Activated protein C resistance in anterior ischaemic optic neuropathy

Mean Platelet Volume in Patients with Nonarteritic Anterior Ischemic Optic Neuropathy

Objective. We aimed to investigate the mean platelet volume (MPV) of the patients with nonarteritic anterior ischemic optic neuropathy (NAION). Methods. The medical records of 46 patients with the diagnosis of NAION and 90 control subjects were retrospectively evaluated. All participants underwent complete ocular examination including intraocular pressure (IOP) measurement. Hematocrit, MPV, hemoglobin, and platelet levels of the patients with NAION were compared with those of control subjects. Results. There was no significant difference between the groups in platelet counts (p = 0.76). NAION group had significantly higher MPV values (8.25 ± 1.26 fL) than that of control subjects (7.64 ± 1.01 fL) (p < 0.001). Multivariate logistic regression analysis showed that MPV is an independent predictor of NAION (odds ratio = 1.61; 95% confidence interval (CI) = 1.13–2.28; p = 0.007). The mean IOP was significantly higher in NAION group (p < 0.001). IOP was also found as an independent predictor of NAION according to the regression analysis (OR = 1.27; 95% CI = 1.08–1.48; p = 0.003). Conclusion. Our results demonstrated that the MPV values were significantly higher in NAION patients, suggesting that larger platelets may contribute to the pathogenesis of the NAION.

Increased level of platelet P-selectin in nonarteritic anterior ischemic optic neuropathy

PURPOSE

P-selectin receptor is expressed in platelets and endothelial cells in a cell-activation-dependent manner. Platelet P-selectin (CD62) levels may become elevated in a number of vasoocclusive diseases, including arteriosclerosis, atherothrombosis, and diabetes mellitus (DM). Nonarteritic anterior ischemic optic neuropathy (NAION) is associated with a sudden loss of vision due to the vascular insufficiency of ciliary arteries supplying the optic nerve. In this study, our aim was to investigate the presence of increased platelet reactivity in the development of NAION.

METHODS

Twenty-one NAION patients, 39 healthy control subjects, and 44 patients suffering from diabetes mellitus (DM) were examined in our case-control, pilot study. Platelet activation was investigated by flow cytometric analysis of the mean fluorescence intensity (MFI) of CD62 on platelets. These results were compared among the different study groups.

RESULTS

NAION patients showed considerably although not significantly (p = 0.2017) higher P-selectin MFI values (71.98 ± 40.30) versus healthy subjects (55.48 ± 20.95), insulin-dependent DM patients (50.02 ± 13.08), and non-insulin-dependent DM subjects (54.72 ± 24.74). However, logistic regression analysis resulted in a statistically significant adjusted effect on the odds of NAION when CD62 MFI values were logarithmically transformed (OR: 3.86, 95 % CI: 1.10 to 13.53, p = 0.0346).

CONCLUSION

Elevated platelet CD62 positivity may be related to NAION, suggesting a possible role of enlarged platelet activity in the generation of this type of ischemic optic neuropathy.

Nonarteritic anterior ischemic optic neuropathy and double thrombophilic defect: a new observation

We report the first case of nonarteritic anterior ischemic neuropathy (NAION) associated with double thrombophilia: protein S deficiency and prothrombin G20210A mutation. A 58-year-old man is presented including the clinical and laboratory findings, cardiovascular profile and thrombophilia screening. The patient presented with 3/10 vision and an inferior altitudinal defect in the right eye. Funduscopic examination of the right eye revealed a hyperemic optic disk with blurred superior optic disk border and sectoral nerve fiber layer edema. Complete blood count, erythrocyte sedimentation rate and C-reactive protein were normal, suggesting a NAION. A workup of cardiovascular risk factors revealed hyperlipidemia, arterial hypertension and high-risk asymptomatic coronary artery disease. Due to the family history of deep vein thrombosis in the patient's daughter, a thrombophilia screening was additionally performed. The results revealed a double thrombophilic defect, namely congenital protein S deficiency and heterozygosity for prothrombin G20210A mutation, which were also identified in the patient's daughter. Anticoagulant warfarin therapy was initiated and the patient underwent a triple bypass surgery. At three-month follow-up, the right optic disk edema had resolved, leaving a pale superior optic nerve head. Visual acuity in the right eye had slightly improved to 4/10; however, the dense inferior altitudinal field defect had remained unchanged. The patient is currently treated with warfarin, atorvastatin, irbesartan and metoprolol. This case suggests that the first line of investigation in all patients with NAION involves assessment of cardiovascular risk factors. However, careful history taking will identify NAION patients who are eligible for additional thrombophilia screening: young patients without vasculopathic risk factors, bilateral or recurrent NAION, idiopathic or recurrent venous thromboembolism (VTE), positive family history of VTE, and VTE in young age or in unusual sites (e.g. cerebral, hepatic, mesenteric, or renal vein).

Ischemic optic neuropathy

Anterior ischemic optic neuropathy (AION) is a common cause of visual loss in patients over 50 years of age. Optical coherence tomography has provided new information which may have implications regarding future approaches to management.

Increased relative mitochondrial DNA content in leucocytes of patients with NAION

AIM

To investigate possible changes in relative mitochondrial DNA (mtDNA) content in patients with non-arteritic anterior ischaemic optic neuropathy (NAION).

METHODS

19 patients with NAION were compared to 32 controls matched for age, sex distribution, and ethnicity. DNA was extracted from leucocytes and competitive multiplex polymerase chain reaction was carried out with two primer pairs (one pair for mtDNA ND1 gene and the other pair for beta actin nuclear gene) in the presence of a fluorescent dye.

RESULTS

The mean relative mtDNA content in controls (0.93 (SD 0.11); 95% CI 0.89 to 0.97) was significantly less than in NAION patients (2.40 (1.05); 95% CI 1.90 to 2.91; p < 0.001). Relative mtDNA content was negatively correlated with Snellen visual acuity (Spearman's rho; r = -0.37; p = 0.022).

CONCLUSION

Increased relative mtDNA content in NAION patients may imply a response to oxidative stress, possibly in part because of mitochondrial respiratory chain defects. Significantly more non-synonymous mtDNA nucleotide changes, significantly increased relative mtDNA content, and a significant association between relative mtDNA content and visual acuity all imply that mitochondrial abnormalities may be a risk factor for NAION.

Factor V Leiden and its effect on children with cardiac pathology

Factor V Leiden thrombophilia, formed by a genetic mutation, slows the body's anticoagulation response to clot formation. First described in 1994, factor V Leiden mutation has been identified as a contributing risk factor for venous thromboembolism. Although venous thromboembolism is considered rare in the pediatric population, Factor V Leiden has implications for certain at-risk pediatric patients.