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


CONCLUSIONS
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.
Department of Ophthalmology, Prince of Wales Hospital, Sydney, NSW.
S L
SL
Graham
I
I
Goldberg
B
B
Murray
P
P
Beaumont
B H
BH
Chong
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001777:Blood Coagulation / Q000502:physiology; D001778:Blood Coagulation Disorders / Q000097:blood*; D017931:DNA Primers / Q000737:chemistry; D005165:Factor V / Q000235:genetics; D005260:Female; D005902:Glaucoma, Open-Angle / Q000097:blood* / Q000150:complications; D006801:Humans; D008297:Male; D008875:Middle Aged; D009898:Optic Disk; D011486:Protein C / Q000502:physiology*; D012166:Retinal Hemorrhage / Q000097:blood* / Q000209:etiology; D012170:Retinal Vein Occlusion / Q000097:blood*
D017931:DNA Primers; D011486:Protein C; D005165:Factor V