Primary iris pigment epithelium cysts are commonly seen in adults, whereas primary iris stromal cysts characteristically appear in young children.1–6 Primary iris cysts are rare and various forms of treatment have been employed by different treating surgeons, such as aspiration of the cyst,3,5 injection of sclerosing agents,2,3 and en-bloc excision3 along with iris6 or sector iridectomy.3–6 Surgical modalities entailing entry into the anterior chamber can become complicated by the occurrence of iritis,3 cataract,3–6 corneal scarring3 or endothelial damage,2,3 glaucoma,5 or macular edema.6 Less invasive procedures will avoid these inherent risks. We report two cases of iris cyst successfully treated by Nd:YAG laser puncture. To our knowledge, such a treatment modality has not been described earlier.
An 8-year-old boy presented with a history of intermittent blurring of vision in the left eye on bending his head down while reading during the previous year. Initially, the blurring was infrequent; however, the problem had become frequent over the previous 3 to 4 months. He had suffered blunt ocular trauma in the left eye 5 years previously.
The visual acuity was 6/6 in both eyes. There was a primary iris stromal cyst in the inferior quadrant in the mid-peripheral part of the iris. The cyst showed localized mobility and appeared to be attached in the peripheral iris (Fig. 1A). The anterior cyst wall appeared lightly pigmented and was lightly touching the back of the cornea (Fig. 1B). The rest of the ocular examination was within normal limits without any sign of previous ocular trauma. The right eye examination was normal.
Figure 1. (A) Iris Stromal Cyst. (B) Slit-Lamp View Showing Iris Touching the Back of the Cornea. (C) Collapsed Cyst (arrow) After the Nd:YAG Laser Treatment. (D) At 2 Weeks of Follow-Up.
The options of surgical intervention and laser treatment were explained to the patient’s parents, along with possibility of recurrence with either form of treatment. The cyst was treated with Nd: YAG laser shots aimed at the cyst’s wall at a point 1 mm away from the contact point of the cyst and the back of the cornea (the point was approximately midway between the endothelium and the iris). The energy level was 3.2 mJ and two shots were fired. The cyst immediately collapsed and reduced to pea size within a few seconds of the laser shots. The collapsed cyst could be seen lying at the angle of the anterior chamber at the 6-o’clock position (Fig. 1C).
The patient was given topical steroid four times a day, which was tapered over the next 2 weeks. No complication was noted (Fig. 1D). At 2 months of follow-up, there was recurrence of the cyst at the same location (Fig. 2) and it was re-treated with Nd: YAG laser. At 1-year of follow-up, there was no recurrence of the cyst.
Figure 2. Recurrence of Iris Cyst in First Patient at 2-Months Follow-Up.
A 9-year-old boy presented with complaints of abnormal discoloration of the right eye in comparison with the left eye. He had iris stromal cyst in the inferior quadrant of the left eye. The cyst was not touching the back of the cornea. The visual acuity was 6/6 in both eyes and the rest of the ocular examination was within normal limits. Two shots of Nd:YAG laser were fired on the wall of the cyst, away from the area adjacent to the endothelium. The cyst immediately collapsed and disappeared. The patient was given tapering doses of topical steroid for 2 weeks. No complication was noted. There was no recurrence at 10 months after treatment.
Iris cysts are divided into primary and secondary cysts. A primary iris cyst is an epithelial-lined space that involves a portion of the iris and has no recognizable etiology.7 It can be further classified according to its histologic origin (ie, either derived from the epithelium of the iris and the ciliary body or derived from the iris stroma).7 A secondary iris cyst is an epithelial-lined space that involves a portion of the iris and has a recognizable etiology, such as surgical or nonsurgical trauma, drugs, occurrence secondary to an intraocular tumor, or parasites.7
Primary stromal iris cysts are uncommon. Most of the experience accumulated is based on case reports or small case series. Stromal cysts are commonly seen in children, although a few cases have been reported in adults.3–7 They are typically unilateral, solitary, and commonly located in the inferior or temporal aspect of the eye.3 The contents of the cyst are typically clear or slightly turbid.3 In our cases, there was also a single cyst located in the inferior quadrant and the content was clear. Although there was history of trauma in the first patient, the cyst could not be attributed to the trauma because there was no other evidence of injury to the eye. The nature of the trauma was trivial.
Stromal iris cysts are largely asymptomatic or may cause painless decrease in vision. Rarely, they can present with acute symptoms such as photophobia, epiphora, or associated complications.6 Several complications have been reported to be associated with stromal iris cyst, such as corneal edema8 and endothelial touch,8 either true subluxation9 or simulating subluxation of the lens,10 cataract,4 iritis,3 and increased intraocular pressure.11 The only symptom in our first patient was that of blurring of vision on bending the head down, caused by obscuration of the visual axis due to the mobility of the cyst. Although this patient had corneal touch by the cyst, there was no evidence of corneal edema. Our second patient presented due to the cosmetic blemish induced by the cyst.
Although primary stromal cyst can rarely regress spontaneously,3,12 most cases do require treatment due to the progressive increase in the size of the cyst and potential of causing complications. Treatment of asymptomatic cysts is primarily arbitrary due to the paucity of the reports. In the authors’ view, patients with asymptomatic cyst should be closely observed, especially if the treatment requires entering the anterior chamber in very young children. However, if the patient is old enough to cooperate for the slit-lamp delivery of laser treatment, the cyst should be treated after explaining the risk of recurrence.
In view of the rarity of the condition, there is no definite treatment modality described in the literature. Various forms of surgical intervention employed for the treatment of the stromal cysts include needle aspiration of the cyst5 followed by cryotherapy at the limbus to induce scarring of the cyst wall3,5; needle aspiration of the cyst and injection of chemical agents2,3 to induce scarring of the collapsed cyst wall; en-bloc excision3 of the cyst along with a part of the iris6; sector iridectomy,3–6 especially in cases of recurrence; or a combination of these treatment modalities.
The complications associated with surgical intervention can be mild to serious, such as inducing severe iritis,3 cataract,3–6 corneal scarring,3 endothelial damage,2,3 glaucoma,5 or macular edema.6 These complications have the potential to cause further visual morbidity and even amblyopia because most of the patients are in the amblyogenic age group. Enucleation was necessary following complications due to the injection of trichloroacetic acid into the cyst in a 5-month-old child.2
Thus, there is a need for minimally invasive procedures to handle the stromal cysts. There are few reports of treating stromal cysts with argon laser by exophotocoagulation3 or endophotocoagulation.13 Recurrence is probably higher if treated with laser alone because the wall of the cyst is not entirely destroyed. There have been patients in whom the stromal cysts were treated with argon laser without any recurrence, but there is no report of treatment with Nd:YAG laser.
We treated our patients with Nd:YAG laser with an aim of rupturing the cyst wall. As the cyst wall ruptured, the clear fluid was released in the anterior chamber and the wall of the cyst collapsed. The cyst’s fluid was indiscernible from the aqueous humor. There is a risk of recurrence of the cyst, which can be re-treated with laser. We employed the same mode of treatment in both patients, but only one of them had recurrence. The reason for the recurrence in only one patient is obscure.
This is the first documented report of treating iris cysts with Nd:YAG laser. Laser treatment of the cyst averts most of the complications associated with intraocular surgical methods entailing entry into the anterior chamber. Keeping in view the potential of the laser to cure the cyst permanently and the gravity of the anterior segment complications in children, laser therapy should be employed as a first preferred method to treat iris stromal cyst.