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Luis A. Carvalho, Andre Romano, Elizeu Ramos; Construction of a True-depth Quantitative and Low cost 3d Optical Disc Measurement Device and Collaborative Diagnosis using Stereo Images and Videos. Invest. Ophthalmol. Vis. Sci. 2012;53(14):3102.
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One of the main problems with glaucoma throughout the world is that there are typically no symptoms in the early stages. Many people who have the disease do not know they have it and therefore it is important to develop instrumentation that is fast, effective and economic, in order to reach the mass public in the general eye-care centers. In this work we have constructed the hardware and software for a "cost-effective" and non-mydriatic prototype device that allows fast capturing of high resolution quantitative 3d images and videos of the optical disc head and neighboring region (20 degrees field of view)
Using off the shelf optics (Edmund Scientific) and in house hardware and software, stereo images are taken with a 15 GB camera (CANON EOS), which are then processed using a Matlab code for feature extraction and sub-pixel correlation for precise depth computation and 3D image rendering. Disk parameter extraction such as disc/cup diameter, area, volume, and also 3D visualization are possible. 48 eyes of 24 voluntary patients (according to the Declaration of Helsinki), 12 females and 12 males, with average age of 67± 2 ranging from healthy eyes, suspected and advanced glaucoma were examined by 6 experienced clinicians divided into 2 groups of 3, during a period of 2 years, one examination session per semester which included tonometry, perimetry, gonioscopy and pachymetry. The first group used the new instrument and the other group used a traditional 2D retinal camera (CANON CR-2) as control (gold standard)
91.67% of diagnosis for glaucoma patients matched the gold standard for glaucoma, 83.33% for suspected glaucoma and 100% for healthy eyes. Images and 3D rendering (allowing rotation, zoom and PAN in real time) on the new prototype may also be automatically exported to YouTube, a PC or I Pad and may be exchanged through a wireless connection between doctors for real time discussions of each patient
The device and software presented here may serve as a prototype for a growing market which is demanding faster, simpler, easier to operate and more cost effective retinal cameras. It is at the same time precise and flexible, allowing 3D imaging without the use of special goggles, but is easier to use and operate in certain conditions that require limited physical space and time. The main application of this device is in screening examinations and progression/treatment monitoring of glaucoma, and may also be applied to the diagnosis of early vision loss in diabetic retinopathy, age related macular degeneration and other retinal pathologies, therefore adding value to current state-of-the-art retinal cameras as a low-cost preliminary examination instrument
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