Protein Z Plasma Levels are Not Elevated in Patients with Non-Arteritic Anterior Ischemic Optic Neuropathy

Ioannis Asproudis1 , *, Taxiarchis L Felekis1, Spiridon Gorezis2, Lefkothea Dova3, Eleni Dokou3, Georgios Vartholomatos2, Miltiadis Aspiotis1, Nikolaos I Kolaitis2
1 University Eye Clinic of Ioannina, Greece
2 Epirus Vision Center, Ioannina, Greece
3 Haematology Laboratory of the University Hospital of Ioannina, Greece

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© Asproudis et al.; Licensee Bentham Open.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestrictive use, distribution, and reproduction in any medium, provided the original work is properly cited.

* Address correspondence to this author at the University Eye Clinic of Ioannina, Kosti Palama 1, Anatoli-Ioannina 45500, Greece; Tel: 0030- 2651067689; Fax: 0030-2651022928; E-mail:


Background: Protein Z is a glycoprotein that acts as a co-factor for the inhibition of activated coagulation factor X. Protein Z circulating in abnormal levels has been associated with increased risk for acute ischemic events. Non-arteritic Anterior Ischemic Optic Neuropathy (N-AION) is caused by acute ischemic infarction of the optic nerve head, supplied by the posterior ciliary arteries.

Objectives: The aim was to investigate whether there is an association between N-AION and plasma protein Z levels.

Patients and Methods: Twenty-six cases of confirmed N-AION and fifty-two controls were included in the study group. Protein Z was estimated in thawed citrate plasma on both N-AION cases and controls by an enzyme immunoassay. The imprecision of the estimation was satisfactory (CV = 4, 6%).

Results: The controls’ protein Z values distributed within a range 340 to 4200 ng/ml (median = 1420, mean = 1673, SD = 1040 ng/ml). Patients’ protein Z values distributed within a range 420 to 3600 ng/ml (median = 1030, mean = 1520, SD = 939 ng/ml). There was no statistical difference between the two distributions (Independent t-test, p=0.529).

Conclusion: In our study, protein Z levels are not implicated in the pathogenesis of non-arteritic anterior ischemic optic neuropathy (N-AION).

Keywords: Protein Z, Non-arteritic anterior ischemic optic neuropathy.