Pigment Epithelia of the Eye: Cell-Type Conversion in Regeneration and Disease. Grigoryan Eleonora N Life (Basel, Switzerland) Pigment epithelial cells (PECs) of the retina (RPE), ciliary body, and iris (IPE) are capable of altering their phenotype. The main pathway of phenotypic switching of eye PECs in vertebrates and humans in vivo and/or in vitro is neural/retinal. Besides, cells of amphibian IPE give rise to the lens and its derivatives, while mammalian and human RPE can be converted along the mesenchymal pathway. The PECs' capability of conversion in vivo underlies the lens and retinal regeneration in lower vertebrates and retinal diseases such as proliferative vitreoretinopathy and fibrosis in mammals and humans. The present review considers these processes studied in vitro and in vivo in animal models and in humans. The molecular basis of conversion strategies in PECs is elucidated. Being predetermined onto- and phylogenetically, it includes a species-specific molecular context, differential expression of transcription factors, signaling pathways, and epigenomic changes. The accumulated knowledge regarding the mechanisms of PECs phenotypic switching allows the development of approaches to specified conversion for many purposes: obtaining cells for transplantation, creating conditions to stimulate natural regeneration of the retina and the lens, blocking undesirable conversions associated with eye pathology, and finding molecular markers of pathology to be targets of therapy. 10.3390/life12030382

Developmental origin of the posterior pigmented epithelium of iris. Wang Xiaobing,Xiong Kai,Lu Lei,Gu Dandan,Wang Songtao,Chen Jing,Xiao Honglei,Zhou Guomin Cell biochemistry and biophysics Iris epithelium is a double-layered pigmented cuboidal epithelium. According to the current model, the neural retina and the posterior iris pigment epithelium (IPE) are derived from the inner wall of the optic cup, while the retinal pigment epithelium (RPE) and the anterior IPE are derived from the outer wall of the optic cup during development. Our current study shows evidence, contradicting this model of fetal iris development. We demonstrate that human fetal iris expression patterns of Otx2 and Mitf transcription factors are similar, while the expressions of Otx2 and Sox2 are complementary. Furthermore, IPE and RPE exhibit identical morphologic development during the early embryonic period. Our results suggest that the outer layer of the optic cup forms two layers of the iris epithelium, and the posterior IPE is the inward-curling anterior rim of the outer layer of the optic cup. These findings provide a reasonable explanation of how IPE cells can be used as an appropriate substitute for RPE cells. 10.1007/s12013-014-0310-0

Keratin pearl cyst formation after traumatic implantation of an eyelash into the anterior chamber: A case report. American journal of ophthalmology case reports Purpose:We introduce a case with creamy white pearl-like keratin cysts in the anterior chamber after a penetrating injury associated with eyelash implantation. Observations:A 5-year-old girl presented with a history of penetrating corneal injury with a knife ten months ago. An eyelash was removed from the anterior chamber during her previous primary repair. Her parents complained about the presence of a white mass in her repaired eye, which had appeared about nine months after surgery. After the visco-expression of these solid masses, the histopathological evaluation revealed keratinous material surrounded by multinucleated giant cells. Conclusions and importance:In a case of post-traumatic implantation of eyelash into the anterior chamber, despite removing the cilia, cysts may develop, which suggests proliferating epithelial cells embedded within the anterior chamber. 10.1016/j.ajoc.2022.101523

[Free-Floating Intraocular Cysts]. Klinische Monatsblatter fur Augenheilkunde BACKGROUND:Free-floating intraocular cysts may be found in the anterior chamber (FZV) and the vitreous (FZG). The first description of a cyst was 150 years ago, and they are considered to be ocular rarities. MATERIALS AND METHODS:The actual knowledge about FZV and FZG is shown on the basis of two exemplary patients. RESULTS AND DISCUSSION:Patient 1 had a FZV as an incidental finding which had a smooth surface, a slight pigmentation and was translucent. The ultrasound biomicroscopy revealed an echo-free interior space. Without the patient's discomfort and missing treatment indication, a watch-and-wait strategy was chosen. Cysts of the iris can be classified as primary and secondary cysts. Primary cysts of the iris can arise from the stroma as the pigment epithelium wherein it is believed that FZV descend from the pigment epithelium. Secondary cysts and FZV can be generated by tumors, inflammation, epithelial ingrowth, the use of eye-drops or intraocular foreign bodies. Patient 2 showed marked myopic fundus changes and an FZG with a yellowish-greenish surface; the transparency was reduced and the surface was not pigmented. The ultrasound examination also revealed an echo-free interior space. Clinical controls were advised. Congenital and acquired causes are discussed for the formation of FZG. FZG could originate from the pigment epithelium of the iris, but there are conflicting study results. Trauma, inflammation and chorioretinal diseases are considered as a reason for acquired causes of FZG. The genesis, especially of FZG, is still unclear. For the treatment of patients with FZV and FZG, it is important to know the potential causes to be able to make a therapeutic decision. High quality photographic and sonographic documentation is needed in the watch-and-wait strategy. 10.1055/s-0043-105268

Latanoprost Induced Iris Pigment Epithelial and Ciliary Body Cyst Formation in Hypermetropic Eyes. Mohite Abhijit Anand,Prabhu Rangarajan V,Ressiniotis Thomas Case reports in ophthalmological medicine PURPOSE:Latanoprost has become one of the most widely prescribed topical antihypertensive medications in recent years. Yet there have been few reports of secondary iris pigment epithelial (IPE) and ciliary body (CB) cyst formation to date and none, to our knowledge, reported in eyes predisposed to primary angle closure. METHODS:We report the first documented case of bilateral IPE and CB cysts in a hypermetropic patient with prior laser peripheral iridotomies (LPIs) as a rare, delayed side effect of topical Latanoprost treatment. The cysts subsided with discontinuation of Latanoprost, thereby demonstrating a causal relationship. We discuss the pathogenesis of such cysts and advocate using of serial ultrasound biomicroscopic (UBM) images to monitor them. RESULTS AND CONCLUSIONS:Latanoprost may cause iris pigment epithelial and ciliary body cysts that remain clinically undetected. In eyes predisposed to angle closure, such cysts may become clinically detectable and masquerade as iris tumours. Prior laser peripheral iridotomies in these eyes may delay or prevent the detection of these cysts. Ultrasound biomicroscopy (UBM) imaging is therefore a valuable tool in diagnosing and monitoring these cysts. 10.1155/2017/9362163