What is OCT. Overview, Diseases diagnosed by OCT, Limitations, Advantages and Disadvantages.

1. Optical Coherence
Chua, Chelsi Aryll
Flores, Novy Faith
Tomography scan

3. What Is Optical Coherence Tomography?
• Introduced in 1991 by NEEC & MIT
• Similar to ultrasound imaging
• Uses near infrared laser instead of
sound waves
• Characterizes scatter variation

4. What Is Optical Coherence Tomography?
▪It uses light waves to take cross-section pictures of the
retina.
▪It has become the standard of care for the assessment
and treatment of most retinal diseases.
▪ It is similar to a CT scan which is used to image
internal organs inside the body.
▪It uses an array of light to rapidly scan the eye.

5. Retina
▪A layer at the back of the
eyeball containing cells that
are sensitive to light and
that trigger nerve impulses
that pass via the optic nerve
to the brain, where a visual
image is formed.

6. OCT Image of a Normal Eye

7. Preparation for OCT exam
•To prepare you for an OCT exam, an
ophthalmologist may put dilating eye
drops in your eyes. These drops widen
your pupil and make it easier to
examine the retina.

8. Procedure
▪You will sit in front of the OCT machine
and rest your head on a support to keep
it motionless. The equipment will then
scan your eye without touching it.

9. Duration of the OCT exam
▪Scanning takes about 5 – 10 minutes.
▪If your eyes were dilated, they may be
sensitive to light for several hours
after the exam.

10. What conditions can
OCT help to diagnose?

11. MACULAR HOLE
¤ A tear or opening forms in your macula.
¤ As the hole forms, things in your central
vision will look blurry, wavy or distorted.
As the hole grows, a dark or blind spot
appears in your central vision.
¤ A macular hole does not affect your
peripheral (side) vision.
OCT scan results for macular hole

12. | Wrinkles, creases or bulges form on your macula.
| The macula must lie flat against the back of your eye to work properly.
| When the macula wrinkles or bulges, the central vision is affected.
MACULAR PUCKER

13. A swelling or thickening of the eye's
macula, the part of your eye
responsible for detailed, central vision.
MACULAR EDEMA

14. » Happens when a part of the retina called the
macula is damaged.
» With AMD you lose your central vision. You cannot
see fine details, whether you are looking at
something close or far. But your peripheral (side)
vision will still be normal.
» For instance, imagine you are looking at a clock with
hands. With AMD, you might see the clock’s
numbers but not the hands.
AGE-RELATED MACULAR
DEGENERATION (AMD)
OCT Results for age related macular degeneration

15. * a disease that damages the eye’s optic
nerve.
* It usually happens when fluid builds up in
the front part of the eye.
* That extra fluid increases the pressure
in your eye, damaging the optic nerve.
GLAUCOMA
Chronic glaucoma

16. Central serous
chorioretinopathy (CSR)
OCT OF CSR

17. § This is when high blood sugar levels cause damage to blood vessels in the retina.
§ These blood vessels can swell and leak, or they can close, stopping blood from
passing through.
§ Sometimes abnormal new blood vessels grow on the retina.
§ All of these changes can steal your vision.
DIABETIC RETINOPATHY

18. ✓ A condition in which the vitreous gel has an
abnormally strong adhesion to the retina.
✓Over time, the gel tends to pull forward and
can cause vessel and retinal distortion causing
retinal swelling and decreased vision.
VITREOUS TRACTION
OCT of vitreous traction

19. Advantages of OCT
> Non-invasive
> Minimal cooperation needed
> Resolution ~ 10 μm (vs. US=150
μm; UBM=50μm)
> Pick up earliest signs of disease
> Quantitatively monitor
disease/staging

20. Advantages of OCT
>provides a faster and easier method
for diagnosis.
>chances of error are reduced
>gives a better image of the test
results.
>provides broad and dynamic range of
operations.
>involves rapid data acquisition rate.
>uses simple and inexpensive catheter /
endoscope.
>The device used in OCT is portable.

21. Disadvantages of OCT
• Diminished penetration through
retinal/subretinal hemorrhage
• OCT has a limited penetration power. (Requires
pupil diameter > 4 mm)
• Femtosecond laser used in OCT is expensive.
• During OCT, the transverse resolution needs to
be similar to axial resolution.

22. Limitations of Retinal
OCT •Dilation of the pupils may sometimes be
necessary
•Dioptric media must be somewhat
transparent
•Exploration typically limited to posterior pole
•Good lacrimal film necessary

23. • https://www.williamsoneyeinstitute.com/other-
diseases/vitreomacular-traction/
• https://www.aao.org/eye-
health/treatments/what-is-optical-coherence-
tomography - American academy of
ophthalmology
• http://visionsource-
visionhealthinstitute.com/vision-care-
products/advanced-diagnostic-testing/optical-
coherence-tomography-oct/ - Vision Health
Institute
• http://www.c4sightcare.com/page87aa.html
• https://globalnewsinsights.com/2017/07/10/adv
antages-and-disadvantages-of-optical-coherence-
tomography/