Myopic Foveoschisis

What is Myopic Foveoschisis ?

Myopic foveoschisis, also known as myopic traction maculopathy (MTM) or myopic macular schisis, is an uncommon eye condition that affects people with severe short-sightedness (referred to as myopia, and in this case marked by a score of -6.00 or more). People with this condition often have a bulge at the back of the eye, known as a posterior staphyloma, which is thought to contribute to the development of MTM.

People with myopic foveoschisis often experience a slow, but usually worsening, painless loss of vision in one or both eyes. The eyes can be affected at the same time or one after the other. The condition is characterized by a splitting of the retina layers at the back of the eye, a region known as the fovea. This was first reported by Takano and Kishi in 1999.

In the past, it was difficult to diagnose MTM because the high levels of short-sightedness can make it hard for an eye doctor to examine the back of the eye clearly with an ophthalmoscope. However, the development of a high-resolution eye imaging technique called spectral-domain optical coherence tomography (OCT) has made it easier to detect myopic foveoschisis at an early stage and start treatment promptly.

What Causes Myopic Foveoschisis ?

Myopic foveoschisis is a condition that usually affects eyes with high levels of nearsightedness (or “myopia”) and an issue called “posterior staphyloma”. High myopia means your eyes are long-sighted and have trouble seeing things up close.

Antonio Scarpa was the first person to talk about posterior staphyloma, describing it as an abnormal outward bulge in the eyeball. This bulge happens due to changes in a protein in the outer layer of the eye, known as scleral collagen.

However, this bulging doesn’t affect all parts of the eye in the same way. The uneven stretching in the retina – the surface at the back of the eye – is the main culprit for a condition called myopic traction maculopathy. The uneven stretching puts pulling forces on the retina, both along its surface and at right angles to it. This force can cause the layers of the retina to separate, and also lead to the creation of a macular hole – which is a little gap in the part of your eye responsible for sharp, central vision.

Alongside this posterior staphyloma and the lengthening of the eyeball, there are other factors at play. These can include tension from a jelly-like substance at the back of the eye (the premacular cortical vitreous), rigid blood vessels in the retina, or stiffness in the eye’s internal limiting membrane.

In addition, the high levels of nearsightedness can cause other issues. These can include lacquer cracks, which are breaks in the layer underneath the retina due to the irregular shape. It can also lead to a thinning or loss of the layer beneath the retina (choroidal atrophy) and new, unwanted blood vessels growing in the retina (choroidal neovascularization). These problems can all occur in eyes that have myopic foveoschisis.

Risk Factors and Frequency for Myopic Foveoschisis

Pathologic myopia is a condition where people have an extreme level of nearsightedness, indicated by either having a rating higher than -6 D or an eye length longer than 26 mm. It affects about 2% of the global population. Of these, between 8% to 34% developed a condition related to this called myopic traction maculopathy. This condition is more commonly seen in females than males by a ratio of 3:1.

The size of these myopic eyes can continue to grow for many years and at different rates, which is why symptoms can start showing anywhere from early adulthood to later in life. Pathologic myopia can affect anyone, regardless of where they live. The disease tends to progress slowly and can get more severe over time, though sometimes it might not worsen for a while.

• Pathologic myopia is severe nearsightedness, indicated by a rating higher than -6D or an eye length longer than 26mm.
• About 2% of the global population have pathologic myopia.
• Of these, 8% to 34% have myopic traction maculopathy.
• Females are affected more than males at a 3:1 ratio.
• Symptoms can start showing anywhere from early adulthood to later years.
• There is no geographical preference for the disease.
• The disease tends to progress slowly and gets more severe over time, though there may be periods where it does not worsen.

Signs and Symptoms of Myopic Foveoschisis

Myopic traction maculopathy is a condition that can affect people at various stages of life, but it’s most common in middle age. Sometimes people notice it in their early adult years or even in their teens. It’s commonly associated with blurry vision in one or both eyes, mainly in people who are severely nearsighted. However, some people may not have any noticeable symptoms.

This condition usually develops slowly over time. It can affect both eyes at the same time or one eye first, then the other a few months or years later. Other symptoms can include seeing spots or flashes of light, image distortion, or blind spots.

A doctor’s examination can reveal visible thinning of the white part of the eye, the sclera. If the person has previously had laser eye surgery, signs may be detectable on the cornea. Nearsighted eyes generally have a deep space in the front of the eye, the anterior chamber. In older patients, the lens of the eye may show signs of cataracts. When the back of the eye is examined, there may be signs of the vitreous jelly inside the eye detaching from the retina, or areas of degenerative changes in the retina itself.

The doctor may note that the optic nerve head, the disc, appears large. The retina at the back of the eye may show signs of degeneration. Sometimes, the central area of the retina, the macula, might not seem unusual, although it can show changes associated with severe nearsightedness, such as breaks in the layers of the retina, unusual spots, abnormal growth of new blood vessels, or a pushing outwards of the back of the eye.

In some cases, the doctor might see areas of the retina that have thinned and appear lighter in color. There might also be thinning of the retina around the disc or at the back of the eye. Examination with a special lens can indicate the presence of splitting of the layers of the retina at the center, a condition known as myopic foveoschisis. A doctor might identify shallow retinal detachments or holes in the macula through a microscope examination of the eye.

Testing for Myopic Foveoschisis

To evaluate a condition called myopia (more commonly known as nearsightedness), your eye doctor will conduct a fundus evaluation, which is essentially a close examination of the back part of your eye. This evaluation uses two types of lens, specifically a 20-D and a 90-D lens. This procedure allows your doctor to inspect the various abnormalities that can be present because of myopia. Another method for examining your eye is using a type of microscope known as a slit-lamp along with a 90D lens. This can help your doctor identify signs of potential complications related to myopia such as myopic traction maculopathy, a condition that can lead to blurred or distorted vision.

Spectral-domain optical coherence tomography (SD-OCT) is a crucial tool for diagnosing myopic traction maculopathy. This advanced technology shows in detail the different layers of the retina, which is the thin tissue layer at the back of the eye. The OCT can show the formation of small pockets of fluid (cystic cavities) within the retina, which causes the layers of the retina to separate, leading to a thicker inner layer and a thinner outer layer. When these cystic cavities occur in both the inner and outer layers of the retina, it’s referred to as compound foveoschisis. The OCT can also detect other features such as the existence of an epiretinal membrane, which is a thin layer of tissue over the retina, and disruptions in the junction between the inner and outer segments of the retina’s photoreceptors (the cells that detect light).

Since the eyes of people with myopia often tend to be large, use of larger OCT scans (12 mm) is often required. The scanning process needs to cover the entire backside of the eye (the posterior pole) and should be done both horizontally and vertically. However, myopic traction maculopathy can’t be fully diagnosed based solely on OCT. Therefore, doctors will need to take photographs of your fundus (the interior surface of the eye) for a complete assessment. Regular 30-degree photos might not provide a full evaluation, so wide-field fundus photos are usually preferred. These photos offer an extensive view, and help the doctor clearly understand the location and extent of staphyloma, an outpouching or bulging in the eye that can occur in severe myopia.

Treatment Options for Myopic Foveoschisis

Myopic traction maculopathy is a rare eye disease that can only be treated with surgery, and there isn’t a widely agreed-upon treatment plan. Therefore, different surgeons worldwide resort to their expertise and experiences to tailor treatment options best suited for their patients.

One surgical method showing promising results in managing myopic traction maculopathy involves a procedure called pars plana vitrectomy along with peeling off the internal limiting membrane (ILM), the innermost layer of the retina. It is believed that this process not only eases the strain on the macula (the part of the eye responsible for sharp and detailed vision) but also reduces the chance of the disease coming back by eliminating possible growth of cells. However, due to the high skill level required and the risk of creating a macular hole (a tiny break in the macula), some surgeons might be hesitant to use this approach.

Scleral buckling is another treatment option. This technique works by applying an external pressure on the retina, which in turn eases the tension on the macula. The advantage of scleral buckling comes from it being performed outside of the eye (extraocular), lowering the chance of cataract (clouding of the eye lens) and accidental holes in the retina. This method might also speed up recovery compared to ILM peeling.

Before the surgeon decides on a treatment plan, they need to understand the direction of the force that’s causing the strain on the retina. Depending on whether the force is directed side to side (tangential) or front to back (perpendicular), the surgeon will then choose a surgical method that can counterbalance these forces.

For patients with a macular hole, which can be caused by tangential forces, the most effective treatment is generally pars plana vitrectomy with ILM peeling. Other patients whose retinas split or detach (schisis and detachment) should undergo a scleral buckling procedure to counteract the perpendicular forces.

But, it is also possible that some patients might experience a combination of both tangential and perpendicular forces, such as in the case of a detached retina with a macular hole. In such instances, combining the pars plana vitrectomy with ILM peeling and scleral buckling may be the most effective treatment option.

If the force causing the strain on the retina is not accurately identified and properly countered, the problem may persist or even get worse, and the patient’s condition might deteriorate further. So, it’s important that the doctors customize the surgical approach based on the particular patterns of the patient’s retinal condition.

What else can Myopic Foveoschisis be?

Myopic foveoschisis can lead to a slow loss of vision in highly nearsighted eyes. There are also other reasons that people with nearsightedness may experience a decrease in their vision. These could be:

• Myopic choroidal neovascularization (new blood vessels forming under the retina)
• Retinal detachment (the retina lifting or pulling from its normal position)
• Lamellar or full-thickness macular hole (a small break in the macula, located in the center of the eye’s light-sensitive tissue)
• Forster-Fuch spots at the fovea (spots appearing in the central portion of the retina)

Taking a detailed medical history, performing a thorough eye examination, and smart use of diagnostic tools usually help to determine the correct diagnosis.

What to expect with Myopic Foveoschisis

The success of a surgery is often dependent on a patient’s ability to see clearly before the operation. The lower the vision or the more trouble a person has seeing, the more difficult it may be for the surgery to be successful. If vision issues have been a problem for a long time, it’s unlikely that full vision will be restored. Conditions like a detached or damaged central part of the retina (foveal detachment and a full-thickness macular hole) make the success of the surgery less likely.

Other factors also make it hard for the surgery to improve vision. These include high axial length (an eye that is longer than normal), deep staphyloma (an indentation or dip in the eye caused by scar tissue), and the thinning of the layer of blood vessels at the back of the eye (choroidal thinning). These conditions can lead to a poorer recovery of vision and incomplete healing of the eye’s structure.

Possible Complications When Diagnosed with Myopic Foveoschisis

The surgical treatment of MTM (Myopic Traction Maculopathy) isn’t easy. This is mainly because the visual contrast in eyes with high degrees of myopia (short-sightedness) is generally weak, making the removal of the ILM (a thin, fragile membrane in the eye) quite tough. As this membrane is so delicate, it can unintentionally rip during surgery, which could lead to the creation of a macular hole after the operation. To prevent this, some surgeons might opt for a procedure where they avoid tearing the ILM near the fovea (the most sensitive part of the retina).

Following surgery, patients can also experience the formation of a cataract, especially after a procedure called pars plana vitrectomy and gas tamponade. Another surgical method called macular buckling can be quite tough and may result in some problems like incomplete resolution or recurrence of MTM, detachment of the choroid (the layer filled with blood vessels in the eye), bleeding under the retina, or the buckle pushing through the skin after the operation.

Possible Issues after Surgery:

• Difficulty seeing contrasts in high myopia eyes
• Ripping of the ILM during surgery
• Creation of a macular hole post the surgery
• Formation of a cataract
• Incomplete resolution or recurrence of MTM
• Detachment of the choroid
• Bleeding under the retina
• Buckle pushing through the skin after the operation.

Preventing Myopic Foveoschisis

Patients with very high nearsightedness often face multiple complications and it’s essential that they regularly visit a specialist for their retinas, which is the back part of the eye. If these patients experience any new vision-related issues like a decrease in their vision, seeing floaters (small spots or specks that float in their field of vision), seeing flashes of light, distorted vision, or blind spots (scotoma), they should let their retina specialist know right away. It’s crucial that patients with high nearsightedness have their retinas checked at least once or twice a year. This is to detect any new developments like ‘lattice degeneration’ or a tear in the retina. Lattice degeneration is a type of thinning of the outer retina that can increase the risk of retinal tears and detachment.