OCT (Optic Coherence Tomography) 1)Noninvasive 2) non-contact imaging 3)Millimeter penetration Aproximately 2-3 mm in tissue with micrometer scale (axial and transverse resolution) not only the retina and optic nerve but also anterior segment of the eye
4) Ist demonstrated in 1991 (20 years ago) 5) Today we have the conventional OCT with an axial resolution of < 10 µ m and 3Dimentional (3D) OCT with a much higher resolution of 5 µ m
OCT principle 1) 1)Is similar to ultrasound 2) 2)Uses echoes to locate structures within the body
Light speed and sound The speed of light being almost a million times faster than sound allows measurement of structures with a resolution of < 10 microns compared to 100 microns scale for ultrasound.
OCT Can clearly image the cornea, sclera, iris and lens in the anterior segment. using infrared light having a wave length of 13.1 nm
Radial line OCT compared to 3D- OCT In contrast to radial – line,3D- OCT captures a dense, uniform grid of data that is unlikely to miss small, focal lesions.
Role of OCT imaging OCT is useful in the diagnosis and staging of diseases which help in their management, assessing the response to treatment and in monitoring the progress of the disease.
Resolution power Current commercial OCT scanners offer a resolution of 8-10 micron that is at least 10 time better than ultrasound
OCT Colors Tissues with higher reflectivity such as RPE appear in brighter colors ( red- white)– and less dense structures, such as vitreous and intraretinal fluid, appear in darker colors. (blue- black )
Retinal thickness Macular thickness with Topcon 3D –OCT ( Indian eyes ) Foveael thickness 154-282 micron Other parts 210 -311 micron
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