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Nutrients Oct 2020Cataracts or clouding of the lens is the leading cause of blindness in the world. Age and diabetes are major risk factors, and with an increasing aging and diabetic... (Review)
Review
Cataracts or clouding of the lens is the leading cause of blindness in the world. Age and diabetes are major risk factors, and with an increasing aging and diabetic population, the burden of cataracts will grow. Cataract surgery is an effective way to restore vision; however, alternatives to cataract surgery are required to reduce the looming cataract epidemic. Since it is well established that oxidative damage plays a major role in the etiology of cataracts, antioxidants have been promoted as therapies to delay and/or prevent cataracts. However, many antioxidant interventions including vitamin C have produced mixed results as anti-cataract therapies. Progress has been made towards our understanding of lens physiology and the mechanisms involved in the delivery and uptake of antioxidants to the lens which may guide future studies aimed at addressing some of the inconsistencies seen in previous animal and human studies. Of interest is the potential for vitamin C based supplements in delaying the onset of cataracts post vitrectomy which occurs in up to 80% of patients within two years. These targeted approaches are required to reduce the burden of cataract on hospitals and improve the quality of life of our aging and diabetic population.
Topics: Aging; Animals; Antioxidants; Ascorbic Acid; Cataract; Diabetes Complications; Dietary Supplements; Humans; Nutritional Physiological Phenomena; Oxidative Stress; Risk Factors; Vitrectomy; Vitreous Body
PubMed: 33066702
DOI: 10.3390/nu12103142 -
Experimental Eye Research Mar 2017The crystalline lens plays an important role in the refractive vision of vertebrates by facilitating variable fine focusing of light onto the retina. Loss of lens... (Review)
Review
The crystalline lens plays an important role in the refractive vision of vertebrates by facilitating variable fine focusing of light onto the retina. Loss of lens transparency, or cataract, is a frequently acquired cause of visual impairment in adults and may also present during childhood. Genetic studies have identified mutations in over 30 causative genes for congenital or other early-onset forms of cataract as well as several gene variants associated with age-related cataract. However, the pathogenic mechanisms resulting from genetic determinants of cataract are only just beginning to be understood. Here, we briefly summarize current concepts pointing to differences in the molecular mechanisms underlying congenital and age-related forms of cataract.
Topics: Aging; Animals; Cataract; Crystallins; Humans; Lens, Crystalline; Mutation
PubMed: 27334249
DOI: 10.1016/j.exer.2016.06.011 -
Annual Review of Vision Science Sep 2019Cataract, the clinical correlate of opacity or light scattering in the eye lens, is usually caused by the presence of high-molecular-weight (HMW) protein aggregates or... (Review)
Review
Cataract, the clinical correlate of opacity or light scattering in the eye lens, is usually caused by the presence of high-molecular-weight (HMW) protein aggregates or disruption of the lens microarchitecture. In general, genes involved in inherited cataracts reflect important processes and pathways in the lens including lens crystallins, connexins, growth factors, membrane proteins, intermediate filament proteins, and chaperones. Usually, mutations causing severe damage to proteins cause congenital cataracts, while milder variants increasing susceptibility to environmental insults are associated with age-related cataracts. These may have different pathogenic mechanisms: Congenital cataracts induce the unfolded protein response and apoptosis. By contrast, denatured crystallins in age-related cataracts are bound by α-crystallin and form light-scattering HMW aggregates. New therapeutic approaches to age-related cataracts use chemical chaperones to solubilize HMW aggregates, while attempts are being made to regenerate lenses using endogenous stem cells to treat congenital cataracts.
Topics: Apoptosis; Cataract; Crystallins; Eye Diseases, Hereditary; Humans; Stem Cell Transplantation
PubMed: 31525139
DOI: 10.1146/annurev-vision-091517-034346 -
Indian Journal of Ophthalmology Dec 2017Pediatric cataract is a leading cause of childhood blindness. Untreated cataracts in children lead to tremendous social, economical, and emotional burden to the child,... (Review)
Review
Pediatric cataract is a leading cause of childhood blindness. Untreated cataracts in children lead to tremendous social, economical, and emotional burden to the child, family, and society. Blindness related to pediatric cataract can be treated with early identification and appropriate management. Most cases are diagnosed on routine screening whereas some may be diagnosed after the parents have noticed leukocoria or strabismus. Etiology of pediatric cataract is varied and diagnosis of specific etiology aids in prognostication and effective management. Pediatric cataract surgery has evolved over years, and with improving knowledge of myopic shift and axial length growth, outcomes of these patients have become more predictable. Favorable outcomes depend not only on effective surgery, but also on meticulous postoperative care and visual rehabilitation. Hence, it is the combined effort of parents, surgeons, anesthesiologists, pediatricians, and optometrists that can make all the difference.
Topics: Blindness; Cataract; Child; Global Health; Humans; Morbidity
PubMed: 29208814
DOI: 10.4103/ijo.IJO_1023_17 -
Nature Mar 2016The repair and regeneration of tissues using endogenous stem cells represents an ultimate goal in regenerative medicine. To our knowledge, human lens regeneration has...
The repair and regeneration of tissues using endogenous stem cells represents an ultimate goal in regenerative medicine. To our knowledge, human lens regeneration has not yet been demonstrated. Currently, the only treatment for cataracts, the leading cause of blindness worldwide, is to extract the cataractous lens and implant an artificial intraocular lens. However, this procedure poses notable risks of complications. Here we isolate lens epithelial stem/progenitor cells (LECs) in mammals and show that Pax6 and Bmi1 are required for LEC renewal. We design a surgical method of cataract removal that preserves endogenous LECs and achieves functional lens regeneration in rabbits and macaques, as well as in human infants with cataracts. Our method differs conceptually from current practice, as it preserves endogenous LECs and their natural environment maximally, and regenerates lenses with visual function. Our approach demonstrates a novel treatment strategy for cataracts and provides a new paradigm for tissue regeneration using endogenous stem cells.
Topics: Animals; Cataract; Cataract Extraction; Epithelial Cells; Eye Proteins; Homeodomain Proteins; Homeostasis; Humans; Lens, Crystalline; Macaca; PAX6 Transcription Factor; Paired Box Transcription Factors; Polycomb Repressive Complex 1; Proto-Oncogene Proteins; Recovery of Function; Regeneration; Repressor Proteins; Stem Cells; Vision, Ocular
PubMed: 26958831
DOI: 10.1038/nature17181 -
BMC Cell Biology Jan 2017The lens is an avascular organ composed of an anterior epithelial cell layer and fiber cells that form the bulk of the organ. The lens expresses connexin43 (Cx43),... (Review)
Review
The lens is an avascular organ composed of an anterior epithelial cell layer and fiber cells that form the bulk of the organ. The lens expresses connexin43 (Cx43), connexin46 (Cx46) and connexin50 (Cx50). Epithelial Cx50 has critical roles in cell proliferation and differentiation, likely involving growth factor-dependent signaling pathways. Both Cx46 and Cx50 are crucial for lens transparency; mutations in their genes have been linked to congenital and age-related cataracts. Congenital cataract-associated connexin mutants can affect protein trafficking, stability and/or function, and the functional effects may differ between gap junction channels and hemichannels. Dominantly inherited cataracts may result from effects of the connexin mutant on its wild type isotype, the other co-expressed wild type connexin and/or its interaction with other cellular components.
Topics: Animals; Cataract; Connexins; Humans; Intercellular Signaling Peptides and Proteins; Lens, Crystalline; Mutation; Signal Transduction
PubMed: 28124626
DOI: 10.1186/s12860-016-0116-6 -
Clinical Genetics Aug 2013The pathogenesis of inherited cataracts of all kinds recapitulates the developmental and cell biology of the lens. Just as each novel mutation provides additional... (Review)
Review
The pathogenesis of inherited cataracts of all kinds recapitulates the developmental and cell biology of the lens. Just as each novel mutation provides additional information about the structural or functional biology of the affected gene, each newly identified gene provides insight into the developmental and cellular biology of the lens. The set of genes currently known to be associated with cataract is far from complete, especially for age-related cataract, and there is much additional information to be discovered through further genetic studies.
Topics: Age Factors; Cataract; Homeostasis; Humans; Lens, Crystalline; Mutation
PubMed: 23647473
DOI: 10.1111/cge.12182 -
The Cochrane Database of Systematic... Jan 2018Cataract formation or acceleration can occur after intraocular surgery, especially following vitrectomy, a surgical technique for removing the vitreous that is used in... (Review)
Review
BACKGROUND
Cataract formation or acceleration can occur after intraocular surgery, especially following vitrectomy, a surgical technique for removing the vitreous that is used in the treatment of many disorders that affect the posterior segment of the eye. The underlying problem that led to vitrectomy may limit the benefit from removal of the cataractous lens.
OBJECTIVES
To evaluate the effectiveness and safety of surgery versus no surgery for postvitrectomy cataract with respect to visual acuity, quality of life, and other outcomes.
SEARCH METHODS
We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2017, Issue 5), MEDLINE Ovid (1946 to 17 May 2017), Embase.com (1947 to 17 May 2017), PubMed (1946 to 17 May 2017), Latin American and Caribbean Health Sciences Literature database (LILACS) (January 1982 to 17 May 2017), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com); last searched May 2013, ClinicalTrials.gov (www.clinicaltrials.gov); searched 17 May 2017, and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en); searched 17 May 2017. We did not use any date or language restrictions in the electronic searches for trials.
SELECTION CRITERIA
We planned to include randomized controlled trials (RCTs) and quasi-RCTs that had compared surgery versus no surgery to remove the lens from eyes of adults in which cataracts had developed following vitrectomy.
DATA COLLECTION AND ANALYSIS
Two review authors independently screened the search results according to the standard methodological procedures expected by Cochrane.
MAIN RESULTS
We found no RCTs or quasi-RCTs that had compared surgery versus no surgery to remove the lens from eyes of adults in which cataracts had developed following vitrectomy.
AUTHORS' CONCLUSIONS
There is no evidence from RCTs or quasi-RCTs on which to base clinical recommendations for surgery for postvitrectomy cataract. There is a clear need for RCTs to address this evidence gap. Such trials should stratify participants by their age, the retinal disorder leading to vitrectomy, and the status of the underlying disease process in the contralateral eye. Outcomes assessed in such trials may include changes (both gains and losses) of visual acuity, quality of life, and adverse events such as posterior capsular rupture and retinal detachment. Both short-term (six-month) and long-term (one- or two-year) outcomes should be examined.
Topics: Adult; Cataract; Cataract Extraction; Humans; Postoperative Complications; Quality of Life; Visual Acuity; Vitrectomy
PubMed: 29364503
DOI: 10.1002/14651858.CD006366.pub4 -
Eye (London, England) Nov 2017PurposeThe purpose of this study is to compare the amplitudes and peak times of the flicker electroretinograms (ERGs) recorded before and after cataract surgery with the... (Comparative Study)
Comparative Study
PurposeThe purpose of this study is to compare the amplitudes and peak times of the flicker electroretinograms (ERGs) recorded before and after cataract surgery with the RETeval system (LKC Technologies, Gaithersburg, MD, USA) from eyes without dilation.Patients and methodsThirty-two eyes of 32 patients (77.3±6.5 years) that had grade 2 Emery-Little nuclear or cortical cataract without any other abnormalities were studied. Flicker ERGs were recorded with the RETeval system under mydriatic-free conditions. Skin electrodes were used to pick-up the ERGs that were elicited by white light delivered at a rate of 28.3 Hz and intensity of 2, 8, and 32 Td-s. The amplitudes and peak times of the flicker ERGs before and after cataract surgery were compared.ResultsThe mean amplitudes were significantly increased after the removal of the cataractous lenses at the three stimulus intensities (2 Td-s, P<0.0001; 8 Td-s, P<0.0001; and 32 Td-s, P<0.0001). The mean peak times of the flicker ERGs elicited by 2 and 8 Td-s were significantly shortened after the surgery (2 td-s, P<0.0001 and 8 td-s, P=0.0127) but not at 32 td-s (P=0.595).ConclusionsThese results indicate that the presence of cataracts will affect both the amplitudes and the peak times of the flicker ERGs even if the cataract is mild. In addition, the results indicate that as stimulus intensity increases, the peak times is less affected by a cataract. The clarity of the crystalline lens should be considered when interpreting the flicker ERGs recorded with the RETeval system.
Topics: Aged; Aged, 80 and over; Cataract; Cataract Extraction; Dark Adaptation; Electroretinography; Female; Flicker Fusion; Follow-Up Studies; Humans; Male; Middle Aged; Mydriasis; Ophthalmoscopy; Photic Stimulation; Postoperative Period; Preoperative Period; Prognosis; Retinal Cone Photoreceptor Cells; Retrospective Studies; Visual Acuity
PubMed: 28622319
DOI: 10.1038/eye.2017.110 -
Indian Journal of Ophthalmology Nov 2023
Topics: Humans; Infant, Newborn; Cataract; Eye; Iatrogenic Disease; Retinopathy of Prematurity; Gestational Age; Retrospective Studies; Laser Coagulation
PubMed: 37869997
DOI: 10.4103/IJO.IJO_2744_23