Optical coherence tomography (OCT) is a non-invasive imaging technique that uses light to capture high-resolution cross-sectional images of the retina and anterior segment of the eye. OCT works by measuring the interference of light reflected from tissues to create 3D images. It is analogous to ultrasound imaging but uses light instead of sound. OCT is useful for diagnosing and monitoring various retinal conditions and diseases like macular degeneration as well as measuring eye structures. Some common applications of OCT include detecting macular holes, cysts, detachments and membranes in the retina.

1. EYE-OCT.(OPTICAL COHERENCE
TOMOGRAPHY )
Presented by SANJIB PASHI

2. Eye + Optical Coherence Tomography =EYE-OCT.
LIGHT CONSTAN
T
PHASE
DIFFEREN
CE
“SLICES”HUMAN
EYE

3. What is Optical coherence tomography?
 noncontact, noninvasive imaging technique
used to obtain high resolution cross-sectional
images of the retina and anterior segment.
 Three-dimensional imaging technique with
ultrahigh spatial resolution
 Measures reflected light from tissue
discontinuities
 Based on interferometry
 involves interference between reflected light
and a reference beam.

4. Optical coherence tomography-The process is similar to
that of
ultrasonography, except that light is used instead of sound
waves.
Analog to
ultrasound

5. Principle of OCT
 Interferometry is the
technique of
superimposing
(interfering ) two or more
waves, to detect
differences between
them.
 Interferometry works
because two waves with
the same frequency that
have the same phase
will add each other while
two waves that have
opposite phase will

6. Principle of OCT
 Light from a source is
directed onto a partially
reflecting mirror and is
split into a reference and
a measurement beam.
 The measurement beam
reflected from the
specimen with different
time delays according to
its internal
microstructure.

7. Principle of OCT
 The light in the reference
beam is reflected from a
reference mirror at a variable
distance which produces a
variable time delay.
 The light from the specimen,
consisting of multiple echoes,
and the light from the
reference mirror, consisting of
a single echo at a known
delay are combined and
detected.

8. Different kind of OCT.
Time domain OCT
Frequency domain OCT (FD-OCT)
Spatially encoded frequency domain OCT
(spectral domain or Fourier domain OCT)
Time encoded frequency domain OCT (also
swept source OCT)

9. Why we need OCT.?
 Measles infections
can harm the front
or back of the eye,
possibly causing
vision loss or
blindness

10. Six Ways Measles Can Affect the
Eyes
Conjunctivitis: Redness and watery eyes
from conjunctivitis occur in nearly all measles
patients. This type of pink eye usually develops early on
in the disease and is a hallmark symptom along with fever,
cough and a runny nose, often occurring before the telltale
rash.
Keratitis: Keratitis is an infection of the cornea, the
window of the eye. In comparison with conjunctivitis,
keratitis has more severe symptoms and far more
dangerous consequences. Symptoms include pain,
redness, tearing and light sensitivity. It can feel as though
foreign particles are lodged in the eye.
Corneal scarring: Corneal ulcers are open sores
on the front of the eye that can occur when infected, either
via the measles virus or from a bacterial infection that
develops secondary to measles.

11. Six Ways Measles Can Affect the
Eyes
Retinopathy: While rare, there are documented
cases where the measles virus destroys the retina, a layer
of cells in the back of the eye that convert light energy into
electrical impulses that go to the brain.
Optic neuritis: This inflammation affects the optic
nerve that sends signals from the back of the eye to the
brain. This complication is relatively rare but can occur in
measles patients who also develop encephalitis, or brain
swelling, though cases without encephalitis have also
surfaced. Acute cases may be treated with corticosteroids.
Like retinitis, vision loss from optic neuritis can be
temporary or permanent.
Blindness: Measles is a leading cause of childhood
blindness in developing countries where immunization
programs for this disease are less established or often
interrupted by conflict. When compounded by malnutrition,
particularly vitamin A deficiency, measles is associated
with corneal scarring from ulceration and keratitis, two of
the most likely reasons for blindness from measles.
Blindness from optic neuritis has also been noted.

12. OCT. scan procedure of retinas

13. Regions
For purposes of analysis, the OCT image of the retina can be subdivided vertically into
four regions
the pre-retina
the epi-retina
the intra-retina
the sub-retina

14. Anomalous structures
pre-retinal membrane
epi-retinal membrane
Vitreo-retinal strands
vitreo-retinal traction
pre-retinal neovascular membrane
pre-papillary neovascular membrane

15. A pre-retinal membrane with traction on the
fovea
Preretinal macular fibrosis has
been variously termed by
various investigators as surface
wrinkling retinopathy,
cellophane membrane or
cellophane maculopathy,
preretinal traction membrane,
macular pucker etc.

16. a pigment epithelial detachment is causing
the convexity
The outer segments of the
photoreceptors receive oxygen
and nutrition from the choroid. If
the retina is detached from the
choroid, the photoreceptors will
fail. The fovea has no retinal
blood vessels and depends
wholly on the choroid for its
oxygen, so detachment of the
macula leads to permanent
damage to the cones and rods at
the posterior pole, and loss of
vision.

17. Macular cyst
A cyst caused by vitreous
traction in the macula, the
tiny oval area made up of
millions of nerve cells
located at the center of the
retina responsible for
sharp, central vision.

18. Macular hole
The center of the macula is the
fovea. Foveal cysts are caused by
vitreous traction. Eyes that develop
foveal cysts may remain stable,
develop full-thickness macular holes

19. Serous retinal pigment epithelial
detachment (PED)
A serous pigment epithelial
detachment occurs when the
sensory retina detaches from the
pigment epithelial layer due to
inflammation, injury, or vascular
abnormalities. A serous pigment
epithelial detachment often
occurs in conjunction with
central serous chorioretinopathy.
This is because of the fluid that
accumulates in the subretinal
space.

20. Scanning Tips
 Minimize patient fatigue by keeping scan time to a minimum. Never scan an eye
for more than 10 minutes
 Keep the cornea lubricated. Use artificial tears and have the patient blink when
you are not saving a scan pass.
 Reflectivity may be further enhanced by moving the
focus knob on the side of the OCT unit