Vitreous fluorophotometry in the alloxan- and streptozocin-treated rat

Since serum fluorescein levels are altered in various experimental states, we examined the relationship between serum and vitreous fluorescein levels. We also injected streptozocin, alloxan, and alloxan with glucose pretreatment do determine whether alterations in the blood-retinal barrier are directly attributable to drug toxicity. When corrected for serum levels, one- and two-hour vitreous fluorescein levels increased above prediabetic values two days after streptozocin or alloxan administration; two-hour readings were higher. Rats treated with alloxan plus glucose did not become diabetic or show elevated vitreous fluorescein levels. Insulin treatment of alloxan-induced diabetic rats resulted in normal vitreous readings without normoglycemia. These results suggest that vitreous readings should be corrected for serum levels and that observations at two hours could be more sensitive than at one hour. Furthermore, the observed alterations in blood-retinal barrier function are not attributed to drug toxicity.