Full-field optical coherence tomography (FF-OCT) is a non-scanning horizontal cross-sectional imaging technique based on interference microscopy. By employing a high-definition microscopic imaging system and a low-coherence interferometer, we have achieved sub-cellular level biological tissue imaging. The majority of conventional FF-OCT imaging has involved the ex vivo imaging of rat or porcine retinas, and high-resolution retinal images have been demonstrated. However, in vivo retinal imaging has not been realized, due to slow measurement speed. We have built a high-speed imaging system and have applied the new FF-OCT system to anterior segment imaging of the rat in vivo. Feasibility studies of FF-OCT human retinal imaging were then performed. Visualization of retinal nerve fiber bundles is demonstrated for the first time, to the best of our knowledge.
Retinoscopy is the most generally satisfactory and accurate method of objectively determining refraction. Its chief value, however, lies in providing a starting point for subjective testing. In the hands of a skilled technician, a very high degree of accuracy can be attained, under favorable circumstances on the order of 0.25D in power and 5° in axis of astigmatism. However, it is a method that cannot be learned from books, but only through long and painstaking practice. Many textbooks give detailed accounts of the underlying theory of retinoscopy. Such explanations, together with the complex diagrams that usually accompany them, are useful as reference material, but are too cumbersome to recall clearly for any length of time. In this paper, the optical principles of retinoscopy is easily and clearly explained by simple geometrical formulae.
Purpose: To measure sensitivities of cone and rod systems separately and easily, using the modified automated perimeter.
Methods: Visual field testing was performed in 114 eyes without eye disease, 1 eye with retinal pigmentosa and 1 eye with achromatopsia, using 500 and 650nm stimuli after 30 minutes of dark adaptation (500 and 650nm stimuli represent rod and cone systems).
Results: In the eyes without eye disease, the relative sensitivities at the fovea were lower than at the periphery with 500nm stimulus, and higher than at the periphery with 650nm stimulus. In 1 eye with retinal pigmentosa, the relative sensitivities decreased significantly at the periphery with both 500 and 650nm stimuli. In the eye with achromatopsia, the relative sensitivities increased with 500nm stimulus.
Conclusions: The testing time of this modified automated perimeter did not differ from that of a standard automated perimeter. This study indicates that the sensitivities of cone and rod system sensitivities can be measured separately and easily using this modified automated perimeter. These results could be useful for general clinical practice.
In this research we conducted multispectral analysis for fundus imaging, which enabled us to simulate how fundus chromaticities change depending on the spectral distributions of the illumination light source. Our results show that the spectral distributions of the light directly affect fundus chromaticities. The longer the wavelength component in the light source, the more the fundus chromaticities shift toward yellow. Our results suggest that multispectral information is useful in finding the best light source spectral distribution for imaging the fundus, which could enable easy detection of abnormal parts of the fundus.