No abstract available

[en] Measurements of the incident dose on the eye have been taken during the tomographic examinations of the middle ear. These measurements have been effectuated without any protection of the eye, and with a Pb-diagram protection, thickness 2mm. The tomograph which has been used is an Italian one (Eurostrator-Zuder, Genoa) provided with complex radiation movements (circular, spiral) and which gives technical results such as the Polytom (generally used for these researches) but which has a focus-film distance of 1m instead of 1.40m. The average incident dose on the crystalline lens is high (11.7R); the use of the Pb-diaphragm reduces the dose considerably (0.65R) without any significant imperfections on the radiological image

[en] There is ample anatomical, physiological and psychophysical evidence that the mammilian retina contains networks that mediate interactions among neighboring receptors, resulting in intersecting transformations between input images and their corresponding neural output patterns. The almost universally accepted view is that the principal form of interaction involves lateral inhibition, resulting in an output pattern that is the convolution of the input with a ''Mexican hat'' or difference-of-Gaussians spread function, having a positive center and a negative surround. A closely related process is widely applied in digital image processing, and in photography as ''unsharp masking''. The authors show that a simple and fundamentally different process, involving no inhibitory or subtractive terms can also account for the physiological and psychophysical findings that have been attributed to lateral inhibition. This process also results in a number of fundamental effects that occur in mammalian vision and that would be of considerable significance in robotic vision, but which cannot be explained by lateral inhibitory interaction

No abstract available

[en] The method to detect cornea surface topography is suggested, providing for high accuracy and operativeness, when obtaning information on the cornea form and shape. The device for realization of the method, an image registered, a diagram of the output signal of an optical electron receiver are shown. It is shown that the accuracy of topography determination of cornea surface by means of the above method increases approximately 3-5 times

[en] Intravitreal drug delivery is a commonly used treatment for several retinal diseases. The objective of this research is to characterize and quantify the role of the vitreous humor motion, induced by saccadic movements, on drug transport processes in the vitreous chamber. A Perspex model of the human vitreous chamber was created, and filled with a purely viscous fluid, representing eyes with a liquefied vitreous humor or those containing viscous tamponade fluids. Periodic movements were applied to the model and the resulting three-dimensional (3D) flow fields were measured. Drug delivery within the vitreous chamber was investigated by calculating particle trajectories using integration over time of the experimental velocity fields. The motion of the vitreous humor generated by saccadic eye movements is intrinsically 3D. Advective mass transport largely overcomes molecular diffusive transport and is significantly anisotropic, leading to a much faster drug dispersion than in the case of stationary vitreous humor. Disregarding the effects of vitreous humor motion due to eye movements when predicting the efficiency of drug delivery treatments leads to significant underestimation of the drug transport coefficients, and this, in turn, will lead to significantly erroneous predictions of the concentration levels on the retina. (paper)

[en] Published in summary form only

[en] Purpose: The subject of this study was to define age-related and gender-dependent changes in MR features of the lacrimal gland. Material and Methods: MR images were retrospectively analyzed in 104 normal subjects aged 2-79 years to measure thickness and area of the lacrimal gland, its MR signal intensity ratio, and SD of the MR signal intensity profile. Results: Thickness and area of the lacrimal gland decreased with age in women (p<0.001), but not in men. Furthermore, MR signal intensity ratio of the lacrimal gland showed an age-related increase in women (p<0.001), but not in men. On the other hand, SD of the MR signal intensity increased with age in both women and men (p<0.001). Conclusion: These findings demonstrate that gender has a significant influence on lacrimal gland structure during development and aging. (orig.)

[en] Standard CT examinations of the orbit and the petrous bone were simulated with a tissue-equivalent human skull phantom on a Somatom DR 2 scanner. The orientation of the scan planes and the scan parameters including thickness, number of slices and mAs were varied according to the assumed diagnostic problems. The total radiation doses in the region of the eye lenses were measured with thermoluminescent dosimeters. If the globes are located within the X-ray field, the total radiation doses received by the lenses increased with the number and the thickness of the slices and the mAs. The highest radiation doses were found in contiguous thinsection scans of the orbit in axial (52 mGy) or direct coronal (47 mGy) orientation. In cases where the globes were located outside the X-ray field, the radiation doses received by the eye lenses could be reduced by a factor of 16, resulting in only 3.1-3.4 mGy for a complete axial study of the inner ear. Recommendations are given how to reduce the radiation exposure to the eye lenses without loss of diagnostical information. (orig.)

[en] Objective: To identify if anisometropic amblyopia is associated with changes in optic disk morphology. Methods: The study comprised a total of 80 eyes recruited from Shifa Foundation Community Health Centre and the Pakistan Institute of Medical Sciences, Islamabad between May and October 2012. Anisometropic amblyopia was the only cause of disability (visual acuity >6/12) in amblyopic eyes whereas normal eyes had a best corrected visual acuity of 6/6 and no morbidities. Patients with other causes of amblyopia, co-morbid ocular diseases, and in whom a good-quality image could not be obtained were excluded. Mean retinal nerve fiber layer thickness was analysed using Heidelberg retina tomograph. Analysis of frequency distribution, probability and regression were run on the data collected during the study using SPSS version 15.0. Results: The mean age of the patients was 23.85+-5.85 years. The retinal nerve fibre layer thickness ranged between 0.09mm and 0.35 mm (mean: 0.23mm+-0.07) in amblyopic eyes, and between 0.18mm and 0.36mm (mean: 0.25mm+-0.05) in normal eyes. The difference was not statistically significant (p=0.087). No association was found between the retinal nerve fiber layer thickness or the age and refractive error of patients. Conclusion: The optic disk does not appear to be the site of morphological changes in amblyopia. (author)