Biomedical image processing

1. Utilization Of Portable Digital
Camera For Detecting Cataract
By-Rahul Dey
EE14MTECH11033

2. Facts regarding our Eye
• Eye is nearly a sphere
with diameter 20mm.
• Our eye can distinguish
nearly 10million colors.
• If we compare our eye to
a digicam then it is about 576MP.
• On an average we blink about 17 times,a
minute i.e nearly 5.2million times a year.
• Staring directly into the sun will make us blind.
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3. Structure Of The Eye
• Three membrane enclose the eye: the
cornea&sclera outer cover;the choroid &
the retina
• Cornea is tough transparent tissue,that
covers the outer of the eye.
• Sclera is an opaque membrane that
encloses the remainder of eye.
• Choroid is also a membrane that contains
network of blood vessel that serves as
the source of nutrition to eye.
• The iris contracts or expand to control
the light entering eye.
• Lens & cornea helps in refracting light to
the retina.
• Ciliary body are the muscles which helps
in changing the focal length of the lens.
• When the eye is focusing an object, its
image is formed over retina,with the help
of receptors viz.rods & cones.
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4. What is Cataract?
• Cataract is clouding in the eye lens that affects our
vision.
• There are mainly three types of cataracts.
a) Immature – In this type of cataract,a whitish color
just appears inside pupil,condition is not so serious.
b) Mature – In this type of cataract,the entire lens is
opaque and swollen,medical attention is required
c) Hypermature – In this type of cataract,the lens is
dehydrated, and much more whitish color is
exhibited inside pupil,immediate surgery is required.
• Cataract can occur in both the eyes or can affect one
eye. 4

5. Causes of cataract
• Mostly cataract is caused due to ageing.
• Some of the other factors causing cataracts are:
i. U.V rays from sunlight or other source.
ii. Diabetes.
iii. Hypertension.
iv. Smoking.
v. High myopic eye.
• Another theory for cataract formation is
that,cataract is caused by oxidative changes in the
human lens.
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6. Detection
• Usually opthalmologists will use various
instruments like slit lamp or
opthalmoscope to determine the type ,
opacity & location of the cataract and
to distinguish it from other eye defects.
• Basically the working principle both the
instruments are same,that is they use a
light source to determine the condition
of patient’s lens.
• However the main disadvantage of
instruments like this is that,they are
costly and require special training for
operating.
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7. Proposed Methodology
• In this method, the information is extracted from pupil area.
• The methodology is based on the specular reflection
analysis,because it is always brighter than surrounding area and
is not dependent on illumination condition.
• The steps in the process is pupil localization,which has to be
done in four stages:
a) The image size is changed to 50% to ease the image
processing.
b) Masking step,namely the seperation process of the facial
image based on the skin color.This is done with the help of
MatLab in the image processing toolbox,by defining the Region
Of Interest.
c) Cutting the eye area.This is based on the normal fact that eye
region forms the one-third of the facial length.
d) Pupil step,after taking out the eye image we have to determine
the center point of circle,which is the center point of the pupil.
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8. Proposed Methodology(contd..)
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9. Specular Reflection Analysis
• The core of the proposed methodology is
specular reflection analysis.
• Light hits the frontal surface of the lens &
makes a reflection called frontside
reflection.
• But light also hits the backside of the lens.
• For a normal eye ,there is no whitish layer
inside the lens so,it will be reflected
again,this is known as backside reflection.
• For a medium or serious condition as
there is lot of clouding in lens,backside
reflection will not occur.
• Using this image data we can plot
backside reflection vs d(d is the distance
between center of pupil and center of
frontside reflection)
• The relation is
A=d+r-δ
A=length of backside reflection from pupil
r=radius of pupil
δ=radius of backside reflection
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10. Practical screening system & data
acquisition
• For getting perfect data,the patient and the
camera should be in appropriate position.
• In the proposed method light is attached to the
camera.
• The main purpose of the data acquisition is:
a) Getting an optimal position between camera
and eye lens.
b) Getting an optimal pupil size to get an
appropriate distance between two reflection.
• The lens is ellipsoidal,biconvex in shape.
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11. Implementation Of Data Acquisition
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Side view of camera configuration
View from above camera configuration

12. Practical screening system & data
acquisition(contd..)
• In this data acquisition part,there are
three conditions:
a) 1st condition where reflection does
not occur inside the lens.
b) 2nd condition where only the
frontside reflection occurs & can be
observed inside the lens.
c) 3rd is an appropriate
condition,where the frontside &
backside reflection can be seen on
the same image plane.
• During simulation ,we change the
position of the camera with light
attached based on angle ψ between
camera & eye lens.
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13. Equipment used in the system
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Scale Chin rest & Tripod
Digicam with flash Computer

14. Conclusion
Merits
• Cost effective.
• Can be used in rural areas
where there is limitation of
health facilities.
• it is very useful for
determining people who
need a surgery as soon as
possible.
Demerits
• Positioning the camera to
get the best image.
• Insufficient image quality.
• Uncontrolled illumination.
• Only distinguish between
serious and non serious
condition.
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15. References
• http://cdn.intechopen.com/pdfs-
wm/39272.pdf
• http://web.media.mit.edu/~pamplona/CATRA
/
• http://www.medicinenet.com/cataracts/articl
e.htm
• https://images.google.com/
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