Vitrectomy is a surgical removal of some or all of the vitreous humor from the eye. It may be performed when there is a retinal detachment, since removing the vitreous gel gives the ophthalmologist better access to the back of the eye. Vitrectomy may also be performed to clear blood and debris from the eye, to remove scar tissue, or to alleviate traction on the retina.
Anterior vitrectomy entails removing small portions of the vitreous from the front structures of the eye - often because these are tangled in an intraocular lens or other structures. Pars plana vitrectomy is a general term for a group of operations accomplished in the deeper part of the eye, all of which involve removing some or all of the vitreous - the eye's clear internal jelly.