Sökning: "Spherical lens"

Visar resultat 1 - 5 av 12 avhandlingar innehållade orden Spherical lens.

1. 1. MULTIFOCAL SPHERICAL FISH LENSES

   Författare :Yakir Gagnon; Biologiska institutionen; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Multifocal Lens; Adaptation; Dispersion; Spherical lens; Model; Fish; Ray-trace; Longitudinal Chromatic Aberration; Longitudinal Spherical Aberration; Modulation Transfer Function; Point Spread Function; Refractive Index Gradient;

   Sammanfattning : Vision is an important source of information for many animals. The lens plays a central role in the visual pathway and hence the ecology of these animals. Fish have spherically shaped crystalline lenses that contain a gradient of refractive index. Like all refracting elements, lens performance depends on the wavelength of the refracted light. LÄS MER

3. 2. Manipulation of Ocular Aberrations in Myopes

   Författare :Baskar Theagarayan; Jörgen Gustafsson; Frank Schaeffel; Linnéuniversitetet; []
   Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Myopia; Spherical aberration; Accommodation; Contact lens; Visual acuity; Peripheral aberrations; Optometry; Optometri; Optometry; Optometri;

   Sammanfattning : Myopia is a major cause of vision loss throughout the world. High myopia is associated with severe eye diseases like maculopathy, retinal detachment and glaucoma. The prevalence of myopia is increasing, and varies by country and by ethnic group. In some Asian populations the prevalence is 70%-80%. LÄS MER

4. 3. Fish Lenses : Anatomy and Optics

   Författare :Tomasz M Kozłowski; Funktionell zoologi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Plasticity; Development; Cellular structure; Lens fiber cells; Modeling; Laser Scanning; Schlieren photography; Fast Fourier Transform FFT ;

   Sammanfattning : I have investigated some of the biological regulatory mechanisms governing the development of crystalline lenses. I used fish as model animals because they possess optically interesting lenses, while the geometrical simplicity of fish lenses allows for studies that are difficult or impossible with the lenses of other animals. LÄS MER

5. 4. Ocular aberrations and visual quality in aspherical and multifocal contact lenses

   Författare :Anna Lindskoog Pettersson; Karolinska Institutet; Karolinska Institutet; []
   Nyckelord :Contact lenses;

   Sammanfattning : Good visual quality and precise accommodation are required to be able to focus objects at distance and near, and are essential in order to be able to perform most tasks in life. Most eyes are not ideal eyes, i.e., they have different refractive errors which distort the produced image. LÄS MER

7. 5. Accommodation : clinical and theoretical investigations

   Författare :Marika Wahlberg Ramsay; Karolinska Institutet; Karolinska Institutet; []
   Nyckelord :Accommodative insufficiency;

   Sammanfattning : Background: Accommodative insufficiency (AI) is a relatively common visual anomaly in children and young adults with an estimated prevalence of about 5%. Patients with AI usually suffer from blur, headaches and asthenopia associated with near work. LÄS MER