Open Access

Purpose: Although the frequency in which practitioners are fitting scleral contact lenses is increasing, the recommendation for proper tear layer depth (thickness) varies amongst experts. The main goal of this paper is to clinically verify the effect of varying tear layer depths on induced corneal edema during lens wear. Methods: Ten subjects with healthy eyes were fitted with scleral lenses on their right eye. Each of them was fit with two different lenses: one with an apical clearance of 200 μm and another with an apical clearance of 600 μm. They wore the lenses for 8 hours on two different days, with at least a one week wash-out period. Lenses were applied at 8 a.m. on each of the testing days. Pachymetry measurements were taken one day prior to lens wear at 4 p.m., on the day of wear prior to lens application, and after removal of the lenses at 4 p.m. Measurements were collected using both the Pentacam® HR Corneal Tomographer, as well as the Visante Anterior Segment Optical Coherence Tomographer (OCT). The apical clearance was measured using the Visante OCT at two intervals during the test day: immediately after application of the lens and immediately prior to the removal of the lens. Results: In this study, there was found to be no significant difference in corneal edematous response during lens wear between the two test groups. The study shows that the eyes with the lenses have a statistically significantly thicker cornea compared to the non-lens-wearing eye after wearing either lens for 8 hours, lying within clinically and physiologically acceptable limits. Conclusion: Our clinical results do not correlate with current theoretical calculations, which predict a greater amount of corneal swelling with increasing tear layer thickness. It has to be evaluated if the effect on corneal edema changes with longer wearing periods, larger samples or other influences. Key words: scleral (contact) lens, corneal edema, pachymetry, tear layer thickness, vaulting, apical clearance

In der Arbeit wurde eine GC-MS-Methode zur Quantifizierung von 21 identifizierten Aromastoffen, die aus getoasteten Eichenholzchips in Wein übergehen, entwickelt. Diese Methode wurde für die ausgewählten Substanzen unter Einbeziehung der Festphasenextraktion mittels des internen Standard 2-Octanol kalibriert. Die Analyte zeigten mit Ausnahme von Syringaaldehyd lineares Verhalten bei Korrelationen von 0,986 bis 0,999. Die Nachweisgrenzen, die über das Signal-zu-Rausch-Verhältnis ermittelt wurden, lagen im Bereich von 0,03 bis 0,47 µg/l. Der Test auf Wiederholbarkeit ergab mit Werten von kleiner 10% für die meisten untersuchten Stoffe in Rot- und Weißwein zufrieden stellende Werte. Mit der entwickelten Methode wurden Barriqueweine des Handels und selbst hergestellte Chipsweine untersucht. Bei der Untersuchung der Chipsweine, die nach einem vollen Versuchsplan hergestellt wurden, zeigten sich signifikante Einflüsse durch die Faktoren Kontaktzeit, Toastung und Größe sowie durch die Wechselwirkung Toastung-Größe auf die Konzentrationen der meisten identifizierten Substanzen. Bei der Betrachtung der Konzentrationen der ausgewählten Substanzen in Barriqueweinen zeigten sich signifikante Unterschiede zu den entsprechenden Konzentrationen in den hergestellten Chipsweinen. Diese signifikanten Unterschiede wurden mittels Hauptkomponentenanalyse und anschließender Klassifizierung über die SIMCA-Methode dazu genutzt, um die önolgischen Verfahren Chipsbehandlung und Barriquefasslagerung zu differenzieren.

Eine detaillierte Auswertung des Corneo-Skleral-Profils ist für die Anpassung von weichen Kontaktlinsen und Sklerallinsen von besonderer Relevanz. Das Ziel dieser Studie ist es, das Profil der limbalen Sklera anhand des Zusatzmoduls CSP-Report der OCULUS Pentacam® zu beschreiben. Hierbei soll überprüft werden, ob der CSP-Report Ergebnisse bisheriger Studien bestätigt und somit zukünftig zur Simulation von Sklerallinsen verwendet werden kann.

The direct ophthalmoscope is a retinal screening tool that has been in existence and development for more than 150 years, yet, the rapid influence of technological evolution in screening tools, has left the direct ophthalmoscope untouched. The main purpose of this master thesis is to determine if the direct ophthalmoscope has reached its maximum potential of development and, additionally, to determine if a further development, including a more electronic input, would be feasible.

A good stereopsis (depth perception) is needed in everyday life, regardless whether a person is a professional driver or chef. Good estimation of distance, and of what is further and what closer, could mean the difference between a crushed and a whole car or between a bloody and a healthy finger. The main theme of this Master thesis is detect and quantify major factors in depth perception. Do the younger estimate the depth better than the older; do they have better depth perception with greater or smaller pupil distance; does depth perception depend on gender; what happens with stereopsis when vision is fogged by +0,5 and +1,0 D? These are the questions dealt with in this Master thesis. To answer these questions measurements were made on 51 subjects (mean age 45,0 +/- 13,32 years) of whom 25 were women, mean age 45,5 +/-13,55 years (12 with PD<62 mm, mean and 13 with PD>66 mm) and 26 men, mean age 44,4 +/- 13,34 years (13 with PD<62 mm and, 13 with PD >66 mm). Each of these four groups was further divided by age (one in range 20 to 35 years and second in range 50 to 65 years). The measurements were made with a few assumptions. The first assumption was that stereopsis is in direct correlation with visual acuity, the second assumption was that persons with bigger interpupillar distance have better stereopsis, and the third assumption was that with age the stereopsis ability decreases. The measurements were done with modified Frisby–Davis test expanded from four geometrical shapes to twenty-five circles. The stereopsis was measured with full refractive correction at 4,5 and 3,0 meters. Later, stereopsis was measured with fogging with +0,5 and +1,0 D at the 4,5 and 3,0 meter distances. Statistically there is no correlation (or very weak) between stereopsis and the visual acuity for whole group of 51 test persons, but if only young test persons are taken in consideration, the correlation becomes significant, r(20)=0,566, p=0,009 at 4,5 m and r(20)=0,456, p=0,043 at 3,0 m and that matches the assumption. Stereopsis is in no or weak positive correlation with pupil distance r(51)=0,059, p=0,679, which is in total contrast to the assumption. Stereopsis is in positive correlation with age at 4,5 meters measuring distance, r(51)=0,371, p=0,007, which corresponds to assumption. In addition, stereopsis is better in females than in males by 32,5%. Based on the results it can be concluded that the stereopsis is in negative correlation with age, in positive correlation with visual acuity, females have better stereopsis than males and statistically, the correlation between stereopsis and pupil distance (PD) has not been proved. The most important conclusion is that the decreased visual acuity brings significant fall of stereopsis. A deficit in refraction of -0,50 D decreases stereo acuity by about 90% (nearly 2x) and a deficit of -1,0 D decreases stereo acuity by about 220% (about 3x). Keywords: Stereopsis, stereo acuity, depth perception, pupil distance (PD), visual acuity (VA).