Ophthalmic manifestation of congenital protein C deficiency

Under normal conditions activated protein C is a natural anticoagulant that cleaves 2 activated coagulation factors, factor Va and factor VIIIa, there by inhibiting the conversion of factor X to factor Xa and of prothrombin to thrombin. Additionally, activated protein C enhances tissue-plasminogen ac tivator-mediated fibrinolysis by inhibition of plasminogen activator inhibi tor-1. This results in an increase in circulatory plasminogen activator lev els.(1) Protein C deficiency, a genetic or acquired thrombophilic abnormality, has been demonstrated to predispose to episodes of potentially blinding and let hal thromboembolic events.(2,3) Heterozygous-deficient subjects usually rem ain asymptomatic until adolescence or adulthood. In homozygous-deficient pa tients, protein C activity is usually less than 1% (reference range, 70%-14 0%),- resulting in thromboembolism as early as in the neonatalperiod.(4-11) The major clinical symptoms in affected newborn infants have been purpura fulminans, vitreous hemorrhage, and central nervous system thrombosis. The age of onset of the first symptoms has ranged from a few hours to 2 weeks a fter birth, usually after an uncomplicated full-term pregnancy and delivery .(4-11) In contrast to the genetic form, acquired neonatal protein C deficiency occ urs particularly in ill preterm babies. Typical complications of prematurit y such as respiratory distress syndrome, necrotizing enterocolitis, and neo natal sepsis may also be present.(7) In the medical literature, there are only a few reports of homozygous prote in C deficiency in neonates.(4-11) We present 2 cases of homozygous protein C deficiency with ocular and extraocular manifestation.