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Purpose: This study aimed to compare the changes in the lacrimal functional unit in the following two models of neurogenic dry eye syndrome: sensory denervation of the cornea versus autonomic denervation of the lacrimal gland. Methods: The neural network supports the lacrimal functional unit. It can be divided into afferent (sensory) and efferent (autonomic) pathways and is affected by severe diseases that compromise the lacrimal functional unit. Male Wistar, 8-week-old rats were divided into the following three groups: 1) control naïve (n=16 animals); 2) autonomic denervation: where rats were subjected to right lacrimal gland nerve ablation and evaluated after 1 and 2 months (1M and 2M) after the procedure (n=7 animals per subgroup, autonomic denervation 1M and autonomic denervation 2M, respectively); 3) sensory denervation induced by 0.2% benzalkonium chloride eye drops, twice a day for 7 days in the right eye (n=10 animals). The corneal sensitivity was measured using the eye wipe test with capsaicin (10 µM). The quantitative real-time PCR was performed to compare the mRNA expressions of proinflammatory cytokines, such as Il-1β, Il-6, Tnf, Mmp9, in the cornea, trigeminal ganglion, and lacrimal gland. In addition, the mRNA of the promitotic factors in the lacrimal gland, such as Bmp7, Runx1, Runx3, Fgf10, and Smad1, was compared. Results: Sensory denervation induced corneal hyperalgesia (p=0.001). Sensory denervation and autonomic denervation increased the mRNA of proinflammatory cytokines in the cornea and lacrimal gland (p

The burden of corneal blindness and visual deficiency can be felt worldwide. Its association with several endemic diseases such as childhood blindness, trauma, infectious keratitis (including variants caused by herpes, hanseniasis, and fungi), vitamin A deficiency, diabetes mellitus, and other dry eye syndromes reflects its poorly understood underlying mechanisms and suggests that the actual frequency of the disease is underestimated. The low effectiveness of preventive and therapeutic strategies against corneal scarring or deformity predicts a high frequency of patients with corneal blindness in the future. Corneal blindness is associated with environmental factors and socioeconomic limitations that restrain health assistance and maintain a modest efficiency of the current therapeutic strategies for resolving corneal diseases in large-scale programs. We present here a critical review of the concepts associated with corneal blindness that need to be considered when planning strategies to prevent and treat corneal blindness worldwide (to be able to leave Plato’s cave, where corneal blindness is encaged.