Small irregular lesions at the pupil margin in an infant do not require further evaluation. Small iris nevi are common and also do not require evaluation unless abnormal growth occurs. Children with other iris abnormalities should be referred to a pediatric ophthalmologist.

Lisch nodules are almost pathognomonic of neurofibromatosis, and evaluation for other abnormalities associated with neurofibromatosis should be performed.

What Shouldn’t Be Missed

Although extremely rare, large iris cysts or iris distortion due to intraocular tumors (diktyoma) may cause glaucoma, eye pain, redness, and corneal clouding. This requires immediate evaluation.

• 1. Iris cysts. Cysts of the iris are not common, but may occur in otherwise normal children. Small, scalloped irregularities at the pupil margin are almost always benign (Figure 17–1). Large iris cysts are very rare. They may cause vision loss (Figure 17–2).
  
• 2. Lisch nodules. Lisch nodules almost always occur in children with neurofibromatosis. They are usually not present in infancy. The incidence and number of lesions increase with age. By age 20, more than 95% of patients with neurofibromatosis have Lisch nodules. Lisch nodules are small, tan, and slightly elevated from the iris surface (Figure 17–3A and B). The Lisch nodules do not cause any vision problems. They play an important role in establishing a diagnosis.
  
• 3. Iris nevi. Iris nevi present as areas of irregular pigment on the surface of the iris. They are most easily noticed when the nevi are brown and the underlying iris pigment is fair (Figure 17–4). These are flat (rather than elevated like Lisch nodules), but this feature cannot be accurately assessed without a slit lamp. Iris nevi in children are almost always benign.