Tissue remodeling in adult vernal keratoconjunctivitis

Ocular Manifestations in Children with Vernal Keratoconjunctivitis

BACKGROUND

Vernal keratoconjunctivitis (VKC) is a chronic, recurrent, and frequently severe allergic ocular condition predominantly impacting children and adolescents in tropical and subtropical areas. It profoundly affects patients' quality of life owing to its chronic symptoms and possible vision-threatening effects. Notwithstanding progress in comprehending VKC, its ocular symptoms and therapeutic approaches necessitate ongoing assessment.

AIMS

This review summarizes the main factors to consider when diagnosing, treating, and managing patients with VKC based on the current literature in this field.

METHODS

This comprehensive review examined peer-reviewed literature from 2010 to 2024 obtained from PubMed. The selection criteria encompassed research addressing the clinical presentation, diagnostic difficulties, and therapy of visual symptoms in pediatric patients with VKC. The publications chosen were those focusing on those that elucidate the pathophysiology, consequences, and innovations in treatment methodologies.

RESULTS

The ocular manifestations of VKC are varied and characterized by prominent symptoms such as severe itching, photophobia, lacrimation, and a viscous mucoid discharge. Clinical manifestations range from conjunctival hyperemia and limbal thickening to severe consequences that jeopardize vision, including shield ulcers and keratoconus. Improvements in imaging techniques such as anterior segment optical coherence tomography (AS-OCT) and in vivo confocal microscopy have enhanced diagnostic accuracy. The pharmacological approach has transitioned to steroid-sparing techniques, prioritizing mast cell stabilizers, antihistamines, and immunomodulators such as cyclosporine. Novel therapies, including biologics that target interleukin pathways, demonstrate potential in refractory instances. Nonetheless, access to modern medicines is restricted in resource-limited environments.

CONCLUSIONS

VKC poses considerable diagnostic and treatment difficulties due to its chronic nature and possible consequences. This review emphasizes the necessity for prompt diagnosis and customized management approaches to avert vision impairment. Despite considerable advancements in comprehending VKC's etiology and therapy, inequalities in access to sophisticated care highlight the necessity for global activities to guarantee equitable treatment alternatives.

Dry eye and systemic diseases

Tear film instability and reduced tear production initiate a vicious circle where hyperosmolarity, ocular inflammation, and apoptosis may induce a damage of the ocular surface including keratitis which is all included in a common condition called dry eye disease (DED). DED can be apparently an isolated ocular surface condition; however, multiple ocular and systemic risk factors have been identified. The association with systemic diseases such as autoimmune diseases, hormonal imbalance, dietary imbalance, metabolic diseases, infections, psychological conditions, and aging together with external causative factors may act independently or interacting each other to initiate and/or perpetuate signs and symptoms typical of this very common ocular surface disease. Rheumatological disorders are most typically associated with dry eye; therefore, strict interaction with rheumatologists is important for the diagnosis and management of DED patients. In the present narrative review, we highlight associations between DED and some of the systemic disorders that may be implicated in the development of the disease.

Chronobiological and neuroendocrine insights into dry eye

Dry eye, a prevalent ocular surface disease, is significantly influenced by modern lifestyle factors such as night-shift work and extended screen time. Emerging evidence suggests a strong correlation between disturbances in circadian rhythm, sleep disorders, and dry eye. However, the precise underlying mechanisms remain unclear. Recent studies have underscored the crucial role of circadian rhythms and neuroendocrine regulation in maintaining ocular surface health. Advances in treatment strategies targeting neuroendocrine pathways have shown promising developments. This review explores the interplay between circadian rhythms, neuroendocrine regulation, and the ocular surface, examines the impact of circadian disruption on the pathophysiology of dry eye, and proposes intervention strategies to alleviate dry eye associated with disturbances in circadian rhythms.

Androgens and androgen receptor directly induce the thickening, folding, and vascularization of the seahorse abdominal dermal layer into a placenta-like structure responsible for male pregnancy via multiple signaling pathways

Seahorses exhibit the unique characteristic of male pregnancy, which incubates numerous embryos in a brood pouch that plays an essential role in enhancing offspring survivability. The pot-belly seahorse (Hippocampus abdominalis) possesses the largest body size among seahorses and is a significant species in Chinese aquaculture. In this study, we revealed the cytological and morphological characteristics, as well as regulatory mechanisms, throughout the entire brood pouch development in H. abdominalis. The brood pouch originated from the abdominal dermis, extending towards the ventral midline. As the dermal layers thicken, the inner epithelium folds, the stroma loosens, and vascularization occurs, culminating in the formation of the brood pouch. Furthermore, through transcriptomic analysis of brood pouches at various developmental stages, 8 key genes (tgfb3, fgf2, wnt7a, pgf, mycn, tln2, jund, ccn4) closely related to the development of brood pouch were identified in the MAPK, Rap1, TGF-β, and Wnt signaling pathways. These genes were highly expressed in the pseudoplacenta and dermal layers at the newly formed stage as examined by in situ hybridization (ISH). The angiogenesis, densification of collagen fibers, and proliferation of fibroblasts and endothelial cells in seahorse brood pouch formation may be regulated by these genes and pathways. Additionally, the expression of the androgen receptor gene (ar) was significantly upregulated during the formation of the brood pouch, and ISH confirmed the expression of the ar gene in the dermis and pseudoplacenta of the brood pouch, highlighting its role in the developmental process. Androgen and flutamide (androgen receptor antagonist) treatments significantly accelerated the formation of the brood pouch and completely inhibited its occurrence respectively, concomitant to the upregulated expression of differentially expressed genes involved above signaling pathways. These findings demonstrated that formation of the brood pouch is determined by androgen and the androgen receptor activates the above signaling pathways in the brood pouch through the regulation of fgf2, tgfb3, pgf, and wnt7a. Interestingly, androgen even induced the formation of the brood pouch in females. We firstly elucidated the formation of the seahorse brood pouch, demonstrating that androgens and their receptors directly induce the thickening, folding, and vascularization of the abdominal dermal layer into a placenta-like structure through multiple signaling pathways. These findings provide foundational insights to further exploring the evolution of male pregnancy and adaptive convergence in viviparity across vertebrates.

Vernal Keratoconjunctivitis: Immunopathological Insights and Therapeutic Applications of Immunomodulators

Vernal keratoconjunctivitis (VKC) is a complex and multifactorial disease process that employs Th2 cell-mediated immunologic processes, which involves the overexpression of interleukin 4 (IL-4), IL-5, IL-9, IL-13, and IL-31, and the activation of mast cells that release IL-5 and CCL-11, recruiting eosinophils to the site of inflammation. The disease primarily affects young males and is more common in regions with warm climates. VKC is characterized by persistent and recurrent conjunctival inflammation that can adversely affect the patient's quality of life, and, when inadequately treated, may lead to a host of ocular complications, such as corneal shield ulcers and scarring. The major distinct forms of VKC include limbal or palpebral, which may occur in combination. The clinicopathological features of VKC include the presence of pseudogerontoxon, limbal gelatinous hyperplasia, and perilimbal hyperpigmentation. Topical immunomodulators are effective anti-steroidal options for controlling severe and chronic cases of VKC. This review will provide a brief overview of topical immunomodulators, including cyclosporin and tacrolimus, and will highlight the clinical manifestations, pathological mechanisms, and fibroproliferative changes in the conjunctiva that can result from recurrent disease.

Vernal keratoconjunctivitis in adults: a narrative review of prevalence, pathogenesis, and management

Vernal keratoconjunctivitis (VKC) is a chronic, progressive, allergic ocular surface disorder that can lead to sight-threatening complications. VKC occurs primarily in children and generally resolves about the time of puberty; however, case series and retrospective analyses indicate that approximately 10% of patients with VKC are adults, and that a subset of adult cases develop after puberty. Consequently, two age-related variants of VKC have recently been described: early-onset VKC-which manifests during childhood and persists into adult life-and late-onset disease, which emerges de novo after puberty. Although the signs and symptoms of adult and childhood VKC are similar, adult VKC is a long-lasting disease characterized by severe inflammation and increased risk of conjunctival fibrosis, which may place adult patients at higher risk for sight-threatening complications and adverse impacts on daily life. This review discusses the epidemiology, signs, symptoms, immunopathogenesis of adult VKC variants, and highlights current gaps in research and management of patients with this condition.

Vernal Keratoconjunctivitis: A Systematic Review

Vernal keratoconjunctivitis (VKC) is a chronic, bilateral corneal and conjunctival problem which typically presents in young individuals. VKC is characterized by itching, photophobia, white mucous discharge, lacrimation, foreign body sensation, and pain due to corneal involvement of shield ulcers. Vernal keratoconjunctivitis is categorized within ocular diseases. The diagnosis is clinical, as no sure biomarkers pathognomonic of the disease have yet been identified. The VKC therapy relies on different types of drugs, from antihistamines and topical steroids to cyclosporine or tacrolimus eye drops. In extremely rare cases, there is also the need for surgical treatment for the debridement of ulcers, as well as for advanced glaucoma and cataracts, caused by excessive prolonged use of steroid eye drops. We performed a systematic review of the literature, according to PRISMA guideline recommendations. We searched the PubMed database from January 2016 to June 2023. Search terms were Vernal, Vernal keratoconjunctivitis, and VKC. We initially identified 211 articles. After the screening process, 168 studies were eligible according to our criteria and were included in the review. In this study, we performed a systematic literature review to provide a comprehensive overview of currently available diagnostic methods, management of VKC, and its treatments.