution, we prevented protide precipitation allowing correct glucose determination. Those interferences are rare, but present a real analytical difficulty. Biologists should be aware of those interferences because of dramatics consequences.

Anomalous coagulation factors in non-arteritic anterior ischemic optic neuropathy with central retinal vein occlusion: A case report.

RATIONALE: Non-arteritic anterior ischemic optic neuropathy (NAION) is characterized by sudden, painless visual loss and optic disc edema. NAION occurs mainly in the presence of cardiovascular disease and hypercoagulability, mainly in patients over 50 years of age. We experienced a case of NAION associated with central retinal vein occlusion (CRVO) in a young man with no underlying disease. PATIENT CONCERNS: A 46-year-old man was referred to our clinic following a sudden loss of vision in his right eye. The patient exhibited no underlying disease and reported no ongoing medication. Significant visual loss and visual disturbance of the right eye were observed. The pupil of the right eye was enlarged and an afferent pupillary defect was observed. On fundus examination, retinal hemorrhage was observed in the peripheral retina; macular edema was observed in optical coherence tomography analysis. However, optic disc edema was not evident. No abnormal findings were found in routine blood tests for hypercoagulability. After 3 days of steroid intravenous injection, macular edema disappeared and visual acuity was improved, but optic disc edema began to appear. One week later, optic disc edema was evident and visual acuity was significantly reduced; thus, the patient was diagnosed with NAION. In fluorescein angiography, peripheral retinal ischemia was observed, suggesting that CRVO was complicated. Blood tests, including analysis of coagulation factors, were performed again, showing that coagulation factors IX and XI were increased. DIAGNOSES: Anomalous coagulation factors in non-arteritic anterior ischemic optic neuropathy with central retinal vein occlusion. INTERVENTIONS: Systemic steroids were administered. OUTCOMES: One month later, optic disc edema and retinal hemorrhage gradually diminished and eventually disappeared; however, visual acuity did not recover. CONCLUSION: In young patients without underlying disease, cases of NAION require careful screening for coagulation disorders. Even if there is no abnormality in the test for routine coagulation status, it may be necessary to confirm a coagulation defect through an additional coagulation factor assay.

The use of emergency apheresis in the management of plasma cell disorders.

Hyperviscosity syndrome (HVS) develops most commonly in Waldenström's macroglobulinemia (WM) and multiple myeloma (MM). Plasmapheresis is the immediate therapy and very effective at relieving symptoms by removing paraprotein. The most commonly used replacement fluid is 4%-5% human albumin in physiologic saline. FFP may be used in patients with coagulation abnormalities. Plasmapheresis should be continued until acute symptoms abate. Hyperviscosity impairs the circulation in the retina and causes hemorrhages around the small retinal vessels. Early diagnosis and urgent plasmapheresis may reduce blindness caused by retinal hemorrhages and/or retinal detachment. In HCV related mixed cryoglobulinemias, plasmapheresis is indicated if rapidly evolving life-threatening disease with immunosuppressive agent exists. In non-infectious mixed cryoglobulinemia plasmapheresis is indicated when the disease manifestations are severe, as a second line option. In WM patients with hyperviscosity symptoms and IgM > 4 g/dL, preemptive plasmapheresis is recommended to prevent an IgM flare with rituximab. Certain IgG/A MGUS-associated neuropathy patients may benefit from plasmapheresis. For cast nephropathy (suspected or biopsy proven), plasmapheresis is recommended when the sFLC ≥ 500 mg/l and as early as possible (<1 month with kidney injury). Theoretically, extracorporeal removal alone, without efficient tumor killing, could not reduce sFLC due to high production by the tumor mass and rapid rebound between compartments.

Macular hemorrhages associated with neonatal polycythemia and thrombocytopenia: A case report.

BACKGROUND: Thrombocytopenia occurs in 51% of neonates with polycythemia and is independently associated with growth restriction. Increased hematocrit is associated with decreased platelet count. The possibility of a hemorrhage should be noted. CASE DESCRIPTION: A Chinese male newborn presented with elevated hemoglobin and hematocrit levels. The platelet count decreased to 10×109/L during the 1st week after birth and remained abnormal at day 12. Vitreous turbidity of the right eye was detected 2 days later and was suspected of stemming from endophthalmitis or ocular inflammation. Two weeks later, vitreous turbidity decreased and a macular hemorrhage became visible. Optical coherence tomography confirmed the diagnosis of a retinal hemorrhage. CONCLUSION: Thrombocytopenia associated with polycythemia can induce a vitreous hemorrhage, which may be confused with ocular infection or inflammation.

Relationship between HbA1c and risk of retinal hemorrhage in the Japanese general population: The Circulatory Risk in Communities Study (CIRCS).

AIMS: Retinal hemorrhage is an important finding on fundus photography. Diabetes mellitus is a cause of retinal hemorrhage, although other causes exist. We sought to better characterize the association between retinal hemorrhage and HbA1c in the Japanese population. METHODS: We conducted a prospective study of 11,644 Japanese men and women aged 30-78years between 2001 and 2011. Fundus photography was performed as part of an annual cardiovascular disease risk survey. HbA1c was determined by the latex coagulation method throughout the study. We used logistic regression models to examine the association between HbA1c and the risk of retinal hemorrhage and diabetic retinal hemorrhage. RESULTS: During a median follow-up period of 4.6years, 509 retinal hemorrhages, including 96 diabetic retinal hemorrhages, were diagnosed. HbA1c was positively associated with the risk of retinal hemorrhage and diabetic retinal hemorrhage among subjects not taking medication for diabetes mellitus at baseline, but not among subjects who were taking medication at baseline. CONCLUSIONS: HbA1c was positively associated with the risk of retinal hemorrhage and the subcategory of diabetic retinal hemorrhage among subjects not taking medication for diabetes mellitus at baseline. The association was evident for diabetic retinal hemorrhage, compared with retinal hemorrhage.

Association Between Platelet Function and Disc Hemorrhage in Patients With Normal-Tension Glaucoma: A Prospective Cross-Sectional Study.

PURPOSE: To evaluate the association between platelet function and disc hemorrhage in patients with normal-tension glaucoma. DESIGN: Prospective, cross-sectional study. METHODS: Study involved a total of 315 subjects, including patients with normal-tension glaucoma and disc hemorrhage (n = 120), patients with normal-tension glaucoma without disc hemorrhage (n = 75), and healthy individuals (control group, n = 120). A detailed eye examination including visual field testing, color disc photography, optical coherence tomography scanning, and measurement of collagen/epinephrine closure time using a platelet function analyzer were performed for all subjects. RESULTS: The collagen/epinephrine closure time (s) as measured by the platelet function analyzer was approximately 14%-24% longer in the normal-tension glaucoma and disc hemorrhage group compared with the other groups (141.92 ± 53.44 [with normal-tension glaucoma and disc hemorrhage] vs 124.60 ± 46.72 [with normal-tension glaucoma without disc hemorrhage] vs 114.84 ± 34.84 [healthy individuals], 1-way analysis of variance test, P < .001). The activated partial thromboplastin time (s) value of the normal-tension glaucoma with disc hemorrhage group was also higher than the control group. Stepwise multiple logistic regression analysis revealed that only a longer collagen/epinephrine closure time (OR adjusted for age, sex, prothrombin time, activated partial thromboplastin time, diabetes mellitus, hypertension, hypotension, heart disease, hypothyroidism, migraine, stroke, hypercholesterolemia: 2.94; 95% CI: 1.40-6.17) was independently associated with disc hemorrhage. A similar trend was observed when platelet function was compared among the 3 groups with respect to age. CONCLUSIONS: Our results suggest that platelet function is significantly associated with disc hemorrhage in patients with normal-tension glaucoma. Delayed absorption resulted from prolonged bleeding due to delayed platelet aggregation may have an effect on the detectability of disc hemorrhage in patients with normal-tension glaucoma.

Laboratory evidence of disseminated intravascular coagulation is associated with a fatal outcome in children with cerebral malaria despite an absence of clinically evident thrombosis or bleeding.

BACKGROUND: A procoagulant state is implicated in cerebral malaria (CM) pathogenesis, but whether disseminated intravascular coagulation (DIC) is present or associated with a fatal outcome is unclear. OBJECTIVES: To determine the frequency of overt DIC, according to ISTH criteria, in children with fatal and non-fatal CM. METHODS/PATIENTS: Malawian children were recruited into a prospective cohort study in the following diagnostic groups: retinopathy-positive CM (n = 140), retinopathy-negative CM (n = 36), non-malarial coma (n = 14), uncomplicated malaria (UM), (n = 91), mild non-malarial febrile illness (n = 85), and healthy controls (n = 36). Assays in the ISTH DIC criteria were performed, and three fibrin-related markers, i.e. protein C, antithrombin, and soluble thrombomodulin, were measured. RESULTS AND CONCLUSIONS: Data enabling assignment of the presence or absence of 'overt DIC' were available for 98 of 140 children with retinopathy-positive CM. Overt DIC was present in 19 (19%), and was associated with a fatal outcome (odds ratio [OR] 3.068; 95% confidence interval [CI] 1.085-8.609; P = 0.035]. The levels of the three fibrin-related markers and soluble thrombomodulin were higher in CM patients than in UM patients (all P < 0.001). The mean fibrin degradation product level was higher in fatal CM patients (71.3 µg mL(-1) [95% CI 49.0-93.6]) than in non-fatal CM patients (48.0 µg mL(-1) [95% CI 37.7-58.2]; P = 0.032), but, in multivariate logistic regression, thrombomodulin was the only coagulation-related marker that was independently associated with a fatal outcome (OR 1.084 for each ng mL(-1) increase [95% CI 1.017-1.156]; P = 0.014). Despite these laboratory derangements, no child in the study had clinically evident bleeding or thrombosis. An overt DIC score and high thrombomodulin levels are associated with a fatal outcome in CM, but infrequently indicate a consumptive coagulopathy.

Bevacizumab in macular serous detachments associated with Waldenstrom's macroglobulinemia.

Waldenström's macroglobulinemia (WM) is a lymphoproliferative B-cell disorder characterized by monoclonal proliferation of immunoglobulin M. WM can be associated with impressive hyperviscosity retinopathy and a unique tendency to develop serous macular detachments. These have been described as immunogammopathy maculopathy and portend a poor visual prognosis, often persisting despite multiple plasmapheresis treatments. In this case report, the authors demonstrate the accelerated resolution of hyperviscosity retinopathy and associated macular detachments in a patient with WM with marked visual improvement. This case report serves to raise awareness of the potential role of anti-vascular endothelial growth factor modulation in the treatment of patients with hyperviscosity retinopathy associated with WM.

A pilot clinical study on the effectiveness of mesoglycan against diabetic retinopathy.

PURPOSE: A double-blind placebo-controlled study on 68 patients suffering by Diabetic Retinopathy was aimed in order to evaluate the effectiveness of Mesoglycan in this pathology. This drug is particularly interested in treatment of disorders of microcirculation. MATERIALS AND METHODS: The two treatments were randomly assigned to each patient, using a 100 mg/day dosage of Mesoglycan, and both treatments were prescribed for 6 months. The efficacy of both treatments was based on clinical and instrumental check. RESULTS: The clinical results that emerged in the group treated with Mesoglycan were excellent, although observations are on a limited number of patients appears a direct action of Mesoglycan on the endothelium retinal blood vessels and circulation. Indeed, in the observed patients, was detected a significant reduction of microhemorrhages, microaneurysms and exudates. The same cannot be said of the placebo group; none of patients of that group showed signs of clinical improvement at the end of the study. CONCLUSION: Data emerging from our study show a direct action of Mesoglycan on endothelium retinal blood vessels and circulation, as we observed in patients we found a significant reduction in the number of microhemorrhages, microaneurysms and exudates. This action can be explained by the characteristics of drug as antithrombotic profibrinolytic and anti-edema, already found in vitro and experimentally. We conclude that our preliminary study showed an encouraging clinical efficacy, together with excellent tolerability, and therefore our objective has been met, which was to verify the existence of the prerequisites for a larger clinical study.

Serum interferon-gamma/interleukin-4 imbalance in patients with Eales' disease.

BACKGROUND: Eales' disease (ED) is an idiopathic obliterative vasculopathy that usually affects the peripheral retina of young adults. The aim of this study is to investigate Th1/Th2 serum cytokine profiling in patients with ED. METHODS: This study included 30 male patients with ED and 10 healthy controls. The ED patients were divided into two subgroups: the vitreous haemorrhage (VH) group (n = 18) and non-vitreous haemorrhage (NVH) group (n = 12). Sixteen patients (six from the VH group and 10 from the NVH group) received glucocorticoid treatment for three months and were followed for six months. Levels of six cytokines including interferon-gamma (IFN-gamma), tumour necrosis factor-alpha (TNF-alpha) and four interleukins (IL-2, IL-4, IL-5 and IL-10) in the serum samples were determined by Luminex assays. RESULTS: Compared to controls, ED patients showed significantly higher levels of IL-10 and TNF-alpha, increased IFN-gamma/IL-4 (Th1/Th2) ratio, and lower levels of IL-4 (p < 0.05). Glucocorticoid treatment caused a restoration in the cytokine levels and the IFN-gamma/IL-4 ratio. Multivariate analysis revealed that reduced IL-4 (less than 4 pg/ml) and elevated IL-10 (greater than 4 pg/ml) levels were independent predictors of ED with odds ratios of 0.024 (95% CI, 0.002-0.255; p = 0.002) and 12.108 (95% CI, 1.045-140.233; p = 0.046), respectively. CONCLUSION: The findings demonstrate for the first time that there is an imbalance of Th1/Th2 cytokines in ED patients, which can be reversed by glucocorticoid treatment. Additionally, both IL-4 and IL-10 might represent potential diagnostic markers for the disease.

Interleukin-1 and tumor necrosis factor-alpha: novel targets for immunotherapy in Eales disease.

BACKGROUND: Eales disease is an idiopathic obliterative vasculopathy that primarily affects the peripheral retina of young adults. The authors evaluated interleukin 1 beta (IL-1beta), interleukin-6 (IL-6), Interleukin-10 (IL-10), and tumor necrosis factor-alpha (TNF-alpha) in the serum of patients with Eales disease stages for the first time. METHODS: The study group consisted of 45 consecutive patients of Eales disease [inflammatory stage (n = 15) and proliferative stage (n = 30)] and 28 healthy controls. Immunoassays for the quantification of the levels of four cytokines including IL-1beta, IL-6, IL-10, and TNF-alpha in the serum samples were performed using ELISA kits. RESULTS: IL-1beta, IL-6, IL-10, and TNF-alpha levels were found to be increased significantly in the inflammatory stage of Eales disease as compared to controls (p < .001). IL-1beta levels decreased significantly during the proliferative stage of the disease as compared to the inflammatory stage (p = .03). TNF-alpha levels increased significantly during the proliferative stage as compared to the inflammatory stage (p = .02). CONCLUSIONS: Raised levels of IL-1beta and TNF-alpha were observed in the inflammatory stage and persisted in the proliferative stage of the disease. The IL-1 system and TNF-alpha represent novel target for immunotherapy for controlling inflammatory activity and/or the associated long-term sequelae related to angiogenesis in Eales disease.

Hemorheologic abnormalities associated with HIV infection: altered erythrocyte aggregation and deformability.

PURPOSE: To investigate possible alterations of erythrocyte aggregation and deformability, which are factors that can influence blood flow, in human immunodeficiency virus (HIV)-infected individuals and to determine whether these factors are related to the severity of immunodeficiency. METHODS: Laboratory evaluations were performed on 46 HIV-infected individuals and 44 HIV-negative control subjects. Current and nadir (lowest previous) CD4+ T-lymphocyte counts were identified for each subject. Erythrocyte aggregation was measured using a fully automatic erythrocyte aggregometer. Factors related to erythrocyte aggregation were also determined: erythrocyte sedimentation rate (ESR), zeta sedimentation ratio (ZSR), and plasma fibrinogen levels. Erythrocyte deformability was observed at various fluid shear stress levels, with a laser diffraction ektacytometer. Correlations were sought between each of these measures and current or nadir CD4+ T-lymphocyte counts, and each measure was compared between three subgroups based on current and nadir CD4+ T-lymphocyte counts (severely immunosuppressed, immune reconstituted, never severely immunosuppressed). RESULTS: The following parameters were significantly different between HIV-infected subjects and controls: increased erythrocyte aggregation, at stasis (P < 0.001) and low shear stress (P < 0.001), increased ESR (P < 0.001), increased ZSR (P < 0.028), increased serum fibrinogen (P = 0.015), and decreased erythrocyte deformability (P < 0.001). Only erythrocyte aggregation at stasis correlated significantly with current CD4+ T-lymphocyte count (r = - 0.344, P = 0.022). None of the parameters was significantly different between HIV-infected subgroups. CONCLUSIONS: Increased aggregation and decreased deformability of erythrocytes are associated with HIV-infection regardless of the severity of immunodeficiency. HIV-infected individuals may be at risk for progressive retinal microvascular damage from persistent hemorheologic abnormalities, despite immune reconstitution associated with potent antiretroviral drug therapies.

Hemorheologic abnormalities associated with HIV infection: in vivo assessment of retinal microvascular blood flow.

PURPOSE: To evaluate retinal microvascular blood flow in human immunodeficiency virus (HIV)-infected individuals using scanning laser Doppler flowmetry (SLDF) and to seek correlations between flow and various laboratory measures that may predict alterations in flow. METHODS: The Heidelberg Retina Flowmeter and SLDF software were used to acquire in vivo retinal blood flow data from 24 HIV-infected individuals and 16 HIV-negative control subjects. In each subject, separate scans were performed in each of six retinal regions: nasal parapapillary retina; macula; and the superior, nasal, inferior, and temporal periphery. Erythrocyte aggregation (assessed in vitro by a fully automatic erythrocyte aggregometer and by zeta sedimentation ratio [ZSR, a hematocrit-independent sedimentation rate]), serum fibrinogen level, plasma viscosity, and leukocyte rigidity (assessed in vitro with a cell transit analyzer) were compared with flow in selected regions. RESULTS: Flow was significantly higher in the periphery (superior, nasal, inferior, temporal) than in the posterior retina (nasal parapapillary retina, macula). Flow was highest in the temporal periphery for both HIV-infected subjects and control subjects. Flow in the posterior retina was significantly lower in HIV-infected subjects than in control subjects (P < 0.0001). Among HIV-infected individuals, flow in the macula correlated negatively with ZSR (r = -0.397, P = 0.0547) and leukocyte rigidity (r = -0.505, P = 0.0119). CONCLUSIONS: Microvascular blood flow in the posterior retina is reduced in HIV-infected individuals. Both increased erythrocyte aggregation and increased leukocyte rigidity contribute to this hemorheologic abnormality.

Massive subhyaloidal hemorrhage associated with severe PAI-1 deficiency.

PURPOSE: To report an association between spontaneous subhyaloidal hemorrhage and severe plasminogen activator inhibitor-1 (PAI-1) deficiency. METHODS: Case report. RESULTS: A 29-year-old woman presented with sudden, painless visual loss to hand motion in her right eye. Ophthalmoscopy showed a massive subhyaloidal hemorrhage. The patients' medical history was negative for cardiovascular risk factors, trauma, infections or bleeding complications. Further investigation into possible causes revealed hyperfibrinolysis secondary to severe PAI-1 deficiency. The non-clearing subhyaloidal hemorrhage was successfully treated by pars plana vitrectomy, and her visual acuity improved to 20/20. CONCLUSION: When ordering laboratory tests in patients with spontaneous subhyaloidal hemorrhage to rule out fibrinolytic disorders, severe PAI-1 deficiency should be considered in the differential diagnosis. Selective screening may be helpful in identifying ophthalmologic patients with hyperfibrinolysis, especially in young individuals with subhyaloidal hemorrhages in the absence of other recognized risk factors.

HLA typing in patients of Eales disease.

OBJECTIVE: To determine any predisposition of haplotypes with Eales disease. DESIGN: A case control study. PLACE AND DURATION OF STUDY: This study was started in February 2002 and data collected till April 2003 at Eye Department of Military Hospital, Rawalpindi. PATIENTS AND METHODS: The frequency of HLA antigens both class-I and II by complement dependent standard lymphocytotoxicity test was studied in 32 patients of Eales disease (group-I) and 32 age and gender matched normal persons as controls (group-II). Both patients and controls underwent complete ocular and clinical examination and were followed up for one year. RESULTS: Mean age was 30.8 years. HLA DR3 was found in 20 patients of group-I and none in group-II. HLA types A1, B8, B5 (51) and DR 15 (2) were found in 12 out of 32 patients of eales disease and none in controls. HLA DQ2 and DR52 was found in 28 cases of group-I as compared to 18 cases of group-II (p = .005). CONCLUSION: HLA phenotypes HLA DR3, A1, B8, B5 (51) and DR 15 (2) occurred in majority of cases of Eales disease, whereas these were not found in controls which was statistically significant. Similarly, HLA DQ2, DR52 and Bw6 was found in higher frequency in Eales patients and thus strongly associated with it. We conclude that certain HLA haplotypes have a possible predilection for Eales disease.

[The content of D-dimer in peripheral blood as observed studied in thrombohemorrhagic lesions of the retina]. / Izuchenie soderzhaniia d-dimera v perifericheskoi krovi pri trombogemorragicheskikh zabolevaniiakh setchatki.

The content of D-dimer in peripheral blood was studied in thrombohemorrhagic lesions of the retina. 60 patients with retinal pathology of the retina, i.e. thrombosis of retinal veins, exudative-hemorrhagic stage of central chorioretinal dystrophy and preproliferative diaichbetic retinopathy with pronounced exudative hemorrhagic maculopathy, were examined. A higher concentration of D-dimer in peripheral blood was shown to be indicative of affected general hemostasis. The below main parameters, which matter in progression of thrombohemorrhagic conditions should be determined, apart from D-dimer, for choosing an adequate medicamental therapy: aggregation ability of platelets, activated partial thromboplastin time, antithrombin-III, protein-C, prothrombin time, soluble complexes of fibrinmonomer, thrombin time, plasma fibrinogen and fibrinolytic plasma activity.

Correlation between retinal microcirculation and blood viscosity in patients with hyperviscosity syndrome.

Hyperviscosity syndrome leads to vascular disturbances in different organs. In the retina typical ophthalmoscopic changes can be found including dot and blot hemorrhages, retinal and optic nerve head edema, and increased diameter of retinal veins. In this study we examined the retinal microcirculation in patients with hyperviscosity syndrome. Nineteen patients (14 patients with Waldenstroem's macroglobulinemia, two patients with kryoglobulinemia, three patients with plasmacytoma) were examined. All patients underwent a video fluorescein angiography. In all angiograms the arteriovenous passage time (AVP) and the arm retina time (ART) were quantified. In addition, hematocrit (Hct) and plasma viscosity (ETA) were measured. In patients with hyperviscosity syndrome AVP was significantly prolonged in comparison to healthy volunteers (AVP: 2.5+/-1.3 s vs. 1.5+/-0.4 s; p < 0.01). The ART showed no significant differences. Plasma viscosity was doubled in patients as compared with reference values (ETA: 2.57+/-1.5 mPa s vs. 1.24+/-0.08 mPa s; p < 0.01). In this study we showed an increase in plasma viscosity as well as an increase in arteriovenous passage time. This may result in retinal circulatory disturbances and may cause the typical fundus changes in patients with hyperviscosity syndrome.

Activated protein C resistance--low incidence in glaucomatous optic disc haemorrhage and central retinal vein occlusion.

PURPOSE: Activated protein C (APC) resistance has recently been reported as conferring a sevenfold increase in the risk of venous thrombosis. It is linked to a genetic mutation in the factor V gene which occurs commonly (about 2% to 4% of the community have the mutation). Glaucoma patients with nerve fibre layer (NFL) haemorrhages on the optic disc and patients with central retinal vein occlusion (CRVO) were tested for APC resistance to determine if there was an association. METHODS: Twenty-three patients with glaucomatous NFL haemorrhages and 23 patients with CRVO were tested. The CRVO cases included 11 with relatively young age of onset (mean 45.1 +/- 6.9 years) without conventional vascular risk factors. Eighty randomly selected Red Cross blood donor samples and 33 staff members were tested as controls. Clotting times with and without exogenous APC were recorded and an APC ratio determined. Cases with APC resistance were tested to confirm that they had the factor V Leiden gene. RESULTS: No cases of APC resistance were identified in the glaucoma patients and only one of the younger CRVO patients tested positive, but four of 113 controls tested positive. The difference in prevalence between groups is not significant. The mean APC ratios for the three groups were very similar: NFL haemorrhages 5.46(+/- 1.62), CRVO 5.70(+/- 1.56), controls 5.34 ( +/- 1.19) p > 0.5. CONCLUSION: There was not clear association detected between glaucomatous NFL haemorrhages or CRVO and APC resistance in this sample of patients. This negative finding is important due its known association with venous thrombosis elsewhere in the body.