A pneumovitrector for the diagnostic biopsy of the vitreous

A full-function vitrectomy instrument (pneumovitrector) developed by the author is described. This instrument is composed of an aspirating and cutting system combined with an infusion line for injecting air or gas into the vitreous cavity. Simultaneous injection of gas and removal of the vitreous pneumovitrectomy allows for a large vitreous biopsy specimen that has not been diluted with infusion fluid and does not reduce the intraocular pressure. A biopsy of the vitreous is performed for the diagnosis of intraocular infection and ocular involvement in reticulum cell sarcoma (non-Hodgkin's lymphoma). While aspiration of a small amount of liquid vitreous is often sufficient for the diagnosis of bacterial endophthalmitis, a larger volume of liquid and solid vitreous is needed for the establishment of diagnoses such as fungal endophthalmitis and intraocular lymphoma. Diagnostic vitrectomy is performed using either a 20-gauge needle or a 22-gauge needle or a miniaturized vitrectomy system. In the latter case, vitrectomy instruments are often combined with either an infusion cannula or an infusing fiber optic light probe. In most situations, 0.1 to 0.2 ml of vitreous is removed prior to injection and replacement of the volume of the vitreous , in order to obtain the maximum amount of undiluted vitreous for culture or histologic evaluation. Although a complete vitrectomy can be performed and the aspirate collected in the vitrectomy cassette can be spun down to obtain solid material, this procedure is generally done in the operating room. Aspiration of the vitreous for the biopsy without simultaneous replacement of the vitreous volume limits the amount of biopsy specimen that can be taken and is accompanied by the collapse of the eye as a result of hypotony. To overcome this problem, a miniaturized instrument (pneumovitrector) has been developed by this author.