Developement of optical coherence tomography and its ophthalmologic application

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We established a prototype device of optical coherence tomography for ophthalmologic application in order to obtain noninvasively high-resolution tomographic images of anterior part of eyes. This device was built by the Michelson's theory using low-coherence infrared light. First, we investigated the most appropriate engineering set-up regarding light pass, super luminescent diode, beam-splitter, mirror etc., for this device, and finally achieved the depth resolution under 9 mum and the detectable level over 100 dB.After numerous improvements in the prototype device, we applied this to pig corneas to obtain A-mode images. A-mode images disclosed fine corneal structures, and the corneal thickness measured by this device was well correlated with that of ultrasonic pachometry. We further obtained fine B-mode images manually from central corneas with or without epithelium. Thus, we could differentiate abraded corneas from normal corneas using this device. The corneo-scleral junctional area showed a gradual change of scattering lights from corneal to scleral side. As a result, we have obtained almost all technical information regarding optical coherence tomography for the anterior segment of the eye. Therefore, we are now planning to make a second generation of optical coherence tomography for clinically applying human corneas and scleras.