Secondary Prevention of Retinoblastoma Revisited: Laser Photocoagulation of Invisible New Retinoblastoma

Abstract

Invisible retinoblastoma tumors are now detected with screening for retinal tumors in at-risk neonates (those inheriting RB1 pathogenic alleles from affected parents) using handheld OCT. Laser photocoagulation is challenging, requiring exact localization of a tumor invisible to indirect ophthalmoscopy and standard imaging. We describe OCT-guided localization and photocoagulation of these invisible tumors with 1-year follow-up. Retrospective, noncomparative, single-institutional, observational case series. Children with any clinically invisible retinoblastoma tumor that was detected on OCT posterior pole screening. OCT revealed round homogeneous invisible tumors within the inner nuclear layer. Software calipers placed beside anatomic retinal landmarks (branched/curved vessels, fovea, or optic disc) mapped the tumor location and extent. A single laser (532 nm) burn flagged the location, and OCT evaluated the tumor-laser burn relationship; laser treatment was then continued in the correct location. Post-laser OCT ensured complete treatment. Accuracy (frequency of geographic miss and skip areas), effectiveness (recurrence rate), and burden (scar size and characteristics at final follow-up) of laser treatment. Eleven new invisible posterior pole tumors in 7 eyes of 5 children were treated by this technique. Localization and tumor-laser burn relationships were accurate in 11 of 11 tumors (100%, 95% confidence interval [CI], 49.9-100), and all showed swelling and hyper-reflectiveness of the tumor in post-laser OCT. Two photocoagulation sessions (2 weeks apart) were sufficient to successfully manage 9 of 11 tumors (82%, 95% CI, 37.4-100) with resulting permanent flat scars. One tumor (9%, 95% CI, 0.2-50.6) developed OCT-detected subclinical recurrences within 3 months, treated by 1 laser session. No treatment scar showed gliosis, foveal involvement, or retinal traction at 1-year follow-up. Scar expansion occurred in 1 tumor (9%, 95% CI, 0.2-50.6), and all scars (100%, 95% CI, 49.9-100) showed pigmentary changes. The OCT-guided localization and photocoagulation technique is valuable in achieving precision results in managing invisible new retinoblastoma tumors. This technique shows a potential to improve outcomes of secondary prevention screening for retinoblastoma.