27 research outputs found
Quantitative measurement of pseudoexfoliation in the anterior segment of the eye performed in visible light
Introduction: Pseudoexfoliation syndrome (PEX) is a systemic disease involving the accumulation of pathological material deposits in the tissues of the anterior segment of the eye. The problem of modern ophthalmology is a quantitative assessment of the severity of PEX in the diagnosis and evaluation of the treatment progress in patients.Material and method: For the purposes of this study, 52 images of the anterior segment of the eye with the resolution of M 脳 N = 1280 脳 960 pixels were obtained in jpg format using the slit lamp CSO 450-SL. The patients were aged 50-80 and were recruited from Poland. All patients who participated in the study provided written informed consent after explanation of the nature and possible consequences of the study. The image analysis method proposed by the authors contains the calculation of the direction field, setting a straight perpendicular line passing through each pixel of the edge of the pupil, the calculation of the intersection of straight lines in order to determine the central point of the pupil position, the detection of the contour of PEX and the outer border of the iris with the use of the polar coordinate system. All analyzed parameters were set automatically with one exception parameter chosen manually depending on the slit lamp type.Results: A fully automatic measurement of PEX was carried out with the proposed method. Quantitative results enable to perform reproducible tests independently of the research centre. Owing to the image analysis method proposed by the authors, it is possible to obtain results in no more than 1 second on the Intel Core 2 Quad CPU 2.50 GHz with a measurement error below 3%. Other known methods of image analysis and processing that are compared in this paper give results with a greater error (4-35%) which depends on the degree of magnification (脳6, 脳16, 脳20) and are not fully automatic.Conclusions: The methods of image analysis and processing enable a quantitative, repeatable and automatic measurement of the severity and progress of PEX syndrome. They support medical diagnosis and automatic archiving of results
Comparative Study of Anterior Eye Segment Measurements with Spectral Swept-Source and Time-Domain Optical Coherence Tomography in Eyes with Corneal Dystrophies
Purpose. To compare anterior eye segment measurements and morphology obtained with two optical coherence tomography systems (TD OCT, SS OCT) in eyes with corneal dystrophies (CDs). Methods. Fifty healthy volunteers (50 eyes) and 54 patients (96 eyes) diagnosed with CD (epithelial basement membrane dystrophy, EBMD = 12 eyes; Thiel-Behnke CD = 6 eyes; lattice CD TGFBI type = 15 eyes; granular CD type 1 = 7 eyes, granular CD type 2 = 2 eyes; macular CD = 23 eyes; and Fuchs endothelial CD = 31 eyes) were recruited for the study. Automated and manual central corneal thickness (aCCT, mCCT), anterior chamber depth (ACD), and nasal and temporal trabecular iris angle (nTIA, tTIA) were measured and compared with Bland-Altman plots. Results. Good agreement between the TD and SS OCT measurements was demonstrated for mCCT and aCCT in normal individuals and for mCCT in the CDs group. The ACD, nTIA, and tTIA measurements differed significantly in both groups. TBCD, LCD, and FECD caused increased CCT. MCD caused significant corneal thinning. FECD affected all analyzed parameters. Conclusions. Better agreement between SS OCT and TD OCT measurements was demonstrated in normal individuals compared to the CDs group. OCT provides comprehensive corneal deposits analysis and demonstrates the association of CD with CCT, ACD, and TIA measurements
Structural, ultrastructural and morphometric study of the zebrafish cornea: a model for human corneal diseases?
The structural and ultrastructural organization of the ocular surface of Vertebrates is still partial and often controversial. A morphological and morphometric study of the adult zebrafish (Danio rerio) cornea was performed to provide a comprehensive description of its layers and to compare its organization to the human cornea [1,2]. The eyes of adult zebrafish were processed for light, transmission and scanning electron microscopy and a morphometric analysis was performed on several morphological parameters. The zebrafish cornea is thinner in its central part, while it is thicker in its periphery. Only four layers are present, as no Descemet membrane can be demonstrated. The epithelium is formed by 5-8 layers of polygonal cells, identified as superficial, intermediate and basal, and provided of an evident peripheral cytoskeleton. The Bowman layer is particularly thin (~ 250 nm) and is placed between the basal cells and the first stromal lamella. The stroma is formed by 26-40 lamellae of collagen fibers, among which only occasional keratocytes are present, generally in the posterior part. The endothelium is formed by a single layer of flat polygonal cells, 1-1.5 渭m thick. The morphometric analysis showed mild differences between the central and the peripheral cornea; furthermore, the epithelium/stroma ratio is 0.89, while it is 0.09 in the human cornea. It can be concluded that, even if the general organization of the zebrafish cornea is similar to that of mammals, there are also several significant differences, such as the presence of a very thin Bowman layer, the reduced thickness of the stroma and the absence of the Descemet membrane. Therefore, caution is required when findings obtained from zebrafish as an experimental model are applied to normal or pathological corneas in other species, such as rodents or humans
Novel Diagnostic Methods in Ophthalmology
In the last 10 years, there has been huge progress in the general understanding of ocular disorders due to the availability and development of new in vivo imaging techniques, such as anterior and posterior eye segment optical coherence tomography as well as biochemical methods allowing rapid confirmation of clinical diagnosis.Introducing noninvasive diagnostic methods in ophthalmology led to an improvement in early differential diagnosis of conditions such as corneal dystrophies, dry eye disease, and various retinal and optic nerve diseases.Recent advances in diagnostic methods have also impacted the treatment methods. This book intends to provide the reader with a comprehensive overview of current ocular diagnostic methods, including the theoretical basis as well as practical approaches and usage in clinical practice