From the Ocular Oncology Service, Wills Eye Institute, Thomas Jefferson University, Philadelphia, Pennsylvania.
Supported by a donation from Michael, Bruce, and Ellen Ratner, New York, New York (JAS, CLS); the Paul Kayser Award of Merit in Retina Research, Houston, Texas (JAS); Mellon Charitable Giving from the Martha W. Rogers Charitable Trust (CLS); the Retina Society Research Award (CLS); and the Eye Tumor Research Foundation, Philadelphia, Pennsylvania (CLS).
The authors have no financial or proprietary interest in the materials presented herein.
Address correspondence to Carol L. Shields, MD, Ocular Oncology Service, Suite 1440, Wills Eye Institute, 840 Walnut Street, Philadelphia, PA 19107. E-mail: firstname.lastname@example.org
Iris cysts are uncommon and are classified based on origin from iris stroma or iris pigment epithelium (IPE). IPE cysts are further anatomically divided into central (pupillary), midzonal, peripheral (iridociliary), and dislodged types.1 IPE cysts arise from the posterior layer of the iris and have a lumen filled with transparent fluid lined by a monolayer of IPE cells.1,2
Peripheral IPE cysts are difficult to visualize and manifest indirectly as a bulge in the iris stroma. Central (pupillary) IPE cysts manifest directly as a dark mass at the pupillary margin. Imaging tools such as transillumination or ultrasound biomicroscopy can confirm the cystic nature of IPE cysts. In this report, anterior-segment optical coherence tomography (AS-OCT) was employed to document the natural progression of a central (pupillary) IPE cyst.
A 3-year-old healthy girl was noted by her mother to have a painless, black iris lesion for 7 months (Fig. A). There was no previous trauma or miotic drug use. Visual acuity was 20/30 in both eyes. Intraocular pressures and fundus examination were normal in both eyes. The right eye displayed a round black iris mass at the inferotemporal pupillary margin measuring 1.5 × 1.5 × 2.0 mm. AS-OCT showed an inflated, thin-walled cyst with clear lumen attached by a strand to the IPE, consistent with a central IPE cyst (Fig. B). Additionally, a small, deflated, pedunculated cyst was detected just superior to the inflated cyst at the pupil. There were no cysts in the left eye. Observation was advised.
Figure. A 3-Year-Old Girl with Black, Pupillary Margin Iris Pigment Epithelial Cyst. (A) At Presentation, the Round, Inflated Black Cyst at the Pupillary Margin Overhangs the Iris Stroma. (B) Anterior-Segment Optical Coherence Tomography (AS-OCT) of Figure a Displays the Thin-Walled, Inflated Cyst at the Pupillary Margin, Arising from a Strand of Iris Pigment Epithelial Cyst. (C) Three Months Later, the Cyst Is Deflated with a Collapsed Appearance. (D) AS-OCT of Figure C Displays the Irregular, Collapsed Cyst with Abrupt Optical Shadowing.
Over a 3-month interval, the patient’s mother commented that the lesion was smaller. The IPE cyst in the right eye had deflated (Fig. C) and the collapsed cyst was visualized on AS-OCT as an irregular surface with no lumen and abrupt optical shadowing (Fig. D). There were no cells or debris in the anterior chamber and the intraocular pressures were normal.
Ultrasound biomicroscopy and AS-OCT are both important tools for cross-sectional in vivo imaging of the anterior segment of the eye. Ultrasound biomicroscopy is ideal for imaging ciliary body lesions and solid structures because the sound waves penetrate opaque tissue with little shadowing of detail. However, ultrasound biomicroscopy imaging requires more technical input with an eyelid speculum water bath filled with isotonic saline on the eye and probe placement near the surface of the cornea. Each ultrasound biomicroscopy study takes approximately 10 minutes to perform.3 Additionally, ultrasound biomicroscopy for children often requires anesthesia.
AS-OCT is a non-contact, patient-friendly, optical imaging method that provides excellent rapid resolution (< 10 μm) of structural details. AS-OCT is ideal for viewing the cross setion of the cornea, anterior chamber and angle, and anterior portion of the iris. Details posterior to the iris are generally shadowed and these clinically undetectable lesions are better imaged with ultrasound biomicroscopy.4,5 AS-OCT can be performed in children in the office setting and our patient was only 3 years old. In our case using AS-OCT, the cyst was clearly visualized and there was minimal shadowing. Details regarding cyst size, shape, and luminal features were documented. Following deflation, the irregular, collapsed surface of the cyst was seen and the dense pigmentation caused shadowing.
Primary IPE cysts are uncommon and display clinical features that differentiate them from solid intraocular tumors such as melanoma and epithelioma (adenoma) of the IPE. Melanoma of the ciliary body and iris typically reveal a solid stromal mass with feeder vessels and occasional tumor seeding into the angle. Similar to melanoma, most pupillary IPE cysts show blockage of light with transillumination. Imaging with ultrasound biomicroscopy or AS-OCT is vital for differentiating solid from cystic tumors.
In a comprehensive analysis of 234 patients with IPE cysts, Lois et al. found 6 (3%) central, 50 (21%) midzonal, 170 (73%) peripheral, and 8 (3%) dislodged.2 The mean age at presentation of central IPE cyst was 20 years (range: 11 weeks to 36 years). Central IPE cysts were unifocal (50%) or multifocal (50%) and involvement was unilateral (67%) or bilateral (33%). Most IPE cysts have a benign clinical course and treatment is often not warranted.
Most IPE cysts are typically unassociated with systemic abnormalities. However, multiple central (pupillary) IPE cysts have been associated with familial aortic dissection. Lewis and Merin6 reported a case of a 30-year-old woman with central IPE cysts (also termed “flocculi”) who underwent aortic dissection repair 10 years earlier. The patient was reported to have a strong family history of iris cysts in her mother, maternal aunt, and maternal grandmother. All affected family members died from ruptured aortic aneurysms between the ages of 30 and 50 years. The authors concluded that central IPE cysts could be associated with aortic abnormalities with an autosomal dominant transmission with variable expressivity. In our case with a solitary pupillary margin cyst, there was no history or findings of aortic abnormalities.
AS-OCT is a useful device allowing noninvasive, non-contact, real-time, cross-sectional images of high quality of the anterior segment. In this case, AS-OCT allowed us to diagnose and monitor the natural progression of a central IPE cyst.
- Shields JA. Primary cysts of the iris. Trans Am Ophth Soc. 1981;79:771–809.
- Lois N, Shields CL, Shields JA, Mercado G. Primary cysts of the iris pigment epithelium: clinical features and natural course in 234 patients. Ophthalmology. 1998;105:1879–1885. doi:10.1016/S0161-6420(98)91034-X [CrossRef]
- Augsberger JJ, Affel LL, Benarosh DA. Ultrasound biomicroscopy of cystic lesions of the iris and ciliary body. Tr Am Ophth Soc. 1996;94:259–271.
- Lara-Medina FJ, Ispa-Callen MC, Nunez A, et al. Exploration of the anterior segment by optical coherence tomography-3 [article in Spanish]. Arch Soc Esp Oftalmol. 2006;81:647–652.
- Marigo FA, Esaki K, Finger PT, et al. Differential diagnosis of anterior segment cysts by ultrasound biomicroscopy. Ophthalmology. 1999;106:2131–2135. doi:10.1016/S0161-6420(99)90495-5 [CrossRef]
- Lewis RA, Merin LM. Iris flocculi and familial aortic dissection. Arch Ophthalmol. 1995;113:1330–1331.