ANTERIOR SEGMENT CLINICAL UPDATE Identifying and Managing Iris Cysts rimary iris cysts originate in the 1 2 iris pigment epithelium or iris Pstroma, and secondary iris cysts are stimulated by outside factors. Most of these cysts are quite rare, but some can cause visual problems, requiring treatment. In addition, differential diagnosis is crucial to rule out more se­ rious problems, mainly malignancies.1 3 4 Types of Iris Cysts Although iris cysts are relatively rare, the following are more commonly seen. Iris pigment epithelium cysts. The most common type of iris cyst, iris pig­ ment epithelium cysts tend to show up on routine examinations because they TYPES OF CYSTS. (1) Iris pigment epithelium cyst. (2 and 3) Iris stromal cysts. (4) are asymptomatic and rarely cause vi­ Epithelial inclusion cyst, or epithelial “downgrowth.” sual problems, said Prithvi Mruthyun­ jaya, MD, MHS, at Stanford University or vitreous. They are translucent with said Michael E. Snyder, MD, at Cincin­ in Palo Alto, California. Although these speckles of light brown and are usually nati Eye Institute. cysts are typically referred to the ocular benign, said Dr. Mruthyunjaya. “When surface epithelial cells get in­ oncologist as a single iris mass of un­ Stromal cysts. Arising from the side the eye, they do not behave nicely,” known origin, he said, they are often front part of the iris, stromal cysts tend he said. “If they start forming an iris multifocal and bilateral. to be translucent­white and can more cyst, they are unlikely to cause imme­ Located underneath the iris, these readily deform the struc ture of the iris diate sight­impairing complications as cysts push the iris forward, creating itself than iris pigment epithelium cysts long as they remain encased. But if they a dome­shaped surface, said Zélia M. do, said Dr. Mruth yunjaya. “This cyst break or start growing into important Corrêa, MD, PhD, at the University of can be confused for an iris melanoma, structures of the eye, they can, rarely, Cincinnati. They may be midzonal, especially if it is strongly pigmented, cause fairly profound vision loss and right in the middle of the iris leaflet, making it look like a nodule.” sometimes loss of the eyeball itself.” In but also can be located at the inner or Epithelial downgrowth cysts. Fol­ children younger than age 10, he added, outer edges of the iris, near the pupil or lowing trauma—from either surgery or these cysts can cover the pupil space, ciliary body, potentially making them injury—epithelial cells may be trans­ leading to amblyopia. a diagnostic challenge. In some cases, mitted from the outside of the eye to Because they grow toward the inside these cysts may also detach from the iris the inside, or cells inside the eye may of the eye, Dr. Corrêa prefers to call and float freely in the anterior chamber transdifferentiate into epithelial cells, them epithelial ingrowth—rather than downgrowth—cysts. “Although they may start developing years after the BY ANNIE STUART, CONTRIBUTING WRITER, INTERVIEWING ZÉLIA M. CORRÊA, initial trauma,” she said, “they are very MD, PHD, PRITHVI MRUTHYUNJAYA, MD, MHS, AND MICHAEL E. SNYDER, MD. aggressive and can grow quickly, almost EYENET MAGAZINE • 27 like a tumor, acquiring a surprising size.” Another interesting feature of these cysts, said Dr. Mruthyunjaya, is the When Cancer Is a Concern proteinaceous reflectivity of the cystic “Although it is easier to assume that small lumps or bumps in the iris are fluid—they are not completely clear. benign,” said Dr. Corrêa, “in the back of your mind, you need to consider other more serious differential diagnoses. Always remember that tumors can be Confirming a Cyst Diagnosis occasionally associated with cysts or have a cystic component.” “I want to be able to properly identify Most worrisome. In her practice, Dr. Corrêa has seen a number of iridocil- the location and origins of a cyst,” said iary melanomas with a cystic component located right at the root of the iris. Dr. Mruthyunjaya. “That will involve “I’ve also seen patients with medulloepithelioma, a rare type of neuroectoder- a thorough history; complete exam­ mal tumor that can be aggressive and have a prominent cystic component, ination, including a gonioscopy and especially ones in the ciliary body.” Most worrisome, she said, are tumors in the examination of the anterior segment; transition between the iris and ciliary body. They are usually hidden, harder to and imaging. Sometimes looking at diagnose, and trickier to treat. “You must rely on imaging such as high-resolu- both eyes also provides clues about the tion ultrasound because it’s hard to visualize them directly or indirectly,” she said. etiology of the cyst.” Other serious signs. “Any time you see an iris lesion associated with prom- In the case of a suspected downgrowth inent episcleral blood vessels, unexplained acute increase in intraocular pres- cyst, he added, confirming etiology sure, or iris heterochromia,” she said, “a neoplasm should be in the differential might also involve looking for surgical diagnosis.” Also, patients with localized graying or darkening of the sclera wounds or previous operative notes. should be cautiously evaluated to rule out a melanocytic tumor, she said. Don’t overlook history. “Curious Using transillumination, it is possible to identify a melanocytic lesion, which and peculiar stories have underscored almost always will cast a dark shadow. the importance of history­taking for me,” said Dr. Corrêa. She recounted the story of a civil engineer who felt “a slight snag” in his eye while overseeing the doctor in charge of monitoring OCT helpful in imaging peripheral the paving of a road. A tiny piece of grav­ the eyedrops, especially if the cyst has cysts, Dr. Corrêa warned that it may el had lodged in his iris, but it didn’t become quite large. not be possible to see the full extent of raise red flags until months later when Imaging. To rule out other problems these cysts with OCT, especially if they his vision became blurry from a devel­ and diagnose an iris cyst, ophthalmol­ are large. oping cyst. Complicating matters, said ogists may use either anterior segment Advantages of ultrasound. Dr. Corrêa, the cyst looked like a tumor OCT or high­resolution ultrasound High­resolution ultrasound of the because the gravel was dark in color. biomicroscopy (UBM), said Dr. Corrêa. anterior segment provides a very good Dr. Snyder mentioned another “As long as you scan the whole cyst view, allow ing you to visualize thin instance in which history­taking is and have a good enough image of the walls and hollow cavities, indicating a critical: Ask patients if they have trav­ lesion, you’re in great shape,” she said, fluid­filled cyst, versus the solid nature eled to other parts of the world where adding that each diagnostic modality of a malignancy, said Dr. Snyder. In parasites are endemic; they may have has its advantages. addition to looking at the quadrant of experienced a parasitic infection. “Par­ Advantages of OCT. Anterior seg­ the suspected cyst, Dr. Mruthyunjaya’s asites that travel to the eye, such as Cys- ment OCT may identify small cystic initial evaluation involves a scanning ticercus cellulosae, can cause cysts that structures, giving early confirmation protocol around the peripheral part of can be quite dangerous. If you inad­ of diagnosis. However, it does have the iris and ciliary body—as well as the vertently open the cyst and expose the limitations. For example, in patients other eye. “It’s striking how often you parasite to the eye, it can die, causing a with dark irides, the OCT signal may will find tiny cysts in multiple locations significant inflammatory response.” become attenuated, said Dr. Mruthyun­ that weren’t detected clinically.” Other questions to ask. Dr. Corrêa jaya. Also, the pigmentation or size of Dr. Corrêa also uses UBM for surg­ counsels colleagues to take time to talk the cyst may prevent ideal resolution, ical planning. “It’s easier to turn the with the patient and ask questions like he said. “But I’ve been impressed with probe around and get a feel for the these: How long have you been aware the ability to penetrate even small cysts,” extent of the cyst and consistency of the of the cyst? How long has it been since he said, adding that repeatedly scan­ tissue.” Those who lack experience with your last ophthalmology visit? What ning the same area also provides a use­ UBM should consider referring this kind of exam did you receive? Did you ful way to follow up on a cyst’s growth out, she said. have your pupils dilated? over time. OCT also has the advantage What’s next? If you see a lesion with If a cyst appears suddenly, said of no contact with the patient’s eye, a solid component, you might confirm Dr. Mruthyunjaya, it’s worth asking said Dr. Corrêa, which can be especially this with magnetic resonance imaging, whether the patient is on prostaglandin helpful for younger patients. said Dr. Corrêa, and even biopsy for analogs, which can affect cyst size. Alert Although Dr. Mruthyunjaya finds confirmation of malignancy. 28 • JANUARY 2018 When Treatment Is Needed Drainage and injection. Dr. Corrêa In most cases, Dr. Corrêa simply also likes to treat ingrowth cysts by Coming in the next observes iris pigment epithelial and using a needle to drain the cyst, inject stromal cysts. alcohol inside it, and then deflate the ® Conditions dictate choices. How­ cyst. “In case there is any sign of residu­ ever, said Dr. Corrêa, treatment may al epithelium on the surface of the iris, be needed if there are other problems I use an endolaser probe to treat the such as increasing eye pressure or area and make sure any epithelial cells Feature multiple cysts occluding the angle.