Iris Cysts: Causes, Signs and Symptoms, Diagnosis, and Management

Introduction

Iris cysts are epithelium-lined cavities comprising a layer of the iris. The iris of the eye is the colored component that encompasses the pupil. Iris cysts may or may not have a recognizable cause or etiology. It can be either a primary or secondary cyst based on the development. It may develop in both adults and children.

What Causes an Iris Cyst?

The iris cysts are multifactorial. They occur due to several reasons, such as:

• Surgery.

• Trauma.

• Iris cysts can also occur secondary to intraocular tumors such as iris melanoma and medulloepithelioma.

• Certain medications like mitotic and prostaglandins can also induce medication-induced iris cysts.

What Are the Types of Iris Cyst?

Iris cysts can be majorly divided into two types based on their cause.

• Primary iris cysts develop without any recognizable cause. However, they can be congenital.

• Secondary iris cysts develop due to the presence of an underlying cause.

Based on the anatomical structure of the cysts, it is of two types:

• Stromal Iris Cysts: They appear on the anterior surface of the iris and get transilluminated by light.

• Iris Pigment Epithelium Cysts: These cysts appear as thin-walled fluid-filled cavities seen more often on the posterior surface of the iris.

How Does an Iris Cyst Develop?

Iris cysts can affect both adults and children. Stromal cysts of the iris are more common in children than in the iris pigment epithelium cysts, which are more common in adults. Secondary cysts associated with trauma and implantation cysts are more common in males.

The exact mechanism involved in the formation of iris cysts is not known. Several controversial theories regarding the formation of iris cysts are documented. The iris pigment epithelium cysts are thought to occur from the remnants of the marginal sinus of the iris region. In contrast, stromal cysts are thought to occur due to the entrapment of ectodermal tissue during the embryo development of the lens vesicle.

What Are the Signs and Symptoms of Iris Cysts?

Patients with iris cysts usually do not present with specific symptoms and remain asymptomatic. However, with an increase in the size of the lesion, the patients may complain of :

• Blurred vision.

• Pain in the eyes.

• Eye sensitivity to light (photophobia).

• In congenital cases, patients may report the presence of spots in the iris region.

• Iris cysts may show both multiple or bilateral presentations.

• Iris cysts with a history of trauma present as solid masses with or without surface epithelium.

How Are Patients With Iris Cysts Diagnosed?

Diagnosing the iris cysts involves complete history taking, clinical evaluation, and imaging of the patients suffering from the condition.

• Upon history taking, patients with a congenital cyst inform the spots in the iris region, especially in the second decades of their life.

• Physical examination of the iris reveals complete or collapsed cysts. The iris pigment epithelium cysts appear as brown or black velvety masses, showing no transillumination. At the same time, the stromal cysts appear as clear cavities that transilluminate in shining light.

• Fine needle aspiration of the cystic content is performed to diagnose the cyst histopathologically.

• Imagings such as-

  • Ultrasound biomicroscopy is the gold standard imaging technique for diagnosing the iris cyst. The cyst appears as thin areas with hyperechoic walls.

  • Ultrasound B imaging is performed to view the cyst's internal and external structure and extent.

  • Anterior segment optical coherence tomography is mainly helpful for small lesions present on the anterior surface of the eye.

What Are the Conditions That Are Similar to Iris Cysts?

Conditions that share similarities with the iris cysts are:

• Cystic lesions like primary iris pigment epithelial cyst and epithelial down growth.

• Solid tumors like melanocytic nevus, melanocytoma, and Lisch nodules.

• Epithelial lesions like the iris pigment epithelium adenoma and medulloepithelioma.

How Are Patients With Iris Cysts Managed?

Patients with iris cysts can be managed both surgically and medically.

• Iris cysts that are caused due to miotics can be managed with 2.5 percent Phenylepinephrine.

• Stable cysts do not require any specific treatment. However, large lesions require surgical management. The various surgical treatment includes the following:

• Laser treatments like Argon laser and Nd: YAG treats cysts.

• Cystic contents are cleared with alcohol, followed by the injection of sclerotic agents that leads to the closure of the cavity. Sclerosing agents used include Trichloroacetic acid, 5-Fluorouracil, and Mitomycin C.

• En bloc excision or complete removal of the cyst is performed. The excision can be accompanied with or without cryotherapy. However, aggressive treatment can lead to collateral damage to the surrounding structures.

• Secondary iris cysts require aggressive surgical excision followed by devitalization of the tissues using vitrectomy (surgery performed to correct defects in the vitreous and retinal region, lensectomy (a surgical procedure that removes lens or part of the lens), or destruction of the residual cells.

What Are the Complications of an Iris Cyst?

The iris cyst can cause secondary complications depending on its size and location. The cyst can compress the adjacent structures. Several other complications associated with the lesion include:

• Angle-closure glaucoma.

• Plateau iris syndrome.

• Focal cataract.

• Inflammation of the iris (iritis).

• Edema of the cornea.

• Subluxation of the lens.

Surgery of the cyst is not without any complications. The severity of the complication depends on the number of tissues removed from the surgical site. The difficulties of the surgery include:

• Formation of cataract.

• Glaucoma.

• A transient or temporary inflammation of the anterior segment.

Iris cysts enjoy a good prognosis, with most lesions resolved spontaneously. However, secondary cysts, especially those with epithelial down growth, have poorer prognoses.

What Factors Affect the Prognosis of the Iris Cysts?

The prognosis of the disease associated with poor prognosis includes:

• Large size.

• Young age.

• The opposition of the lens or cornea.

• Decreased visual acuity.

Some iris cysts, especially the stromal ones, can recur compared to epithelial pigment cysts.

Conclusion

Iris cysts are epithelium-lined spaces containing a layer of the iris. It can occur congenitally or can be associated with secondary conditions. Patients with cysts are mostly asymptomatic or can also complain of blurred vision. The cyst is primarily diagnosed using the ultrasound biomicroscopy method. Smaller lesions resolve themselves; larger and recurrent lesions may require aggressive surgical intervention.