Introduction: Corneal alkali burns cause corneal infection, ulceration, perforation, neo-vascularization (NV) and opacification resulting in permanent visual impairment.  Aim of the work: This study was aimed at comparing the outcome of early and late administration of adipose derived stem cells on corneal alkali burn.  Materials and methods: Twenty eight adult male albino rats (12 weeks old), 180-200 grams body weight, in addition to ten rats used as a source for ADSCs. Rats were divided into 4 groups. Group I (control); group II (corneal alkali burn): subjected to corneal alkali burn injury using NaOH. Group III (early administration of stem cells): the injury was performed as in group II then the rats were received an injection of adipose derived stem cells (ADSCs) one hour after injury. Group IV (late administration of stem cells): rats were subjected to corneal alkali burn then were given ADSCs 3 weeks after injury. Rats of group III and IV were sacrificed 3 and 6 weeks post injury respectively. Corneal sections were stained with hematoxylin & eosin, masson's trichrome and immunohistochemichal stains for anti-vascular endothelial growth factor (VEGF) and anti-Caspase 3. Morphometric and statistical studies were done.  Results: In alkali burn group, abnormal architecture of the corneal tissue with complete loss of part of the epithelium, widely separated collagenous bundles and congested blood vessels were observed. However, ADSCs therapy resulted in regeneration of corneal epithelium and reduction of apoptotic cells. In addition, less separation of collagen bundles and disappearance of neovascularization were more pronounced in early ADSCs treatment. These results were confirmed morphometrically, in comparison to alkali burn group.
Conclusion: Both early and late treatment with ADSCs had effective role in corneal repair. However, early treatment with ADSCs had better effect than late treatment on corneal wound healing.