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Michael R. Wang, Jianhua Wang, Hui Lu; Novel Optical Coherence Tomography With Double Scan Depth For Ophthalmology Applications. Invest. Ophthalmol. Vis. Sci. 2012;53(14):3123.
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© ARVO (1962-2015); The Authors (2016-present)
To develop and test novel optical coherence tomography with double scan depth for imaging the entire anterior segment of the human eye.
A spectral domain optical coherence tomography (SD-OCT) system was constructed using conventional assembly consisting of a superluminescent light source, a fiber beam splitter, an object arm scanner, an optical spectrometer, and a reference arm. 7.3 mm scan depth has been achieved. Such scan depth is not quite enough to cover the entire anterior segment of the eye. There have been reports on doubling the scan depth by using reference arm modulation and phase unwrapping during Fourier transform computation or by using a spectrometer with doubling the amount of pixels. We present here a simple and effective patent pending technique to double the scan depth without changing spectrometer or performing reference arm modulation. It is accomplished by fast synchronized switching selection of two different pre-set reference arm lengths for two different A-scans to effectively double the SD-OCT scan depth. The technique can also be used with more spectrometer pixels to further extend the SD-OCT scan depth. With the existing SD-OCT of 7.3 mm scan depth, we achieved 14.6 mm scan depth using such technique, effectively covering the entire anterior segment of the human eye including cornea, anterior chamber, and the crystalline lens. A superluminescent diode-based light source (SLD by Inphenix) with center wavelength of 840 nm and full-width at half maximum bandwidths of 50nm was used in the system. The scan speed was 24K A-scan per second. An AVIIVA e2V CCD line camera was used. Five eyes of 5 subjects (3 males and 2 females) were imaged with the system. Real-time double depth OCT scan was demonstrated.
The entire anterior segments of all 5 eyes were successfully visualized with the constructed SD-OCT system of double scan depth. The system software has been updated to allow synchronized reference arm selection and A-scan. Real-time observation of the entire anterior segment of the eye is accomplished with image qualify comparable with non-double-depth SD-OCT system.
We developed the novel SD-OCT system that double the conventional scan depth without being limited by the spectrometer hardware. The scan depth is more than enough for imaging the entire anterior segment of the human eye.
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