Eqn. Eye Res. (1986) 42, 467477 Ocular Fluorophotometry in the Normal- and Diabetic Monkey CARL W. JONES, JOSE G. CUNHA-VAZ, RAN C. ZEIMER, MARK M. RUSIN, PATRICIA W. LANGENBERG, CHARLES M. VYGANTAS, MARK 0. M. Tso AND OLGA JONASSON Departments of Ophthalmology, Surgery, and Public Health Sciences (Biometry), University of Illinois College of Medicine, Chicago, Illinois, U.S.A. (Received 19 June 1985 and accepted 25 October 1985) Kormal- and diabetic rhesus monkeys without retinopathy demonstrable by ophthalmoscopy or fluorescein angiography were examined with ocular fluorophotometry to detect alterations in their blood-ocular barriers. All vitreous Auorophotometry values were corrected for fluorescence attributable to background levels and then normalized to a blood fluorescein level of 10 pg ml-‘. Reproducibility studies demonstrated an average coefficient of variation of 017 for all animals combined. Insulin-dependent monkeys, both pancreatectomized and strepozotocin-treated, dem- onstrated significantly higher posterior vitreous fluorescence levels than either control animals or monkeys treated with streptozotocin that were not insulin-dependent. These results cannot be attributed to differences in fluorescein binding or to vitreous abnormalities. However, 14 out of 24 (58 %) of the insulin-dependent animals exhibited posterior vitreous fluorescence values within two standard deviations of the control mean. No correlation was apparent between the vitreous values and age or duration of treatment. No difference in anterior chamber concentrations was found between groups after correction. Our results indicate that alterations in the blood-retinal barrier can occur in insulin-dependent diabetic monkeys before development of retinopathy. Key words: diabetes; ocular fluorophotometry ; blood-retinal barrier; monkey; permeability. 1. Introduction Ocular fluorophotometry is a non-invasive technique that measures the concentration profiles of fluorescent dyes in the ocular media. The results from this method augment information obtained from fluorescein angiography, which may be performed in the samepatients. Fluorophotometry detects fluorescein concentrations that are several orders of magnitude less than is possible to obtain with angiography. Therefore, fluorophotometry has been used as a probe to examine diabetic patients at a stage of their diseasebefore fluorescein leakage can be observed by retinal angiography. Cunha-Vaz and other investigators have demonstrated higher levels of fluorescein in the posterior vitreous of the eyes of diabetic persons compared with nondiabetic control subjects in somestudies (Cunha-Vaz, Abreu, and Campos, 1975; Waltman et al., 1978; IY.ernell, Larsson, Ludvigsson and Tenland, 1980; White, Waltman, Krupin and Santiago, 1982; Bursell et al., 1984; Kayazawa, 1984; Cunha-Vaz et al., 1985). These results have been interpreted as early evidence of alteration of the blood-ocular barriers in diabetes, and may be one of the first changesto occur in the diabetic eye (Cunha-Vaz, Fonseca, Abreu and Ruas, 1979; Cunha-Vaz, Goldberg, Vygantas and Noth, 1979). Over the past 12 years we have studied various pathologic manifestations of the diabetic state in the monkey. During this time we have not observed the advanced macro- or microangiopathy that often typifies long-standing, severediabetes in human Please send reprint requests to Dr Cunha-Vaz, Department of Ophthalmology. Eye and Ear Infirmary, 1855 W. Taylor Street, Chicago, IL 60612. 00144835/86/050467 + 1 I $0390/O 0 1986 Academic Press Inc. (London) Limited