High-Energy Electrons Used to Inhibit Experimental Intraocular Proliferation and Detachment

Abstract

Irradiation of rabbit eyes with high-energy electrons was used to test the inhibition of experimental intraocular proliferation and retinal detachment, produced by intravitreal implantation of 250,000 homologous fibroblasts. After irradiation with 2,000 rad, started 5 days after implantation, 45% of eyes (9 of 20) still manifested traction detachment. When the dose was increased to 3,000 rad and radiation treatment was started 1 day after implantation, proliferation and traction detachment were observed in only 10% of eyes (2 of 20). No acute damage to retinal tissue or nerve fibers was observed. Because it is easily available, simple in application and dose adjustment, and without toxic side effects, radiation therapy should be considered as an effective alternative to drug treatment for the inhibition of intraocular proliferation and detachment. Statistically significant results of this investigation suggest its use combined with surgery in certain reproliferative cases in man.

Experimental Posterior Perforating Ocular Injury in Rabbit Eyes: Effects of Radiotherapy with or without Intravitreal Cyclosporin on Vitreous Proliferation

“…In doses higher than 3,000 rad (30 Gy), tissue damage could be caused by irradiation itself [20] . In another study, Binder et al [21] used a dose of 3,000 cGy (30 Gy) to inhibit proliferative vitreoretinopathy in human eyes, but did not fi nd a statistically signifi cant difference between irradiated and nonirradiated eyes.…”

Experimental perforating injury with high energy electrons to inhibit intraocular proliferation

“…Gamma radiation has proven its antiproliferative effect in the treatment of intraocular tumors, pseudopapillar edema, and malignant exophthalmus of human eyes. Binder et al (1987) demonstrated that in the fibroblast model the fractionized radiation therapy with high energy electrons and a dose of 3000 cGy is more effective for the treatment of experimental PVR than various antiproliferative drugs (Binder 1982;Binder et al 1987;Blumenkrantz et al 1984;Lemor et al 1986;Tan0 et al 1980;Cleary & Ryan 1979). The retinal detachment rate was reduced from 85% in the control group to 10% in the treated group during a period of 6 weeks.…”

“…Reduction of this proliferation is therefore one of the main problems in this disease. Antiproliferative preparations, such as dexamethason alcohol, triamcinolone acitonide, 5-fluouracil, daunomicin, and cholchicin, have proven their effectiveness under experimental conditions (Binder 1982;Binder et al 1987;Blumenkranz et al 1984;Lemor et al 1986;Tan0 et al 1980;Cleary & Ryan 1979). Their disadvantages, however, like rapid absorption, inadequate solubility, and possible toxicity have also become manifest.…”

“…In our search for a less toxic and less complicated alternative to the pharmacologic treatment of experimental intraocular proliferation we found fractionized radiation therapy with high energy electrons and a dose of 3000 cGy to be very effective in the treatment of experimental proliferative vitreoretinopathy (PVR) created by fibroblast injection (Binder et al 1987). …”

Proliferative vitreoretinopathy ? is it anything more than wound healing at the wrong place?

“…Numerous experimental models of PVR have been presented (Table 1), one of them using bacteria, blood, and vital dyes long before the terms 'PVR' or 'massive periretinal proliferation (MPP)' were coined [37], and some form of trauma is always applied to the vitreoretinal interface, be it an incision [26,27], a perforating trauma [113], or the inoculation of a multitude of agents into the vitreous, mostly freshly harvested or cultured cells (Table 1). Initially, the rationale of those studies was the wish to reproduce the findings observed in human disease and to obtain a high PVR-rate for further analysis, but soon it became obvious that the real value of experimental models of PVR lies in the evaluation of surgical techniques [28,31], even more of therapeutic drugs [133], and, with minor significance, of therapeutic irradiation [12]. The latter two must be considered an adjunct to highly developed surgical techniques.…”