876 research outputs found
The effect of pterygium surgery on contrast sensitivity and corneal topographic changes
No full textJoo Youn Oh, Won Ryang WeeDepartment of Ophthalmology, Seoul National University Hospital, Seoul, KoreaPurpose: To investigate the effect of pterygium surgery on corneal topography and contrast sensitivity.Patient and methods: The IRB approved this prospective, nonrandomized, self-controlled study. Computerized videokeratography (Orbscan II) was performed in 36 patients with primary pterygia, both before and 1 month after pterygium excision with limbal-conjunctival autografting. The topographic parameters were compared. Spatial contrast sensitivity testing was performed using VCTS 6500. Differences between preoperative and postoperative values were evaluated statistically.Results: The mean Sim K astigmatism and irregularity index, significantly decreased after pterygium surgery. The mean refractive power significantly increased after the operation. The “with-the-rule” astigmatism induced by pterygium became “against-the-rule” astigmatism after pterygium removal (P = 0.041). The contrast sensitivity of 6, 12, and 18 cycles per degree, significantly increased from 1.55 ± 0.28, 0.97 ± 0.47, and 0.29 ± 0.16 to 1.72 ± 0.18, 1.21 ± 0.44, and 0.65 ± 0.48, respectively (P = 0.007, <0.001, <0.001, respectively).Conclusions: Pterygium surgery significantly reduces corneal topographic astigmatism and improves contrast sensitivity.Keywords: corneal topography, visual acuit
Corneal cell viability and structure after transcorneal freezing-thawing in the human cornea
No full textPurpose: Although cryotherapy has long been used to eradicate corneal lesions, there have been no reports of adverse effects of cryotherapy on human corneas. We performed this study to evaluate and characterize ultrastructural damage to the human cornea following the transcorneal freezing-and-thawing procedure. Methods: Seven human donor corneas were randomly divided into three groups. 1, 2, and 3 repetitive freezing-and-thawing procedures were respectively applied to donor corneas in each group. A cryoprobe was cooled to-80°C, and placed on the anterior surface 1.5 mm central to the limbus for 3 seconds. Samples were then allowed to spontaneously defrost. A cornea without the treatment was used as a control. Samples were evaluated through hematoxylin & eosin staining, TUNEL assay, and electron microscopy. Results: After transcorneal cryoinjury, it was observed that corneal endothelial cells were lost and Descemet's membrane was denuded where the cryoprobe was applied. Corneal stromal cells were damaged, and the damage was more marked in the posterior stroma. The extent of damage increased with an increasing number of freezing-thawing repetitions. In contrast, corneal epithelial cells showed no cryo-induced damage, and Bowman's layer remained intact in all groups. Conclusions: The susceptibility to transcorneal cryo-injury differed among the corneal layers; the corneal endothelium was most susceptible, and the epithelium was least susceptible. Caution would thus be advised in regard to the potential damage in corneal endothelium when treating patients with corneal lesions using transcorneal cryotherapy.©2010 Oh et al, publisher and licensee Dove Medical Press Ltd.Y
A Case of Epidemic Keratoconjunctivitis Complicated by Alcaligenes Xylosoxidans Infection
No full textPURPOSE: To report a case of epidemic keratoconjunctivitis complicated by Alcaligenes xylosoxidans. METHODS: A 37-year-old man suffered epidemic keratoconjunctivitis in both eyes. Eleven days later, he developed a corneal ulcer in his left eye. Bacterial staining, culture, and antibiotics sensitivity test were performed from a corneal scrape. RESULTS: The cultures revealed a growth of Alcaligenes xylosoxidans, and the patient was treated with ceftazidime and levofloxacin, based on the sensitivity test results. After 21 days of treatment, the infection was resolved with mild scaring and final vision in the left eye of 20/20. CONCLUSIONS: Alcaligenes xylosoxidans should be considered a rare but potential pathogen able to produce comeal ulcer complication in epidemic keratoconjunctivitis.N
Spontaneous corneal melting during pregnancy: A case report
No full textIntroduction: Biomechanical changes in the cornea during pregnancy might lead to pathological conditions such as corneal perforation or melting. Case presentation: A 33-year-old Asian female who underwent penetrating keratoplasty in both eyes developed corneal melting in the right eye and marginal keratitis in the left eye in her fifth month of pregnancy. Marginal keratitis in the left eye immediately subsided with topical steroid therapy. However, spontaneous corneal melting progressed in the right eye, despite oral steroid therapy and amniotic membrane transplantation. We performed tectonic penetrating keratoplasty and corneoscleral grafting in the right eye. Conclusion: We advise caution in the ophthalmologic care of pregnant patients who have preexisting corneal thinning disorders or who have undergone multiple corneal surgeries, because physiologic changes during pregnancy might contribute to corneal changes leading to spontaneous melting especially in patients with compromised cornea. © 2009 Oh et al; licensee Cases Network Ltd.Y
Clinical features, predisposing factors, and treatment outcomes of scleritis in the Korean population.
No full textTo evaluate the clinical features, associated factors, and treatment outcomes of scleritis in the Korean population. Medical records were retrospectively reviewed for 94 eyes of 76 patients with scleritis. Clinical features of scleritis, including systemic disease, presence of microorganisms, serologic markers, history of previous ocular surgery, and use of immunosuppressants were investigated and compared amongst the subtypes of scleritis. Treatment outcomes were evaluated using best corrected visual acuity (BCVA) and time to scleritis remission. Nodular scleritis was the most common form observed, followed by necrotizing scleritis with inflammation, diffuse scleritis, and necrotizing scleritis without inflammation, respectively. A total of 16 of 76 patients (21.1%) had connective tissue diseases. Eleven cases (14.5%) had infectious scleritis, of which bacteria (54.5%) and fungi (45.5%) were the causative microorganisms. Thirty-three patients (43.4%) had previous ocular surgery, mostly pterygium excision. Notably, a history of pterygium excision was significantly associated with development of necrotizing and infectious scleritis (odds ratio [OR], 399 and 10.1; p < 0.001 and 0.002, respectively). In addition, patients with necrotizing scleritis were more likely to have infectious scleritis (OR, 11.7; p = 0.001). BCVA after treatment and time to remission also showed significant differences among the different scleritis subtypes. Systemic immunosuppression was required in addition to steroids for treating diffuse and necrotizing scleritis. Careful taking of patient history including previous pterygium excision should be performed, especially in patients with necrotizing and infectious scleritis. In addition, evaluation of microbiological infection can be crucial for patients with necrotizing scleritis and history of pterygium excision.Y
Health consultation, W.R. Grace exfoliation facility : Phoenix, Maricopa County, Arizona
No full textabstract: The W.R. Grace facility in Phoenix, Arizona, received vermiculite concentrate from the Libby, Montana, vermiculite mine. W.R. Grace Company has owned and operated the Arizona site since 1964. In 1964 W.R. Grace purchased the company that had previously occupied the site and, following the relocation of its vermiculite exfoliation furnace from Glendale, Arizona, began processing vermiculite concentrate and marketing it under the Zonolite® brand. The objective of this health consultation is to evaluate exposure pathways and potential health effects in those persons who, between 1964 and 2002, may have been exposed to Libby asbestos as a result of vermiculite concentrate processing activities and waste materials from the W.R. Grace exfoliation facility in Phoenix.Under cooperative agreement with the Agency for Toxic Substances and Disease Registry.Includes bibliographical references (p. 22-24)
Aspergillus fumigatus scleritis associated with monoclonal gammopathy of undetermined significance.
No full textA 68-year-old woman presented with pain in her left eye. Necrosis with calcium plaques was observed on the medial part of the sclera. Aspergillus fumigatus was isolated from the culture of the necrotic area. On systemic work-up including serum and urine electrophoresis studies, the serum monoclonal protein of immunoglobulin G was detected. The patient was diagnosed with monoclonal gammopathy of undetermined significance and fungal scleritis. Despite intensive treatment with topical and oral antifungal agents, scleral inflammation and ulceration progressed, and scleral perforation and endophthalmitis developed. Debridement, antifungal irrigation, and tectonic scleral grafting were performed. The patient underwent a combined pars plana vitrectomy with an intravitreal injection of an antifungal agent. However, scleral and intraocular inflammation progressed, and the eye was enucleated. Aspergillus fumigatus was isolated from the cultures of the eviscerated materials. Giemsa staining of the excised sclera showed numerous fungal hyphae.Y
Combined corneal allotransplantation and vitreoretinal surgery using an Eckardt temporary keratoprosthesis: analysis for factors determining corneal allograft survival
No full textPurpose: To evaluate the outcome of corneal allotransplantation in combined penetrating keratoplasty and vitreoretinal surgery using a temporary keratoprosthesis, and to determine the factors affecting corneal allograft survival. Methods: We reviewed the medical charts of eleven patients who had undergone combined corneal allotransplantation and pars plana vitrectomy using an Eckardt temporary keratoprosthesis, for the treatment of corneal opacification and vitreoretinal disease. The survival rates of the corneal grafts were assessed, and patient demographics, the diagnosis of corneal and retinal disease, the preoperative ocular characteristics, and surgical methods were compared between the group with graft survival and that with graft failure. Results: The causes of corneal opacification were corneal laceration (four eyes), infectious keratitis (four eyes), atopic keratitis (one eye), rejected corneal graft (one eye), and uveitis-related bullous keratopathy (one eye). The preoperative diagnoses included endophthalmitis (six eyes), posterior uveitis (one eye), vitreous opacity or hemorrhage (two eyes), and rhegmatogenous retinal detachment (two eyes). The survival rate of the corneal allografts was 27.3% (3/11 eyes). The mean survival time was 391 days during the mean follow-up period of 687 days. The retinal surgery was successful in 81.8% (9/11 eyes) of cases. The presence of active inflammation in the cornea at the time of surgery was significantly correlated with graft rejection (P=0.004). Other factors, including age, the presence of glaucoma, type of corneal and retinal disease, or type of retinal surgery, such as silicone oil injection and gas tamponade, had no significant correlation with graft rejection. Conclusion: Combined corneal allotransplantation and pars plana vitrectomy using a temporary keratoprosthesis allowed for successful surgical intervention in vitreoretinal disease. However, only 27.3% of corneal allografts survived, depending on the presence of active inflammation in the cornea. © 2014 Lee et al.Y
Description of the KNMI Operational Wave Forecast Model GONO
No full textThe purpose of this report is to give a description of the GONO computercode, which is operational at KNMI for many years now. The program was developed by J.W. Sanders, and its deep water version is based on a Norwegian wave prediction model. built by C. Haug in the sixties. Shallow water effects are however important in the southern part of the North Sea. giving a limitation of the wave growth and causing important swell dissipation. A discussion of the shallow water effects. as present in GONO, is given by Sanders in Ref. 3. The computer code GONO is written in ALGOL60 and operational on the Burroughs 6700 of KNMI. The program GONO calculates wind speed. wind direction and sea energy at every grid point of the GONO grid (cf. Appendix A) and swell energy at a limited number of points only (we call these points swell points). GONO runs every six hours and it gives a 12 and 24 hours forecast as well as results based on analyzed weather maps. In the winter of '79-'80 the output of GONO was compared with measurements and the operational wave model of Bracknell (United Kingdom). (The latter GONO version differs a little bit from the version here described). The preliminary results of this comparison are given in Ref. 4. A reasonable agreement of significant wave height and low-frequency energy, as given by GONO, with the observations was found. The present version of GONO, with small modifications compared to the previous version, is operational since the end of February 1980. Essentially, the GONO model is based on two steps. First. the sea energy at every grid point is determined. To this end advection of energy is treated by means of a finite difference scheme whereas the growth of the wave energy is calculated by means of an empirical growth curve (assuming that the wave spectrum has a fixed form). The second step is the calculation of the swell. Of course, in principle swell can be treated likewise, but then one has to store swell energy (and its direction) at every time, at every grid point for every frequency band. Also. this finite difference scheme is rather crude for swell propagation. whereas. because of stability reasons. there is an upper bound for the propagation speed (in the present case the upper bound is given by 13.87 m/s). If one is only interested in swell information at particular points (swell points), it is tempting to use a ray technique. The advantage of this technique is that it is very accurate. Swell is determined in this fashion in GONO.GON
Tungsten biochemistry of Pyrococcus furiosus
No full textTungsten is the heaviest element that exhibits biological activity (atomic number 74), when it is present in an enzyme. It is taken up by cells in the form of tungstate, and it is subsequently processed into an organic cofactor referred to as tungstopterin, which is found as active center in several enzymes. Pyrococcus furiosus is a hyperthermophilic archaeon that grows anaerobically at an optimal temperature of 100 ËšC, strictly dependent on the presence of tungstate. Over the last years, P. furiosus has become a model organism for hyperthermophiles, as many of its proteins have been the subject of research and its genome has been sequenced. Also regarding tungsten metabolism P. furiosus can be considered as a model: four tungsten containing aldehyde oxidoreductases were already characterized in some detail before the initiation of this study. In this thesis several aspects of tungsten metabolism in P. furiosus have been further explored: its tungstate transport system has been identified and characterized (WtpABC), studies on aspects of tungsten cofactor biosynthesis have been carried out and a new tungsten-containing aldehyde oxidoreductase (AOR), WOR5, has been purified and characterized.Applied Science
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