PURPOSE: To assess the prevalence and location of Lisch nodules among patients with neurofibromatosis type 1. PATIENTS AND METHODS: This was a prospective observational case series in which 369 consecutive patients from a neurofibromatosis clinic participated. Predetermined inclusion and exclusion criteria were applied to these participants. The presence of Lisch nodules was determined by one of the authors (SMC). The percentage of patients with neurofibromatosis type 1 with Lisch nodules was calculated. Lisch nodules were characterized as being distributed superiorly, inferiorly, or equally in each eye. The percentage of eyes in each group was ascertained. RESULTS: Among patients of all ages with neurofibromatosis type 1, 63.2% had Lisch nodules, whereas 92% of postpubertal patients had Lisch nodules. Among eyes with Lisch nodules, 80% had an inferior distribution. CONCLUSIONS: This study corroborated previously reported data regarding the prevalence of Lisch nodules in patients with neurofibromatosis type 1 and found that Lisch nodules were predominantly located inferiorly on the iris. The authors propose that exposure to sunlight may be the mechanism for this distribution of hamartomatous nodules.
PURPOSE: To assess the prevalence and location of Lisch nodules among patients with neurofibromatosis type 1. PATIENTS AND METHODS: This was a prospective observational case series in which 369 consecutive patients from a neurofibromatosis clinic participated. Predetermined inclusion and exclusion criteria were applied to these participants. The presence of Lisch nodules was determined by one of the authors (SMC). The percentage of patients with neurofibromatosis type 1 with Lisch nodules was calculated. Lisch nodules were characterized as being distributed superiorly, inferiorly, or equally in each eye. The percentage of eyes in each group was ascertained. RESULTS: Among patients of all ages with neurofibromatosis type 1, 63.2% had Lisch nodules, whereas 92% of postpubertal patients had Lisch nodules. Among eyes with Lisch nodules, 80% had an inferior distribution. CONCLUSIONS: This study corroborated previously reported data regarding the prevalence of Lisch nodules in patients with neurofibromatosis type 1 and found that Lisch nodules were predominantly located inferiorly on the iris. The authors propose that exposure to sunlight may be the mechanism for this distribution of hamartomatous nodules.