Vitamin A is an essential fat-soluble vitamin that occurs in various chemical forms. It is essential for several physiological processes. Either hyper- or hypovitaminosis can be harmful. One of the most important vitamin A functions is its involvement in visual phototransduction, where it serves as the crucial part of photopigment, the first molecule in the process of transforming photons of light into electrical signals. In this process, large quantities of vitamin A in the form of 11-cis-retinal are being isomerized to all-trans-retinal and then quickly recycled back to 11-cis-retinal. Complex machinery of transporters and enzymes is involved in this process (i.e., the visual cycle). Any fault in the machinery may not only reduce the efficiency of visual detection but also cause the accumulation of toxic chemicals in the retina. This review provides a comprehensive overview of diseases that are directly or indirectly connected with vitamin A pathways in the retina. It includes the pathophysiological background and clinical presentation of each disease and summarizes the already existing therapeutic and prospective interventions.

: Purpose:  To analyse the anterior lens capsule thickness and ultrastructure changes of intumescent white cataracts in comparison with nuclear cataracts to prove possible structural reasons for surgical difficulties with the intumescent white cataract.Methods:  Anterior lens capsules from 35 eyes with intumescent white and 35 eyes with nuclear cataracts were analysed for their thickness by semithin sections technique and for morphological characteristics by transmission electron microscopy.Results:  Capsule thickness was not significantly different in intumescent white compared to nuclear cataracts (mean values 17.5 and 18.5 μm, respectively, p = 0.369). The main morphological features of capsules were extrusions of capsule at the basement membrane‐epithelial border embedding cellular material which were significantly more frequent in intumescent cataracts. Filaments in the basement membrane as well as rarefication of its structure and lamellae were often concomitant with the extrusions.Conclusions:  Anterior capsules of white intumescent cataracts do not differ in thickness but have different ultrastructure morphology compared to nuclear cataracts. The extrusions of basement membrane at the basement membrane‐epithelial border towards epithelium, the filamentary inclusions within basement membrane and its rarefication could be the structural causes of tensile weakness and hence additional reason to surgical problems.

The cornea is a vital component of the visual system, and its integrity is crucial for optimal vision. Damage to the cornea resulting from trauma, infection, or disease can lead to blindness. Corneal regeneration using mesenchymal stem cells (MSCs) and MSC-derived extracellular vesicles (MSC-EVs) offers a promising alternative to corneal transplantation. MSCs are multipotent stromal cells that can differentiate into various cell types, including corneal cells. They can also secrete a variety of anti-inflammatory cytokines and several growth factors, promoting wound healing and tissue reconstruction. This review summarizes the current understanding of the molecular and cellular mechanisms by which MSCs and MSC-EVs contribute to corneal regeneration. It discusses the potential of MSCs and MSC-EV for treating various corneal diseases, including corneal epithelial defects, dry eye disease, and keratoconus. The review also highlights finalized human clinical trials investigating the safety and efficacy of MSC-based therapy in corneal regeneration. The therapeutic potential of MSCs and MSC-EVs for corneal regeneration is promising; however, further research is needed to optimize their clinical application.