Vitrectomy Equipment

Everything There Is to Know About Vitrectomy Equipment

Vitrectomy is a surgical procedure undertaken by an ophthalmologist in which a small cut is made in the vitreous to suction humor gel that fills the eye cavity to replace it with saline. This is done to gain better access to the retina as vitreous should be clear so that light passes through it to make an image on the retina. 

Due to various diseases, fluid enters the vitreous, clouding it and filling it with blood, debris, and hard scars, which prevent light from reaching the retina. At the back of the eye is the retina, which is a layer of cells that sends visual data to the brain. Vitrectomy is a type of operation in which fluid in the eye is removed for the treatment of macular holes, laser repair of retinal detachment, and removal of scar tissue. Once the surgery is completed, a saline, gas bubble or silicone oil may be injected into the vitreous gel to help position the retina properly. 

History

The procedure, vitrectomy, was founded between late 1969 and early 1970 by Robert Machemer with the contributions of Thomas M. Aaberg. The procedure is a connection between the construction of an extensive collection of methods that develop technique-driven technology. Prior to machine-based vitrectomy, David Kasner created the open sky cellulose sponge, and many ophthalmologists injected air, gases, silicone oil, and saline in the vitreous. Also, they injected aspirated liquid vitreous and used scissors in the vitreous cavity all before the development of a mechanized vitreous cutter. 

The Pars Plana method developed by Robert Machemer was aimed at reducing the need for keratoplasty. This procedure is a general term for a group of operations accomplished in the deeper part of the eye, all of which involve removing vitreous humor, which is the eye's clear internal jelly. This method introduced the operation with a closed system in which the intraocular pressure is controlled. 

Indications to use

These are various diseases for which vitrectomy is the only option for treatment. 

1. Blockage of Blood Drainage into Retina:

Retinal arterial occlusions are common in patients with high cholesterol levels, hypertension, diabetes, and stroke. This occurs with a blockage in the blood vessels supplying the retina, raising the pressure in the retina, which can cause bleeding, swelling, and fluid leaks. This is also known as retinopathy. In the eyes, there is a continuous need for the blood supply to deliver oxygen. Hence, any blockage in the retinal vessels can cause harm due to a lack of oxygen supply. In a stroke, a small blood clot blocks the blood flow to one of the arteries in the brain, and the area not receiving blood becomes damaged. The same happens when the retinal artery is occluded and cannot supply blood to the eye’s structures.

There are two types of blockage:

• Central retinal vein occlusion

• Branch retinal vein occlusion

These two retinal vein occlusion (RVO) can cause the following issues:

Macular edema: When there is fluid in the macula, which is the central, small area of the retina that gives a clear vision of a subject. When macular edema develops, blood and fluid accumulate in the macula, and swelling can occur. Blurred vision, pain, difficulty in readings, sensitivity, and appearance of a straight line on a page with an attempt to read are signs of macular edema.

Neovascularization: Due to retinal vein occlusion, the retina begins the formation of new, abnormal blood vessels called neovascularization. So, these abnormal blood vessels cause blood or fluid leaking into the vitreous, which is the jelly-like, thick solution found inside the eye. This can lead to the loss of vision, detachment of the retina from the back, bleeding from ruptured blood vessels, and glaucoma.

Neovascular glaucoma: The formation of new blood vessels in the iris and iridocorneal angle can block humor outflow in the eye, increasing intraocular pressure and causing severe pain.

Blindness: If occlusion in the retinal vein is not treated, it can lead to permanent damage to vision, which is irreversible. So, RVO requires immediate surgery to prevent permanent vision loss.

To treat all the complications of damaged blood vessels, surgeons use the vitrectomy technique, pain killer, corticosteroids, and eye drops. 

2. Infection:

Endophthalmitis is a condition in which inflammation can occur in the interior part of the eye. This infection may also develop as a complication in immunocompromised persons (e.g., diabetes) after surgery in intraocular cavities and can be the symptoms of vision loss. This can also occur with some toxic agent accumulation retained by the native lens after surgery.

Patients with endophthalmitis need surgery (Pars Plana Vitrectomy) urgently. Evisceration is required to eliminate a severe and obstinate infection, which could end in blindness and pain in the eyes, so in the case of allergic reactions, asteroids injection is helpful.

3. Macular pucker:

The macula provides a sharp, bright image when reading, writing, or driving. However, with the presence of scar tissue (macula pucker) in the center of the macula, images become blurred and distorted. If the symptoms are more severe, an ophthalmologist does surgery to remove vitreous and scar tissue on the macula. This flattens the macula and gradually returns your vision.

4. Diabetic retinopathy 

There are two types of diabetic retinopathy. The proliferative type involves the growth of new abnormal blood vessels within the eye (also known as a vitreous hemorrhage), resulting in the development of thick fibrous scar tissue on the surface of the retina, ultimately separating it. Mostly diabetic retinopathy is treated during the early stages via laser therapy in the physician's office to avoid any problems. When bleeding or retinal detachment occurs, vitrectomy is done to clear the blood, and membranectomy is opted to remove scar tissue.

Complications

Vitrectomy is effective but with some complications. According to the American Society of Retina Specialists, most have a 90% success rate. 

In rare cases, complications can occur, especially in immunocompromised patients or those with a history of eye conditions or surgery.

  • Inflammation, redness, swelling may happen.
  • Internal bleeding can occur
  • Infection (endophthalmitis)
  • Increased pressure or reduced pressure 
  • Cataract
  • Swelling of the central part of the retina (macula)
  • Change in vision
  • Retinal detachment
  • Diplopia
  • Discoloration
  • Loss of vision
  • Allergic reactions/ overreaction
  • Wrinkle in the retina

Types of Procedures

There are two different types of procedures:

1. Anterior Vitrectomy

On rare occasions, the vitreous gel escapes from the anterior chamber of the eye, causing symptoms such as trauma, cataracts, and issues with the lenses. To avoid these pathologies and their further consequences, an anterior vitrectomy can be performed. Not only will this procedure reduce the risks involved, but it will also promote the recovery of the visual system. Ophthalmologists receive expert training in eye surgery during their residency, which helps them perform this procedure on patients who require it. 


2. Posterior Vitrectomy

During the developmental phase of a newborn, the vitreous humor supports the layers in the eye. Normally, this vitreous is completely clear all through the years of adulthood and fills the entire vitreous cavity, which is the whole area of the eye, from the front to the back. This cavity, along with the retinal pigment epithelium, choroid, and sclera, and retina, form the posterior segment of the eye. 

This procedure is also known as Pars Plana vitrectomy and is legally done by a retina specialist only. 

 

Procedure

Before the start of this operation, you are advised not to eat or drink anything for at least 8 hours before the surgery. Once everything is prepared, you will be given mild anesthesia to numb the area of concern. 

Surgical Method:

In the procedure, the following steps that take place.

  1. First, the eyelids are opened fully for maximum clearance and exposure. 
  2. Then, a cut is made through the first layer of the eye. 
  3. The second cut is made into the sclera, which is the white tissue inside. 
  4. Next, cutters, scissors, and forceps are inserted through the cuts. 
  5. Removal of vitreous along with other concerned tissues, through any one of these openings.
  6. The removed vitreous is now replaced with an alternative substance, such as gas or a saline solution.
  7. Laser or other required procedures to fix the retina or remove damaged parts can be performed. 
  8. The tools are removed, and the openings are stitched back, if necessary. 

How the Procedure Works

The operation is carried out by the use of machines relevant to the procedure. Various types of vitrectomy machines are available for purchase. 

Vitrectomy Machines

Different types of machines are available in the market. These include:

Vitrectomy cutter:

The cutter, size, speed, geometry, design, and duty cycle, all affect the efficiency and effectiveness of the machine as well as the procedure. The smaller the size of the cutters, the more convenient it is for the doctor. Micro incision vitrectomy system (MIVS) involves the use of smaller probes. Similarly, the modernized, faster cutter speeds have improved the quality of procedures in the surgical field ever since Machemer developed the vitreous infusion suction cutter (VISC). These fast cutters can perform at a speed of 16,000 CPM (cuts per minute),  

An increase in the port diameter resulted in higher flow rates but only to a certain limit. 

Endoillumination:

This procedure involves the usage of strong light sources and filters to improve tissue visualization of the retina. However, there is a risk of photochemical toxicity, and the surgeons need to be careful about this effect. It is important to do thorough research on vitreoretinal instruments

Wide-angle view system:

A good view is crucial during vitreoretinal surgery. The surgeon needs to have a wide and clear view of the eye and its structures. The wide-angle viewing systems were introduced in 1980 to fulfill the demands of surgeons and make procedures easier, simpler, and more efficient. 

Conclusion

In today's day and age, this is a promising procedure producing good results and positive feedback. It is an outpatient surgery but a main surgical procedure for patients of the vitreous humor. This procedure’s objective is to improve vision through hemorrhage management, retinopathy, and edema. 

Apart from this, vitrectomy is also important for the diagnosis and management of uveitis, which is the inflammation of the middle layer of the eye (uvea). Following the procedure, vitrectomy patients can be discharged and are free to go home after a period of observation. This period may be overnight or a day at max.