Presse


An analysis of anterior scleral shape and its role in the design and fitting of scleral contact lenses

Die mit dem Karl Amon Award 2015 ausgezeichnete Master Thesis von Markus Ritzmann hat es in das Journal "Contact Lens and Anterior Eye" geschafft. Der Artikel ist unter folgendem Link erhältlich: https://www.sciencedirect.com/science/article/pii/S1367048416301783



Master Thesis plus Publication for Dissertation 


"Herleitung der Abbildungsgleichungen zur Berechnung der Abbildungsfehler höherer Ordnung einer lokalen Wellenfront bei der Lichtbrechung" von Gregor Esser, E-Mail: gregor_esser@t-online.de

In dieser Master Thesis werden durch analytisches Differenzieren des vektoriellen Brechungsgesetzes die Abbildungsgleichungen zur Berechnung der Abbildungsfehler höherer Ordnung hergeleitet. Somit ist es erstmalig möglich, die Schnittweiten- und die Coddington-Gleichung (Abbildungsfehler 2. Ordnung) auf die Abbildungsfehler höherer Ordnung (Koma und sphärische Aberration) zu erweitern. Mit den hergeleiteten Gleichungen können nun die Abbildungsfehler höherer Ordnung sehr schnell analytisch berechnet werden.

Abstract


Purpose. It is known from literature how to calculate the second order aberrations (power and astigmatism) of a local wavefront after the refraction at a given surface. In the case of orthogonal incidence this relation is described by the “Vergence Equation” and in the case of oblique incidence by the Coddington Equation. It is the purpose of this study to extend the Generalized Coddington Equation to the case of Higher Order Aberrations (Coma and spherical Aberration).

Methods. The incoming wavefront, the refracting surface and the outgoing wavefront are each described by power series expansions. The coefficients of the power series of the incoming wavefront and the refracting surface are each determined by the local aberrations. With the directional derivatives of the incoming wavefront and the refracting surface its normal vectors are calculated. The normal vector of the outgoing wavefront is calculated from the normal vectors of the incoming wavefront and the refracting surface by the vectorial refractive law. The coefficients of the power series of the outgoing wavefront are determined by the derivatives of the normal of the outgoing wavefront. The local aberrations, in turn, are calculated from the coefficients of the power series of the outgoing wavefront.

Results. It was possible to derive analytically, also for oblique incidence, the dependency of the local aberrations of the outgoing wavefront on the aberrations of the incoming wavefront and the refracting surface. The connection and the interaction of the aberrations of the refracting surface and the incoming wavefront with the outgoing wavefront are determined. Thus it was possible to extend both the Vergence Equation and the Generalized Coddington Equation to Higher Order Aberrations. The outcome in the case of no incidence and only one aberration of the same order by the incoming wavefront and the refraction surface, e.g. spherical aberration SphAber, is equivalent to the Vergence Equation S’ = S + D with SphAber’ = SphAber + SphAberS.

With the formulas derived in this work, it is now possible to calculate the local Higher Order Aberrations of the outgoing wavefront directly in an analytical way from the aberrations of the incoming wavefront and the refracting surface.

Keywords: wavefront · Higher Order Aberration · Coddington Equation · Coma · spherical Aberration



Master Thesis: Examples for Download 


"FoCoSi Follicular-like Conjunctivitis associated with Siliconhydrogels" by Michael Wyss

The purpose of this study is to prescribe follicular-like conjunctivitis associated with Siliconhydrogels (FoCoSi) in silicone hydrogel contact lens wearers as a novel subtype of the well prescribed contact lens induced papillary conjunctivitis (CLPC).

Download the thesis here:


"Measurement of Dynamic Visual Acuity with Augmenting Landolt Rings" by Nataša Vujko Muždalo

The purpose of this study was to investigate the correlation of measured visual acuity (VA) both static and dynamic obtained with static and dynamic measuring tests, as well as, response time to visual stimulus and analysis of its influence on dynamic visualacuity. The aim was to compare the results gathered for the three age groups and analyze the possible differences.

Download the thesis here:


"Clinical Effect of Tear Layer Thickness on Corneal Edema During Scleral Lens Wear" by Christiane Arlt

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.

Download the thesis here:




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