BAK1 and Allergy: However, during in vitro and ex vivo studies, eye-drops containing different doses of BAK had an effect on the ocular surface, possibly due to the presence of BAK.4–6 In cell culture, it was seen that BAK induced epithelial cell death,7 pro-inflammatory or pro-apoptotic mediators,8 and oxidative stress, including mitochondrial activity and glutathione injury.9 On the ocular surface of patients with glaucoma, BAK induced complex inflammatory mechanisms, causing both allergy and toxicity.4