Utilization of portable digital camera for detecting cataract
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Utilization Of Portable Digital Camera For Detecting Cataract
Utilization Of Portable Digital Camera For Detecting CataractBy-Rahul DeyEE14MTECH11033
Facts regarding our EyeEye is nearly a sphere with diameter 20mm.Our eye can distinguish nearly 10million colors.If we compare our eye toa 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. 2
Structure Of The EyeThree membrane enclose the eye: the cornea&sclera outer cover;the choroid & the retinaCornea 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.
3What is Cataract?Cataract is clouding in the eye lens that affects our vision.There are mainly three types of cataracts.Immature In this type of cataract,a whitish color just appears inside pupil,condition is not so serious.Mature In this type of cataract,the entire lens is opaque and swollen,medical attention is requiredHypermature 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.4Causes of cataractMostly cataract is caused due to ageing.Some of the other factors causing cataracts are:U.V rays from sunlight or other source.Diabetes.Hypertension.Smoking.High myopic eye.
Another theory for cataract formation is that,cataract is caused by oxidative changes in the human lens.
5DetectionUsually 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 patients lens.However the main disadvantage of instruments like this is that,they are costly and require special training for operating.6
Proposed MethodologyIn 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:The image size is changed to 50% to ease the image processing.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.Cutting the eye area.This is based on the normal fact that eye region forms the one-third of the facial length.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.
Specular Reflection AnalysisThe 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 isA=d+r-A=length of backside reflection from pupilr=radius of pupil=radius of backside reflection9
Practical screening system & data acquisitionFor 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:Getting an optimal position between camera and eye lens.Getting an optimal pupil size to get an appropriate distance between two reflection.The lens is ellipsoidal,biconvex in shape.10Implementation Of Data Acquisition11
Side view of camera configuration
View from above camera configurationPractical screening system & data acquisition(contd..)In this data acquisition part,there are three conditions:1st condition where reflection does not occur inside the lens.2nd condition where only the frontside reflection occurs & can be observed inside the lens.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 between camera & eye lens.12
Equipment used in the system13
Chin rest & Tripod
Digicam with flash
ComputerConclusion MeritsCost 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.DemeritsPositioning the camera to get the best image.Insufficient image quality.Uncontrolled illumination.Only distinguish between serious and non serious condition.14References http://cdn.intechopen.com/pdfs-wm/39272.pdfhttp://web.media.mit.edu/~pamplona/CATRA/http://www.medicinenet.com/cataracts/article.htmhttps://images.google.com/