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Sclera
Selected AbstractsApatite Deposition on NaOH-Treated PEEK and UHMWPE Films for Sclera Materials in Artificial Cornea Implants,ADVANCED ENGINEERING MATERIALS, Issue 7 2010Monica Pino Abstract Cornea implants consist of a clear optic portion with a surrounding ring known as the skirt, which needs to integrate with the sclera. However, currently used skirt materials lead to poor tissue integration. Improvements in this respect may be achieved by using a bioactive skirt material that adapts to the metabolic activity of the cornea. Polyether etherketone (PEEK) and ultra-high molecular weight polyethylene (UHMWPE) might provide interesting alternatives, if they can be rendered bioactive. We, therefore, investigated the potential of surface-modifying PEEK and UHMWPE films through the use of a two-step treatment. This process involved a suitable chemical surface modification (via immersion in NaOH), with subsequent formation of apatite layers on the polymers' surfaces through exposure to supersaturated simulated body fluid (1.5 SBF). In the present work the effect of 5 and 10,M NaOH on formation of the apatite layer has been investigated with regard to wettability and topography features. In addition, the chemical stability of the apatite layer formed has been analyzed. Our data demonstrate that with an increase in NaOH concentration the wettability of the polymer increased, whilst some changes to the polymer film topography (increase/decrease in roughness) were observed. Most beneficially, the apatite layer that subsequently was grown on pre-treated PEEK and UHMWPE films through immersion in 1.5 SBF contained phosphate and carbonate ions, in similar ratios to those found in the apatite in dentine, thus, promising good in vivo bioactivity of these polymer films,a necessity if they are to be integrated into artificial cornea. [source] Tetracycline and other tetracycline-derivative staining of the teeth and oral cavityINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 10 2004Andrés R. Sánchez DDS Tetracyclines (TCN) were introduced in 1948 as broad-spectrum antibiotics that may be used in the treatment of many common infections in children and adults. One of the side-effects of tetracyclines is incorporation into tissues that are calcifying at the time of their administration. They have the ability to chelate calcium ions and to be incorporated into teeth, cartilage and bone, resulting in discoloration of both the primary and permanent dentitions. This permanent discoloration varies from yellow or gray to brown depending on the dose or the type of the drug received in relation to body weight. Minocycline hydrochloride, a semisynthetic derivative of tetracycline often used for the treatment of acne, has been shown to cause pigmentation of a variety of tissues including skin, thyroid, nails, sclera, teeth, conjunctiva and bone. Adult-onset tooth discoloration following long-term ingestion of tetracycline and minocycline has also been reported. The remarkable side-effect of minocycline on the oral cavity is the singular occurrence of "black bones", "black or green roots" and blue-gray to gray hue darkening of the crowns of permanent teeth. The prevalence of tetracycline and minocycline staining is 3,6%. The mechanism of minocycline staining is still unknown. Most of the reviewed literature consisted of case reports; longitudinal clinical trials are necessary to provide more information on the prevalence, severity, etiology and clinical presentation of tetracycline and TCN-derivative staining in the adult population. [source] Acute febrile neutrophilic dermatosis (Sweet's syndrome) with nodular episcleritis and polyneuropathyINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 2 2002Taizo Kato MD A 56-year-old Japanese housewife presented with multiple erythematous lesions in association with ocular hyperemia and pain in the right upper and lower extremities, including the hands and feet. These symptoms were preceded by a sore throat with persistent fever higher than 38.5 °C for about 1 week. Dermatologic examination showed tender, dull-red, erythematous lesions, measuring 1,2 cm in diameter, located predominantly on the forehead, cheeks, auricular region, neck, forearm, hands, and feet. A biopsy specimen obtained from an erythematous lesion on the right forearm revealed prominent edema in the papillary dermis and remarkable inflammatory cell infiltration throughout the entire dermis (Fig. 1). The infiltrate predominantly consisted of neutrophils and nuclear dust without signs of vasculitis. In routine examination, the leukocyte count was 15,000/mL (normal range, 4000,8000/mL) with severe neutrophilia (80%). The C-reactive protein (CRP) level was 17.65 mg/dL (normal range, < 0.5 mg/dL) and the anti-streptolysin (ASLO) level was 611 IU/mL (normal range, < 166 IU/mL). In human leukocyte antigen (HLA) testing, HLA-A2, -B39, -B35, -Cw2, and -Cw7 were positive, and HLA-B51, -B54, and -Cw1 were negative. Figure Figure 1 . Histologic picture showing a dermal infiltrate of neutrophils Ocular hyperemia was caused by episcleritis forming a nodule and surrounding congestion of the superficial episcleritic vessels at the central portion of the sclera (Fig. 2). The patient suffered from pain once an hour, continuing for about 3 min, at the lateral portion of the right upper and lower extremities, as well as the right small finger. Neurologic examination demonstrated moderate or slight muscle weakness in the extremities. Hand grasping powers were 9 and 7 kg on the right and left, respectively. The patient was right-handed. Dysesthesia and paresthesia were also observed on the hands and feet. The deep tendon reflexes were preserved, however, even in the distal portion of the upper and lower limbs. In addition, essential tremor localized to the neck was recognized. Magnetic resonance imaging did not show any episodes of transient abnormal signal intensity in the central nervous system. Figure 2. Nodular episcleritis (right eye). Telangiectasia of winding vessels with nodular elevation was observed at the upper portion of the sclera The patient was treated with prednisolone (initial dose of 30 mg/day) and intravenous injection of cefazolin sodium (2 g/day for 5 days). Almost complete regression of the ocular and neurologic manifestations, as well as the skin lesions, was achieved in 2 weeks. Prednisolone was reduced gradually and suspended after 4 weeks. Leukocyte and neutrophil counts, CRP, and ASO returned to normal on suspension of therapy. Slight paresthesia remained in the right small finger even after stopping steroid. There was no recurrence at follow-up 6 months later. [source] Histological biocompatibility of new, non-absorbable glaucoma deep sclerectomy implantJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2007Jakub J. Ka Abstract We performed this study to compare the intrascleral biocompatibility of three materials: non-absorbable hydrogel contact lens polymer, non-absorbable silicone rubber, and absorbable cross-linked sodium hyaluronate. Intrascleral implantation of three different materials was performed in 13 healthy, pigmented rabbits. Implants of methacrylic hydrogel, silicone rubber, and cross-linked sodium hyaluronate were implanted in 10, 8, and 8 eyes, respectively. The animals were euthanized at 7, 30, 180, and 360 days post implantation. The eyes were enucleated and immediately fixed in 10% buffered formalin. Semithin sections were cut and stained with hematoxylin-eosin. Light microscope analysis of the specimens was performed. The least severe inflammatory reaction was observed with cross-linked sodium hyaluronate implants. The number of inflammatory cells in proximity to methacrylic hydrogel and silicone implants at all periods of follow up was similar. The thickest fibrous capsule was observed with silicone implants (average, 28.38 ± 11.17 ,m). This area was thinner with methacrylic hydrogel implants (average, 14.90 ± 5.57 ,m) and was thinnest around sodium hyaluronate implants (average, 7.21 ± 2.33 ,m). For each type of implant, the wall on the conjunctival side of the fibrous capsule was significantly thicker than the wall on the choiroidal side. The space between the implant, scleral flap, and bed was filled soon after surgery with connective tissue rich in vessels. In our study, cross-linked sodium hyaluronate had the highest intrascleral biocompatibility. Although the inflammatory responses of the sclera to methacrylic hydrogel and silicone rubber were similar in nature, a thicker fibrous capsule was generated around silicone implants. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006 [source] Gelatin-based biomimetic tissue adhesive.JOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2006Potential for retinal reattachment Abstract An adhesive that cures under moist/wet conditions could facilitate surgical procedures for retinal reattachment. We are investigating an adhesive that mimics the factor XIIIa-mediated crosslinking of fibrin that occurs in the late stages of the blood coagulation cascade. Specifically, we use gelatin as the structural protein (in place of fibrin), and crosslink gelatin using a calcium-independent microbial transglutaminase (in place of the calcium-dependent transglutaminase factor XIIIa). Injection of gelatin and microbial transglutaminase (mTG) into the vitreous cavity of Sprague Dawley white rats did not elicit structural or cellular damage to the retina as evidenced from histological evaluation 2 weeks post-injection. Qualitative in vitro studies indicate that the gelatin,mTG adhesive binds to bovine retinal tissue under wet conditions. Quantitative lap-shear tests were performed with more robust bovine tissue from the choroid and sclera. The lap-shear strength of the biomimetic gelatin,mTG adhesive was independent of tissue-type and ranged from 15 to 45 kPa, which is comparable to the values reported for other soft-tissue adhesives. These studies suggest that the mTG-crosslinked gelatin may provide a simple, safe, and effective adhesive for ophthalmic applications. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006 [source] In vitro femtosecond laser subsurface micro-disruption inside human cornea and pre-cleared scleraLASER PHYSICS LETTERS, Issue 6 2010A.A. Alekhin Abstract Micro-incisions were fabricated inside human cornea and sclera in vitro using single femtosecond laser pulses. In these experiments sclera was for the first time pre-cleared by means of a biocompatible and clinically safe (non-toxic) natural agent (refractive-index matching 40%-glucose solution in water), partially replacing water in the tissue comparing to its severe dehydration by previously used agents. Basic operational parameters of the corresponding microsurgical procedures are reported. (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Clinical study of hereditary disorders of connective tissues in a Chilean populationARTHRITIS & RHEUMATISM, Issue 2 2006Joint hypermobility syndrome, vascular Ehlers-Danlos syndrome Objective To demonstrate the high frequency and lack of diagnosis of joint hypermobility syndrome (JHS) and the seriousness of vascular Ehlers-Danlos syndrome (VEDS). Methods Two hundred forty-nine Chilean patients with hereditary disorders of the connective tissues (CTDs) and 64 control subjects were evaluated for the diagnoses of JHS and VEDS using the validated Brighton criteria, as compared with the traditional Beighton score. In addition, the presence of blue sclera was determined, with the degree of intensity graded as mild, moderate, or marked. Results The frequency of hereditary CTDs was 35%, with diagnoses of JHS in 92.4% of subjects, VEDS in 7.2%, and osteogenesis imperfecta in 0.4%. The Beighton score proved to be insufficient for the diagnosis of JHS (35% of subjects had a negative score), whereas the Brighton criteria yielded positive findings (a diagnosis of JHS) in 39% of control subjects. Blue sclera was frequent, being identified in 97% of JHS patients and 94% of VEDS patients. Moderate osteopenia/osteoporosis was observed in 50% of patients with VEDS and 26% of those with JHS. Dysautonomia, dyslipidemia, and scoliosis were more frequent in VEDS patients than in JHS patients. The typical JHS facial appearance and the "hand holding the head sign" were identified. Raynaud's phenomenon was extremely rare in JHS patients (2%). Ruptured uterus and cerebral aneurysm occurred in 12% and 6% of VEDS patients, respectively. Spontaneous pneumothorax was more frequent in VEDS patients (11%) than in JHS patients (0.9%). Conclusion JHS is very frequent but usually undiagnosed. The Beighton score is an insufficient method for JHS diagnosis. We recommend that physicians learn to recognize the typical facial features of JHS and be able to identify blue sclera. We also propose that validated hypermobility criteria be routinely used. Further research is needed to determine why the prevalence of JHS is so high in Chile. [source] Oral mucosal diseases: the inflammatory dermatosesAUSTRALIAN DENTAL JOURNAL, Issue 2010M Schifter Abstract The oral inflammatory dermatoses is a term used to describe a number of predominantly immune-mediated disorders: lichen planus (LP), erythema multiforme (EM), the vesiculobullous diseases pemphigoid (MMP), pemphigus (PV) and epidermolysis bullosa acquisita (EBA). These conditions are characterized by frequent involvement of the oral mucosa and often associated with extraoral manifestations, particularly of the skin, but can involve the eyes, both the conjunctiva and sclera, the nasal and pharyngeal mucosa, as well as the genitals. Given their frequent, and sometimes initial involvement of the oral mucosa, oral health professionals need to be both familiar with the clinical features and presentations of these conditions, and appreciate their critical role in management. This paper reviews the clinical features and presentation of the oral dermatoses, provides guidance as to the appropriate investigations needed to differentiate and correctly diagnose these conditions, details the aetio-pathology of these diseases and discusses their management. [source] Central corneal thickness in children with growth hormone deficiencyACTA OPHTHALMOLOGICA, Issue 6 2010Fulvio Parentin Acta Ophthalmol. 2010: 88: 692,694 Abstract. Purpose:, To evaluate central corneal thickness (CCT), intraocular pressure (IOP) and eye refraction in patients with congenital growth hormone (GH) deficiency. Methods:, Retrospective case series. Forty-five patients with growth defect treated with recombinant GH and 45 healthy children underwent ophthalmological examination, including CCT measurements, applanation tonometry and cycloplaegic refraction. Results:, The average CCT in the GH deficiency group was 570.6 ,m [standard deviation (SD) 37.4]. In the control group, it was 546.0 (SD 24.9). The average IOP in the GH deficiency group was 18.2 mmHg (SD 3.4). In the control group, it was 14.6 (SD 2.0). The mean refractive error (spherical equivalent) in the GH deficiency group was 0.59 D (SD 1.9). In the control group, it was 0.11 (SD 2.1). Conclusion:, GH and insulin-like growth factor 1 are involved in ocular growth by influencing the synthesis of the extracellular matrix of the sclera. Children with congenital GH deficiency or insensitivity have a mean hyperopic defect related to a shorter axial length. A number of studies have demonstrated that CCT in newborns is significantly greater than in adults; a decrease in CCT is closely correlated with an increase in corneal diameter. This finding suggests that the growth of the eye, with possible remodelling and stretching of collagen fibres, may play an important role in the reduction of corneal thickness in the first years of life. Therefore, we conclude that a greater CCT can represent a sign of a delayed growth of the eye in patients with GH deficiency. Finally, our study confirms the influence of corneal thickness on IOP measures, and the prevalence of hyperopia among children with growth defect. [source] 2453: Optic disc in the picture: novel imaging techniquesACTA OPHTHALMOLOGICA, Issue 2010W DREXLER Purpose Advances in light sources and detection technologies enabled a paradigm shift in retinal OCT imaging performance. ,Snap-shot OCT' enabling isotropic sampling over 512x512x1024 voxels with 600 frames/second in less than a second is now possible. Methods The resolution advantage in conjunction with full volumetric sampling has enabled the development of more informative indices of axonal damage in glaucoma compared with measurements of RNFL thickness and cup to disc ratio provided by other devices. A novel mapping method was developed, the three-dimensional minimal distance (3D-MDM) as the optical correlate of true retinal nerve fiber layer thickness around the optic nerve head region. In a preliminary study relation between the cross-sectional areas of the retinal nerve fiber layer and the optic nerve was found to be a sensitive measure of axon loss. Results In addition to all the major layers of the retina, the entire choroid down to the lamina cribrosa and sclera can now be visualized. This enables unprecedented information about choroidal vasculature without any contrast agents, choroidal thickness and will enable quantification of choroidal blood flow in the near future. Furthermore this technique allows tissue to be imaged in vitro with an image resolution better than 1-2 µm, allowing to image single cells and detect pre-apoptotic signatures using OCT. RGC-5 cells were imaged using a sampling rate 1024x512x1024 voxel at 800 nm central wavelength and a bandwidth of 230 nm, enabling the detection of optical signatures at different pre-stages of programmed cell death. Conclusion Significantly increased OCT imaging speed and tissue penetration might enable novel insights and diagnostic opportunities in the diagnosis and therapy monitoring of glaucoma. Commercial interest [source] 4361: Management of orbital tumours with adjuvant iodine brachytherapy using "inverted" plaquesACTA OPHTHALMOLOGICA, Issue 2010T KIVELÄArticle first published online: 23 SEP 2010 Purpose To describe our experience in using "inverted" iodine plaques as adjuvant treatment after resection of orbital tumours. Methods Between 1999 and 2007, three patients (ages 17-48 years) underwent resection of an lacrimal gland tumour followed by application of an "inverted" iodine plaque manage any microscopic infiltration, i.e. a gold plaque carrying iodine-125 seeds on its convex rather than concave surface. In a fourth instance, the seeds were placed on the convex surface of a ruthenium rather than a gold plaque to manage an eye with a late extraocular recurrence of an irradiated uveal melanoma following resection of the extension. Results The diameter of the plaque was 20 mm. It was sutured to the sclera so that when the eye was in primary position the lacrimal fossa was targeted. When the eye moved, the irradiated volume naturally enlarged. A 40-56 Gy dose was calculated to the depth of 10 mm, and the dose at 5 mm was then calculated as 80-134 Gy. Treatment time was 59-154 hours. In one case, the iodine seeds were placed asymmetrically to limit radiation damage to the eyelid skin. In two patients, transient erythema of the upper eyelid developed, which resolved in a few months time. In case of the extraocular melanoma, dose was the same. Recurrent tumours have not developed. Conclusion An "inverted" iodine plaque is one option for adjuvant irradiation of the orbit which shields the eye from radiation damage. [source] 2355: Biomechanical analysis of the pressure-volume relationship in a statically loaded human eyeACTA OPHTHALMOLOGICA, Issue 2010AA STEIN Purpose To develop an approach for estimating the mechanical characteristics of the individual eye in the ophthalmologic procedures based on static load application (tonometry, et al.). Methods The fibrous coat is mathematically modeled as a soft elastic shell (cornea) connected with an elastic system that mainly consists of the sclera and is characterized by a single elastic constant describing its response to the intraocular pressure. A function representing the intraocular volume as a function of two variables, the intraocular pressure and the load applied, called the volume function is introduced. This function is then specified on the basis of a simple model characterized by two elastic constants in the case of an applanating load. Results A general method of estimating the integral elastic behavior of the individual eye is developed and specific relationships between elastic constants important in different loading processes are obtained. Conclusion The method developed makes it possible to reliably estimate the integral elastic behavior of the fibrous coat and, as a result, to obtain more correct data on the intraocular pressure and other mechanical characteristics. Although in different loading processes (for example, in tonometry and inflating the eye by a liquid volume) different integral elastic contacts are involved, the model proposed provides a means for obtaining efficient approximate relationships between these constants. [source] The treatment of uveal melanoma by ruthenium plaquesACTA OPHTHALMOLOGICA, Issue 2009B DAMATO Purpose Plaque radiotherapy is the first choice of treatment for choroidal melanomas. The standard practice is to position the plaque centrically in relation to the tumour, with a 2mm physical safety margin in all directions. The author has developed techniques for administering brachytherapy with plaques positioned eccentrically, with their posterior edge aligned with the posterior tumour margin. This allows a higher apex dose to be given while reducing the radiation delivered to optic nerve and fovea. Methods The tumour is localized by transillumination and its anterior margin marked on the sclera with a pen. The 'plaque-tumour difference' measurement is then marked on the sclera at the point where the anterior plaque margin should be. A transparent plaque template is sutured to the sclera. The position of the plaque is checked with a right-angled fibre-optic transilluminator, which is passed through a perforation near the posterior edge of the template. If the template is positioned correctly, then with binocular indirect ophthalmoscopy one should see the 'sunset sign', which occurs when the transilluminator is exactly at the posterior tumour margin. Results Eccentric ruthenium plaque positioning has been practised in Liverpool for over a decade. The results have been published. Local tumour control rates have been good (partly because of case selection). Radiation maculopathy and optic neuropathy have been rare if the tumour has not extended within 1 mm of these structures. The main cause of visual loss has been maculopathy, caused by exudation from the irradiated tumour. Methods for treating such exudation are described. Conclusion Plaque radiotherapy is effective for choroidal melanomas up to 5 mm in thickness. It achieves good local tumour control with preservation of vision in most cases. [source] Why do we need a biomechanical approach to the ocular rigidity concept?ACTA OPHTHALMOLOGICA, Issue 2009KE KOTLIAR Ocular rigidity in ophthalmology is generally assumed to be a measurable surrogate parameter related to the biomechanical properties of the whole globe. Clinical tonometry and tonography, as well as recently developed methods to assess the ocular pulse amplitude and pulsatile ocular blood flow and measurements with the ocular response analyzer are based on the concept of ocular rigidity. Clinical concepts of ocular rigidity describe a resulting effect without considerations of possible diverse morphology and material properties of the different ocular tissues. It is commonly accepted that ocular rigidity is related to the elasticity of the sclera. Many formulations are however dependent on the internal volume of the globe, intraocular pressure, corneal biomechanics and thickness of the corneoscleral shell. Sometimes this is extended to biomechanical properties of the ocular vasculature and perfusion pressure. Therefore ocular rigidity is expressed in various units and has different physical meanings but the same name is used which is confusing. Ocular biomechanics introduces parameters of elasticity and viscoelasticity of the sclera, cornea and other tissues which consider the morphology of the different tissues describing their mechanical properties such as: Young's modules of the sclera and Poisson's ratios of the cornea. When applying these rigorous statements and methods of biomechanical modeling a unified concept for ocular rigidity can be developed in order to link the limited clinical concepts, to improve them and to better understand the results of clinical measurements. [source] Biomechanical models for clinical data analysis of pressure-volume relationship in the human eyeACTA OPHTHALMOLOGICA, Issue 2009S BAUER Purpose To develop mechanical models describing the pressure-volume relationship for the human eye and to compare the results obtained with clinical data in order to find out which mechanical characteristics affect this relationship most significantly. Methods The fibrous coat is treated as a connected elastic shell consisting of two spherical segments with different radii and mechanical characteristics. The dependence of the intraocular pressure on the volume is analyzed using three different models in which the sclera and the cornea are modeled (1) by soft shells; (2) by transversally isotropic shells with small tension modules in the transverse direction; and (3) by 3D elastic solids. The models are studied analytically and numerically, the latter using FEM ANSYS software. Results The results are obtained over a wide range of parameters using all three models. Conclusion The models proposed predict a generally nonlinear relationship between the intraocular pressure and volume. The parameters of both the sclera and the cornea affect this relationship, the role of the sclera being more important. In the first approximation the simple soft shell model is in good agreement with the clinical data. [source] Ocular rigidity and ocular response analyzerACTA OPHTHALMOLOGICA, Issue 2009E IOMDINA Purpose To study ocular rigidity and sclera crosslinking level at diferent stages of primary open angle glaucoma (POAG). Methods Biomechanical parameters of the eye especially corneal hysteresis (CH, mm Hg) were measured in 238 patients (311 eyes) aged 40-84 (median age 67.4 yrs) at various stages of compensated primary open-angle glaucoma using Reichert Ocular Response Analyzer (ORA). Besides, scleral samples obtained during sinus trabeculectomy combined with sclera trephination in the inferio-exterior quadrant of 28 patients (28 eyes) with various stages of POAG were studied using differential scanning calorimetry (Mettler TA 4000 with DSC20 cell). Results Average value (median) of CH gradually decreased from 10.1 mm Hg in the initial glaucoma stage (I) to 9.1 mm Hg in the developed (II) and 8.6 mm Hg in the advanced (III) glaucoma stage. The decrease of this clinical parameter is caused by structural and biochemical damage of the corneoscleral coat. In stage I, endothermic scleral collagen transition occurred at the median thermal peak Tm=60.3 grad.C, while in stages II and III the median peaks of scleral collagen melting emerge at higher temperatures: Tm=62.0 grad.C and Tm=64.5 grad.C, respectively (p<0,05). This testifies to a significant increase of scleral cross-linking and ocular rigidity during glaucoma development. Conclusion Biomechanical and biochemical disorders of glaucomatous sclera may cause clinical changes of ocular rigidity of eyes with POAG. This may be an important link of POAG pathogenesis requiring special therapy. [source] Evidence for altered ocular rigidity in glaucomaACTA OPHTHALMOLOGICA, Issue 2009L SCHMETTERER Purpose Based on theoretical models and animal studies altered biomechanical properties of the optic nerve head and the sclera have been implicated in the pathophysiology of glaucoma. Only few data have, however, demonstrated such biomechanical alterations in vivo. We tested the hypothesis that patients with primary open angle glaucoma (POAG) have an abnormal structural stiffness based on measurements of intraocular pressure amplitude and ocular fundus pulsation amplitude. Methods Seventy patients with POAG and 70 healthy control subjects matched for age, gender, intraocular pressure and systemic blood pressure were included in this study. The ocular pulse amplitude (PA) was assessed with pneumotonometry. The fundus pulsation amplitude (FPA) was measured using laser interferometry. Based on the Friedenwald equation a coefficient of structural stiffness (E1) was calculated relating PA to FPA. Results Systemic blood pressure, intraocular pressure, and ocular perfusion pressure was comparable between glaucoma patients and healthy control subjects. FPA as well as PA was lower in patients with glaucoma than in healthy controls. The calculated factor E1 was significantly higher in patients with POAG (0.0454 ± 0.0085 a.u.) than in healthy control subjects (0.0427 ± 0.0058 a.u., p = 0.03). Conclusion This study is indicative of increased structural stiffness of the sclera in patients with POAG. This is in agreement with a number of previous animal experiments and supports the idea that the biomechanical properties of ocular tissues play a role in the process of glaucomatous ONH damage. [source] Primary vitrectomy in retinal detachment: is scleral buckling still indicated?ACTA OPHTHALMOLOGICA, Issue 2009CJ POURNARAS Purpose The surgical management of rhegmatogenous retinal detachment has evolved due to introduction of primary pars plana vitrectomy (PPV). The choice of primary vitrectomy has grown over recent years even for managment of simple retinal detachment. Methods Review of reports on primary vitrectomy treatment for rhegmatogenous uncomplicated retinal detachment. Evaluation of optimal indications of vitreectomy for specific types of retinal detachments. Results Comparaison of primary vitrectomy with scleral buckling had failed to demonstrate advantage of this method regarding anatomical and functional results. Vitrectomy avoids some of the complications associated with scleral buckling, such as diplopia, choroidal detachment, perforation of the sclera, abnormalities in the eyelid, but it carries higher risks of several other complications,including cataract formation in phakic eyes, glaucoma and other problems with tamponade, and new retinal breaks. Data from case series and randomized studies suggest that primary detachments in phakic eyes may be treated successfully with scleral buckling or vitrectomy, whereas vitrectomy appears to be preferable for corresponding detachments in pseudophakic eyes. Conclusion The choice of primary PPV in new uncomplicated retinal detachment remains to the surgeon's discretion and skills due to lack of controlled randomized trials covering the large spectrum of the retinal detachment pathology. [source] How do we get started with offering MOOKP clinical service?ACTA OPHTHALMOLOGICA, Issue 2009M FUKUDA Modified osteo-odonto keratoprosthesis (MOOKP) is complicated two step surgery. Firstly, we must understand why it is effective for visual recovery of end-stage ocular surface diseases like Stevens- Johnson syndrome. MOOKP have a lot of advantages compared to other K-pros, for example the using auto tissue of canine tooth root and buccal mucous membrane, the tight adhesions between optical cylinder and canine tooth root, the adhesion between MOOKP lamina and sclera or cornea, the strong ocular surface by auto buccal mucous membrane, no inflammation on the back of optical cylinder and so on. However, the precise surgical techniques and proper instructions are necessary to succeed the very first case in newly set surgical center. In Japan, we successfully set up the MOOKP center and did perform 4 cases of MOOKP since 2003. We share our experience about it and point out our modification adjustable for Japanese patients. [source] An audit of eccentrically-positioned ruthenium plaque radiotherapy of choroidal melanoma in LiverpoolACTA OPHTHALMOLOGICA, Issue 2009A RUSSO Purpose Brachytherapy is usually administered with the plaque overlapping the entire tumour margin by at least 1-2mm. With posterior tumours, our practice is to position the plaque with its posterior edge aligned with the posterior tumour margin. We audited ocular outcomes after eccentrically-placed ruthenium plaque radiotherapy of choroidal melanoma. Methods Patients were included if receiving primary ruthenium brachytherapy for choroidal melanoma during the three years up to the 31st July 2007. A perforated template was used to facilitate plaque positioning. For posterior tumors, the template was positioned so that trans-illumination produced a glow at the posterior tumour margin (,sunset sign'). Minimum doses of 300-350 Gy and 80-90 Gy were prescribed to the sclera and apex, respectively. Results The cohort comprised 162 patients (93 female and 69 male). The time to the last known visual acuity had a median of 23 months. The initial visual acuity was 20/40 or better in 94.6%, 20/60 to 20/200 in 13.0% and worse than 20/200 in 1.9% of patients. The tumours had a mean basal diameter of 11.7mm. Ten tumours exceeded 5.4 mm in height. Tumour extension to within 5mm of optic disc, fovea or both occurred in 18 (11.1%), 28 (17.3%) and 27 (16.7%) cases respectively. Risk factors for visual loss were proximity to optic disc or fovea, initial visual acuity worse than 20/40 and tumour height exceeding 5.4 mm. In 66 patients with none of these risk factors, 92% retained 20/40 or better and 5 had vision of 20/60 , 20/200. In 72 with one risk factor, 74.3% retained 20/16 , 20/40 and 95.7% had vision of 20/200 or better. In 12 patients with 2 risk factors, these percentages were 25.0% and 91.7%. Only 3 patients had 3 risk factors and one retained vision of 20/200 or better. Tumours distanced < 5 mm to fovea were divided in 3 groups, and visual acuity analysed. Three patients had local tumour recurrence and were treated respectively by proton beam radiotherapy, plaque radiotherapy and enucleation (the only eye lost in this series). Conclusion Eccentric plaque radiotherapy of choroidal melanoma achieves good rates of local tumour control, ocular retention and preservation of vision. [source] The distribution of neuroglobin in mouse eyeACTA OPHTHALMOLOGICA, Issue 2009Y YOU Purpose To determine the distribution of neuroglobin (Ngb) in mouse eye. Ngb is predominantly expressed in the nervous system,and at particularly high levels in the retina. Ngb may serve as a reactive oxygen scavenger and may protect the tissue of eye from ischemia/hypoxia injuries. However,the distribution of Ngb in the eye is still controversial. Methods Two polyclonal antibodies against Ngb were used in this immunohistochemical study, both of which were raised in rabbits. One of these two antibodies was generated against the whole recombinant protein of mouse Ngb and the other was generated against amino acid positions 55-70 of mouse and human Ngb. The expression of Ngb was analyzed with light microscopy on tissue sections. Results These two antibodies showed comparable results. Ngb was expressed in the layers of the retina, including the ganglion cell layer, inner and outer nuclear layers, inner and outer plexiform layers, the inner segments of the photoreceptors and the retinal pigment epithelium. Ngb was also detected in other structures of the eye, including the epithelium and endothelium of cornea,the stroma of iris,the ciliary body, the lens epithelium, and the sclera. However, Ngb was not expressed in the corneal stroma, the lens capsule, the lamellar fibers of lens, the pigment epithelium of ciliary body or the pigment layer of iris. Conclusion Ngb was found widely distributed in mouse eye. This finding can be explained by the fact that most of the structures of the eye originated from neural crest/neural ectoderm. Future experiments will focus on the distribution of Ngb at the mRNA level (in situ hybridization),and the quantitative expression levels at baseline and after hypoxic/ischemic challenge. [source] Hunter's syndrome and buphthalmos in a girl: an unusual ophthalmic associationACTA OPHTHALMOLOGICA, Issue 2009S SETHI Purpose To report an unusual ophthalmic presentation of a case of Hunter's syndrome/MPS II. Methods A sixteen-year-old girl presented to us with total loss of vision and forward protrusion OU since early childhood. Detailed examination, including slit lamp biomicroscopy, Intra ocular pressure (IOP) and fundoscopy was carried out. Thorough systemic evaluation including Computed Tomography (CT), metabolic and genetic analysis was undertaken in collaboration with internists. Results Characteristic facies, detection of glycosaminoglycan (GAG) variants in urine (chondroitin sulfate B and heparin sulfate) and iduronate-2-sulphatase activity in fibroblasts/leucocytes confirmed the diagnosis of MPS II. Child had severe photophobia but with no perception of light OU. OU buphthalmos with Haab's striae was noted, making a clear view of the fundus difficult. IOP OU was elevated, and 90D slit lamp biomicroscopy revealed a total glaucomatous optic atrophy in both eyes. On CT there was thickening and edema of preseptal and periorbital soft tissue with marked thinning of the optic nerves with prominent perineural CSF sleeves, indicative of marked optic atrophy. Conclusion Glaucoma is a known association of Hurler's, Scheie's and Maroteaux-Lamy syndromes but not Hunter's. In fact, there is only one report of suspected angle closure glaucoma in MPS II. Buphthalmos is not a likely presentation as the sclera in these patients is known to be thickened due to deposition of GAG. To the best of our knowledge, this is the first case report of buphthalmos in association with MPS II. The importance of a meticulous examination in this subset of patients cannot be overemphasised. An appropriate and timely intervention may result in a better quality of life for them. [source] In vitro transcorneal and transscleral diffusion of radiolabeled compounds in human and rabbit cornea and in human, monkey, dog, and rabbit scleraACTA OPHTHALMOLOGICA, Issue 2009CB STRUBLE Purpose To determine the in vitro diffusion of selected compounds across the cornea or sclera of humans, monkeys, dogs, and rabbits. Methods Human and NZW rabbit corneas were obtained and the epithelium was removed from one cornea of each pair. Corneas were mounted in chambers with 3H-water or 3H-dexamethasone on the epithelial side and BSS solution on the endothelial side. Serial aliquots were taken from each chamber and assayed by LSC. Scleral sections from human, NZW rabbit, dog, or monkey eyes were mounted in perfusion chambers. Adjacent sclera was used for H&E histology. 3H-water, 3H-dexamethasone, or 70kD-14C-dextran were added to the episcleral surface while perfusing BSS across the choroidal side. Serial aliquots were collected up to 5 hrs and assayed by LSC. Scleral permeability (ktrans) was calculated. H&E slides were used to determine scleral thickness. Results 3H-water diffused through cornea faster than 3H-dexamethasone, especially with denuded epithelium. Scleral thickness and molecular weight were determinant of diffusion in sclera. Monkey sclera was thinnest, followed by dog, rabbit, and human. ktrans for 70kD-14C-Dextran and 3H-dexamethasone were greatest in monkey, followed by dog, rabbit, and human. ktrans values for 3H-water were similar in all species, and greater than values for 14C-dextran and 3H-dexamethasone. Conclusion These studies demonstrate permeability of cornea and sclera in human and animal models with compounds of varied molecular weights representative of drugs being developed for treatment of ocular diseases. The results of this study indicate that these techniques are valuable as screening tools in the development of ocular drugs. [source] Sensitivity of applanation tonometry readings to the geometrical parameters of the sclera and the shape of the corneaACTA OPHTHALMOLOGICA, Issue 2009E VORONKOVA Purpose To study the effect of the geometrical parameters of a cornea (the thickness and difference of corneal shape from spherical segment) on applanation tonometry readings. Methods The mathematical model for Goldmann and Maklakov tonometers is developed. The corneoscleral shell is modeled as two conjugated transversal isotropic elliptic (with non-zero eccentricity) shells (cornea and sclera) with different mechanical properties. The baseline (prior to loading) two-segment shell is assumed to be filled with incompressible liquid under pressure. Simulated IOP measurements are obtained for Goldman and 5-g and 10-g Maklakov tonometers. To analyze the effect of the eyeball geometry on IOP readings the elastic constants of cornea and sclera are varied and geometrical parameters (such as central corneal thickness, cornea and sclera radii of curvature, scleral thickness, ratio of anterior-posterior eye axis lengths vs. the equator diameter) are varied. Simulated calculations are compared with experimental data. Results The results are obtained over a wide range of parameters of the sclera and cornea. Conclusion If the shape of a cornea differs from spherical it could cause the measurement error of tonometry IOP readings ranged between 3% and 25%. Significant sensitivity of the Goldmann tonometer to corneal thickness compared to Maklakov's method may be explained with smaller contact zone and, hence, the larger influence of the flexural (bending) deformation, which depends on the thickness of a shell. Contrariwise the change of the radius of curvature of cornea affects greatly on the results obtained with Maklakov tonometer. [source] Long-term biomechanical properties of rabbit sclera after collagen crosslinking using riboflavin and ultraviolet A (UVA)ACTA OPHTHALMOLOGICA, Issue 2 2009Gregor Wollensak Abstract. Purpose:, Scleral crosslinking by the photosensitizer riboflavin and ultraviolet A (UVA) has been shown to increase significantly the scleral biomechanical rigidity and might therefore become a possible sclera-based treatment modality for progressive myopia. In the present study, the long-term effect of the new crosslinking method on biomechanical properties was investigated in the rabbit sclera. Methods:, A 10 × 10 mm sector of the equatorial sclera of nine Chinchilla rabbit eyes was treated in vivo using a UVA double diode of 370 nm with a surface irradiance of 3 mW/cm2 and application of 0.1% riboflavin-5-phosphate drops as photosensitizer for 30 min. Three days, 4 months and 8 months postoperatively, biomechanical stress,strain measurements of the treated scleral strips were performed and compared to contralateral control sclera using a microcomputer-controlled biomaterial tester. In addition, routine histological controls were performed. Results:, Following the crosslinking treatment, Young's modulus was increased by 320% after 3 days, 277% after 4 months and 502% after 8 months, and ultimate stress by 341% after 3 days, 131% after 4 months and 213.8% after 8 months versus the controls. The decrease in ultimate strain was between 24% and 44.8%. On histology, no tissue damage was detected. Conclusion:, Our new method of scleral collagen crosslinking proved very effective and constant over a time interval of up to 8 months in increasing the scleral biomechanical strength. Therefore, the new treatment might become an option for strengthening scleral tissue in progressive myopia and other conditions associated with weakened sclera. There were no side-effects on the retina or retinal pigment epithelium. The new crosslinking treatment could now be tested in a suitable myopia model (like the tree shrew) and finally in human eyes. [source] Long-term biomechanical properties after collagen crosslinking of sclera using glyceraldehydeACTA OPHTHALMOLOGICA, Issue 8 2008Gregor Wollensak Abstract. Purpose:, Chemical crosslinking by glyceraldehyde has been shown to increase significantly the biomechanical rigidity of sclera. It might therefore become an option for a sclera-based treatment of progressive myopia. The present pilot study was designed to test the long-term biomechanical efficiency of the new crosslinking method. Methods:, Six Chinchilla rabbits were treated with sequential sub-Tenon's injections of 0.15 ml 0.5 m glyceraldehyde, which were given in the supero-nasal quadrant of the right eye (OD) five times over 14 days. The rabbits were killed 4 months and 8 months after crosslinking treatment, respectively. Biomechanical stress,strain measurements of scleral strips from the treatment area were performed and compared to non-treated contralateral control sclera using a microcomputer-controlled biomaterial testing device. In addition, the eyes were examined histologically by light microscopy to evaluate possible side-effects. Results:, Following the crosslinking treatment, the ultimate stress was 10.2 ± 2.3 MPa after 4 months and 8.5 ± 2.2 MPa after 8 months versus 2.4 ± 0.3 MPa in the controls (increases of 325% and 254.17%, respectively); Young's modulus was 104.6 ± 13.7 MPa after 4 months and 53.2 ± 5.2 MPa after 8 months versus 9.6 ± 1.3 MPa in the controls (increases of 989.6% and 554.17%, respectively); and ultimate strain was 15.8 ± 1.5% after 4 months and 24.1 ± 0.7% after 8 months versus 38.4 ± 4.6% in the controls (decreases of 58.84% and 37.24%, respectively). Histologically, no side-effects were found. Conclusion:, Our new method of scleral collagen crosslinking proved very efficient in increasing scleral biomechanical strength over a period of up to 8 months. Glyceraldehyde can be applied easily by sequential parabulbar injections. Before clinical application in myopic patients, a study in an animal myopia model is recommended. [source] Micro Incisional Vitrectomy (MIVS): a new device for trocar insertionACTA OPHTHALMOLOGICA, Issue 2008S RIZZO Purpose Despite its clinical advantages, MIVS poses significant challenges in performing airtight incisions especially dealing with 23-gauge system. Aim of this paper was to assess the feasibility of performing 23-g MIVS using an injector system for trocar insertion. Methods 60 consecutive eyes of 56 patients underwent 23-g pp vitrectomy and gas endotamponade for the treatment of Regmatogenous Retinal detachment and Diabetic Prolipherative Retinopathy by the same surgeon (SD). 30 eyes were operated on with standard one-step 23-g and 30 using a prototype of injector holding the same 23-g trocar cannula system. The trocar squeezed into the plunger of the injector. The device had a metallic terminal oriented with a fix angle, allowing the insertion in the settled direction, able to fix the globe and displace the conjunctiva at the same time.Main outcome measure were sclerotomies airtightness, surgical time and complications. Results In the 30 eyes operated with the 23-g ones step system 9 sclerotomies were sutured, in 5 refilling was required. Mean surgical time were 54 minutes. In the 30 eyes operated with the new device, the inserter was easy to apply in all cases and was useful especially in the nasal quadrant. Also dealing with sunken eyes the inclination of the system 5-10° tangential to the sclera was easily achieved. No suture was placed, refilling was needed in 3 cases. Mean surgical time was 45 minutes. No complications due to these device were highlighted. Conclusion The new injector was safe and effective. The device facilitates the insertion manoeuvre allowing easier and quicker trocar positioning helping the airtight wound construction. MIVS success lie in the surgeon's skill but also in the development of the technology and instrumentations. [source] Characterization within and around the Limbal Epithelial CryptACTA OPHTHALMOLOGICA, Issue 2007AM YEUNG Purpose: The Limbal Epithelial Crypt (LEC) is an anatomical structure that is found between the junction of the cornea and sclera and is in a unique position to make it an ideal structure to examine further. Previous studies have demonstrated the LEC to have properties that suggest it may be a stem cell niche. Basal cells of the LEC are significantly smaller than basal cells found in adjacent rete pegs, and morphologically they have a higher nuclear:cytoplasmic ratio. We set out to examine LEC further by exploring the surrounding LEC matrix proteins, and with known differentiation markers. Methods: Donated corneo-sclero rims were cut into eight equal sized pieces and frozen. Each piece was cut into 7,m serial sections, and was examined by microscopy for LEC structures. Identified LEC was collected on slides and stored until they were fixed in acetone and processed by standard immunofluorescence techniques for each differentiation marker. Results: Tenacin C was more positively taken up by the basement membrane of the LEC compared with the surrounding limbus. In addition, staining for desmoglein was negative against isolated small subpopulations of cells within the basal regions of the LEC. Conclusions: The LEC structure demonstrates properties that may identify this as a possible stem cell niche. Further studies are necessary to determine the significance of the LEC in its role in stem cell maintenance. [source] Effects of intraperitoneal vitamin E, melatonin and aprotinin on leptin expression in the guinea pig eye during experimental uveitisACTA OPHTHALMOLOGICA, Issue 1 2006Aysel Kükner Abstract. Purpose:,To observe ultrastructural changes and leptin expression in the guinea pig eye during experimental uveitis (EU) and the effects of vitamin E, melatonin and aprotinin on leptin expression. Methods:,Thirty male guinea pigs were randomly classified into five groups. Group 1 was the control group. Groups 2, 3, 4 and 5 received intravitreal injections of bovine serum albumin (BSA) to induce EU. At the same time on the third day, groups 3 (EU + vitamin E), 4 (EU + melatonin) and 5 (EU + aprotinin) received intraperitoneal vitamin E (150 mg/kg), melatonin (10 mg/kg) and aprotinin (20 000 IU/kg), respectively. On the sixth day, histopathological and clinical scoring of inflammation were performed, and leptin expression was investigated in the retina, choroid, sclera, episclera and cornea, and compared. Results:,There was a remarkable increase in leptin expression in the retina, choroid, sclera and episclera in the EU group. Leptin expression in the treatment groups was similar to that in the control group. At light and electron microscopic levels, ganglion cells were oedematous and inner plexiform layer thickness had increased in the EU group retinas. Oedema was decreased in the treatment groups. Comparison of the EU and treatment groups revealed significant differences histopathologically and clinically. Conclusion:,Experimental uveitis causes an increase in leptin expression in the retina, choroid, sclera and episclera of guinea pigs. Vitamin E, melatonin and aprotinin inhibit this increase. Leptin seems to be closely related to ocular inflammation. [source] Dissection and cotransplantation of large pieces of RPE and neural retina; effect of protease K on the developmentACTA OPHTHALMOLOGICA, Issue 1 2000Rajesh Kumar Sharma ABSTRACT. Purpose: This study attempts to cotransplant large pieces of the RPE and neural retina in the subretinal space of rabbits by using protease K for dissection of the donor tissue, and to investigate the effect of dissection technique on the development of the grafts. Methods: Eyes from 15-day-old pigmented rabbit embryos were partly digested by protease K to assist dissection of sclera and the choroid from RPE and neural retina. Large pieces of RPE and the neural retina thus obtained were cotransplanted into the eyes of adult albino rabbits who were allowed to survive for up to 63 days. The transplants were examined under light microscope. Results: It was possible to transplant large sheets of RPE and neural retina together. Both the RPE and the neural retina survived after cotransplantation. Retinal pigment epithelium survived in layers, but at places formed clusters. In cotransplants neural retina formed rosettes, developed gliosis, and photoreceptors failed to develop outer segments, possibly due to the action of protease K. Conclusion: Proteases seem to be injurious for the development of the neural retina. [source] | |||||||||||||