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Accommodation stimulus-response function (ASRF) and its relationship to retinal image quality were investigated using a modified wavefront sensor. Ten subjects were presented with six vergence stimuli between 0.17 D and 5 D. For each vergence distance, ocular wavefronts and subjective visual acuity were measured. Wavefronts were analysed for a fixed 3-mm(More)
We undertook a detailed analysis of the wavefront aberrations of the eyes of 20 young progressing myopes (mean age=22 years; mean spherical equivalent=-3.84 D, range -1.00 to -7.5 D) and twenty young age matched emmetropes (mean age=23 years; mean spherical equivalent=-0.00 D, range +0.25 to -0.25 D). A wavefront sensor was used to measure the ocular(More)
PURPOSE To investigate the effects of eyelid pressure on corneal shape and corneal aberrations during reading. METHODS Twenty young subjects with normal ocular health were recruited for the study. The experiment was conducted early in the morning, with subjects instructed not to perform any prolonged reading before the experiment. Corneal topography of(More)
Analysis was undertaken of the retinal image characteristics of the best-spectacle corrected eyes of progressing myopes (n = 20, mean age = 22 years; mean spherical equivalent = -3.84 D) and a control group of emmetropes (n = 20, mean age = 23 years; mean spherical equivalent = 0.00 D) before and after a 2h reading task. Retinal image quality was calculated(More)
PURPOSE To compare lid-induced changes in corneal optics following reading, microscopy and computer work. METHODS Nine subjects with normal ocular health were recruited for the study. Five subjects were myopic, two were emmetropic, one was astigmatic and one was hyperopic. Corneal topography was measured before and after 60 mins of reading a novel,(More)
PURPOSE To establish repeatability and validity of a partial coherence interferometry (PCI) device in patients with astigmatism. SETTING Industry and university. DESIGN Observational studies. METHODS A prospective study determined the agreement between the IOLMaster 500 PCI device and the Marco 1-position manual keratometer for measurement of mean(More)
PURPOSE Videokeratoscopes provide a wealth of information about the topography of the ocular surface. Although there have been numerous studies of the accuracy and precision of videokeratoscopes with inanimate test objects, little information exists on their precision (repeatability) for real eyes. METHODS To investigate the stability of the ocular(More)
PURPOSE To investigate whether there are significant changes in corneal topography during accommodation in normal corneas and corneas that are pathologically thinner due to keratoconus. METHODS A videokeratoscope was modified to present an accommodation stimulus that was coaxial with the instrument's measurement axis. Six subjects with normal corneas and(More)
PURPOSE To evaluate whether significant change occurs in the topography of the anterior or posterior cornea or in corneal thickness with accommodation. SETTING Contact Lens and Visual Optics Laboratory, School of Optometry, Queensland University of Technology, Brisbane, Queensland, Australia. METHODS Corneal data were acquired for 12 young, healthy(More)
PURPOSE To investigate analytically whether higher-order wavefront errors comprising combinations of trefoil along 30 degrees (trefoil30), vertical coma, and spherical aberration could provide cues to sphero-cylindrical refractive error development. METHODS A total of 25 test wavefronts, subdivided into five different types and five levels of higher-order(More)