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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 -
Medicina 2022
Topics: Humans; Lens Subluxation; Lens, Crystalline; Lenses, Intraocular
PubMed: 35904923
DOI: No ID Found -
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 -
Acta Ophthalmologica May 2017To evaluate the impact of pseudoexfoliation syndrome on intraocular lens (IOL) dislocation after phacoemulsification cataract surgery and explore possible associations... (Meta-Analysis)
Meta-Analysis Review
PURPOSE
To evaluate the impact of pseudoexfoliation syndrome on intraocular lens (IOL) dislocation after phacoemulsification cataract surgery and explore possible associations related to surgical technique.
METHODS
We systematically searched the MEDLINE, Embase, Web of Science, Cochrane, and Lilacs databases and grey literature sources and identified (on March 1, 2016) 14 cohort and case-control studies comparing IOL dislocation in patients with and without pseudoexfoliation syndrome who had undergone phacoemulsification. Study quality was assessed using the STROBE scale. An inverse-variance fixed-effects model was used to calculate weighted odds ratios (ORs) and 95% confidence intervals (CI).
RESULTS
The pooled analysis yielded an OR of 6.02 (95% CI: 3.7, 9.79) for IOL dislocation in patients with pseudoexfoliation, and similarly, high ORs were detected for both early and late (3 months after surgery) dislocation (OR 5.26; 95% CI: 1.05; 26.32 versus OR 6.02; 95% CI: 3.67; 10.17). No significant associations were detected when the results were stratified by year, incision size or use of hooks or retractors.
CONCLUSIONS
Patients with pseudoexfoliation syndrome have a high risk of late IOL dislocation after phacoemulsification cataract surgery, and this risk may be related to the use of large incisions and hooks or retractors.
Topics: Cataract Extraction; Exfoliation Syndrome; Foreign-Body Migration; Humans; Lenses, Intraocular; Postoperative Complications; Prosthesis Failure
PubMed: 27569700
DOI: 10.1111/aos.13234 -
The New England Journal of Medicine Sep 2017
Topics: Aged; Ectopia Lentis; Female; Humans; Iris; Marfan Syndrome
PubMed: 28902597
DOI: 10.1056/NEJMicm1615424 -
International Ophthalmology Apr 2023The aim of this study was to evaluate ocular and systemic risk factors for posterior chamber intraocular lens dislocation, as well as forms of manifestation.
PURPOSE
The aim of this study was to evaluate ocular and systemic risk factors for posterior chamber intraocular lens dislocation, as well as forms of manifestation.
METHODS
A retrospective case-control study were all patients presented in the period 2012-2016 having intraocular lens dislocation and being treated with implantation of an iris-fixated intraocular lens was conducted at the University Hospital Mainz. As controls, pseudophakic patients presenting for other reasons were included.
RESULTS
150 eyes of 150 patients (mean age 72.7 ± 12.4 years, range 24-93 years) with IOL dislocation and 150 eyes of 103 controls were included in this study. The average time between primary implantation and IOL luxation was 86 months (iQR: 39.25-127 months) for all dislocations. Previous pars plana vitrectomy (PPV) (crudeOR = 2.14 (95% CI 1.23, 3.72), p = 0.011) and PEX (crudeOR = 11.6 (4.79, 28.12), p < 0.001) was linked with a higher risk of IOL luxation. Luxation occurs also earlier in patients with previous PPV and PEX than in eyes with neither PEX nor previous PPV (82.2 vs. 127 months). Rhegmatogenous retinal detachment was the major pathology that required a previous PPV for eyes with an IOL dislocation (57%). The average time between PPV and IOL dislocation was 74.67 months (range 0-186 months).
CONCLUSION
Patients with a coexistence of both: PEX and a previous PPV had an elevated risk of IOL dislocation, and also had a shorter time interval between primary IOL implantation and IOL dislocation followed by eyes with PEX only and eyes with only a previous PPV.
Topics: Humans; Young Adult; Adult; Middle Aged; Aged; Aged, 80 and over; Lens Implantation, Intraocular; Retrospective Studies; Case-Control Studies; Visual Acuity; Lenses, Intraocular; Vitrectomy; Lens Subluxation; Risk Factors; Postoperative Complications
PubMed: 36149618
DOI: 10.1007/s10792-022-02529-6