The kynurenine pathway (KP) is the primary route of tryptophan metabolism in most mammalian cells, with approximately 95% of dietary tryptophan being converted into kynurenine and its downstream metabolites. Kynurenine is a central metabolite of tryptophan and possesses anti-inflammatory, antioxidant, and neuroprotective properties. Current research has shown that the KP plays a role in various diseases such as keratitis, cataract, glaucoma, and diabetic retinopathy. It was deeply involved in ocular pathophysiology through multiple mechanisms, including immunomodulation, antioxidant activity, neuroprotection, and mediation of photodamage. This paper presents a review of the role of KP in the eye and their related mechanisms in ocular diseases, including keratitis, cataract, glaucoma, and diabetic retinopathy, along with an outlook on future research.

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