This retrospective study from a single-centre referral university hospital in Germany analysed data collected between 1991-2019 to comment on management and complications of undetected retinoblastoma eyes following vitrectomy. The 10 patients included had a mean age of 36.1 months (range 14 months – 6.5 years) at vitrectomy and a unilateral retinoblastoma at later diagnosis. The mean referral time after vitrectomy was 21 days (ranging from three days – two months). Unspecified unilateral inflammation (n=5) was the most frequent misdiagnosis resulting in vitrectomy and included: uveitis, toxocariasis, or endophthalmitis. Diagnosed retinoblastoma eyes were staged in accordance with the International Intraocular Retinoblastoma Classification and were as follows: six as group E, one as group B, and one as group D. Groups A and B are confined to the retina whereas C-E represent adjacent tissue invasion. All patients received magnetic resonance imaging (MRI) of eye, brain, and spinal cord as well as a lumbar puncture. The authors attached copies of MRI images, a fundus photograph, and a histology slide. Histology revealed optic nerve infiltration (n =4), choroidal infiltration (n =6), scleral infiltration (n=2), and extra-ocular extension (n=1). The authors commented on the lack of tumour invasion in patients with a 25-G system for sclerotomy site compared to the three affected eyes where a 20-G system was used. Adjuvant therapy post-enucleation consisted of four to six cycles of systemic chemotherapy and radiotherapy or proton beam therapy and / or iodine seed therapy. On follow-up (ranging from 11 months – 20 years) nine patients were free of metastases or recurrence with the exception of the child presenting with bone marrow metastasis. Prognosis is known to worsen with treatment delay as a result of tumour cell invasion of the nervous system, regional lymph nodes, or bone. Furthermore, vitrectomy in undetected retinoblastoma is an important iatrogenic risk factor. The authors emphasise awareness of retinoblastoma as a differential diagnosis, especially given its atypical presentation in older children. Lastly, they stress the significance of non-invasive diagnostics and if a vitrectomy has been performed, initiation of aggressive treatment.