Toxic Keratitis After Application of Custard Apple Seed for Head Lice Infestation, Purpose: To report the clinical features and outcomes of toxic keratitis after application of powdered custard apple seeds for hair washing for head lice infestation. Methods: Retrospective review of all patients with toxic keratitis after application of powdered custard apple seed for head lice infestation during the time period from January 2015 to December 2017. Demographic details, clinical features, and visual outcomes were documented. Results: Thirty-one eyes of 19 patients with toxic keratitis after application of crushed custard apple seeds for head lice infestation were included in the study. Eighteen females and 1 male with a median age of 14 years [interquartile range (IQR) 12–34 years] presented with severe epiphora, congestion, photophobia, and defective vision (median logMar visual acuity 0.4, IQR 0.2–0.8) after application of custard apple seed powder for hair washing. Ten eyes (32.2%) had an epithelial defect (median size 9 mm2, IQR 5–12 mm2), and 21 (67.7%) eyes had punctate epithelial erosions. All the patients were treated with topical antibiotics, and at 3 days follow-up, all of them had resolution of symptoms and signs with a median logarithm of the minimum angle of resolution (logMAR) visual acuity of 0 (IQR 0–0.2). Conclusions: Health education about the harmful effect of this traditional practice for head lice infestation will prevent further similar events.