A. Takeuchi et al., THE RATE AND SOURCE OF ALBUMIN ENTRY INTO SALINE-FILLED EXPERIMENTAL RETINAL DETACHMENTS, Investigative ophthalmology & visual science, 35(11), 1994, pp. 3792-3798
Purpose. To investigate the rate and source of albumin entry into expe
rimental nonrhegmatogenous detachments. Methods. Detachments were made
in Dutch rabbits by injecting Hanks' balanced salt solution into the
subretinal space through a micropipette. Subretinal fluid was withdraw
n 0 to 4 hours later through a similar micropipette and analyzed for o
smolality and albumin content (by gel electrophoresis). Sodium iodate
was injected intravenously in some rabbits to damage the retinal pigme
nt epithelium (RPE). In some rabbits fluorescein isothiocyanate albumi
n (FITC-albumin) was injected intravitreally or intravenously to measu
re its entry into the subretinal fluid by fluorophotometry. Results fr
om 4 to 8 eyes were averaged for each data point. Results. The albumin
concentration and total amount of albumin in the subretinal fluid inc
reased steadily over 4 hours in retinal detachments initially filled w
ith Hanks' solution. Pretreating rabbits with sodium iodate injection
resulted in a 50-fold increase in the rate of albumin entry, although
the levels were still low relative to those of serum. Intravitreal FIT
C- albumin entered the subretinal fluid at a rate independent of sodiu
m iodate damage, but intravenous FITC-albumin only entered the subreti
nal space after RPE damage. Subretinal fluid osmolality remained withi
n the range of 291 to 294 mOsm/kg, irrespective of sodium iodate damag
e or differences in the rate of fluid absorption. Conclusions. These r
esults indicate that albumin can diffuse into the rabbit subretinal sp
ace from both vitreous and bloodstream, although entry from serum requ
ires damage to the RPE. Subretinal fluid appears to be transported act
ively (control eyes) or passively (iodate-damaged eyes) out of the sub
retinal space, despite albumin entry and without major osmolar shifts.