Overview of Scleral Buckling
Retinal detachment is when the layer of tissue at the back of the eye, called the retina, separates from the layer underneath it. There are different types of retinal detachment, but one kind, known as rhegmatogenous retinal detachment, can cause a sudden and painless loss of vision. This detachment happens when fluid gets into the space between the retina and the layer underneath through a break in the retina tissue. The rate at which people experience this type of retinal detachment varies, but studies suggest it’s between 6.3 and 17.9 cases for every 100,000 people.
For a long time, this type of retinal detachment was thought to be untreatable. However, a doctor named Jules Gonin proved that this wasn’t the case. He discovered that retinal breaks, or tears, were the cause of the detachment, not the result of it. Gonin also pioneered the first successful surgery to treat retinal detachment. This procedure involved locating the retinal breaks, draining the fluid between the retina and the layer beneath, and using heat to close the break.
His work set the foundation for the principles followed in retinal detachment surgeries today, which include locating the retinal break, forming a bond between the retina and the layer beneath at the break, and bringing the break in the retina closer to the underlying layer.
Surgeon Ernst Custodis pioneered another important procedure for retinal detachment in 1949, known as scleral buckling. This surgery did not drain the fluid between the retina and the underlying layer but used a material to push the wall of the eye closer to the retina, closing the break. This procedure was later improved by modifying the materials used and the techniques followed.
Today there are different surgical options for treating retinal detachment, including pneumatic retinopexy, scleral buckling, and pars plana vitrectomy. The last mentioned method has become increasingly popular due to its advantages. However, with this surge in vitrectomy, the number of scleral buckling procedures have decreased. It’s vital to remember though that scleral buckling still has comparable results to vitrectomy in treating retinal detachment and remains a vital tool for eye surgeons.
Anatomy and Physiology of Scleral Buckling
To understand the process of ‘scleral buckling’ (SB), a surgical procedure used to fix a retina that has become detached, we need to understand some key parts and features of your eye.
Firstly, there’s something called Tenon’s capsule. This is like a protective layer covering your eyeball, and it stretches from the edge of your cornea (the transparent part of the eye that covers the iris and pupil) to the optic nerve that sends vision signals to the brain. Your eye has several muscles that move it and these muscles pass through this capsule like your hand going into a glove. When performing SB, surgeons need to work around this layer delicately, so as not to hurt your eye muscles.
Adjacent to the back part of your eye is an area called the ‘ora serrata’, and like the ‘spiral of Tillaux’ located on the outside, it is a place where muscles attach.
The vitreous is a gel-like substance filling most of your eye. It rests some distance from the ‘spiral of Tillaux’.
Your eye has more specific muscles, like the superior oblique (SO) and inferior oblique (IO) muscles. These traverse under other muscles and need to be navigated carefully during surgery to avoid damage.
Your eye also has specific arteries that provide blood supply to the front part of your eye. These arteries are very close to where your eye muscles attach and need to be handled carefully to protect your eye’s blood supply.
Moreover, one significant point to note is the presence of vortex veins – these are specific blood vessels in your eye that you can think of like drain pipes that guide blood away. Extra care needs to be taken not to damage these during the procedure.
Now let’s talk about why we need this surgery. The retina, which is a thin layer at the back of your eye, can sometimes tear or become detached due to a tugging force exerted by the vitreous. This force might be due to gravity, sudden eye movements, or trauma. Once torn, fluid from inside the eye can leak into the underlying space and detach the retina.
The term “buckle” means deform or bend. SB is designed to form a kind of indentation or dent on the outer wall of the eye, which in turn changes the shape of the inner wall of the eye where the retina has detached. This change in direction helps to break the pull of forces causing the tear and stops fluid passing into the detached area, assisting the retina to reattach itself. The procedure also reduces the diameter of the vitreous base, which helps in reducing the tugging force and lowers the chance of future tears.
Why do People Need Scleral Buckling
A procedure known as scleral buckling (SB) may be the best treatment option in certain situations. Below is a list of the conditions where this treatment has been found particularly effective:
- Younger patients
- Patients whose eyes still have their natural lens (termed as ‘Phakic eyes’)
- People with a high degree of short-sightedness, a condition called ‘high myopia’
- If there’s no Posterior Vitreous Detachment (PVD), a condition where the back portion of the eye’s jelly-like substance pulls away from the retina
- When there are no advanced Proliferative Vitreoretinopathy (PVR) changes, a condition that causes the retina to scar or wrinkle. However, if the scarring is at a lower level (grade C1), SB can still be used
- When retinal detachment (RRD) originates from breaks that are towards the front of the eye, or anterior to the equator
- If the RRD is caused due to retinal dialysis, a condition where the retina gets separated from the outer layer of the eye.
When a Person Should Avoid Scleral Buckling
Sometimes a person can’t have a buckling surgery (SB) for the retina, like in the following scenarios:
If someone’s sclera (the white part of the eye) has become very thin or is damaged, we call this scleromalacia.
Advanced PVR changes refer to severe changes to the retina as a result of scar tissue forming. This can stop SB from being effective.
If there’s too much blood or a noticeable cataract in the clear, jelly-like substance filling the back of the eye (the vitreous), this can stop the doctor from seeing the back of the eye. This condition is known as dense vitreous hemorrhage.
Having previous surgery to treat glaucoma (a condition that damages the optic nerve) would make SB a risky option too.
A big tear in the retina or a detached retina, which we call RRD (rhegmatogenous retinal detachment), might make it impossible to do SB successfully.
Similarly, if RRD is because of retinal breaks at the back of the eye, the operation may not be possible.
Equipment used for Scleral Buckling
When doing SB surgery, which is a type of surgery to treat complications in the eye, doctors use a variety of specialized equipment. Most importantly, they use a tool called a cryotherapy machine, different kinds of silicon buckles, and suture materials.
Three methods are used for treating retinal breaks (tears in the back layer of the eye) during this surgery: diathermy, cryotherapy, and laser photocoagulation.
Diathermy uses heat to treat the retinal break, but it cannot be applied directly on the sclera (the white part of the eye) because it may cause damages. Hence, it is used alongside scleral implants (silicone pieces placed under the layers of eye tissue).
Laser photocoagulation is another method, but it only works when the retina is still attached to the eye’s back wall. Cryotherapy is a preferred treatment for retinal breaks during SB surgery.
Cryotherapy works on the Joule-Thompson principle, stating that gas temperature drops when it is allowed to pass through a small hole. Here, a cryoprobe, a tool using pressurized gas, rapidly lowers the temperature inside the probe, producing a freezing effect. It’s used directly on the sclera to encourage the retina to stick back in place. The freezing effect causes water inside cells to form icy crystals, injuring the tissue and encouraging healing later. The gas used for this technique is usually nitrous oxide, which is stored in a blue cylinder.
The surgeon has to ensure that the cryoprobe and the nitrous oxide cylinder are correctly working before starting the operation.
Different forms of silicone buckles are used in SB surgery. They can be placed either directly on the sclera or inside a tunnel created in the eye tissue. The buckles are made of a material called polydimethylsiloxane, which is safe, flexible, and doesn’t allow bacteria to grow on it.
There are four types of these buckles: bands and strips, implants and wedges, tires, and sponges. Bands and strips encircle the eyeball to support its structure. Implants and wedges need a cut in the sclera for insertion and are not commonly used. Tires support the retinal break, and they are often used in a circle around the eye globe. Sponges are mainly used to help treat breaks that are behind the eye, but they can also encircle the eye. The one downside with sponges is that they can potentially absorb fluid and bacteria, increasing the risk of infection.
Stitches or sutures are used to hold buckles in place and are typically made of polyester. They come with a spatulated needle that is shaped in a way for easy stitching in the sclera.
Who is needed to perform Scleral Buckling?
The operation is complex and takes a lot of time and practice to learn properly. It’s usually carried out by eye doctors who are specially trained in surgeries related to the part of the eye where the retina and vitreous are (the back, inside part of your eye).
A study by Sagong and his team suggested that a doctor needs to have done around 30 similar operations to get consistently good results. Because the operation requires a lot of practice to get right, there are special training models used by doctors to practice the different stages of the surgery.
Pujari and his team came up with a training model that uses artificial eyes attached to mannequins. This helps doctors practice how to put the stitches in the right place.
Preparing for Scleral Buckling
The operation is usually carried out with local anesthesia near the eye. This involves a balanced mixture of two types of anesthesia, lidocaine, and bupivacaine, along with an enzyme called hyaluronidase. This mixture helps in numbing the area around the eye and ensuring it doesn’t move during the procedure. If the patient is a child or unable to stay still, general anesthesia, which can make the patient sleep, can be used.
To make sure that the doctor can easily perform the surgery, the patient’s head is positioned so that the neck is a bit extended. This gives the doctor a clear and comfortable access to the eye. The skin around the eye is then cleaned with a sterilizing solution that contains 10% povidone-iodine. This helps reduce the risk of infection during and after the operation. To further clean the area, topical drops containing 5% povidone-iodine solution are placed in the thin, clear tissue lining the inner part of the eyelid and the white part of the eye (conjunctival sac). Once the skin has completely dried up, a clean, self-sticking covering is placed to maintain a sterile surgical environment.
How is Scleral Buckling performed
The success of retinal surgery is largely dependent on accurately finding and pinpointing all the tears or breaks in the retina. Every suspected break must be checked before the operation because any that are missed and left untreated could lead to the surgery failing. It’s worth knowing that about 50% of retinal detachments involve more than one break or tear. A doctor named Lincoff created a set of rules that help in determining the location of the primary or main breaks, depending on the specific characteristics of the detachment.
The usual process of the surgery involves:
1. Removing part of the clear skin-like tissue covering the white part of the eye. This is done with a special type of forceps and scissors. Care needs to be taken to prevent this layer from tearing while being pulled back.
2. Preparing the eye muscles: Special temporary stitches are placed on all four rectus muscles (the muscles that move your eye left, right, up, and down). These stitches are used to move and hold the eyeball steady during the surgery. Any resistance felt while hooking the muscle indicates the hook is not placed correctly.
3. Checking the surface of the eyeball for thin areas.
4. Finding the retinal breaks: The retina is examined with a tool called an indirect ophthalmoscope. Once the breaks are found, they are marked on the surface of the sclera (white part of the eye) with a heat source or a special pen.
5. Treating the retinal breaks: This is done using a technique called cryotherapy, which involves freezing the tissue around the retinal breaks. The surgeon must make sure to avoid the veins around the break while carrying out this process, as well as avoiding excess treatment as it could cause complications.
6. Using exoplants: Exoplants are patches or support devices placed over the retinal breaks to provide support.
7. Placing sutures (stitches): These are placed either before or after the exoplants are inserted. The satisfactory exposure of the scleral surface is very crucial for placing the sutures.
The rules and procedures described above provide a standard guideline to the surgeons for performing successful surgeries to treat retinal breaks, thus preventing vision loss.
Possible Complications of Scleral Buckling
There are chances of complications occurring during and after SB surgery. Let’s explain those in simpler terms.
First, let’s discuss the potential complications during the surgery:
– While giving anesthesia, complications can rarely occur, including accidental injury to the eye (0.06 to 0.13% of cases), eye bleeding, vision loss, double vision, and even breathing issues due to accidental injection into the spinal cord. Severe eye bleeding may require additional minor surgery.
– When the surgeon is securing the eye muscles, there can be issues like irregular heartbeat, muscle damage, loss of muscle, damage to the blood vessels, and accidental injury to the white part of the eye.
– While identifying the area of detachment, there can be damage to the blood vessels and accidental piercing of the white part of the eye. If a blood vessel tears, it needs to be sealed off promptly.
– Placing stitches on the white part of the eye might accidentally pierce the eye leading to drainage of fluid, creation of a retinal tear, loss of vitreous jelly, subretinal or below choroid bleeding, and lowering of eye pressure.
– The process of fluid drainage could be complicated by damaged blood vessels, bleeding, incarceration or wrongful positioning of the retina or vitreous gel, vitreous bleeding, lowering of eye pressure, and separation of the choroid along with bleeding or fluid buildup.
Now, let’s discuss the complications that can occur after surgery:
Early complications may include swelling of the eyelids, conjunctiva and cornea, dysfunctional eye muscles, decreased blood supply to the front part of the eye, glaucoma, re-opened retinal breaks, re-detachment of the retina, choroidal detachment, and persisting subretinal fluid.
– If there is decreased blood supply to the front part of the eye, the patient might feel extreme pain and experience degraded vision. The front part of the eye might swell, shallow the anterior chamber, develop marked inflammation, get a cloudy lens, and take up a dumb-bell shape. Mild conditions may be treated with eye drops while severe cases might need the removal of the encircling band.
– Acute glaucoma might occur when the ciliary body detaches. It can be treated with eye drops, however, if these don’t work, choroid drainage might be needed.
– Chronic glaucoma might occur due to a response to steroids.
– Subretinal fluid might persist for up to 3 months despite closure of all breaks in a few cases. Such patients can be monitored safely.
– Recurrence of the detachment of the retina demands a thorough evaluation and suitable treatment.
Late complications might include double vision, changes in the focusing power of the eyes, exposure of the buckle, infection at the buckle site, through-and-through erosion, swelled macula, membrane on the retina, and changes related to the cells forming scars.
– Double vision might occur due to physical muscle constraints or lack of blood supply. Such patients might initially be treated with prisms and in case it persists, eye muscle surgery might be needed.
– The change in the focusing power of the eyes is primarily due to changes induced by the surgery. Excessive post-operative astigmatism might occur due to the use of the radial elements and myopic shift might occur due to an increase in the axial length or forward displacement of the lens.
– Pain, redness, and discharge usually indicate exposure of the buckle which might need the removal of the buckle.
– Scarring cells form most commonly after successful SB surgery, causing vision loss. Also, instances of swelled macula ranges from 5.6 to 43.0% and incidence of the formation of a membrane on the retina ranges from 7.7 to 18.0%. These complications usually occur due to inflammation resulting from cryopexy.
What Else Should I Know About Scleral Buckling?
Scleral buckling (SB) is a type of eye surgery that is considered safe and refined. It doesn’t interfere with the jelly-like substance in your eye, known as the vitreous. This surgery doesn’t need highly advanced machines and is considerably cheaper than another type of eye procedure called vitrectomy.
While vitrectomy may be a better choice for eyes with serious changes due to Proliferative Vitreoretinopathy (PVR, a condition that can cause retinal detachment), SB provides similar results in terms of structure and function for uncomplicated primary Retinal Detachment (RRD). RRD is when the thin layer at the back of your eye detaches from its normal position.
It’s becoming even more necessary to become proficient in this surgery as the number of nearsightedness (myopia) cases is increasing rapidly, and it’s expected that more young patients will develop RRD in the future.
