Acta ophthalmologica
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This thesis addresses several aspects of glaucoma diagnostics from both a clinical and a screening perspective. New instruments for diagnosing glaucoma have been developed over the past years, but little information is available regarding their performance as screening methods and their usefulness in ordinary clinical practice. PURPOSE OF THE RESEARCH UNDERLYING THIS THESIS: The objectives of this research were as follows: to compare the accuracy of results of analysis of the optic nerve head (ONH) achieved by computerized imaging using the Heidelberg Retina Tomograph (HRT) and by subjective assessment performed by physicians with different degrees of experience of glaucoma (paper III); to evaluate the effect of a continuous medical education (CME) lecture on subjective assessment of the ONH for diagnosis of glaucoma (paper II); to investigate subjective assessment of perimetric test results by physicians with varying knowledge of glaucoma with a trained artificial neural network (ANN) and to compare the certainty of the classifications (paper IV); and to compare the diagnostic performance of time-domain Stratus optical coherence tomography (OCT) with that of spectral-domain Cirrus OCT (paper I), frequency doubling technology (FDT) screening perimetry and scanning laser polarimetry with the GDx variable corneal compensator (VCC) in a random population-based sample and in patients with glaucoma of varying disease severity. ⋯ The HRT MRA performed better than most physicians and was consistent with the glaucoma experts. These results suggest that MRA can be a valuable tool for diagnosing glaucoma in ordinary practice, particularly when only a few glaucoma experts are available. Even though MRA provided 100% sensitivity in eyes with advanced glaucoma, it probably does not offer sufficient specificity to make it suitable as a screening method. Continuing medical education on ONH analysis had a small, but positive effect on diagnostic accuracy for glaucoma. An ANN trained to classify visual fields seemed to perform at least as well as most of the participating physicians, whose performances were remarkably similar regardless of their level of experience. This indicates that available tools for interpreting SAP findings are helpful in assessments of visual field test results. However, SAP is associated with learning effects (Heijl et al. 1989) that may entail low specificity for untrained subjects, and hence, it is not an ideal screening method for glaucoma. By comparison, the screening test of FDT is rapid and easy, but it is probably less suitable for screening purpose, because some eyes with advanced glaucoma were missed in this investigation. GDx VCC images for a relatively large number of eyes could not be analysed and is thus not appropriate for screening. The OCT instruments offer both high sensitivity and high specificity, and all eyes with advanced disease were correctly classified as glaucomatous in this evaluation. However, these instruments are still expensive and require special operator skills. Additional development to obtain OCT instrument that is more compact, easier to use and less expensive might render such tomography suitable as a screening tool for glaucoma.
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Acta ophthalmologica · Feb 2013
Comparative StudyUse of amphoteric rinsing solution for treatment of ocular tissues exposed to nitrogen mustard.
Ocular exposure to mustard agents may cause severe and prolonged injury to the anterior segment tissues. Effective decontamination of the external eye surface after exposure is of paramount importance. The purpose of the present study was to assess the effectiveness of Diphoterine rinsing solution (DRS) in reducing ocular damage after exposure to nitrogen mustard (NM) and to compare it with normal saline solution. ⋯ The findings of this study indicate the effectiveness of DRS in reducing of NM-induced ocular injuries. Its use should be considered as an immediate treatment modality following exposure to mustard agents to reduce potential ocular injury.
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Acta ophthalmologica · Feb 2013
Histopathological changes after deep anterior lamellar keratoplasty using the 'big-bubble technique'.
During deep anterior lamellar keratoplasty (DALK), endothelium and Descemet's membrane are separated from the corneal stroma by intrastromal air injection ('big-bubble technique'). The aim of our study is to analyse histopathological changes in host corneal tissue caused by air insufflation in patients with keratoconus, their variability in 10 patients and their possible clinical implication. ⋯ Our results show that 'big-bubble DALK' causes significant intrastromal air accumulations in the cornea. Pathologists should be conscious of this phenomenon and the high topographic variability. Intrastromal air in the recipient rim may be accompanied by a decrease in mechanical stability and could contribute to postoperative suture loosening.