remove the edges present outside the circle

i am able to detect the circle in an eye image but along with circle i am also getting other extra edges . how do i remove that?please help i have uploaded both original image and processed image

gray=imread('008_1_1.jpg');
%gray=rgb2gray(gray);
t4=imresize(gray,[512,512],'bilinear');
%imshow(t4);
%set(gcf,'Units','Normalized','OuterPosition',[0 0 1 1]);
binary=imbinarize(t4,.4);
%imshow(binary);
%binary=imcrop(binary);
g=fspecial('gaussian',[512 512],15);
ig=imfilter(binary,g,'same');
bw2=edge(ig,'canny',0.53,10);

%k=get(handles.id1,'String');
filen=['100.png'];
%basefile=sprintf('%d.png',k);
fullfilenam=fullfile('C:\Users\AKSHATHA\Documents\MATLAB\database\eyeimages',filen);
imwrite(bw2,fullfilenam);

Answer 1

[KALYAN ACHARJYA]

Is this one you are looking for? This bwareafilt extract objects from binary image by size.

Here assuming that the circle size is maximum in all cases, if not result will different

result=bwareafilt(binary_image,1);
imshow(result);

Hope it Helps!

[akshatha nayak]

It work only for some images