OCT Ocular Coherence Tomography Dr Alan Mendelsohn

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INTRODUCTION: • ------------------------- • • OCT is an optical instrument that can perform cross-sectional image of biological tissue within less than 10 micron axial resolution using light waves • • Retina is easily accessible to the external light, hence it is specially suited for retinal disorder • • The information provided by OCT is similar to in vivo histopathology of the retina • EXAMPLE: •  Zeiss stratus OCT •  Topcon 3D OCT-1000 • PRINCIPLE OF OCT: • -------------------------------- • • It is a imaging technology projected light beam (820nm) near infrared light • • The beam is then split into two beam (Probe beam Reference beam) by Beam splitter • • Probe beam reach to the target tissue (retina) reference beam reach to the reference mirror • at a known distance • • The echo time delay of light reflected various layer of target tissue (retina) is compared with • the echo time delay of light reflected from the reference mirror • • A positive interference is produced when light reflected from target tissue reference mirror • arrives simultaneously • • This interference is measured by a photodetector which finally produce a range of time delays • for comparison • • The interferometer integrates several data points over 2mm depth to construct a tomogram • of retinal structures • • It is real time tomogram using false color scale different colors represent light • backscattering from the different layers of retina • OCT SYSTEM CONSIST OF: • ------------------------------------------ • • Fundus viewing unit • • Interferometer unit • • Computer display • • Control panel • • Color inkjet printer • GENERATION OF • ---------------------------- • • OCT- 1: • o 1st generation • o Transverse resolution 20 micron • o Axial resolution 10 micron • • OCT-2: • o 2nd generation • o Transverse resolution 20 micron • o Axial resolution 10 micron • o Better user interference • • BOTH OCT-1 OCT-2: • o acquire 100 vertical scan in approximately 1.2 sec • • OCT-3: • o 3rd generation • o Axial resolution 7-8 micron • o Acquire 512 vertical scan • COLOR CODING OF OCT SCAN: • ------------------------------------------------ • • RED-YELLOW COLORS: represents areas of maximal optical reflection backscattering • • BLUE BLACK: Represents areas of minimal optical refelection backscattering • VARIOUS PATTERN OF B-SCAN: • -------------------------------------------------- • • CIRCULAR SCAN FOR THE ONH RNFL: • This generates a plot of the peripapillary RNFL thickness which is important in • glaucoma diagnosis monitoring • • RADIAL LINE THROUGH ONH: • Consist of 6-24 slices through a common central point on the ONH • • MACULAR RADIAL LINES: Used to measure retinal thickness • • FOR DETAILS NOTE; • VISIT OUR WEBSITE: https://www.smartopto.blogspot.com • • OUR OTHERS VIDEOS: • Binocular Subjective Refraction: • Part-1: • Binocular Subjective refraction- Intr... • Part-2: • Septum Method - Turville Infinity Bin... • Part -3: • Polarization Method - Polarized Targe... • Part -4: • Fogging Method - Binocular Subjective... • Part-5: • Steps of Binocular Subjective Refract... • Biometry: • Part-1: • Introduction Of Biometry | Smart Opto... • Paet-2: • Biometry-2 | Measurement of Axial len... • Part-3 • Biometry-3 | Measurement of Corneal ... • Optical Coherence Topography: • Full: • Optical Coherence Tomography - OCT (F... • Part-1: • Optical Coherence Tomography - OCT | ... • Part-2: • Optical Coherence Tomography - OCT | ... • Dry Eye: • Part-1: • Dry Eye - Introduction and Mechanism ... • Part -2: • Dry Eye - Classification and Cause (w... • Part -3: • Dry Eye - Clinical Features and Inves... • Part -4: • Dry Eye – Treatment (within 4:30 mins... • Part -5: • Tear Film Break-up Time Test (Within ... • Part- 6: • Schirmer test - Dry Eye within 2:30 min • Full: • Dry Eye - Full Tutorial • Myopia • Part-1: • Myopia - Introduction and Etiology (w... • Part-2: / dvrkegdkxq • Part-3: • Myopia - Clinical Picture (within 3:3... • Part -4: • Myopia - Ocular examination or Invest... • Part -5: • Myopia - Management or Treatment 5/5

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