Optical Coherence Tomography - OCT (Full)
HTML-код
- Опубликовано: 29 авг 2024
- 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
PROCEDURE OF OCT:
"""""""""""""""""""""""""""""""""""
• STEP-1: PATIENTS DATA
Activation of instrument & entering patients data
• STEP-2: PATIENTS PREPARATION:
Pupil dilate with mydriatics (tropicamide)
Asked to look into the internal fixation target light in the
ocular lens
• STEP-3: PROTOCOL FOR SCAN ACQUISITION:
Selected as per the case requirements
The scanning beam is placed on the target area and scans
are obtained
• STEP-4: PRODUCTION & DISPLAY IMAGE:
Several data points are integrated by the interferometer to
construct a tomogram of the target area
The tomogram is displayed in either grey scale or false color
on a high-resolution computer screen
Anterior segment OCT ises notentiined here by the otherwise very nice presentation
Simple and clear explanation.
Stay with us.
Thank you,
Team Smart Optometry
Thank you sir for explaining easy way
Stay with us and share with your friends.
Thank you,
Team Smart Optometry.
Thank you so much for explaining it in a very simple manner....
Stay with us and share with your friends.
Thank you,
Team Smart Optometry.
Most welcome 😊
Nice presentation.
▪️Stay with us and share with your friends.
▪️Don't forget to download our App "Optometry Notes and MCQs ". It's available in Play Store.
Thank you,
Samir Sutradhar.
thanks for this!
Stay with us and share with your friends.
Thank you,
Team Smart Optometry.
Thank you sir for explaining easy way,and can you share the photo of the principle of the OCT
Page no: 491
Google drive link: drive.google.com/file/d/1OQF0-CYHEsa2EVev2Jj1iFAeKTb5xDPG/view?usp=drivesdk
Stay with us and share with your friends.
Thank you,
Team Smart Optometry.
Thank u so much ❤️
Stay with us and share with your friends.
Thank you,
Team Smart Optometry.
thank you
Thanks
ONH is optic nerve head right?
Not optic nerve hypoplasia
Yeah..
It was a mistake from our side. Sorry for that...
Thank you,
Team Smart Optometry.
Please share ppt link
Please check the description for notes.
Ppt is not available for this presentation.
Thank you,
Team Smart Optometry.
Dr plez i want books related to this video
Optics and Clinical Refraction by Ak Khurana
A part
Nures aduise drs.2418/snc