No abstract

Retinoblastoma, on flow cytometric analysis, revealed two distinct subpopulations with variable expression of stem cell and retinal progenitor markers. In these populations, the FSC(lo)/SSC(lo) subpopulation appeared to be more primitive, since they expressed stem cell (CD44) and retinal progenitor markers (PROX1 and Syntaxin 1A) combined with a relatively lower percentage of differentiated markers. Moreover, the FSC(hi)/SSC(lo) subpopulation showed a higher percentage of differentiated markers (CD90 and CD133).

Aim To evaluate the effectiveness of anterior chemodenervation of levator palpebrae superioris with Botulinum toxin type A (Botox s ) to induce temporary ptosis for corneal protection, and assess the incidence of superior rectus underaction. Methods Prospective interventional case series. Patients with ocular surface pathology requiring temporary tarsorrhaphy underwent transcutaneous anterior chemodenervation of levator palpebrae superioris with Botox s . The onset and duration of ptosis, corneal healing, and superior rectus underaction was evaluated. Results Ten eyes of 10 patients underwent transcutaneous anterior chemodenervation of levator muscle. Five patients had Bells palsy with exposure keratopathy, four patients had persistent epithelial defect, and one had neurotrophic ulcer. The median age at presentation was 30 years. Median dose of Botulinum toxin injection was 12.5 U (range 10-15 U). The mean palpebral fissure height of 9 mm (SD72.1 mm) before injection, reduced to 2.8 mm (SD71.9 mm) at 1-week post-injection. More than 50% reduction in palpebral fissure height was seen in nine out of 10 eyes (90%, 95% CI 71.4-100%) at 1 week, seven of nine eyes (77.8%, 95% CI 50.6-100%) at 2 weeks, and two of nine eyes (22.2%, 95% CI 0-49.4%) at 4 weeks, and returned to pretreatment level after mean duration of 9.2 weeks (range 5-16 weeks). Superior rectus underaction was not noted in any of the patient (95% CI 0-30%). Corneal pathology improved in all cases. Conclusion Anterior chemodenervation of levator palpebrae superioris with Botulinum toxin type A (Botox s ) induces significant temporary ptosis and aids in corneal healing. Anterior placement of the toxin injection may avoid superior rectus underaction.