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- Popovic, Zoran, 1966, et al.
(författare)
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Dual Conjugate Adaptive Optics Prototype for Wide Field High Resolution Retinal Imaging
- 2012
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Ingår i: Adaptive Optics Progress. - Rijeka : Intech. - 9789535108948 ; , s. 3-21
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Retinal imaging is limited due to optical aberrations caused by imperfections in the optical media of the eye. Consequently, diffraction limited retinal imaging can be achieved if optical aberrations in the eye are measured and corrected. Information about retinal pathology and structure on a cellular level is thus not available in a clinical setting but only from histological studies of excised retinal tissue. In addition to limitations such as tissue shrinkage and distortion, the main limitation of histological preparations is that longitudinal studies of disease progression and/or results of medical treatment are not possible. Adaptive optics (AO) is the science, technology and art of capturing diffraction-limited images in adverse circumstances that would normally lead to strongly degraded image quality and loss of resolution. In non-military applications, it was first proposed and implemented in astronomy. AO technology has since been applied in many disciplines, including vision science, where retinal features down to a few microns can be resolved by correcting the aberrations of ocular optics. As the focus of this chapter is on AO retinal imaging, we will focus our description to this particular field.
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| 2. |
- Popovic, Zoran, 1966, et al.
(författare)
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Noninvasive imaging of human foveal capillary network using dual-conjugate adaptive optics.
- 2011
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Ingår i: Investigative ophthalmology & visual science. - : Association for Research in Vision and Ophthalmology (ARVO). - 1552-5783. ; 52:5, s. 2649-55
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To demonstrate noninvasive imaging of human foveal capillary networks with a high-resolution, wide-field, dual-conjugate adaptive optics (DCAO) imaging instrument. METHODS: The foveal capillary networks of five healthy subjects with no previous history of ocular or neurologic disease or surgery were imaged with a novel high-resolution, wide-field DCAO instrument. The foveal avascular zone (FAZ) in each image was defined using a manual procedure. An automated algorithm based on publicly available and custom-written software was used to identify vessels and extract morphologic FAZ and vessel parameters. Capillary densities were calculated in two annular regions of interest (ROIs) outside the FAZ (500 μm and 750 μm outer radius from the foveal center) and in the superior, inferior, temporal, and nasal quadrants within the two ROIs. RESULTS: Mean FAZ area was 0.302 ± 0.100 mm(2), and mean capillary density (length/area) in the inner ROI was 38.0 ± 4.0 mm(-1) and 36.4 ± 4.0 mm(-1) in the outer ROI. The difference in ROI capillary density was not significant. There was no significant difference in quadrant capillary density within the two ROIs or between quadrants irrespective of ROI. CONCLUSIONS: The authors have demonstrated a technique for noninvasive imaging and semiautomated detection and analysis of foveal capillaries. In comparison with other studies, their method yielded lower capillary densities than histology but similar results to the current clinical gold standard, fluorescein angiography. The increased field of view of the DCAO instrument opens up new possibilities for high-resolution noninvasive clinical imaging of foveal capillaries.
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| 3. |
- Sjöstrand, Johan, 1936, et al.
(författare)
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The decline in visual acuity in elderly people with healthy eyes or eyes with early age-related maculopathy in two Scandinavian population samples
- 2011
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Ingår i: ACTA OPHTHALMOLOGICA. - 1755-375X. ; 89:2, s. 116-123
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: This study aimed to analyse the decline in visual acuity (VA) during normal ageing in two Scandinavian population samples of subjects aged ≥ 70 years and to study the age-specific decline in VA in eyes with early age-related maculopathy (ARM). METHODS: We carried out a cross-sectional analysis of data pertaining to VA in the better eye in one population sample from Oulu (OU), Finland (aged 70-82 years) and a second population sample from Gothenburg (GG), Sweden (aged 82 or 88 years). The change in VA with age was evaluated in healthy eyes (OU, n = 119; GG, n = 40) and in eyes with early ARM (OU-ARM, n = 22; GG-ARM, n = 114) using linear regression or logistic regression. The results were compared with those of previous reports. RESULTS: Our population samples showed a significant decrease with age in VA in healthy eyes in subjects aged ≥ 44 years using both statistical models. Comparisons with previous reports demonstrated a homogeneity in the decline in VA with age. On average, 0.3 logMAR are lost from middle age up to 88 years, presumably as a result of physiological ageing. In early ARM, the rate of age-specific decline in VA more than doubled and the prevalence of VA < 0.5 markedly increased. CONCLUSIONS: Visual acuity in healthy eyes declines with age from middle age onwards. The decrease in VA possibly accelerates in subjects aged > 70 years, although no significant evidence for this was found. An age-specific decline in VA is shown in eyes with early ARM. These results are important for the evaluation of age-specific treatment results.
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