In vitro and animal experiments were performed to evaluate the character of retina and pigment epithelium (RPE) damage induced by ultrasonic stream from the tip of a phacofragmentor and to establish the protective properties of perfluorocarbon liquid (PFCL).Methods
During mechanical vitrectomy in 12 rabbit eyes, the retina were exposed to ultrasound from different distances and with different powers, with and without PFCL. Electron microscopic examination was then performed to assess damage.Results
Ultrasound failed to penetrate the layer of PFCL in vitro. In eyes not injected with PFCL, exposure to the stream from 2 mm and 4 mm at both 50% and 100% powers led to retinal hole formation within 45 to 155 seconds. Damage to the RPE was found in the projection of the hole and within 1 mm from its edge under intact retina. After exposure from 6 mm and in eyes injected with PFCL, the retina and RPE were unchanged.Conclusion
It is concluded that the ultrasonic stream from a phacofragmentor may damage the retina sufficiently to cause tears, but that the interface between perfluoro-n-octane and intraocular fluid provides a reflective surface that protects the posterior pole from the stream induced by ultrasound.