Paediatric secondary intraocular lens estimation from the aphakic refraction alone: comparison with a standard biometric technique.
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AIM: To compare the following two methods of paediatric secondary posterior chamber intraocular lens (PCIOL) determination with the Holladay formula: (1) estimation from the aphakic refraction alone (using assumed keratometry (K) of 44 diopters); and (2) calculation based on preoperative measured biometry. METHODS: (1) Retrospective medical record review in a referral eye hospital of children with aphakia aged < or =12 years who underwent secondary PCIOL implantation with an Alcon MA60BM lens; (2) PCIOL determination for a plano refraction by the above two methods (estimation and calculation); and (3) prediction of pseudophakic refraction for the PCIOL actually implanted by the above two methods compared with the actual pseudophakic refraction. RESULTS: 50 eyes of 30 children with aphakia were studied. The estimated (mean, 95% confidence interval (CI)) secondary PCIOL values (25.81, +/-1.65 D) and the calculated secondary PCIOL values (26.35, +/-1.50 D) were not significantly different (mean absolute value of the difference 1.86 D, 95% CI +/-0.41 D) by the two-tailed paired t test at alpha = 0.05 (p = 0.11). For each eye, the pseudophakic refractions predicted by the two methods for the PCIOL that was actually implanted differed, both from each other and from the actual pseudophakic refraction (repeated-measures analysis of variance, p<0.001; Tukey test, p<0.01). CONCLUSIONS: The method of PCIOL estimation from the aphakic refraction alone provides values similar to those obtained by a standard technique and can be useful if biometry is unavailable. Targeting a pseudophakic refraction in paediatric aphakia is prone to error. (+info)
Foxe view of lens development and disease.
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The recent identification of a mutation in Foxe3 that causes congenital primary aphakia in humans marks an important milestone. Congenital primary aphakia is a rare developmental disease in which the lens does not form. Previously, Foxe3 had been shown to play a crucial role in vertebrate lens formation and this gene is one of the earliest integrators of several signaling pathways that cooperate to form a lens. In this review, we highlight recent advances that have led to a better understanding of the developmental processes and gene regulatory networks involved in lens development and disease. (+info)
Chronic 3,4-dihydroxyphenylalanine treatment induces dyskinesia in aphakia mice, a novel genetic model of Parkinson's disease.
(19/85)
L-DOPA-induced dyskinesia (LID) is one of the main limitations of long term L-DOPA use in Parkinson's disease (PD) patients. We show that chronic L-DOPA treatment induces novel dyskinetic behaviors in aphakia mouse with selective nigrostriatal deficit mimicking PD. The stereotypical abnormal involuntary movements were induced by dopamine receptor agonists and attenuated by antidyskinetic agents. The development of LID was accompanied by preprodynorphin and preproenkephalin expression changes in the denervated dorsal striatum. Increased FosB-expression was also noted in the dorsal striatum. In addition, FosB expression was noted in the pedunculopontine nucleus and the zona incerta, structures previously not examined in the setting of LID. The aphakia mouse is a novel genetic model with behavioral and biochemical characteristics consistent with those of PD dyskinesia and provides a more consistent, convenient, and physiologic model than toxic lesion models to study the mechanism of LID and to test therapeutic approaches for LID. (+info)
Motor deficits and altered striatal gene expression in aphakia (ak) mice.
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Like humans with Parkinson's disease (PD), the ak mouse lacks the majority of the substantia nigra pars compacta (SNc) and experiences striatal denervation. The purpose of this study was to test whether motor abnormalities in the ak mouse progress over time, and whether motor function could be associated with temporal alterations in the striatal transcriptome. Ak and wt mice (28 to 180 days old) were tested using paradigms sensitive to nigrostriatal dysfunction. Results were analyzed using a linear mixed model. Ak mice significantly underperformed wt controls in rotarod, balance beam, string test, pole test and cotton shred tests at all ages examined. Motor performance in ak mice remained constant over the first 6 months of life, with the exception of the cotton shred test, in which ak mice exhibited marginal decline in performance. Dorsal striatal semi-quantitative RT-PCR for 19 dopaminergic, cholinergic, glutaminergic and catabolic genes was performed in 1- and 6-month-old groups of ak and wt mice. Preproenkephalin levels in ak mice were elevated in both age groups. Drd1, 3 and 4 levels declined over time, in contrast to increasing Drd2 expression. Additional findings included decreased Chrnalpha6 expression and elevated VGluT1 expression at both time points in ak mice and elevated AchE expression in young ak mice only. Results confirm that motor ability does not decline significantly for the first 6 months of life in ak mice. Their striatal gene expression patterns are consistent with dopaminergic denervation, and change over time, despite relatively unaltered motor performance. (+info)
Perinatal ablation of the mouse lens causes multiple anterior chamber defects.
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PURPOSE: The purpose of this study was to reassess the role of the lens as an "embryonic organizer" of ocular tissues. METHODS: We ablated the lens in mice by lens-specific expression of an attenuated version of diphtheria toxin A subunit(Tox176) driven by a modified crystallin promoter. Alterations in the differentiation programs of ocular tissues were examined by hematoxylin and eosin staining, in situ hybridization, and immunohistochemistry. RESULTS: Transgenic mice in the family OVE1757 exhibited severe microphakia. Apoptotic lens fibers were seen by embryonic day 15 (E15) and the lenses were completely ablated by post natal day 8. Multiple defects were seen in the anterior chamber. Corneal endothelial cells did not differentiate properly. The mesenchymal cells that would normally give rise to the endothelial layer were found to express N-cadherin, but they failed to form tight junctions and undergo a mesenchymal-to-epithelial transition. Although early specification of the presumptive ciliary body and iris was detected, subsequent differentiation of the iris was blocked. No dramatic changes were seen in the development of the retina. CONCLUSIONS: These results support the hypothesis that an intact lens is essential for proper differentiation of both the corneal endothelium and the iris and that the lens "organizes" the development of tissues in the anterior chamber. (+info)
Hanging by a thread: the long-term efficacy and safety of transscleral sutured intraocular lenses in children (an American Ophthalmological Society thesis).
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PURPOSE: To evaluate the long-term efficacy, safety, and advisability of using transscleral sutured posterior chamber intraocular lenses (IOLs) in pediatric patients with no capsular support and to determine whether 10-0 polypropylene suture should be used for this purpose. METHODS: A long-term retrospective interventional case series review of 33 eyes of 26 patients who had a sutured IOL at Duke University Eye Center were evaluated for the intraoperative surgical risks, postoperative visual and refractive outcomes, and the number, type, and severity of the postoperative complications. In addition, a survey of pediatric ophthalmologists' experience with suture breakage was performed. RESULTS: Postoperative visual acuity was significantly improved after surgery (P < .001). Predicted vs actual refraction was not significantly different (P = .10) and was within 1.50 diopters of predicted in 66% of patients. A refractive myopic shift occurred over time and was age-dependent. Intraoperative and immediate postoperative complications were minimal and not sight-threatening. Three patients developed subluxation of the IOL secondary to spontaneous 10-0 polypropylene suture breakage at 3.5, 8, and 9 years after surgery. A survey of pediatric ophthalmologists revealed 10 similar cases (mean, 5 years after surgery). CONCLUSION: Transscleral fixation of an IOL in a child appears to be a safe and effective procedure provided that the suture material used is stable enough to resist significant degradation over time. Caution should be exercised in the use of 10-0 polypropylene suture to fixate an IOL to the sclera in children, and an alternative material or size should be considered. (+info)
Interactions between trabecular meshwork cells and lens epithelial cells: a possible mechanism in infantile aphakic glaucoma.
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Sir Nicholas Harold Lloyd Ridley: 10 July 1906 - 25 May 2001.
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Sir Harold Ridley invented and refined the modern miracle of replacing lenses obscured by cataracts with plastic optical lenses, thus rendering a complete cataract cure. This operation, broadly termed the cataract-intraocular lens (IOL) operation, has since brought sight to many millions of people throughout the world, and continues to improve the quality of life of more than 10 million patients worldwide each year. Ridley not only launched this powerful and irreversible forward movement in the field of ophthalmology and the visual sciences, but through it he also helped give birth to the exciting and new field of artificial biodevice implantation as well as transplantation techniques now applied to many other organs and tissues of the body. He has therefore been credited with healing to create the relatively new specialty of biomedical engineering. Few of the millions of patients worldwide who now enjoy the benefits of the modern cataract - IOL operation are aware of the origin of this innovation. Indeed, few eye care professionals - even ophthalmic surgeons who implant them almost daily - are aware of the origin of the IOL - an invention that, as Harold himself liked to say, 'cured aphakia'. (The word aphakia comes from teh Greek, meaning absence of lens, the situation that occurs when a cataractous lens is surgically removed.) (+info)