Abstract
Simple SummaryThe sun is a deadly laser, and its damaging rays harm exposed tissues such as our skin and eyes. The skin’s protection and repair mechanisms are well understood and utilized in therapeutic approaches while the eye lacks such complete understanding of its defenses and therefore often lacks therapeutic support in most cases. The aim here was to document the similarities and differences between the two tissues as well as understand where current research stands on ocular, particularly corneal, ultraviolet protection. The objective is to identify what mechanisms may be best suited for future investigation and valuable therapeutic approaches.Ultraviolet (UV) irradiation induces DNA lesions in all directly exposed tissues. In the human body, two tissues are chronically exposed to UV: the skin and the cornea. The most frequent UV-induced DNA lesions are cyclobutane pyrimidine dimers (CPDs) that can lead to apoptosis or induce tumorigenesis. Lacking the protective pigmentation of the skin, the transparent cornea is particularly dependent on nucleotide excision repair (NER) to remove UV-induced DNA lesions. The DNA damage response also triggers intracellular autophagy mechanisms to remove damaged material in the cornea; these mechanisms are poorly understood despite their noted involvement in UV-related diseases. Therapeutic solutions involving xenogenic DNA-repair enzymes such as T4 endonuclease V or photolyases exist and are widely distributed for dermatological use. The corneal field lacks a similar set of tools to address DNA-lesions in photovulnerable patients, such as those with genetic disorders or recently transplanted tissue.
Highlights
The CorneaThe cornea is the superficial shield at the front of the eye
Lacking the protective pigmentation of the skin, the transparent cornea is dependent on nucleotide excision repair (NER) to remove UV-induced DNA lesions
The corneal structure does vary between species, in terms of Bowman’s layer and Descemet’s membranes, to accommodate different needs and adaptations, all fulfil the basic roles of protection and refraction [4]
Summary
The cornea is the superficial shield at the front of the eye. Its transparency is essential for the transmission of light into the eye and through to the retina, enabling visual perception. The corneal structure does vary between species, in terms of Bowman’s layer and Descemet’s membranes, to accommodate different needs and adaptations, all fulfil the basic roles of protection and refraction [4]. Descemet’s membranes, to accommodate different needs and adaptations, all fulfil the basic roles of protection and refraction [4]. As the epithelial cell population is maintained by limbal stem cells (see Figure 2), the closure of wounds is severely impeded by any damage to their niche, the limbus [20]. UTshihsaoscbcueresnsspheociwficnatlolyfwocituhsUatVthenetneraisnagl limbus, daatmthaegitnegmpliomrablallimceblulssttohaatgisretahteenr cdoengcreenet.raTtehdistooctchuernsasspael cliimficbaulsly(sweeitFhigUuVree3n)t[e3r6i]n.g at the teTwmhaeprsdoesrdathalemlicamegnbetduersliomtfhbtahatel iccseoltrlhnseeaann[dc3o7th]n.ecier ndtersacteenddatnotsthmeanyatshaelnlmimigbruatse(fsreoemFtihgeulrime b3u) s[3to6-] These Biology 2022, 11, x FOR PEER REVIEdWamaged limbal cells and their descendants may migrate from the limbu4s otfow21ards the center of the cornea [37]. None NER, Apoptosis, Antioxidants [53,54] Wound Healing, Autophagy [57,58,59,60] Wound Healing, Autophagy [57,63] Wound Healing, Autophagy [57,67]
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