Antithrombin III activity in subretinal fluid.

Purpose: To evaluate antithrombin III (AT III) activity in subretinal fluid (SRF) and blood plasma.

Methods: Prospective study of 32 patients, aged from 20 to 77 years (mean 53.8 years), undergoing retinal detachment surgery. Patients with vein or arterial disease or any other factors that could affect the parameters evaluated were excluded. Subretinal samples were obtained at the time of routine drainage during retinal detachment surgery. Venous blood samples were taken from the cubital vein into sodium citrate solution (9:1) immediately after induction of anesthesia but before surgery. AT III activity in citrated plasma and in SRF and its relations to patients' age, sex, duration and extent of retinal detachment and degenerative changes of the retina, were evaluated.

Results: The median level of AT III activity in 32 SRF samples was 16.5% (lower quartile 8.5% and upper quartile 23%). The mean level of AT III activity in plasma was 105% (SD 24%). AT III levels in SRF were significantly lower than in plasma (p < 0.0001). We found no correlation between AT III activity in SRF and plasma, and age, sex, the degree of myopia, the duration and extent of retinal detachment, or retinal degenerative changes.

Conclusions: In this study we detected AT III activity in all 32 SRF samples.