Occasionally, during cataract surgery, the natural lens of the eye (which is the cataract), or a portion of the lens, falls into the vitreous cavity. This may cause inflammation in the eye which can cause the normal pressure in the eye to rise to dangerous levels. The dislocated lens can be removed by vitrectomy surgery.

Another problem than can occur during or after cataract surgery is the dislocation of the plastic lens implant, the intraocular lens (IOL); the intraocular lens can fall into the vitreous cavity. This can also occur following trauma to the eye. Vitreous surgery can be done to place the plastic intraocular lens in its proper position. The vitreous is removed and then the lens is grasped with forceps and placed into position where it may be sutured in order to keep it stable.