title: Molecular sieving in suprachoroidal fluid formation in man.
abstract: Suproachoroidal fluid (SCF) obtained at the time of the surgical evacuation of a clinically significant choroidal detachment (CD) was analyzed for its chemical and cellular components in four distinct subgroups: (1) CD following cataract surgery, (2) CD (nonhemorrhagic) following glaucoma surgery, (3) CD (hemorrhagic) following glaucoma surgery, and (4) intraoperative CD during glaucoma surgery in patients with elevated episcleral venous pressure. The fluid obtained in groups 1, 2, and 4 was clear and slightly xanthochromic and contained low-molecular-weight substances in concentrations essentially equal to serum. Proteins and other high-molecular-weight substances were present in lesser amounts than in serum. Albumin, alpha1-antitrypsin, and transferrin were present in amounts approximately equal to those in serum, whereas alpha2-macroglobulin, IgM and IgG were decreased. beta-Lipoprotein and beta-complement were absent. It is postulated that this distribution of serum proteins is a manifestation of molecular sieving and is consistent with the existence of an isoporous membrane between the intravascular and suprachoroidal space with a pore diameter of 144 A. In the intraoperative choroidal effusions, there was evidence for exclusion of more of the lower, as well as all of the higher, molecular weight proteins. This suggested that the degree of molecular sieving increased with increasing filtration rate. In the hemorrhagic SCF, the distinctive character of the fluid and the protein concentrations indicated that the integrity of the capillary membrane was mardkedly disrupted, thereby allowing higher-molecular-weight proteins and cellular elements to enter the space.
mesh_terms: D001205:Ascorbic Acid / Q000032:analysis; D001798:Blood Proteins / Q000032:analysis; D002199:Capillary Permeability; D002829:Choroid / Q000503:physiopathology*; D005122:Exudates and Transudates / Q000032:analysis / Q000502:physiology*; D005128:Eye Diseases / Q000378:metabolism / Q000503:physiopathology; D005136:Eye Proteins / Q000032:analysis; D006801:Humans; D011188:Potassium / Q000032:analysis; D012964:Sodium / Q000032:analysis
chemical_list: D001798:Blood Proteins; D005136:Eye Proteins; D012964:Sodium; D001205:Ascorbic Acid; D011188:Potassium