The fine shadings on the wrinkles make them very plastic. You also cought the expression of her face very well - an aged, an experienced look. A good work! But what is about her eye? There is no black pupil in the center of her iris.
That is really good. I try to do realistic art but I have never done an old person. I imagine it would have been really hard. I looks really good though so I think that it was worth the time and effort.