Iris Cyst

What is Iris Cyst?

Iris cysts are a rare type of eye condition that appear as small, fluid-filled pouches in the iris (the colored part of your eye). The exact cause of these cysts is still unknown, but they are typically seen at birth or connected to eye injury or swelling. The size, form, and exact location of these cysts in the iris can change from person to person.

Most of the time, iris cysts are harmless and don’t cause any symptoms. However, they can sometimes cause issues in the eyes, leading to challenges in identifying and treating them. They can cause vision problems, increased pressure in the eye, or discomfort. It’s crucial to identify iris cysts correctly and to differentiate them from other eye conditions, such as iris melanomas, which may be dangerous and cancerous.

Iris cysts are often found during regular eye check-ups. Various eye imaging methods, such as slit-lamp biomicroscopy, ultrasound biomicroscopy (UBM), or optical coherence tomography, can give a detailed view of the cysts. The treatment plan for iris cysts depends on how large they are and if they affect your vision. Cysts that don’t cause symptoms may just be checked regularly for any changes. On the other hand, cysts causing symptoms may need treatment with medications like atropine, or surgery, which could involve draining the cyst, using laser therapy, or removing it completely. Regular visits to the doctor are needed to track any changes in the cyst.

Timely detection and prompt treatment of iris cysts are key to maintaining eye health and preventing complications.

What Causes Iris Cyst?

Iris cysts are little pockets of fluid that form in the iris, the colored part of your eye. There are two main categories of these cysts. The first group, primary iris cysts, pop up without a known cause. The second group, secondary iris cysts, form due to specific factors.

Primary iris cysts typically develop from the pigmented cells located in the iris and can appear all over, including in the center or at the outer edge of the iris. These cysts can sometimes become dislodged and end up in the front or back chamber of the eye. In certain cases, primary iris cysts can also originate from the iris’s connective tissue, known as the stroma. These are often either congenital (present from birth) or acquired (developed over time).

Secondary iris cysts, on the other hand, can come from a range of causes. They might form due to the growth of epithelial tissue (cells that line certain parts of the body) following eye surgery or injury. Other types include pearl cysts, drug-induced cysts, parasitic cysts, and cysts that develop alongside eye tumors like medulloepithelioma, uveal melanoma, and uveal nevus.

You can further categorize primary cysts based on where they form. For example, iris pigmented epithelial cysts can be classified based on their position in the eye. Some form in the middle of the iris or near its edge. These types of cysts usually aren’t visible to the naked eye and don’t let light through. However, they can sometimes cause linear strands to hang vertically and sway with eye movement when they burst. Thankfully, they don’t usually lead to severe complications like inflammation or vision loss.

Cysts might also originate from the iris stroma, a layer beneath the pigmented cells of the iris. Unlike the more common epithelial cysts, these stromal cysts can cause the iris to deform and might require treatment.

Secondary cysts are grouped based on their causes, with each cause having distinct effects. Implantation cysts can form around a foreign body in the eye or due to cell growth after eye surgery or injury. In some cases, certain medications can induce the formation of cysts. Although it’s rare, inflammation and uveitis, conditions that cause the eye to become swollen, have been linked to the development of iris cysts. Additionally, parasites and intraocular tumors could play a role as well.

Risk Factors and Frequency for Iris Cyst

Iris cysts are unusual and there are no large-scale studies to precisely determine how frequently they occur. In a major study that looked at 3690 iris lesions, or irregularities, at one center, it was found that 21% were cysts. Of these cysts, 87% were pigment epithelial cysts, which form in the colored part of the eye. Among iris stromal cysts, or cysts that form deeper in the tissue of the iris, congenital stromal cysts (or ones present from birth) were more commonly seen in children. In general, secondary cysts are more frequently seen than primary ones. Secondary cysts, often associated with trauma or implant cysts, are more commonly found in males.

• 21% of iris lesions in a major study were cysts.
• 87% of these cysts were pigment epithelial cysts.
• Congenital stromal cysts were more common in children.
• Secondary cysts are more frequent than primary cysts.
• Secondary cysts are more commonly found in males, often linked to trauma or implantation cysts.

Signs and Symptoms of Iris Cyst

Primary iris cysts are often discovered by chance and usually do not cause any symptoms unless they grow big enough to block vision or cause other complications. In children, a specific type of these cysts, known as stromal cysts, can cause lazy eye or misalignment of the eyes. However, in adults, these stromal cysts typically remain the same size.

Stromal cysts happen within the iris tissue and can sometimes distort the iris. In children under 10, they are generally present as a single cyst in one eye. Cysts that appear later in life usually don’t need treatment. Sometimes, free-floating cysts can be found in the front part of the eye or within the jelly-like substance which helps the eye maintain its round shape.

Secondary cysts may be identified with the help of historical clues that can be helpful in categorizing the cyst. Sometimes, patients may have symptoms from secondary inflammation of the iris, different types of glaucoma, and cataracts. Parasitic cysts may not have any symptoms or they may cause a mild inflammation of the iris. These cysts may contain clear fluid and a freely moving parasite segment.

Testing for Iris Cyst

To examine an iris cyst, a comprehensive eye examination is carried out. This includes a thorough examination of the front part of your eye (anterior segment) including using a special lens (gonioscopy) and the back part of your eye (posterior segment). Photos may be taken of your eye during this process to keep a record of any unusual growths like cysts. Some cysts are located on the back of the iris, the colored part of your eye, and might need your pupils to be dilated or a special lens to see them clearly.

One method used in eye examinations is going by the name anterior segment–optical coherence tomography (shortened as AS-OCT). This technology is favored because it gives a highly detailed image of the front part of your eye, including iris cysts. This is similar to ultrasound but provides clearer images. However, there’s a small disadvantage to AS-OCT. It can get interrupted by pigment and structures in your iris, which sometimes makes it tricky to distinguish cysts from solid growths in your eye.

B-scan ultrasonography is another technology used to examine your eye. With it, a probe sends out sound waves to give a picture of the inside of your eye, including iris cysts. It uses a lower frequency that penetrates deeper into the eye, making it useful for looking at hard-to-reach areas.

Unlike the B-scan, ultrasound biomicroscopy (UBM) uses a higher frequency probe, capturing more detailed images, but doesn’t reach as deeply into the eye. This makes it particularly valuable for examining iris cysts and distinguishing them from other groups of cells growing abnormally in your eye. If a cyst appears as a round or oval shape with a clear border and dark center, UBM is typically the best choice.

A fine needle aspiration where a thin needle is used to collect cells or fluid samples from the eye, may be performed when other noninvasive methods are not able to diagnose the problem.

Considered the best practice, UBM is extremely important to thoroughly document and monitor any changes in the eye over time. In cases where there are many clumps of cells present at once in the iris, a genetic test for a specific gene (ACTA2) should be done. If the patient tests positive for this gene, it’s important they understand the potential risk of aortic dissection- a serious condition affecting the main artery carrying blood from the heart. However, it’s also worth noting that only 6% of patients with thoracic aneurysms linked to changes in the ACTA2 gene exhibit this clumping pattern in the iris.

Treatment Options for Iris Cyst

Iris cysts, which are small sacs filled with fluid on your iris (the colored part of your eye), don’t always cause problems. If a cyst is stable and doesn’t cause any discomfort or other difficulties, doctors usually choose to keep an eye on it rather than treat it. However, some cysts, particularly in children, may grow large enough to obstruct vision or cause other issues, such as glaucoma, a condition that damages the eye’s optic nerve. In these cases, intervention is necessary.

There are different types of iris cysts, and their treatment can depend on their type. Most secondary iris cysts caused by trauma to the eye are difficult to treat and they can often grow back after treatment. These situations generally require intervention. Iris cysts in the pigmented epithelium (cells that give color to the iris) can sometimes enlarge and affect your vision, which also require intervention. However, primary pigment epithelial cysts of the iris usually don’t need treatment.

When treatment is required, laser treatment is a common procedure. There are two types of treatments that can be done using lasers, one uses laser energy to burn and shrink the cyst, the other uses lasers to make a hole in the cyst to release the fluid inside it. Both methods are generally safe but have the chance of the cyst growing back.

Another simple technique is to use a fine needle to draw out the fluid from the cyst, deflating it and relieving obstruction. This technique can be particularly useful for larger cysts or in cases where cysts cannot be easily reached for laser therapy. In some cases, after a needle has been used to aspirate, or remove, the fluid, a substance that scars tissue — known as a sclerosing agent — is injected to prevent the cyst from refilling. This technique, however, may require several rounds of treatment and there is also the risk of cysts returning.

In some severe and complicated situations, surgery to remove the cyst, with cryotherapy (use of extreme cold to destroy tissue), is used as a last resort, as the procedure is associated with severe complications. Surgery has the advantage of obtaining a tissue sample for analysis to confirm the diagnosis.

Depending on the cause of the cyst, treatments can vary. In some cases, cysts develop as a result of medication use, and discontinuing the medication can resolve the cyst. If cysts form due to an eye condition called uveitis, they may shrink after the inflammation from uveitis has been treated.

Aggressive surgical intervention is often required for secondary cysts due to the growth of epithelial cells (cells on the surface of the eye) into the eye, particularly after eye injury or surgery. These procedures aim to remove the cyst and the surrounding tissue, but there’s a risk the cyst will grow back if not all of it is removed. On the other hand, if too much tissue is removed, it can cause damage to the eye.

What else can Iris Cyst be?

In the world of eye health, it’s really important to tell the difference between different kinds of iris cysts and rule out if there’s a tumor in the eye. The best way to do this is through extensive clinical examinations and the use of various imaging techniques. Some features can help doctors tell apart iris cysts from eye cancers. Unlike cysts, cancerous tumors are usually solid rather than fluid-filled, have irregular shapes and borders, a rough surface, and typically have visible blood vessels. They also usually extend into the back of the eye and can distort the angle of the eye.

When doctors look at irregularities in the iris, they could be filled with fluid (about 21% of cases) or be solid masses (about 79% of cases). Fluid-filled abnormalities, or ‘cystic lesions’, are usually caused by issues with the pigment-producing cells of the iris and account for 18% of all iris tumors. Stromal cysts, which form in the supportive tissue of the iris, are less common (3% of all iris tumors). The solid iris abnormalities, or ‘tumors’, can either be melanocytic (68%) or nonmelanocytic (11%). Melanocytic ones are tumors related to pigment cells and can include moles, melanoma, melanocytoma, and melanocytosis. Nonmelanocytic iris tumors, on the other hand, include a variety of other disease entities, such as metastatic cancer, vascular abnormalities, and secondary lesions, among others.

Pars plana cysts, cysts that are most common in older adults and found in up to 18% of eyes, are usually non-pigmented and transparent. They might be associated with conditions like multiple myeloma, posterior uveitis, and retinal detachment. The walls of these cysts are filled with hyaluronic acid, a substance that helps maintain eye shape. These cysts typically do not heighten the risk of rhegmatogenous retinal detachment, a type of serious eye condition, although the links between these cysts and the cells of the iris and ciliary body need further research.

Intraocular cysticercus should be considered when diagnosing vitreous cysts. These are cysts that appear in the jelly-like substance that fills the eye (vitreous body). Live cysticercus can be recognized by the waving movements of the cyst wall and the scolex, a part of cysticercus that can independently move when exposed to light during the examination. In an ultrasound, the cysticercus would appear as a cyst with a hyperechoic (bright) structure attached to the wall (the scolex), while vitreous cysts appear as structures with hypoechoic or anechoic (dark) fluid inside.

What to expect with Iris Cyst

The outlook for someone with an iris cyst can vary, depending on its type and size. The iris is the colored part of your eye, and a cyst is a small sac that’s filled with liquid. Primary cysts, which occur on their own, often have a better outcome than secondary cysts, which are linked to other medical conditions. There are two types of primary cysts, and generally, those occurring in pigment epithelial (the layer that gives color to your eyes) have a better prognosis compared to the ones in the stromal part (the supportive framework) of the iris.

Cysts that are big (occupying more than half of the anterior chamber, the front part of the eye), those located against either the cornea (the clear front surface of the eye) or the lens (the part that focuses light onto the retina), and those found in younger patients or those with already decreased vision are linked to a worse prognosis.

It’s important to note that race and gender don’t seem to affect the prognosis of iris cysts.

Possible Complications When Diagnosed with Iris Cyst

The seriousness of complications in eye conditions depends on how big the problem is, where in the eye it’s located, and how it interacts with other parts of the eye. Some potential issues include blocking the path of vision, causing the cornea (the clear front part of the eye) to malfunction, having pigments disperse incorrectly, developing both types of glaucoma (open and closed-angle), experiencing repeated inflammation of the iris (the colored part of the eye), and forming cataracts (cloudiness in the eye lens).

In children, these complications can cause strabismus, a condition where the eyes do not properly align with each other, and amblyopia, also known as “lazy eye.” In rare cases, these problems could even lead to a bleed into the jelly-like substance filling the eye (vitreous hemorrhage) and the formation of a cyst in the white part of the eye (scleral cyst).

Potential Complications:

• Blocking of the path of vision
• Malfunction of the cornea
• Incorrect pigment dispersion
• Development of glaucoma (both open and closed-angle)
• Repeated inflammation of the iris
• Formation of cataracts
• Strabismus and amblyopia in children
• Vitreous hemorrhage
• Scleral cyst formation

Preventing Iris Cyst

It’s important to teach patients about what to expect in the future as well as the importance of keeping a close eye on any shifts in their condition. It’s crucial that they understand the necessity to seek medical help immediately should they notice any major new symptoms or changes in their ability to see. In case of children who have suffered eye injuries resulting in stromal cysts (swellings in the cornea) or secondary iris cysts (swellings in the colored part of the eye), frequent check-ups are needed. The family of the patient should also be informed about the possibility of the disease coming back even after surgery.