[Retinal lesions after transvitreal use of ultrasound]

Removal of a dislocated natural lens into the vitreous cavity is now performed using vitreous surgery techniques combined with intravitreal phacoemulsification via the pars plana. In contrast to the earlier external surgical approach to luxated lenses, postoperative complications, particularly retinal detachment, are rare. However, retinal damage may occur when ultrasound is used at therapeutic intensities. We therefore examined ultrasound-induced retinal lesions produced in rabbit eyes by treating the retina directly with ultrasound using the type of tip conventionally used for pars plana lensectomy (Fragmatom). Histological evaluation showed that acoustic energy at low intensities led primarily to damage of photoreceptor cell outer and inner segments, which correlated with a discrete pigment reaction visible on ophthalmoscopy. More severe lesions were seen in destruction of the inner retina and resulted in retinal blanching or caused a small retinal break. High energy led to a full-thickness retinal defect with rupture of choroidal vessels and heavy bleeding into the vitreous cavity. Within these lesions the retinal pigment epithelium and Bruch's membrane were also disturbed. Our ophthalmoscopical and histological findings indicate that the mechanism of ultrasound-induced chorio-retinal lesions is not exclusively thermal in nature and differs from other coagulation modalities.