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Progress in Retinal and Eye Research May 2021The Zonule of Zinn, or ciliary zonule, is the elaborate system of extracellular fibers that centers the lens in the eye. In humans, the fibers transmit forces that... (Review)
Review
The Zonule of Zinn, or ciliary zonule, is the elaborate system of extracellular fibers that centers the lens in the eye. In humans, the fibers transmit forces that flatten the lens during the process of disaccommodation, thereby bringing distant objects into focus. Zonular fibers are composed almost entirely of 10-12 nm-wide microfibrils, of which polymerized fibrillin is the most abundant component. The thickest fibers have a fascicular organization, where hundreds or thousands of microfibrils are gathered into micrometer-wide bundles. Many such bundles are aggregated to form a fiber. Dozens of proteins comprise the zonule. Most are derived from cells of the non-pigmented ciliary epithelium in the pars plana region, although some are probably contributed by the lens and perhaps other tissues of the anterior segment. Zonular fibers are viscoelastic cables but their component microfibrils are rather stiff structures. Thus, the elastic properties of the fibers likely stem from lateral interactions between microfibrils. Rupture of zonular fibers and subsequent lens dislocation (ectopia lentis) can result from blunt force trauma or be a sequela of other eye diseases, notably exfoliation syndrome. Ectopia lentis is also a feature of syndromic conditions caused typically by mutations in microfibril-associated genes. The resulting ocular phenotypes raise the possibility that the zonule regulates lens size and shape, globe size, and even corneal topology, in addition to its well-recognized role in accommodation.
Topics: Ciliary Body; Ectopia Lentis; Fibrillins; Humans; Lens, Crystalline; Microfibrils
PubMed: 32980533
DOI: 10.1016/j.preteyeres.2020.100902 -
Journal of Clinical Medicine Oct 2020Iridoschisis is a rare condition defined as a separation of the anterior iris stroma from the posterior stroma and muscle layers. In this paper, we review current data... (Review)
Review
Iridoschisis is a rare condition defined as a separation of the anterior iris stroma from the posterior stroma and muscle layers. In this paper, we review current data about the epidemiology, pathophysiology, clinical characteristics and differential diagnoses of this condition and discuss the specificity of surgical treatment of concomitant ocular diseases in iridoschisis patients. Iridoschisis may pose a challenge for both an ophthalmologist in an outpatient setting and an ophthalmic surgeon. Glaucoma, primarily angle-closure glaucoma, is the most often described condition concomitant to iridoschisis. Other ocular abnormalities found relatively often in iridoschisis patients include cataract, lens subluxation and corneal abnormalities. Special attention has been paid to potential complications of cataract surgery and prevention thereof. Beside addressing the practical aspects, we point to discrepancies and suggest topics for further investigation.
PubMed: 33081187
DOI: 10.3390/jcm9103324 -
Indian Journal of Ophthalmology Jul 2022Microspherophakia is a rare developmental abnormality of the crystalline lens with a myriad of ocular and systemic associations. Glaucoma is a serious complication... (Review)
Review
Microspherophakia is a rare developmental abnormality of the crystalline lens with a myriad of ocular and systemic associations. Glaucoma is a serious complication associated with this disorder. Early identification of the disease, timely visual rehabilitation, and appropriate management of the lens and glaucoma can help us prevent blindness from this condition. Multidisciplinary care with lifelong follow-up is recommended, as this typically affects the younger population. Current treatment protocols for this condition are mainly based on case reports and retrospective studies with shorter follow-up. Due to the rarity of this disease, designing a large randomized controlled trial to identify the merits and demerits of each management strategy is challenging. With cataract, glaucoma, and vitreoretinal specialists, each having their preferred way of managing microspherophakic lenses, we decided to do a comprehensive review of the existing literature to devise an integrated approach toward effective management of these patients. This review will collate all evidence and provide a very practical decision-making tree for its management.
Topics: Corneal Diseases; Ectopia Lentis; Glaucoma; Humans; Iris; Randomized Controlled Trials as Topic; Retrospective Studies; Visual Acuity
PubMed: 35791105
DOI: 10.4103/ijo.IJO_2888_21 -
Medicina 2022
Topics: Humans; Lens Subluxation; Lens, Crystalline; Lenses, Intraocular
PubMed: 35904923
DOI: No ID Found -
The New England Journal of Medicine Sep 2017
Topics: Aged; Ectopia Lentis; Female; Humans; Iris; Marfan Syndrome
PubMed: 28902597
DOI: 10.1056/NEJMicm1615424 -
Turkish Journal of Ophthalmology Aug 2023Pseudoexfoliation syndrome (PES) is one of the most common causes of open-angle glaucoma, with a higher risk of vision loss, a higher maximum and mean intraocular... (Review)
Review
Pseudoexfoliation syndrome (PES) is one of the most common causes of open-angle glaucoma, with a higher risk of vision loss, a higher maximum and mean intraocular pressure (IOP) at diagnosis, and a wider range of IOP fluctuation compared to primary open-angle glaucoma. Patients with this syndrome have a ten-fold higher risk of developing glaucoma than the normal population. A definite diagnosis can be made by the observation of pseudoexfoliation material (PEM) on the anterior lens surface, ciliary processes, zonules, and iris. PEM deposits on the zonules may explain the clinically observed zonular weakness and lens subluxation or dislocation. An increased incidence of cataract development is also associated with PES. There is growing evidence for systemic associations of PES with peripheral, cardiovascular, and cerebrovascular system diseases, Alzheimer's disease, hearing loss, and increased plasma homocysteine levels. Indications for surgery are markedly more common in patients with pseudoexfoliation glaucoma than primary open-angle glaucoma. The goal of this article is to review the latest perspectives on the clinical features, therapy, and systemic associations of this clinically and biologically challenging disease.
Topics: Humans; Cataract; Exfoliation Syndrome; Glaucoma; Glaucoma, Open-Angle; Lens Subluxation
PubMed: 37602651
DOI: 10.4274/tjo.galenos.2023.76300 -
Contrast Media & Molecular Imaging 2022To evaluate the imaging characteristics of the lens subluxation with the use of ultrasound biomicroscopy.
BACKGROUND
To evaluate the imaging characteristics of the lens subluxation with the use of ultrasound biomicroscopy.
METHODS
From October 2018 to September 2019, 55 eyes diagnosed with lens subluxation were enrolled in the group. All patients underwent detailed eye examination and panoramic ultrasound biomicroscopy.
RESULTS
The most common sites of lens suspensory ligament injury were superior temporal side (32.73%) and superior nasal side (23.63%). The most common range of subluxation in all patients was 30°. Comparing the measurement indicators of all patients, ciliary body thickness (CBT) in affected eyes was smaller than that in healthy eyes (0.79 ± 0.21, 1.04 ± 0.16), the distance between ciliary process and crystal equator increased (1.91 ± 0.70, 1.17 ± 0.32), and iris-ciliary processes distance (ICPD) increased (1.04 ± 0.51, 0.80 ± 0.17) ( < 0.05). The range of subluxation in patients with lens subluxation was positively correlated with the distance between ciliary processes and the crystal equator.
CONCLUSIONS
The ultrasound biological microscope has a good application significance in the diagnosis of lens subluxation. From this study, we suggest that the three indexes of CBT, ICPD, and the distance between the ciliary process and crystal equator are of high reference value in ultrasound biomicroscopy among patients with lens subluxation.
Topics: Ciliary Body; Glaucoma, Angle-Closure; Humans; Iris; Lens Subluxation; Microscopy, Acoustic
PubMed: 36051917
DOI: 10.1155/2022/7030866 -
Journal of Current Ophthalmology 2023To report a rare case of microspherophakia and lens subluxation in a young patient with Klinefelter syndrome who underwent cataract surgery, emphasizing the importance...
PURPOSE
To report a rare case of microspherophakia and lens subluxation in a young patient with Klinefelter syndrome who underwent cataract surgery, emphasizing the importance of a thorough general health assessment and anamnesis prior to cataract surgery.
METHODS
The case concerns a 52-year-old male referred for phacoemulsification under general anesthesia. A review of literature was performed.
RESULTS
Preoperative assessment revealed a corticonuclear cataract in both eyes, with dislocation of the crystalline lens in the left eye in an area of zonular dehiscence. Upon careful examination, both eyes showed a microspherophakic lens with an increased lens thickness and the lens equator being visible over 360° in the left eye. The patient denied any trauma or medical conditions. His medical health record revealed the coexistence of Klinefelter syndrome (47, XXY). The association between Klinefelter syndrome and microspherophakia has only once been reported in the literature. Intraoperatively, a more cautious approach was withheld and a capsular tension ring was used. Postoperative outcome was successful with good visual outcome and no interoperative complications.
CONCLUSIONS
This case report highlights the importance of proper preoperative assessment before cataract surgery, especially in unusual cases such as early-onset cataract and/or lens subluxation. In addition, it stresses the importance of a systemic and/or genetic evaluation in patients with microspherophakia and an ophthalmological examination in patients with Klinefelter syndrome.
PubMed: 38250495
DOI: 10.4103/joco.joco_291_22