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.
Even before the modern era, some surgeons performed crude vitrectomies. For instance, Dutch surgeon Anton Nuck (1650–1692) claimed to have removed vitreous by suction in a young man with an inflamed eye.[1] In Boston, John Collins Warren (1778–1856) performed a crude limited vitrectomy for angle closure glaucoma.[2]
Each anesthesia technique has its advantages and disadvantages, and the selection of anesthesia will depend on various factors including the surgeon's and patient's choice, disease and additional surgical steps required.[citation needed]
Pars plana vitrectomy
Vitrectomy was originated by Robert Machemer[3] 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.[citation needed]
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 and engineer Steve Charles.[4] 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. Several technologies and systems exist to treat vitrectomy.[5]
Additional surgical steps
Vitrectomy instruments
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 of tissue with jets of fluid.) This layer of unhealthy tissue is called an epiretinal membrane and it can occur in anyone, but is more likely to occur in the elderly or in people who have had prior eye disease or eye surgery.[6] If the patient has an epiretinal membrane and is also complaining of symptoms such as decreased visual acuity, then a membranectomy is performed in addition to the vitrectomy. Complications of this additional step are similar to complications of the standard vitrectomy procedure.[6]
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 – In some cases, gas can be used to help hold the retina in place. Gas, or more typically mixed gas and air, is injected through the sclera and into the posterior segment of the globe. This procedure is often referred to as pneumatic retinopexy. 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.[7]
Silicone oil injection – Similar to an air/gas exchange, or pneumatic retinopexy, the eye can also be filled with liquid silicone to hold the retina in place.[7] In contrast to the pneumatic retinopexy, however, the silicone oil remains in the eye until it is later removed surgically. Oils have less surface tension and buoyancy than gases so the tension exerted by the oil is about 30 times less than that of the gas.[8]
Photocoagulation – In cases when there is a tear in the retina, or when there are unhealthy damaging blood vessels (which can be seen in patients with diabetic retinopathy), laser treatment can be used.[7] In such cases, the laser is used to seal the hole or prevent growth of the unhealthy, damaging blood vessels.
Scleral buckling – placement of a support positioned like a belt around the eyeball to maintain the retina in a proper, attached position. This is referred to as an "exoplant". Placement of the scleral buckle for patients who have had a retinal detachment has been shown to lead to reattachment approximately 80 to 90 percent of the time after one surgery. In cases of failure, most patients are treated with vitrectomy.
Lensectomy – In some cases, a lensectomy, or "cataract surgery", is done in conjunction with the vitrectomy. This extra procedure is performed when the lens of eye is cloudy (cataract), damaged during the vitrectomy, if there is attached to scar tissue, or if the pressure in the eye needs to be lowered (as in the case with some glaucomatous patients).[7]
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 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.[9] Because of possible side effects it is used only in severe cases.
Complications
There are a few complications that can result from vitrectomy surgery. Cataract is the most frequent complication. Many patients will develop a cataract within the first few years after surgery.[10] Because there have been no published controlled trials evaluating the benefits and risks stemming from post vitrectomy cataract surgery, ophthalmologists have no clear evidence to rely upon when counseling patients about cataract surgery.[11]
Other common complications include high intraocular pressure, bleeding in the eye, and retinal edema, swelling in the back of the eye.[12] In most cases, the retinal edema can be managed with over-the-counter medication. In severe cases, this swelling can be treated with intra-ocular injections.[13]
More severe complications after a vitrectomy are endophthalmitis (inflammation of the fluids in the eye) or suprachoroidal hemorrhage (bleeding above the choroidal layer of the eye). Rates of these complications have been reported to be less than 0.5%.
Lastly, although vitrectomy surgery is often done to correct retinal detachments, a subsequent retinal detachment is a possible complication as well. Rates of retinal detachment have been reported to be less than 5%.
A wristband that provides a warning regarding risks post 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 (posturing) has to be maintained, such as face down or sleeping on the right or left side. 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. A Cochrane review found that in one study, cataract surgery was needed within two years for about half of the eyes operated on for idiopathic macular hole, and retinal detachment was found in about one in 20 eyes.[14]
Showing eyes shortly after vitrectomy and removal of bandages
The return of eyesight after vitrectomy depends on the underlying condition which prompted the need for surgery. It also depends on patient age and their visual acuity before surgery. For example, 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.
With a retinal detachment, some very important considerations are how long the retina has been detached, and what part of the retina was detached. For example, if the macula of the retina comes off too, outcomes might not be as good as they would if the macula was still attached. Also, the longer the time between the detachment and the reattachment, the worse the outcomes. Some ophthalmologists believe that if a patient has a retinal detachment that involves the macula and it has been longer than 6 months, then a vitrectomy for that patient is unlikely to help. However, recent studies have shown that visual improvement might still be found in these patients. Given the high variability between outcomes for different patients with retinal detachments, it is very important to be examined by an ophthalmologist as soon as possible.
A Cochrane review found vitrectomy for patients with idiopatic macular hole improved visual acuity by about 1.5 lines on an acuity chart. Macular hole closure was 76% in those treated with vitrectomy compared to 11% in those observed.[14]
Cultural references
In 1996, Spalding Gray, 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.[15]
Diabetic retinopathy, is a medical condition in which damage occurs to the retina due to diabetes mellitus. It is a leading cause of blindness in developed countries.
Floaters or eye floaters are sometimes visible deposits within the eye's vitreous humour, which is normally transparent, or between the vitreous and retina. They can become particularly noticeable when looking at a blank surface or an open monochromatic space, such as blue sky. Each floater can be measured by its size, shape, consistency, refractive index, and motility. They are also called muscae volitantes, or mouches volantes. The vitreous usually starts out transparent, but imperfections may gradually develop as one ages. The common type of floater, present in most people's eyes, is due to these degenerative changes of the vitreous. The perception of floaters, which may be annoying or problematic to some people, is known as myodesopsia, or, less commonly, as myodaeopsia, myiodeopsia, or myiodesopsia. It is not often treated, except in severe cases, where vitrectomy (surgery), laser vitreolysis, and medication may be effective.
Retinoschisis is an eye disease characterized by the abnormal splitting of the retina's neurosensory layers, usually in the outer plexiform layer. Retinoschisis can be divided into degenerative forms which are very common and almost exclusively involve the peripheral retina and hereditary forms which are rare and involve the central retina and sometimes the peripheral retina. The degenerative forms are asymptomatic and involve the peripheral retina only and do not affect the visual acuity. Some rarer forms result in a loss of vision in the corresponding visual field.
The National Eye Institute (NEI) is part of the U.S. National Institutes of Health (NIH), an agency of the U.S. Department of Health and Human Services. The mission of NEI is "to eliminate vision loss and improve quality of life through vision research." NEI consists of two major branches for research: an extramural branch that funds studies outside NIH and an intramural branch that funds research on the NIH campus in Bethesda, Maryland. Most of the NEI budget funds extramural research.
Retinopathy of prematurity (ROP), also called retrolental fibroplasia (RLF) and Terry syndrome, is a disease of the eye affecting prematurely born babies generally having received neonatal intensive care, in which oxygen therapy is used because of the premature development of their lungs. It is thought to be caused by disorganized growth of retinal blood vessels and may result in scarring and retinal detachment. ROP can be mild and may resolve spontaneously, but it may lead to blindness in serious cases. Thus, all preterm babies are at risk for ROP, and very low birth-weight is an additional risk factor. Both oxygen toxicity and relative hypoxia can contribute to the development of ROP.
Eye surgery, also known as ophthalmic surgery or ocular surgery, is surgery performed on the eye or its adnexa. Eye surgery is part of ophthalmology and is performed by an ophthalmologist or eye surgeon. The eye is a fragile organ, and requires due care before, during, and after a surgical procedure to minimize or prevent further damage. An eye surgeon is responsible for selecting the appropriate surgical procedure for the patient, and for taking the necessary safety precautions. Mentions of eye surgery can be found in several ancient texts dating back as early as 1800 BC, with cataract treatment starting in the fifth century BC. It continues to be a widely practiced class of surgery, with various techniques having been developed for treating eye problems.
Phacoemulsification is a cataract surgery method in which the internal lens of the eye which has developed a cataract is emulsified with the tip of an ultrasonic handpiece and aspirated from the eye. Aspirated fluids are replaced with irrigation of balanced salt solution to maintain the volume of the anterior chamber during the procedure. This procedure minimises the incision size and reduces the recovery time and risk of surgery induced astigmatism.
Retinal detachment is a disorder of the eye in which the retina peels away from its underlying layer of support tissue. Initial detachment may be localized, but without rapid treatment the entire retina may detach, leading to vision loss and blindness. It is a surgical emergency.
A posterior vitreous detachment (PVD) is a condition of the eye in which the vitreous membrane separates from the retina. It refers to the separation of the posterior hyaloid membrane from the retina anywhere posterior to the vitreous base.
A scleral buckle is one of several ophthalmologic procedures that can be used to repair a retinal detachment. Retinal detachments are usually caused by retinal tears, and a scleral buckle can be used to close the retinal break, both for acute and chronic retinal detachments.
Intravitreal is a route of administration of a drug, or other substance, in which the substance is delivered into the vitreous humor of the eye. "Intravitreal" literally means "inside an eye". Intravitreal injections were first introduced in 1911 when Ohm gave an injection of air into the vitreous humor to repair a detached retina. In the mid-1940s, intravitreal injections became a standard way to administer drugs to treat endophthalmitis and cytomegalovirus retinitis.
Epiretinal membrane or macular pucker is a disease of the eye in response to changes in the vitreous humor or more rarely, diabetes. Sometimes, as a result of immune system response to protect the retina, cells converge in the macular area as the vitreous ages and pulls away in posterior vitreous detachment (PVD).
A macular hole is a small break in the macula, located in the center of the eye's light-sensitive tissue called the retina.
Intraocular hemorrhage is bleeding inside the eye. Bleeding can occur from any structure of the eye where there is vasculature or blood flow, including the anterior chamber, vitreous cavity, retina, choroid, suprachoroidal space, or optic disc.
Proliferative vitreoretinopathy (PVR) is a disease that develops as a complication of rhegmatogenous retinal detachment. PVR occurs in about 8–10% of patients undergoing primary retinal detachment surgery and prevents the successful surgical repair of rhegmatogenous retinal detachment. PVR can be treated with surgery to reattach the detached retina but the visual outcome of the surgery is very poor. A number of studies have explored various possible adjunctive agents for the prevention and treatment of PVR, such as methotrexate, although none have yet been licensed for clinical use.
Bascom Palmer Eye Institute is the University of Miami School of Medicine's ophthalmic care, research, and education center. The institute is based in the Health District of Miami, Florida, and has been ranked consistently as the best eye hospital and vision research center in the nation.
Vitreous hemorrhage is the extravasation, or leakage, of blood into the areas in and around the vitreous humor of the eye. The vitreous humor is the clear gel that fills the space between the lens and the retina of the eye. A variety of conditions can result in blood leaking into the vitreous humor, which can cause impaired vision, floaters, and photopsia.
Vitreomacular adhesion (VMA) is a human medical condition where the vitreous gel of the human eye adheres to the retina in an abnormally strong manner. As the eye ages, it is common for the vitreous to separate from the retina. But if this separation is not complete, i.e. there is still an adhesion, this can create pulling forces on the retina that may result in subsequent loss or distortion of vision. The adhesion in of itself is not dangerous, but the resulting pathological vitreomacular traction (VMT) can cause severe ocular damage.
Intravitreal injection is the method of administration of drugs into the eye by injection with a fine needle. The medication will be directly applied into the vitreous humor. It is used to treat various eye diseases, such as age-related macular degeneration (AMD), diabetic retinopathy, and infections inside the eye such as endophthalmitis. As compared to topical administration, this method is beneficial for a more localized delivery of medications to the targeted site, as the needle can directly pass through the anatomical eye barrier and dynamic barrier. It could also minimize adverse drug effects on other body tissues via the systemic circulation, which could be a possible risk for intravenous injection of medications. Although there are risks of infections or other complications, with suitable precautions throughout the injection process, chances for these complications could be lowered.
Sickle cell retinopathy can be defined as retinal changes due to blood vessel damage in the eye of a person with a background of sickle cell disease. It can likely progress to loss of vision in late stages due to vitreous hemorrhage or retinal detachment. Sickle cell disease is a structural red blood cell disorder leading to consequences in multiple systems. It is characterized by chronic red blood cell destruction, vascular injury, and tissue ischemia causing damage to the brain, eyes, heart, lungs, kidneys, spleen, and musculoskeletal system.
↑ Machemer R (August 1995). "The development of pars plana vitrectomy: a personal account". Graefe's Archive for Clinical and Experimental Ophthalmology. 233 (8): 453–68. doi:10.1007/bf00183425. PMID8537019.
↑ Petersen J. (1987). "The physical and surgical aspects of silicone oil in the vitreous cavity". Graefes Arch Clin Exp Ophthalmol. 225 (6): 452–6. doi:10.1007/bf02334175. PMID3678857. S2CID9857386.
↑ Roth M, Trittibach P, Koerner F, Sarra G (September 2005). "[Pars plana vitrectomy for idiopathic vitreous floaters]". Klinische Monatsblätter für Augenheilkunde. 222 (9): 728–32. doi:10.1055/s-2005-858497. PMID16175483. S2CID260205524.
↑ Benson WE, Brown GC, Tasman W, McNamara JA (December 1988). "Complications of vitrectomy for non-clearing vitreous hemorrhage in diabetic patients". Ophthalmic Surgery. 19 (12): 862–4. PMID3231410.
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