A histopathologic study of retinal lesions inflicted by transscleral iontophoresis.

In the present study, retinal lesions were induced by transscleral iontophoresis (1.5 mA) in rabbits. The size and severity of the lesions increased with the duration of application (2-25 min). No lesion was noted after less than 1 min application. Immediately after 5 min iontophoresis, the edematous retina exhibited necrotic retinal pigment epithelium (RPE), loss of outer segments, and thinning of the inner and outer nuclear layers. At 5 days after iontophoresis, there was a proliferation of RPE cells and macrophages in the subretinal space, with thinning of the inner and outer retinal layers continuing. By day 14, the retina had been reduced to a glial membrane. Immediately after 15 min iontophoresis, the damaged retina appeared in a mummified form containing no cellular elements. By day 5 thereafter, macrophages and actively proliferating RPE cells had been noted in the necrotic retina. By day 14, a glial membrane had formed.