Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 5 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2002. / Härtill 7 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2005. / Härtill 6 uppsatser.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 6 uppsatser.

The reduction in visual performance typically found in keratoconic patients is believed to be associated with large magnitudes of uncorrected irregular astigmatism and higher-order aberrations (HOAs). Previous studies indicate that correcting HOAs in keratoconus patients may result in an improvement in visual performance. This thesis explores the correction of HOAs using standard sphero-cylindrical and customised aberration-controlling soft contact lenses in 22 patients with keratoconus. The findings of this work may be useful from a clinical perspective, as some keratoconic patients cannot tolerate rigid gas-permeable (RGP) contact lenses and have few alternatives, excluding surgical intervention, for vision correction. This thesis firstly describes a series of preliminary studies conducted to improve our current understanding of the HOAs manifested in keratoconus. The results of these investigations suggested that alterations in aberrations, due to changes in accommodation or variations in the pre-corneal tear film post-blink, were unlikely to hinder the correction of HOAs for keratoconic patients. Equally, it was ascertained that subjective refraction data provided significantly better visual acuity compared to objective, aberrometry-derived refractions for patients with keratoconus. The findings also show that both lower-order aberrations (LOAs) and HOAs displayed a larger degree of variability in keratoconic eyes compared to those previously reported for visually-normal subjects. Furthermore, significant increases in 3rd-order coma root mean square aberrations were found after temporarily suspending RGP contact lens wear for 16 keratoconic patients. The results of two clinical studies suggested that standard sphero-cylindrical soft lenses can, to some extent, mask HOAs in keratoconic patients; however, the visual performances achieved were found to be poorer compared to RGP lenses. Equally, the results showed that RGP lenses provide superior visual performances compared to customised, aberration-controlling lenses, in spite of the customised lenses providing comparable reductions in uncorrected HOAs. The inducement of superfluous HOAs and LOAs, through customised contact lens translations and rotations, were modelled using MatLab (version 7.6.0.324; The Mathworks, Natick, MA, US). The results confirmed that minimising the decentration of aberration-controlling contact lenses, to less than 5 degrees of rotation and less than 0.50 mm of translation, will help to achieve an optimal correction of HOAs. However, more stringent criteria were required for LOAs, where rotational displacements should be reduced to less than 3 degrees and translational displacements should be limited to less than 0.10 mm. In conclusion, the correction of HOAs for patients with keratoconus is possible using customised, aberration-controlling soft contact lenses; however, several factors will govern their success, including the repeatability and accuracy of HOA measurements for these irregular corneas, and the stability of the customised lenses on-eye.

Aberrations affect the operation of optical systems, particularly those designed to work at the diffraction limit. These systems include high-resolution microscopes, widely used for imaging in biology and other areas. Similar problems are encountered in photonic engineering, specifically in laser fabrication systems used for the manufacture of fine structures. The work presented in this thesis covers various aspects of adaptive optics developed for applications in microscopes and laser fabrication. By mathematically modelling a range of idealised fluorescent structures, the effect of different aberrations on their intensity in various microscopes is presented. The effect of random aberrations on the contrast of these different structures is then calculated and the results displayed on idealised images. Images from a two-photon microscope demonstrate the predicted results. The contrast of two structures is compared when imaged first by a conventional microscope and then by the two-photon or confocal sectioning microscopes. The different specimen structures were seen to be affected to varying extents by each aberration mode. In order to correct for aberrations in microscopy and other photonic applications, adaptive elements such as deformable mirrors are incorporated into the optical setups. An important step is to train the deformable mirror so that it produces appropriate mode shapes to apply a phase to optical wavefronts. One such mirror is modelled using the membrane equation to predict the surface shape when an actuator is applied. Each of these influence functions is combined to produce a set of orthogonal mirror modes, which are used to experimentally produce a set of empirical modes in a two-photon microscope. An alternative method of training a deformable mirror from a spatial light modulator is employed. The focal spot of an optical system is imaged to provide a feedback metric for the mirror to replicate the phase pattern on the spatial light modulator. A two-photon microscope with adaptive optics is demonstrated by imaging the brains of Drosophila deep within the bulk, correcting for both system and specimen induced aberrations using the deformable mirror with empirical mirror modes applied. A harmonic generation microscope is also used to image both biological and non-biological specimens whilst performing aberration correction with a deformable mirror. Adaptive optical methods are also applied to a laser fabrication system, by constructing a dual adaptive optics setup to correct for aberrations induced when fabricating deep in the bulk of a substrate. The efficiency and fidelity of fabrication in diamond substrate is shown to be significantly increased as a result of the dual aberration correction. An outstanding problem in microscopy is the effect of spatially variant aberrations. Using measurements from the adaptive microscopes, the extent to which they are present in a range of specimens is quantified. One potential technique to be used to correct for these aberrations is multi-conjugate adaptive optics. Different configurations of a multi-conjugate adaptive optics system are modelled and the improvement on the Strehl ratio of aberrated images quantified for both simulated images and real data. The application of this technique in experimental microscopes is considered.

PAIVA, Jean Carlos Gomes. Biomonitoring genetic of farmers exposed to pesticides in the municipalities of Tiangua and Ubajara (Ceará, Brazil). 2011. 111 f. : Tese (doutorado) - Universidade Federal do Ceará, Programa de Pós-Graduação em Biotecnologia, Renorbio - Rede Nordeste de Biotecnologia. 2011. / Submitted by demia Maia (demiamlm@gmail.com) on 2016-05-23T17:19:06Z No. of bitstreams: 1 2011_tese_jcgpaiva.pdf: 2591728 bytes, checksum: 4776344bdee5aac282c66c0a37608507 (MD5) / Approved for entry into archive by demia Maia (demiamlm@gmail.com) on 2016-05-23T17:19:52Z (GMT) No. of bitstreams: 1 2011_tese_jcgpaiva.pdf: 2591728 bytes, checksum: 4776344bdee5aac282c66c0a37608507 (MD5) / Made available in DSpace on 2016-05-23T17:19:52Z (GMT). No. of bitstreams: 1 2011_tese_jcgpaiva.pdf: 2591728 bytes, checksum: 4776344bdee5aac282c66c0a37608507 (MD5) Previous issue date: 2011