Best feature matcher for iris pictures

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I want to write some code to perform an iris recognition. I've already had a iris pictures which is normalized to cartesian coordinates. I've try to match theese pics using Gabor filter and Hamming distance, but without a success.

So now I'm wondering if in openCV exists a matcher which will be good to provide this kind of recognition? I know there is some predefined matchers, but which one will be the best for very similar pictures? Let me also add that my application should decide if given iris exist already in database or not.

I'm using Java version of openCV