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Posterior Segment (posterior + segment)
Selected AbstractsCyclodextrin microparticles for drug delivery to the posterior segment of the eye: aqueous dexamethasone eye dropsJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 5 2007Thorsteinn Loftsson Delivery of steroids to the retina is currently undertaken with invasive injections into the vitreous cavity. This paper describes a non-invasive method to deliver steroids in therapeutic levels to the retina in rabbits. Dexamethasone was formulated as somewhat water-soluble dexamethasone/,-cyclodextrin (,CD) microparticles in a low-viscosity aqueous eye drop suspension. The mean (± standard deviation) diameter of the particles was 20.4 ± 10.3 ,m, with no particles larger than 60 ,m. The aqueous suspension formulation was tested in rabbits and compared with an aqueous dexamethasone eye drop solution containing randomly methylated ,-cyclodextrin (RM,CD). The dexamethasone concentration was identical in both formulations (15 mg mL,1). The drug was administered to the left eye but determined in both eyes. The amount reaching different eye tissues via the topical route was determined by subtracting the amount found in the right eye from the amount found in the left eye. Two hours after single application of the dexamethasone/,CD eye drops to rabbits the mean (± s.d.) concentration in vitreous was 29 ± 16 ng g,1, 86% of which reached vitreous via the topical route and in retina the concentration was 57 ± 22 ng g,1 (49% via topical route). For the RM,CD the values were 22.6 ± 9 and 66 ± 49 ng g,1 (73 and 14% via topical route), respectively. These steroid levels are comparable with the dexamethasone concentration achieved 1 month after intravitreal injection. The aqueous dexamethasone/,CD eye drop formulation was chemically stable during 7 months storage and well tolerated with no visible short-term side effects. [source] Sight-threatening varicella zoster virus infection after fludarabine treatmentBRITISH JOURNAL OF HAEMATOLOGY, Issue 4 2000Y. L. Chee Varicella zoster virus (VZV) infection involving the posterior segment of the eye after fludarabine treatment has not previously been described. Two patients, who had completed fludarabine treatment 3 and 18 months previously, presented with visual loss that had been preceded by a recent history of cutaneous zoster. The use of the polymerase chain reaction (PCR) for VZV DNA from ocular specimens allowed rapid confirmation of clinical diagnosis and treatment with a good outcome in one patient. With the increasing use of fludarabine and other purine analogues, an awareness of such complications is important because of their potentially sight-threatening consequences. [source] 2414: Laser and vitrectomyACTA OPHTHALMOLOGICA, Issue 2010E STEFANSSON Purpose Modern vitreous surgery involves a variety of treatment options in addition to vitrectomy itself, such as photocoagulation, anti-VEGF drugs, intravitreal steroids and release of vitreoretinal traction. A full understanding of these treatment modalities allows sensible combination of treatment options. Methods Vitrectomy reduces the risk of retinal neovascularization, while increasing the risk of iris neovascularization, reduces macular edema and stimulates cataract formation. These clinical consequences may be understood with the help of classical laws of physics and physiology. The laws of Fick, Stokes-Einstein and Hagen-Poiseuille state that molecular transport by diffusion or convection is inversely related to the viscosity of the medium. When the vitreous gel is replaced with less viscous saline, the transport of all molecules, including oxygen and cytokines, is facilitated. Oxygen transport to ischemic retinal areas is improved, as is clearance of VEGF and other cytokines from these areas, thus reducing edema and neovascularization. At the same time, oxygen is transported faster down a concentration gradient from the anterior to the posterior segment, while VEGF moves in the opposite direction, making the anterior segment less oxygenated and with more VEGF, stimulating iris neovascularization. Results Retinal photocoagulation has also repeatedly been shown to improve retinal oxygenation. Oxygen naturally reduces VEGF production and improves retinal hemodynamics. The VEGF-lowering effect of photocoagulation and vitrectomy can be augmented with anti-VEGF drugs and the permeability effect of VEGF reduced with corticosteroids Conclusion Vitrectomy and laser retinal treatment both improve oxygenation of the ischemic retina, reduce VEGF formation and thereby reduce neovascularisation and edema. [source] Ocular findings among young men: a 12-year prevalence study of military service in PolandACTA OPHTHALMOLOGICA, Issue 5 2010Michal S. Nowak Abstract. Purpose:, To determine the prevalence of ocular diseases among young men and to assess the main ocular causes reflecting discharge from military service in Poland. Methods:, A retrospective review of the medical records of 105 017 men undergoing a preliminary examination for military service during the period 1993,2004. Sample size for the study was calculated with 99% confidence within an error margin of 5%. All of the study participants were White men of European origin, most of whom live or lived in Poland. Data regarding the vision status were assessed in 1938 eyes of 969 participants. Two groups were distinguished based on the age of the participants: group I aged 18,24 years, and group II aged 25,34 years. Results:, Presented visual impairment [visual acuity (VA) < 20/40)] followed by colour vision defects were the most common ocular disorders, accounting for 13.2%. There were statistically significant differences in uncorrected VA as well as in the rates of particular refractive errors in between the age groups (p < 0.05). The prevalence of glaucoma and ocular hypertension was significantly higher in older participants. Six hundred and sixty-seven (68.8%) participants examined medically in the study period were accepted for military service. However, 302 (31.2%) failed their examination and were temporarily or permanently discharged from duty. Fifty-two of them (17.2%) were discharged because of various ocular disorders. The most common causes were high refractive errors, which accounted for 38.5% of all the ocular discharges, followed by chronic and recurrent diseases of the posterior segment of the eye, which accounted for 19.2%. Conclusion:, The prevalence of ocular disorders among young men in an unselected military population was closer to the results obtained in other population-based studies comprising both men and women in the same age group. High refractive errors followed by chronic and recurrent diseases of the posterior segment of the eye are important causes of medical discharges from military service in Poland. [source] Fine-needle aspiration biopsy and other biopsies in suspected intraocular malignant disease: a reviewACTA OPHTHALMOLOGICA, Issue 6 2009Nils Eide Abstract. Ocular oncologists require a strong indication for intraocular biopsy before the procedure can be performed because it carries a risk for serious eye complications and the dissemination of malignant cells. The purpose of this review is to evaluate the extent to which this restricted practice is supported by evidence from previous reports and to outline our main indications and contraindications. The different intraocular biopsy techniques in the anterior and posterior segment are discussed with a focus on our preferred method, fine-needle aspiration biopsy (FNAB). In the literature, complications are typically under-reported, which reduces the possibilities of evaluating the risks correctly and of making fair comparisons with other biopsy methods. In FNAB, the exact placement of the needle is critical, as is an accurate assessment of the size of the lesion. Fine-needle aspiration biopsy is usually not a reliable diagnostic tool in lesions < 2 mm in thickness. It is very advantageous to have a cytopathologist present in the operating theatre or close by. This ensures adequate sampling and encourages repeated biopsy attempts if necessary. This approach reduces false negative results to < 3%. Adjunct immunocytochemistry is documented to increase specificity and is essential for diagnosis and management in about 10% of cases. In some rare pathological processes the diagnosis depends ultimately on the identification of specific cell markers. An accurate diagnosis may have a decisive influence on prognosis. The cytogenetic prognostications made possible after FNAB are reliable. Biopsy by FNA has a low complication rate. The calculated risk for retinal detachment is < 4%. Intraocular haemorrhage is frequently observed, but clears spontaneously in nearly all cases. Only a single case of epibulbar seeding of malignant cells at the scleral pars plana puncture site of transvitreal FNAB has been documented. Endophthalmitis has been reported and adequate standard preoperative preparation is obligatory. An open biopsy is still an option in the anterior segment, but has been abandoned in the posterior segment. Although vitrectomy-based procedures are becoming increasingly popular, we recommend using FNAB as part of a stepwise approach. A vitrectomy-assisted biopsy should be considered in cases where FNAB fails. In any adult patient with suspected intraocular malignancy in which enucleation is not the obvious treatment, the clinician should strive for a diagnosis based on biopsy. When the lesion is too small for biopsy or the risks related to the procedure are too great, it is reasonable to be reluctant to biopsy. The standards applied in the treatment of intraocular malignant diseases should be equivalent to those in other fields of oncology. Our view is controversial and contrary to opinion that supports current standards of care for this group of patients. [source] Scanning beyond the limits of standard OCT: OCT scans of the peripheral retina and the anterior chamber angle with a slitlamp integtrated FD-OCT systemACTA OPHTHALMOLOGICA, Issue 2009M STEHOUWER Purpose Exploring the quality of OCT images of the peripheral retina and anterior chamber angle made through a 3-mirror contactlens and a new FD-OCT device integrated into a slit lamp. Methods Patients with peripheral lesions (n=10) and glaucoma (n=10), seen in the outpatient clinic of the Academic Medical Center, were scanned with a Fourier Domain OCT integrated into a common Topcon slitlamp (SLD light source, central wavelength 830 nm, bandwidth 30 nm, 1024 pixel CCD camera, scan speed 5k A-scans per second, up to 1024 A-scans per b-scan). For posterior segment scans a fast Z-tracking system in the reference arm compensates for the dynamic character (movements of patient, handheld lens, slitlamp) of the examination. Scans of peripheral lesions, and the anterior chamber angle were made with a 3-mirror lens, while simultaneously the lesions were observed with the slitlamp. Results Scans of the peripheral retina obtained with a 3-mirror lens with the FD-OCT integrated into the slitlamp were of reasonably good quality and lesions, like peripheral laser scars, could be clearly identified. Compared to stand alone OCT systems, the integrated OCT system reached more peripheral lesions. The anterior chamber angle scanned through a 3-mirror lens enabled scans of the angle structures. Conclusion It is possible to scan the peripheral retina and anterior chamber angle through a 3-mirror contact lens with the slitlamp with integrated OCT. These scans could be of clinical interest in patients with pathology in the peripheral retina pathology or the anterior chamber angle. [source] Therapeutic efficacy of intravitreal bevacizumab on posterior uveitis complicated by neovascularizationACTA OPHTHALMOLOGICA, Issue 3 2009Shree Kurup Abstract. Purpose:, To evaluate the therapeutic effect of intravitreal bevacizumab in patients with uveitis-associated choroidal/retinal neovascularization. Methods:, Two female patients (40 years, 15 years) with posterior uveitis, (one presumed ocular sarcoidosis, one lupus) were evaluated for neovascularization of the posterior segment. Both patients were given a single dose of 1.25 mg intravitreal bevacizumab. Results:, Significant anatomical and functional recovery was evident in both patients within a few weeks. Conclusion:, In selected uveitic patients, bevacizumab may be an option for managing neovascularization. [source] Role of ocular pigment epithelial cells in regional ocular immunityACTA OPHTHALMOLOGICA, Issue 2008S SUGITA Purpose To whether soluble factors by retinal pigment epithelial cells (RPE) promote the generation of T regulatory cells in vitro. Methods Primary cultured RPE cells were established from normal C57BL/6 mice. T cells were co-cultured with RPE, x-irradiated, and used as regulators (RPE Treg cells). Target bystander T cells were established from normal splenic T cells with anti-CD3 antibodies. T-cell activation was assessed for proliferation by [3H],thymidine incorporation. Expression of cytotoxic T lymphocyte antigen-2, (CTLA-2,) and cathepsin L on RPE and T cells was evaluated with oligonucleotide microarray, RT-PCR, immune staining, western blots and flow cytometry. Recombinant mouse CTLA-2, and anti-mouse CTLA-2, abs were used for the assay. For induction of experimental autoimmune uveitis (EAU), mice were immunized with interphotoreceptor retinoid-binding protein peptide emulsified in complete Freund's adjuvant. Results RPE converted CD4+ T cells into Treg cells by producing and secreting CTLA-2,, a cathepsin L inhibitor. CTLA-2, secreted by RPE cells selectively inhibited cathepsin L in the T cells and the cathepsin L-lacking T cells exhibited Treg phenotype, i.e. expression of Foxp3 and production of transforming growth factor beta (TGF,). CTLA-2, enhanced their production of active forms of TGF,. In addition, CD4+ T cells from EAU-induced cathepsin L knockout (KO) donors contained high population of Foxp3+ T cells and EAU in cathepsin L KO mice was significantly less than those in wild type mice. Furthermore, treatment with recombinant CTLA-2, significantly suppressed EAU. Conclusion These results indicate that immunosuppressive factors derived from RPE participate in the establishment of immune regulation in the posterior segment of the eye. [source] Clinical and molecular aspects of aniridiaCLINICAL GENETICS, Issue 5 2010H Kokotas Kokotas H, Petersen MB. Clinical and molecular aspects of aniridia. Aniridia is a severe, congenital ocular malformation inherited in an autosomal-dominant fashion with high penetrance and variable expression. Eye morphogenesis in humans involves a molecular genetic cascade in which a number of developmental genes interact in a highly organized process during the embryonic period to produce functional ocular structures. Among these genes, paired box gene 6 (PAX6) has an essential role as it encodes a phylogenetically conserved transcription factor almost universally employed for eye formation in animals with bilateral symmetry, despite widely different embryological origins. To direct eye development, PAX6 regulates the tissue-specific expression of diverse molecules, hormones, and structural proteins. In humans, PAX6 is located in chromosome 11p13, and its mutations lead to a variety of hereditary ocular malformations of the anterior and posterior segment, among which aniridia and most probably foveal hypoplasia are the major signs. Aniridia occurs due to decreased dosage of the PAX6 gene and exists in both sporadic and familial forms. The mutations are scattered throughout the gene and the vast majority of those reported so far are nonsense mutations, frameshift mutations, or splicing errors that are predicted to cause pre-mature truncation of the PAX6 protein, causing haploinsufficiency. Here we review the data regarding the mechanisms and the mutations that relate to aniridia. [source] Transcriptional readthrough of Hox genes Ubx and Antp and their divergent post-transcriptional control during crustacean evolutionEVOLUTION AND DEVELOPMENT, Issue 5 2006Yasuhiro Shiga SUMMARY Hox genes are in principle tandemly arranged in an order colinear with their order of expression along the anterior,posterior axis. Combinations of Hox proteins encode information that specifies the unique characteristics of axial regions in the metazoan body plan. The independent regulation of Hox genes achieved by differential promoter activity is essential for the expression of Hox proteins in distinct territories and thereby creating a full repertoire of Hox codes. Here we report the abundant expression of transcriptional readthrough products of two adjacent Hox genes, Ubx, and Antp, in five crustacean species of Branchiopoda and Malacostraca. Bicistronic mRNA places Antp under the control of the Ubx promoter, which is active in the posterior segments of two branchiopodans Daphnia and Artemia, and would normally reduce the complexity of Hox codes if translated. This does not occur, however, as the translational capability of the bicistronic mRNA is limited. In Daphnia, bicistronic Ubx/Antp mRNA produced no significant level of either UBX or ANTP. In Artemia, on the other hand, the bicistronic mRNA produced only UBX, and replaced the role of monocistronic Ubx mRNA. In this way, multiple post-transcriptional control mechanisms in two extant branchiopodans can be seen as preventing the potentially deleterious consequences of Hox gene fusion. [source] Short and long germ segmentation: unanswered questions in the evolution of a developmental modeEVOLUTION AND DEVELOPMENT, Issue 6 2005Paul Z. Liu Summary The insect body plan is very well conserved, yet the developmental mechanisms of segmentation are surprisingly varied. Less evolutionarily derived insects undergo short germ segmentation where only the anterior segments are specified before gastrulation whereas the remaining posterior segments are formed during a later secondary growth phase. In contrast, derived long germ insects such as Drosophila specify their entire bodies essentially simultaneously. These fundamental embryological differences imply potentially divergent molecular patterning events. Numerous studies have focused on comparing the expression and function of the homologs of Drosophila segmentation genes between Drosophila and different short and long germ insects. Here we review these comparative data with special emphasis on understanding how short germ insects generate segments and how this ancestral mechanism may have been modified in derived long germ insects such as Drosophila. We break down the larger issue of short versus long germ segmentation into its component developmental problems and structure our discussion in order to highlight the unanswered questions in the evolution of insect segmentation. [source] Effectiveness of periodontal therapy on the severity of cyclosporin A-induced gingival overgrowthJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 8 2005Mario Aimetti Abstract Aim: The purpose of the present study was to evaluate the clinical effects of aetiological periodontal treatment in a group of transplant patients medicated with cyclosporin A (CsA) who exhibited severe gingival overgrowth. Materials and Methods: Twenty-one patients received oral hygiene instructions, supra- and subgingival scaling and periodontal maintenance therapy and were monitored for 12 months. Full-mouth plaque score (FMPS), full-mouth bleeding score (FMBS), periodontal probing depth and degree of gingival overgrowth (Seymour index GO) were recorded at baseline, 6 and 12 months after treatment. Results: Statistical evaluation revealed that all clinical variables significantly decreased compared with baseline. At baseline 18 out of 21 treated patients (85.71%) exhibited clinically significant overgrowth. Initial GO score of 2.38±1.92 in the anterior sextants and of 1.29±1.59 in the posterior segments were reduced to 0.56±0.83 and to 0.45±0.84 at 12 months (p<0.001). A difference of 1.82 and 0.84 in the severity of treated GO was accompained by a 42% and 34% decrease in FMPS and FMBS, respectively. Conclusions: Aetiological periodontal treatment and regular maintenance therapy were effective in resolving the inflammation and in eliminating the need for surgical treatment in patients receiving CsA. [source] Wasps, beetles and the beginning of the endsBIOESSAYS, Issue 7 2006Alistair P. McGregor Recent papers investigating the genes regulating early embryogenesis in the wasp Nasonia vitripennis1 and the beetle Tribolium castaneum2,4 have provided us with important clues as to how early development is controlled in insects other than higher dipterans such as Drosophila melanogaster. The results of these studies demonstrate that in insects that do not have bicoid, anterior patterning is regulated by a combination of maternal orthodenticle and hunchback. Furthermore, during the evolution of long-germ-band development, Nasonia and Drosophila may have evolved different mechanisms to pattern posterior segments, marginalising the important role of the terminal system in short-germ-band embryos. BioEssays 28: 683,686, 2006. © 2006 Wiley Periodicals, Inc [source] Sensitivity and specificity of a visual acuity screening protocol performed with the Lea Symbols 15-line folding distance chart in preschool childrenACTA OPHTHALMOLOGICA, Issue 6 2006Francesca Bertuzzi Abstract. Purpose:, The aim of this study was to assess the feasibility of a visual acuity (VA) test using the Lea Symbols 15-line folding distance chart and its diagnostic validity in detecting VA deficiency in preschool children. Methods:, A group of 149 children aged 38,54 months underwent VA examination performed with the Lea 15-line folding optotype at a distance of 3 metres, according to a test protocol described in the Methods section. After the VA test, a complete ophthalmological examination, including cycloplegic retinoscopy, a cover test and examination of the anterior and posterior segments, was performed on each child in order to detect any VA-threatening ocular abnormality. The Lea Symbols test's sensitivity, specificity, positive and negative likelihood ratios (LR +, LR ,) and the receiver operating characteristic (ROC) curve were calculated by means of standard procedures using each VA level of the chart from 0.1 to 1 (1,0 logMAR) as a cut-off point. Results:, The Lea Symbols test could be successfully used in 95.9% of the population. The most useful cut-off points for screening preschool children were found to be 0.8 (LR +,5.73, LR ,,0.05) or 0.63 (LR +,11.7, LR ,,0.23). Conclusion:, The Lea Symbols test proved to be clinically useful in detecting VA deficiency in preschool children. The choice between the two best performing cut-off levels should be made according to the expected cost-effectiveness of the screening programme. [source] | |||||||||||||