Longitudinal observation of the retinal nerve fibre layer in glaucoma patients treated with brimonidine combined with timolol or timolol alone

INTRODUCTION. The aim of the study was to evaluate the retinal nerve fibre layer (RNFL) thickness loss in primary open-angle glaucoma (POAG) patients treated topically with anti-glaucoma drops containing brimonidine and timolol combination or solely timolol. MATERIALS AND METHODS. Retrospective case series study of patients with POAG diagnosis followed up for a five-year period. Inclusion criteria were fulfilled by a group of 98 patients consisting of 53 combination and 45 monotherapy treatments. Intraocular pressure (IOP) at the level of 21 mm Hg or below for each measurement was observed in 52 patients, while incidences of pressure above 21 mm Hg were measured in 46 patients. POAG diagnosis was based on standard optical coherence tomography, IOP, and visual field examinations. RESULTS. Mean annual loss of RNFL thickness in the overall study group (if IOP levels are not taken into consideration) treated with timolol monotherapy was 1.8 ± 1.5 μm, while in group treated with brimonidine + timolol combination therapy it was 1.7 ± 1.5 μm (p > 0.05). In selected groups of patients with incidents of pressure rises, the mean annual loss of retinal nerve fibre layer thickness was 1.8 ± 1.6 and 1.9 ± 1.4 μm, respectively, for the monotherapy and combination therapy groups (p > 0.05). In the group of patients with no reported IOL rises, mean annual loss of RNFL thickness was 1.8 ± 0.9 and 1.1 ± 0.4 μm, respectively, for the monotherapy and combination therapy groups (p < 0.01). No significant differences were observed for the visual field mean deviation. CONCLUSIONS. POAG patients with low values of IOP might achieve slower progression of RNFL thinning on brimonidine combined with timolol therapy.

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 × N = 1280 × 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 (×6, ×16, ×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

Corneal Structural Changes in Nonneoplastic and Neoplastic Monoclonal Gammopathies

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The cornea in mucopolysaccharidosis IH-S: structural and ultrastructural study

Type I mucopolysaccharidoses (MPS I) include three autosomal recessive disorders (Hurler, MPS IH; Scheie, MPS IS; and Hurler-Scheie, MPS IH-S) caused by the deficient activity of the lysosomal hydrolase α-L-iduronidase with the consequent accumulation of dermatan and heparan sulfate in the lysosomes of several cell types [1]. MPS IH-S is an attenuated disease and the patients show minor facial and skeletal dysmorphism, regular intelligence, mild cardiac and respiratory disease, hepatosplenomegaly, and a normal lifespan. The most common feature is corneal opacification [2], whose morphological basis was not studied in detail. In this work we performed a structural and ultrastructural analysis of the cornea in a patient with MPS IH-S. The patient underwent penetrating keratoplasty and the corneal button was immediately processed for light and electron microscopy. From the micrographs a morphometric analysis was also performed. The corneal epithelium showed superficial cells with few microfolds and evident intercellular spaces. The wing cell layer was formed either by cells with well-evident tonofilaments and small peripheral clear vesicles, or with bilobed nucleus and large paranuclear vesicles filled with granular material. The basal cells showed polygonal shape, with many small vesicles, placed generally in the supranuclear cytoplasm: the intercellular space was enlarged by granular material. The Bowman’s layer was either normal in thickness and structure, or thinner and formed by granular material of variable electron density. The stroma was formed by irregular lamellae of differently oriented collagen, by a large number of keratocytes filled with vesicles, and by intercellular granular material. The corneal endothelium showed degenerative changes. The morphometric analysis of the collagen fibrils diameter provided a mean diameter of 21.71±2.09 nm. Hemidesmosomes were less numerous in the basal cells when compared to the normal cornea. Stromal keratocytes were reduced in their number, particularly in the anterior stroma. Our data showed in MPS IH-S patient pronounced changes of the epithelium, of the Bowman’s layer and of the stroma, consistent with the corneal opacity. As the etiology of the disease is a deficiency of α-L-iduronidase and the consequent accumulation of glycosaminoglycans, we are of the opinion that the stromal keratocytes are the first cells to be involved in the pathogenesis of the corneal disease. The accumulation of the aberrant products seems able to induce morphological changes of both the Bowman’s layer and the corneal epithelium

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 μm 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