ACTIVATED PROTEIN-C RESISTANCE - LOW INCIDENCE IN GLAUCOMATOUS OPTIC DISC HEMORRHAGE AND CENTRAL RETINAL VEIN OCCLUSION

Purpose: Activated protein C (APC) resistance has recently been report ed as conferring a seven-fold increase in the risk of venous thrombosi s. it is linked to a genetic mutation in the factor V gene which occur s commonly (about 2% to 4% of the community have the mutation). Glauco ma patients with nerve fibre layer (NFL) haemorrhages on the optic dis c 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 patien ts with CRVO were tested. The CRVO cases included 11 with relatively y oung age of onset (mean 45.1 +/- 6.9 years) without conventional vascu lar risk factors. Eighty randomly selected Red Cross blood donor sampl es and 33 staff members were tested as controls. Clotting times with a nd without exogenous APC were recorded and an APC ratio determined. Ca ses with APC resistance were tested to confirm that they had the facto r V Leiden gene. Results: No cases of APC resistance were identified i n the glaucoma patients and only one of the younger CRVO patients test ed positive, but four of 113 controls tested positive. The difference in prevalence between groups is not significant. The mean APC ratios f or 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 w as no 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.