ABSTRACT
Calcein was used in vitreous fluorophotometry (VF) to study the blood-retinal barrier (BRB) in rats with streptozocin-induced diabetes. Calcein was injected intravenously in 18 diabetic rats and sodium fluorescein (NaF) in 12 diabetic rats. VF was performed at 1, 2, 4, 6, 9, and 21 hours following the single injection in these diabetic rats; it was also performed at these times in 24 normal (control) rats. On another day, the same experiment was performed using NaF. There was no significant difference between the two dyes in the diabetic and nondiabetic rats at 1 hour. However, at 4 hours and at later measurement points, there was dye leakage into the vitreous, peaking at 9 hours; the leakage was significantly greater in the diabetic rats. Also, the leakage was significantly greater with calcein than it was with NaF. The data demonstrate that calcein circulates longer and at higher levels than NaF and thus is probably more useful for BRB integrity studies.
Subject(s)
Blood-Retinal Barrier/physiology , Diabetic Retinopathy/physiopathology , Fluoresceins/administration & dosage , Animals , Diabetes Mellitus, Experimental/complications , Fluorophotometry/methods , Injections, Intravenous , Rats , Sodium Fluoride/administration & dosage , Spectrometry, Fluorescence , StreptozocinABSTRACT
We studied the effect of short-term hyperthermia on sclera, choroid, and retina by delivering microwave radiation (2.45 GHz) for 1 minute to 12 eyes of Dutch belted pigmented rabbits. Four eyes each were treated with 43 degrees C, 45 degrees C, and 47 degrees C and followed for 4 weeks. The 43 degrees C group showed minimal disruption of retinal pigment epithelium and outer retina, with pigment migration; the 45 degrees C and 47 degrees C groups showed complete retinal and RPE damage, pigment migration, and glial proliferation. At the same time, the sclera and choroid in all of the eyes remained essentially unchanged. We conclude that microwave-induced hyperthermia can create retinal scarring without significant damage to sclera and choriocapillaris. The next experimental step will be to refine the microwave delivery system to ensure predictable and reproducible lesions.
Subject(s)
Choroid/blood supply , Microwaves/adverse effects , Retina/radiation effects , Sclera/radiation effects , Animals , Body Temperature , Capillaries/radiation effects , Hyperthermia, Induced/adverse effects , Pigment Epithelium of Eye/pathology , Pigment Epithelium of Eye/radiation effects , Rabbits , Retina/pathology , Sclera/ultrastructureABSTRACT
A vitreous fluorophotometry study was performed on rabbits to compare the characteristics of carboxyfluorescein and calcein with those of sodium fluorescein. Our results demonstrated that carboxyfluorescein and calcein attained midvitreous concentrations similar in magnitude to fluorescein approximately one hour after injection of the dye. As long as three to four hours after injection of the dye, the mean fluorescence levels of calcein in the chorioretina were much higher than those of sodium fluorescein and carboxyfluorescein. These results point out that calcein has potential experimental and clinical use as a probe of the blood-ocular barrier as well as in experimental and clinical angiography of the fundus.
