Vitrectomy is surgery to remove some or all of the vitreous humor from the eye. Anterior vitrectomy entails removing small portions of the vitreous humor 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 humor — the eye's clear internal jelly.
Pars plana vitrectomy
Vitrectomy was originated by Robert Machemer with contributions from Thomas M. Aaberg, Sr in late 1969 and early 1970. The original purpose of vitrectomy was to remove clouded vitreous humor — usually containing blood.
The success of these first procedures led to the development of techniques and instruments to remove clouding and also to peel scar tissue off the light sensitive lining of the eye — the retina — membranectomy, to provide space for materials injected in the eye to reattach the retina such as gases or liquid silicone, and to increase the efficacy of other surgical steps such as scleral buckle.
The development of new instruments and surgical strategies through the 1970s and 1980s was spearheaded by surgeon/engineer Steve Charles, M.D. More recent advances have included smaller and more refined instruments for use in the eye, the injection of various medications at the time of surgery to manipulate a detached retina into its proper position and mark the location of tissue layers to allow their removal, and for long term protection against scar tissue formation.
Additional surgical steps
Additional surgical steps involved as part of modern vitrectomy surgeries may include:
Membranectomy – removal of layers of unhealthy tissue from the retina with minute instruments such as forceps (tiny grasping tools), picks (miniature hooks), and visco-dissection (separating layers or tissue with jets of fluid.)
Fluid/air exchange – injection of air into the eye to remove the intraocular fluid from the posterior segment of the globe while maintaining intraocular pressure to temporarily hold the retina in place or seal off holes in the retina. The air pressure is temporary as the posterior segment will soon re-fill with fluid.
Air/gas exchange – injection of gas, or more typically mixed gas and air, into the posterior segment of the globe. Typical gases used are perfluoropropane or sulfur hexafluoride. The gases are mixed with air to neutralize their expansive properties to provide for a longer acting (than air alone) retinal tamponade. The retinal tamponade acts to hold the retina in place or temporarily seal off holes in the retina. The mixed gases disappear spontaneously once they have accomplished their purpose and the posterior segment re-fills with fluid.
Scleral buckling – placement of a support positioned like a belt around the walls of the eyeball to maintain the retina in a proper, attached position.
Conditions which can benefit from vitrectomy include:
Retinal detachment – a blinding condition where the lining of the eye peels loose and floats freely within the interior of the eye. Steps to reattach the retina may include vitrectomy to clear the inner jelly, scleral buckling to create a support for the reattached retina, membranectomy to remove scar tissue, injection of dense liquids to smooth the retina into place, photocoagulation to bond the retina back against the wall of the eye, and injection of a gas or silicone oil to secure the retina in place as it heals.
Macular pucker – formation of a patch of unhealthy tissue in the central retina (the macula) distorting vision. Also called epiretinal membrane. After vitrectomy to remove the vitreous gel, membranectomy is undertaken to peel away the tissue.
Diabetic retinopathy – may damage sight by either a non-proliferative or proliferative retinopathy. The proliferative type is characterized by formation of new unhealthy, freely bleeding blood vessels within the eye (called vitreal hemorrhage) and/or causing thick fibrous scar tissue to grow on the retina, detaching it. Often diabetic retinopathy is treated in early stages with a laser in the physician's office to prevent these problems. When bleeding or retinal detachment occur, vitrectomy is employed to clear the blood, membranectomy removes scar tissue, and injection of gas or silicone with scleral buckle may be needed to return sight. Diabetics should have an eye exam yearly.
Macular holes – the normal shrinking of the vitreous humor with aging can occasionally tear the central retina causing a macular hole with a blind spot blocking sight.
Vitreous hemorrhage – bleeding in the eye from injuries, retinal tears, subarachnoidal bleedings (as Terson syndrome), or blocked blood vessels. Once blood is removed, photocoagulation with a laser can shrink unhealthy blood vessels or seal retinal holes.
Vitreous floaters – deposits of various size, shape, consistency, refractive index, and motility within the eye's normally transparent vitreous humor which can obstruct vision. Here pars plana vitrectomy has been shown to relieve symptoms. Because of possible side effects, however, it is used only in severe cases.
Complications of vitrectomy
Along with the usual complications of surgery, such as infections, vitrectomy can result in retinal detachment. A more common complication is high intraocular pressure, bleeding in the eye, and cataract, which is the most frequent complication of vitrectomy surgery. Many patients will develop a cataract within the first few years after surgery.
Recovery after vitrectomy
Patients use eye drops for several weeks or longer to allow the surface of the eye to heal. In some cases heavy lifting is avoided for a few weeks. A gas bubble may be placed inside the eye to keep the retina in place. If a gas bubble is used, sometimes a certain head positioning has to be maintained, such as face down or sleeping on the right or left side. It is very important to follow the physician’s specific instructions. The gas bubble will dissolve over time, but this takes several weeks. Flying should be avoided while the gas bubble is still present. Problems such as return of the original condition, bleeding, or infection from the surgery may require additional treatment or can result in blindness. In the event that the patient would need to remain face down after surgery, a vitrectomy support system can be rented to help aid during the recovery time. This particular equipment may be used for as little as five days to as long as three weeks.
Vision after vitrectomy
The return of eyesight after vitrectomy depends on the underlying condition which prompted the need for surgery. If the eye is healthy but filled with blood, then vitrectomy can result in return of 20/20 eyesight. With more serious problems, such as a retina which has detached several times, final sight may be only sufficient to safely walk (ambulatory vision) or less.
In 1996, Spalding Gray (June 5, 1941 – ca. January 10, 2004), an American actor, screenwriter and playwright, released Gray's Anatomy, a film monologue describing his experiences dealing with a macular pucker and his decision to undergo surgery.