Overview of Vitrectomy
Pars plana vitrectomy (PPV) is a type of eye surgery first introduced by Robert Machemer. It’s a method used to treat many diseases that affect the back part of the eye, known as the vitreoretinal area. This surgery requires high-level technical skill and knowledge to achieve good outcomes. If successful, PPV can restore vision and improve the quality of life for patients suffering from various vitreoretinal diseases.
Nevertheless, like any surgery, there can be risks of complications. If not carried out correctly, these complications could lead to serious problems, even blindness. But the chances of these happening are low when the operation is done properly. Hence, it’s vital that the healthcare providers performing the operation have a thorough understanding of the procedure, including when to use it, how to carry it out, and how to take care of the patient after the surgery.
Anatomy and Physiology of Vitrectomy
The retina is a part of the eye that helps send what we see to our brain via the optic nerve. It’s made up of nerves, special cells called neurons and glial cells, and blood vessels. Just like the Central Nervous System (CNS) that controls most functions of the body and mind, these components are crucial for the retina’s job. The retina is built in various layers, starting from the inner part to the outer, they include the internal limiting membrane, nerve fiber layer, the ganglion cell layer, inner plexiform, inner nuclear, outer plexiform, outer nuclear, external limiting membrane, inner and outer segments of the photoreceptors, and the retinal pigment epithelial layer.
The vitreous is a gel-like substance that fills a part of the eye called the vitreous cavity and it sticks to the retina at certain points. As we get older, this gel can become more liquid and may detach from the retina, which may lead to tears, breaks, and can result in a detached retina. In a procedure called a pars plana vitrectomy (PPV), the gel is removed to clear away any blood or other substances blocking our view, therefore allowing access to the retina which helps restore our sight. The gel is replaced by a saltwater solution during the treatment.
The choroid, another structure in the eye, offers support to the retina as well as blood supply to its outer layers. Knowing where the blood supply comes from is essential during a PPV to avoid accidental harm, like cutting off the blood supply (ischemia) or causing bleeding (hemorrhage). The blood that nurtures the inner part of the retina comes mainly from the central retinal artery, which divides into other small blood vessels. These small vessels provide most of the blood for the inner retinal layers. The veins of the retina drain into the central retinal vein like a river flowing into a lake. The retina does not have lymphatic vessels, which in other parts of the body help to fight infections and maintain body fluids balance.
In a PPV procedure, doctors access the vitreous cavity through the pars plana, which is the flat part of the ciliary body. The ciliary body is a part of the eye that produces aqueous humor, the clear fluid filling the front of the eye. This area is chosen for PPV because it allows good access to the vitreous gel and doesn’t harm the eye much. Importantly, the pars plana does not have any sensory function and neither produces the clear fluid nor vitreous gel. This is crucial as the eye needs to create new vitreous gel to replace the one removed during a PPV.
Why do People Need Vitrectomy
A vitrectomy is a type of surgery that allows the surgeon to work directly with the vitreous and retina in your eye. This could be recommended for several reasons, and it all depends on what specific issue you are dealing with in relation to either your vitreous or retina.
Most commonly, a vitrectomy is performed when something is making the vitreous of your eye become cloudy, which in turn hurts your vision. For instance, blood building up in the vitreous – a situation known as vitreous hemorrhage. Many conditions can lead to this such as diabetic retinopathy, injuries to the eye, tumors inside the eye, and certain eye-related diseases. If the blood doesn’t clear up on its own, then the vitrectomy surgery is needed to fix the issue.
Another reason for a vitrectomy is for an issue known as rhegmatogenous retinal detachment. This happens when a tear or hole in your retina allows fluid to leak beneath the retina, separating the retina’s layers and causing vision loss. When people have this issue, they usually report visual disturbances, like a curtain-like shadow in their vision. If the fluid spreads to involve the center of the retina, this is known as a ‘mac-off’ detachment. If the fluid buildup has not reached the center of the retina, it is known as a ‘mac-on’ detachment. In both cases, a vitrectomy is performed to remove the fluid and any forces tugging at the retinal tear, which is then sealed up to prevent further fluid access.
Vitrectomies can also be performed to relieve pulling on the retina that’s affecting your vision. This pulling is called ‘traction.’ Conditions like epiretinal membranes and macular holes can cause this and usually affect your central vision. In these cases, a vitrectomy is performed to help relieve this traction and repair the holes or tears.
Additionally, serious diseases like sickle cell or diabetic retinopathy can cause another form of traction, leading to a tractional retinal detachment. To treat the condition, the vitrectomy is performed to relieve the traction causing the detachment and prevent the return of such issues.
Lastly, vitrectomies can be performed to remove a hemorrhage beneath the center of the retina that can affect your vision or to remove foreign objects from the eye that are a result of an injury. In the case of an injury, other procedures might be necessary, emphasizing the importance of having a multi-disciplinary treatment approach.
When a Person Should Avoid Vitrectomy
There are usually no situations that completely rule out Pars Plana Vitrectomy (PPV), a type of eye surgery. However, patients with other serious health conditions may be considered too risky for this operation, especially if the surgery is not urgent. If PPV is necessary to prevent permanent vision loss, the doctor may request a more comprehensive health examination by the anaesthesiologist, with the pre-surgery approval from other specialists as needed.
The only situation where PPV may be reconsidered relates to eye tumours. Particularly with tumours that don’t stick to the tissue around them well, like retinoblastoma, they can spread during a PPV. This spreading is a concern because aggressive tumours can cause severe health problems and can even be deadly if they spread elsewhere in the body.
We must remember, this doesn’t apply to all eye tumours, and there are many cases where PPV is vital in managing these aggressive tumours. So, the approach can differ based on each case and it’s best to work in partnership with an eye cancer specialist for decision-making.
Equipment used for Vitrectomy
Pars Plana Vitrectomy (PPV) is a specialized type of eye surgery that is always performed in an operating room. This means that it requires the usual surgical equipment, but because it’s a unique type of operation, extra tools are needed as well. According to the American Academy of Ophthalmology, the standard equipment for this type of surgery, along with some new additions, include:
* Eyelid speculum: a tool to keep your eyelid open during the operation
* Fine-toothed forceps: small pliers to handle tiny objects
* Wescott scissors: special scissors for medical use
* Toothed forceps: Another type of small pliers
* 20-gauge micro-vitreoretinal blade: a very small surgical blade mainly used to create bigger openings in the sclera (the white part of your eye). This might be needed when larger foreign objects are being removed from inside the eye.
* Infusion cannula with an inserter-cannula system: a small tube used to deliver fluid into your eye
* Vitrectomy suction/cutting system: a device to remove and cut the vitreous humor (a jelly-like substance that fills your eye)
* Corneal lens ring: a tool to support the examination of the eye
* Contact lenses: lenses of different widths are used to focus on different parts of your eye
Additionally, there’s a trocar and cannulas of 23, 25, and 27g sizes. An indirect ophthalmoscope with 20 and 30 diopter lenses is used to examine the inside of your eye. There are also forceps, scissors, and picks specifically designed for intraocular use. In some cases, endolasers, indirect lasers, or cryotherapy probes might be required. The surgeon may use perfluorocarbon liquid, gases, or silicone oil if necessary. A system for inverting wide-angle vitrectomy lenses can help to monitor the operation.
Recently, the use of 3-dimensional systems or a ‘heads-up display’ has become more popular, as they provide many benefits. They offer better ergonomics for surgeons, require less light, and improve training for students and trainees as everyone can observe the three-dimensional details of the procedure.
In some combined cases, additional specialized equipment may be needed. For example, when PPV is combined with anterior segment surgery or with oculoplastic surgery that deals with lid and orbital cases.
Who is needed to perform Vitrectomy?
The operation and the care you receive after the procedure will be carried out by a specialist doctor known as a ‘vitreoretinal surgeon’. This type of surgeon is an expert in problems related to the retina, which is a part of the eye that helps you see. Sometimes, a junior doctor or a student doctor, supervised by a more experienced doctor, may carry out the operation.
If the operation is needed because you have been injured, more eye surgeons may need to join in to help with the repair. If there are any complications, like high pressure inside your eye, a glaucoma specialist may be brought in. Glaucoma is a condition that damages your eye’s optic nerve and can lead to vision loss.
If there are eye tumors that have spread to the area around the eye or other parts of the body, a surgeon who specializes in the structure of the eye (an ‘oculoplastic surgeon’) or a doctor who specializes in cancer (‘oncologic specialist’) might need to be involved.
Preparing for Vitrectomy
If a patient is in a critical condition, a surgery called ‘PPV’ (pars plana vitrectomy) might need to be done urgently, leaving less time for pre-surgery preparation. The first and most crucial step before this eye operation is to find out exactly why the surgery is needed. For this, the doctor will conduct a detailed eye examination using a tool called an ‘indirect ophthalmoscope’ to check the various parts of the eye.
Depending on the situation, an ultrasound may also be used. This is needed if there’s something in the eye, like ‘vitreous opacities’, which prevent a clear look at the retina. The retina is the part of the eye that helps us see. An ultrasound can help detect problems such as obstructions or damage to the ‘vitreous’ (the clear, jelly-like substance filling the eye) and retina. These steps are not just about confirming if surgery is needed urgently, but also about deciding what kind of surgical procedure would be best.
Once the type of procedure is decided, normal pre-surgery steps are followed. These usually include a process called ‘dilation’, which involves making the patient’s eye pupils larger to allow a better view during the surgery.
How is Vitrectomy performed
The procedure involves general anesthesia, just like many other surgical procedures, or can be performed via specialized types of local anesthesia referred to as “peri” or “retrobulbar” block (injections around the eye to numb the area). If required, another specific type of local anesthesia called an “eyelid block” may also be used.
Like all surgeries, it is important to maintain a sterile environment. An ‘eyelid speculum,’ a tool to keep your eye open during surgery, is placed in your eye. The tools necessary for the surgery are introduced through parts of the eye such as the conjunctiva and sclera (outer layers of the eye), allowing the surgeon to look inside your eye with the help of specialized lenses and microscopes. The surgeon creates small openings around the eye, about 3-4 mm away from the cornea for this purpose.
The surgeon uses a special form of viewing system to visualize the inner parts of the eye. This may involve a “contact lens” placed on the eye surface. At this point, the surgeon can start with the main procedure called vitrectomy.
Vitrectomy involves removing vitreous humor, the clear jelly-like substance filling your eye, near the back of the eye. This might be necessary if a part of this vitreous humor was still attached to the macula (area at the center of the retina) or the optic nerve, and causing complications. Different techniques can be employed to ensure this detachment, like using high suction or another technique called ‘bimanual technique’ which uses two tools simultaneously.
In some cases, vitrectomy can be performed if there is bleeding inside your eye that doesn’t clear up on its own. Once the blood is removed and the retina is checked for any damage, further treatment may be required depending on the nature of the blood vessels in the eye and any existing diseases such as diabetes.
If the reason for the surgery is a detached retina, the process to fix it depends on the type of detachment. It may involve removing fluid, sealing any holes or tears in the retina with laser or cryotherapy (a treatment method using cold), and placing gas or silicone into the eye to ensure that the retina stays attached.
Infections in the eye, especially severe ones, may also require vitrectomy. In this case, the vitreous humor is removed to help with getting rid of the infection. A sample of it may also be taken to find out the cause of infection and decide the treatment. After this, medicine is injected into the eye to fight off the infection.
If the eye has sustained any injuries such as tears, dislocations, or increased pressure, a vitrectomy might also be required. In this case, a team of specialists may be needed to treat these issues. In the instance of an accident during cataract surgery where the natural lens falls into the eye, the surgeon will carefully remove it and place a new artificial lens, if the remaining structures in the eye allow it.
Finally, a vitrectomy can also be performed for taking biopsy (sample) to diagnose eye tumors. In this case, the tumor can be sampled using needle aspiration (drawing out cells or fluid from the tumor with a needle) after the vitreous humor is removed.
Once the necessary actions are taken, the instruments inserted into the eye for surgery are removed and any parts of the eye that were opened for the surgery are closed with stitches. This marks the completion of the procedure.
Possible Complications of Vitrectomy
After a surgery called Pars Plana Vitrectomy (PPV), there can be many complications. Just like all surgeries, there’s a chance that problems like an infection or bleeding could happen. Sometimes, there might be issues during the operation that need another surgery to fix. This is why doctors need to carefully monitor patients after the surgery. Usually, check-ups are done one day, one week, four weeks, and three months after. If any complications occur, extra check-ups might be needed.
Soon after the operation, the pressure inside the eye (intraocular pressure) might rise suddenly. This can be dangerous as it can damage the optic nerve, the nerve that lets us see, leading to blindness. To fix this, doctors usually use eye drops that lower the pressure, or sometimes a small procedure to let out some fluid from the eye. Also, in the early days after surgery, you could get corneal epithelial defects. This is like a scratch on the clear layer (cornea) covering the front of the eye, which can cause tearing, blurry vision, and sensitivity to light. Patients with diabetes are more likely to get these scratches. Depending on the size, these defects can be treated with mild methods or might need a follow-up surgery.
Sometimes, a blood clot (hemorrhage) might form inside the eyeball which needs surgery to remove. Other early complications after surgery could be blockage of the central retinal artery, or swelling of the macula, the part of the retina needed for sharp vision. Care is needed during the surgery to avoid injuring the blood vessels. Also, the surgery can sometimes result in tears or breaks in the retina, which can cause the retina to detach. This needs another PPV operation. Any breaks or tears in the retina might need laser treatment or a repeat PPV.
After the surgery, patients can develop a serious eye infection called endophthalmitis, which leads to eye pain, vision loss, a red eye, and pus inside the eye. This is a very serious condition and needs prompt treatment to avoid permanent blindness. Treatment usually involves antibiotics given directly into the eye or through the veins, and sometimes, another PPV operation is needed.
Patients might also develop iris neovascularization and neovascular glaucoma, a condition where abnormal blood vessels grow within the eye. This is common in diabetes patients. The rise in intraocular pressure from this condition can also cause irreversible vision loss and is treated in a similar way to early post-operation rises in the eye pressure. Additional treatments focus on managing diabetes and the damage it causes in the eye.
In the late post-operation period, patients might develop cataracts, a clouding of the eye lens, which affects vision and might need surgery to remove. Sometimes, PPV can cause the front part of the eye to become narrower and secondary glaucoma where the eye pressure rises. This happens when gas and silicone oil used during the operation are in wrong positions, or an iridectomy hasn’t been performed. Iridectomy is a procedure where a portion of the iris is removed to relieve eye pressure; it can also be done as a precaution against secondary glaucoma. This condition is usually treated with eye drops that lower eye pressure, or sometimes with surgery.
What Else Should I Know About Vitrectomy?
Vitrectomy, a specialized eye surgery, can help many patients with sudden or long-term eye conditions, preserving or even restoring their vision. This procedure can notably improve the patient’s quality of life. While the procedure typically has a low risk, there can be serious complications, such as vision impairment or even blindness. However, careful monitoring and management after the surgery can reduce these complications. In sum, vitrectomies are extremely valuable in preventing or even reversing vision loss.
