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Futuristic Approaches in Vitreoretinal Surgery
Published in Pradeep Venkatesh, Handbook of Vitreoretinal Surgery, 2023
Degenerative diseases of the retina, involving the retinal pigment epithelium and photoreceptors, like retinitis pigmentosa, Leber’s congenital amaurosis [LCA], and Stargardt’s disease contribute significantly to the burden of low vision globally. Until a few decades ago, the mechanism of cell death in photoreceptors and retinal pigment epithelium was not known. However, studies on Royal College of Surgeons [RCS] rats have now shown that apoptosis is a predominant method. It has also been found that photoreceptor cell death often occurs secondary to a genetic defect in the neighbouring retinal pigment epithelial cells. It has been demonstrated that in transfected cell cultures and transgenic mouse lines, expression of certain genes can prevent apoptosis. Hence, for gene-mediated disease, advances in gene therapy may play a significant role in preventing, reversing, or retarding the degenerative process. Studies have also tried to precisely determine the nature of cell death in age-related macular degeneration [ARMD].
Rare Earth Nanoparticles Prevent Retinal Degeneration Induced by Intracellular Peroxides
Published in Lajos P. Balogh, Nano-Enabled Medical Applications, 2020
Junping Chen, Swanand Patil, Sudipta Seal, James F. McGinnis
Vision is dependent on rod and cone photoreceptors, and human diseases that cause blindness do so by a variety of primary events that ultimately produce two subsequent effects in the photoreceptor cells. The first effect is thought to be the production of either an acute or a chronic rise in the intracellular concentration of ROIs in the photoreceptor cells, which in turn induces the second effect, the activation of an apoptotic signal transduction pathway and the eventual death of the photoreceptor cells. The intracellular ROIs are especially damaging because they can react with almost every type of organic molecule that exists within the cell. Most of the ROIs within the body are generated by respiration, the use of oxygen to produce energy from the metabolism of organic molecules. The retina of the eye is exposed to large amounts of such toxic compounds, generated by normal oxidative reactions as well as those produced by the constant absorption of photons of light. The retina of the albino rat is extremely sensitive to photon-induced damage, which results in the production of excess ROIs, the subsequent degeneration of the photoreceptor cells, and the loss of visual function [18]. We have used retinal neurons in culture and the light-damage model in vivo to demonstrate and characterize the ability of a suspension of vacancy-engineered nanoceria particles to prevent ROI-induced injury to the photoreceptor cells and to preserve the visual function of the retina.
The Vitiligo (mivit) Mutant Allele of the Microphthalmia Locus, Chromosome 6
Published in John P. Sundberg, Handbook of Mouse Mutations with Skin and Hair Abnormalities, 2020
M. Lynn Lamoreux, Seth J. Orlow
Macrophages (clump cells of Kogani) and abnormal melanocytes are found throughout the uveal tract.6 Progressive loss of photoreceptor cells has been documented.9,10 The retina is morphologically abnormal before birth,11 has distorted cell-cycle kinetics postnatally, and displays reduced phagosome content during the juvenile period when rod outer segments are still present.12
Mapping the Ethical Issues of Brain Organoid Research and Application
Published in AJOB Neuroscience, 2022
Tsutomu Sawai, Yoshiyuki Hayashi, Takuya Niikawa, Joshua Shepherd, Elizabeth Thomas, Tsung-Ling Lee, Alexandre Erler, Momoko Watanabe, Hideya Sakaguchi
For the topic 1), one paper reported brain organoids that possessed direct synaptic connections between cerebral neurons and photoreceptor cells, which responded to external light stimuli (Quadrato et al. 2017). However, the direct connection between cerebral neurons and photoreceptor cells is different from the in vivo visual pathway. In vivo, the photoreceptor cells connect to the optic nerve, which is sent to the bilateral thalamus through electrical and chemical signals and then to the visual cortex (areas 17 and 18) of the cerebrum to be perceived as information in the visual field. Here, all of the distribution of photoreceptor cells, the relay of the thalamus, and the area of the cerebrum to recognize the given light information as the visual field are required.
PJ34 Protects Photoreceptors from Cell Death by Inhibiting PARP-1 Induced Parthanatos after Experimental Retinal Detachment
Published in Current Eye Research, 2021
Kai Dong, Yuanye Yan, Li Lu, Yisai Wang, Jinping Li, Mei Zhang, Jie Ding
Retinal detachment (RD) is an ophthalmic problem and a potential emergency that caused vision decline. The incidence of RD is approximately 6.3–17.9/100,000 people • year, and the natural incidence in individuals is 0.06%.1,2,3 The incidence of RD is increasing year by year. During 2000–2016, the age- and sex-standardized incidence rate of rhegmatogenous retinal detachment increased by more than 50%.4 Although the success rate of surgery is high, visual function recovery after surgery is still not satisfactory, the mean best-corrected visual acuity (BCVA) was only 20/45 (0.354 logMAR) after surgery.5 The visual function damage after RD is mainly because the death of photoreceptor cells, while the mechanisms of photoreceptor cells death are complicated. Therefore, revealing the damage/repair mechanism of photoreceptor cells after RD is of important clinical and practical significance for protecting and restoring residual visual function in patients.
Intravitreal conbercept combined with laser photocoagulation for exudative retinal detachment in a patient with Coats-like retinitis pigmentosa
Published in Ophthalmic Genetics, 2019
Xiaoran Chu, Wei Du, Min Xu, Zhenggao Xie, Jun Zhu, Ying Zhu, Fang Chen
A 14-year-old girl presented with a vision decline in her right eye for 1 week. She had been diagnosed with bilateral RP 7 years ago according to the symptom of progressive nyctalopia, fundus examination and retinal electrophysiology findings. The patient had no systemic disorders and no family history of ocular diseases. At her first visit to our department, her best-corrected visual acuity (BCVA) was counting fingers (CF) in the right eye and 20/40 in the left eye. The anterior segment was normal. Biomicroscopic fundus examination revealed paled waxy optic disks and “bone-spicule-like” pigmentation in midperiphery bilaterally. Telangiectatic vessels, extensive yellowish subretinal exudates, and preretinal hemorrhages were observed in the inferotemporal quadrant of the right eye but no similar lesions in the left eye (Figure 1a,b). Fluorescein angiography (FFA) showed extensive leakages from the irregular, tortuous, and telangiectatic retinal vessels in the corresponding position (Figure 1c). Optical coherence tomography (OCT) examinations showed a serous retinal detachment involving the fovea in the macula of the right eye (Figure 1d). Visual field testing showed bilateral generalized constriction in both eyes, and electroretinography demonstrated the dysfunction of rod and cone photoreceptor cells. According to the clinical manifestations and examinations, the patient was diagnosed with Coats-like RP. We performed a gene testing for the patient and her family members with the aim of detecting mutations in exonic regions of CRB1 gene, and no mutations were found.