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Korean Journal of Ophthalmology : KJO Feb 2023Myopia is the most common refractive error in the world, and its' prevalence continually increases. The potential pathological and visual complications of progressive... (Review)
Review
Myopia is the most common refractive error in the world, and its' prevalence continually increases. The potential pathological and visual complications of progressive myopia have inspired researchers to study the sources of myopia, axial elongation, and explore modalities to arrest progression. Considerable attention has been given over the past few years to the myopia risk factor known as hyperopic peripheral blur, the focus of this review. The primary theories currently believed to be the cause of myopia, the parameters considered to contribute and influence the effect of peripheral blur, such as the surface retinal area or depth of blur will be discussed. The currently available optical devices designed to provide peripheral myopic defocus will be discussed, including bifocal and progressive addition ophthalmic lenses, peripheral defocus single vision ophthalmic lenses, orthokeratology lenses, and bifocal or multifocal center distance soft lenses, as well as their effectivity as mentioned in the literature to date.
Topics: Humans; Myopia, Degenerative; Hyperopia; Retina; Eyeglasses; Lens, Crystalline; Refraction, Ocular
PubMed: 36796348
DOI: 10.3341/kjo.2022.0125 -
Medicina 2022
Topics: Humans; Lens Subluxation; Lens, Crystalline; Lenses, Intraocular
PubMed: 35904923
DOI: No ID Found -
Asia-Pacific Journal of Ophthalmology... 2018Pediatric cataract surgery has seen several advances in techniques, technologies, and conceptual practices. Pediatric cataract management heavily depends on a combined... (Review)
Review
Pediatric cataract surgery has seen several advances in techniques, technologies, and conceptual practices. Pediatric cataract management heavily depends on a combined effort, not only from the ophthalmologist, but also the parents, the anesthetists, and the supporting staff members (eg, optometrists, orthoptists, patient coordinators). Surgical management, though critical, is not the only consideration for these children. Continuing visual rehabilitation and monitoring for complications remain key elements even after the surgery is done. Pediatric cataract surgery is a complex issue best left to surgeons who are familiar with the surgical paradigms and its long-term complications. Key components of surgery are management of posterior capsule and anterior vitreous and intraocular lens (IOL) implantation. It is a preferred practice today to perform a primary posterior capsulorhexis with anterior vitrectomy in younger children (up to 3 to 5 years old). Even in older children (up to the age of 8 years), performing a posterior capsulorhexis without anterior vitrectomy is the preferred approach. Above the age of 8 years, the posterior capsule can be left intact. In-the-bag IOL implantation is almost becoming a norm for children above the age of 1 year. Though there is no universal consensus regarding the earliest age for primary IOL implantation, many surgeons increasingly prefer primary IOL implantation even in infants. Alternate approaches that can avoid anterior vitrectomy like optic capture through the posterior capsulorhexis and bag-in-the-lens are also gaining more and more popularity.
Topics: Capsulorhexis; Cataract Extraction; Child; Child, Preschool; Humans; Infant; Lens Capsule, Crystalline; Lens Implantation, Intraocular; Lenses, Intraocular; Pediatrics; Time Factors; Vitrectomy
PubMed: 28971632
DOI: 10.22608/APO.2017202 -
Journal of Cataract and Refractive... Oct 2021To investigate the characteristics and factors associated with crystalline lens tilt and decentration measured by CASIA2 anterior segment optical coherence tomography.
PURPOSE
To investigate the characteristics and factors associated with crystalline lens tilt and decentration measured by CASIA2 anterior segment optical coherence tomography.
SETTING
Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
DESIGN
Cross-sectional study.
METHODS
1097 eyes of 1097 patients who planned to undergo cataract surgery were enrolled. All patients underwent a general ophthalmologic examination. Lens thickness (LT), front curvature radius (FCR), back curvature radius, lens equator diameter (LED), tilt, and decentration of preoperative crystalline lenses were measured by CASIA2. Univariate and multivariate regression analyses were performed to evaluate the relationships between the tilt and decentration of crystalline lens with related factors.
RESULTS
The natural crystalline lenses showed a mean tilt of 5.16 degrees toward the inferotemporal direction and a mean decentration of 0.22 mm toward the temporal direction. Of the total 1097 eyes, 119 eyes (10.85%) had a tilt greater than 7 degrees, and 89 eyes (8.11%) had a decentration more than 0.4 mm. Multivariate regression analysis showed that larger decentration, thicker LT, shorter axial length (AL), and FCR were associated with greater lens tilt (P < .001, P = .007, P = .006, and P = .003, respectively). In addition, greater tilt, older and thinner LT were correlated with larger decentration (all P < .001).
CONCLUSIONS
Preoperative crystalline lens had a certain degree of tilt and decentration in age-related cataract. The greater tilt of the crystalline lens was, the larger decentration of it was. In addition, AL, FCR, LT, and age also correlated with tilt and decentration.
Topics: Cataract; Cataract Extraction; Cross-Sectional Studies; Humans; Lens, Crystalline; Lenses, Intraocular
PubMed: 33769775
DOI: 10.1097/j.jcrs.0000000000000631 -
Clinical & Experimental Optometry Sep 2002Microspherophakia is present when the crystalline lens is small and relatively spherical with increased antero-posterior thickness. Clinical findings for a patient with... (Review)
Review
Microspherophakia is present when the crystalline lens is small and relatively spherical with increased antero-posterior thickness. Clinical findings for a patient with idiopathic bilateral microspherophakia are described. The patient was moderately myopic with slightly reduced visual acuity. The anterior chambers (R: 1.57 and L: 1.37 mm) were shallow compared with normals (3.46 to 3.80 mm) and the crystalline lenses were thicker (R: 4.77 and L: 4.89 mm) than normal (3.3 to 3.96 mm) with steeper than normal anterior (radii of curvature R: 6.2 and L: 6.3 mm) and posterior (R: 6.3 and L: 5.6 mm) surfaces. Microspherophakia may be associated with various syndromes and there is a strong possibility of glaucoma, particularly if the small lens is displaced.
Topics: Anterior Chamber; Child; Family; Female; Humans; Lens, Crystalline; Medical Records; Myopia; Visual Acuity
PubMed: 12366350
DOI: 10.1111/j.1444-0938.2002.tb03085.x -
Asia-Pacific Journal of Ophthalmology... May 2022
Topics: Capsule Opacification; Humans; Lens Capsule, Crystalline; Lenses, Intraocular
PubMed: 35066520
DOI: 10.1097/APO.0000000000000441 -
Survey of Ophthalmology 2022Infantile cataracts remain one of the most treatable causes of lifelong visual impairment. While the chance of improving vision for children with infantile cataracts has... (Review)
Review
Infantile cataracts remain one of the most treatable causes of lifelong visual impairment. While the chance of improving vision for children with infantile cataracts has never been better, significant global and socioeconomic disparities still exist in their early management. Recent epidemiological studies reveal a stable prevalence of infantile cataracts in high-income countries and highlight challenges in determining the prevalence of infantile cataracts in low-income countries. Detailed descriptions of cataract morphology may inform us as to etiology, provide guidance with regards to surgical approach, and have prognostic value. Molecular genetics is providing new insights into the hereditary bases and potential systemic associations of infantile cataracts. For visually significant infantile cataracts requiring surgery to clear the visual axis, surgical techniques continue to evolve based on the experiences and research efforts of skilled teams worldwide. The most common complications of cataract surgery performed in infancy are visual axis opacification and, in about a third of patients, the long-term development of glaucoma. Children with unilateral cataracts generally see well given the presence of a healthy fellow eye. Better visual outcomes in operated eyes, however, are achieved in the setting of early presentation, bilateral infantile cataracts, absence of nystagmus or strabismus, and consistent amblyopia therapy. While intraocular lenses for infants less than 6 months can result in good visual outcomes, contact lenses may be preferred in situations in which they are available and practical. Many studies have demonstrated the benefits of early surgery for infantile cataract. We must strive for the continued evolution of technologies and strategies that have the potential to further improve these outcomes.
Topics: Cataract; Cataract Extraction; Child; Follow-Up Studies; Humans; Infant; Lens Implantation, Intraocular; Lens, Crystalline; Lenses, Intraocular; Retrospective Studies
PubMed: 35307324
DOI: 10.1016/j.survophthal.2022.03.005 -
Middle East African Journal of... 2014
Topics: Aphakia, Postcataract; Cataract Extraction; Female; Humans; Lens Implantation, Intraocular; Lens Subluxation; Lens, Crystalline; Lenses, Intraocular; Male; Sclera
PubMed: 25371650
DOI: No ID Found -
Physiological Reviews Jan 2010The cells of most mammalian organs are connected by groups of cell-to-cell channels called gap junctions. Gap junction channels are made from the connexin (Cx) family of... (Review)
Review
The cells of most mammalian organs are connected by groups of cell-to-cell channels called gap junctions. Gap junction channels are made from the connexin (Cx) family of proteins. There are at least 20 isoforms of connexins, and most tissues express more than 1 isoform. The lens is no exception, as it expresses three isoforms: Cx43, Cx46, and Cx50. A common role for all gap junctions, regardless of their Cx composition, is to provide a conduit for ion flow between cells, thus creating a syncytial tissue with regard to intracellular voltage and ion concentrations. Given this rather simple role of gap junctions, a persistent question has been: Why are there so many Cx isoforms and why do tissues express more than one isoform? Recent studies of lens Cx knockout (KO) and knock in (KI) lenses have begun to answer these questions. To understand these roles, one must first understand the physiological requirements of the lens. We therefore first review the development and structure of the lens, its numerous transport systems, how these systems are integrated to generate the lens circulation, the roles of the circulation in lens homeostasis, and finally the roles of lens connexins in growth, development, and the lens circulation.
Topics: Animals; Cell Differentiation; Cell Proliferation; Connexins; Gap Junctions; Homeostasis; Humans; Lens, Crystalline
PubMed: 20086076
DOI: 10.1152/physrev.00034.2009 -
Asia-Pacific Journal of Ophthalmology... 2016Improved efficacy, predictability, and safety of modern phacoemulsification have resulted in cataract surgery being considered as a refractive procedure. Refractive lens... (Review)
Review
Improved efficacy, predictability, and safety of modern phacoemulsification have resulted in cataract surgery being considered as a refractive procedure. Refractive lens exchange by definition is a surgery aimed at replacing the cataractous or clear crystalline lens with an intraocular lens (IOL) in cases of high ametropia. The excellent intraocular optics of this procedure provide a better visual outcome as compared with laser refractive surgery in high myopia. With advances in technology and IOL formulas, the predictability of refractive outcome after cataract surgery in high myopes has improved. The option of addressing presbyopia using multifocal/accommodating IOLs or monovision results in patients achieving reasonable spectacle independence. The most important concern with respect to phacoemulsification in high myopia is the risk of pseudophakic retinal detachment. High myopia is an independent risk factor for retinal detachment, and recent publications have reported a much lesser risk of retinal detachment specifically attributable to phacoemulsification in high myopes, especially if a thorough posterior segment evaluation is done and patients are followed up until development of complete posterior vitreous detachment. Refractive lens exchange is an effective and safe option to correct high myopia and can significantly improve quality of life in select patients.
Topics: Humans; Lens Implantation, Intraocular; Lens, Crystalline; Lenses, Intraocular; Myopia; Patient Selection; Phacoemulsification; Postoperative Complications; Quality of Life; Retinal Detachment; Visual Acuity
PubMed: 27898449
DOI: 10.1097/APO.0000000000000241