Without the aid of color contacts, of course. I have hazel eyes, a mix of green and brown, and I could almost swear they’re getting greener. I imagine eye color is a fixed feature but it has, well, caught my eye 
when looking in the mirror. And yes, I’m aware that with hazel eyes, different lighting can bring out or emphasize different colors in the iris. Anyway, is it possible that my eyes are getting more green?
That’d be so effin’ cool.
Eye color changes occur in about 10 percent of adults.
Here’s Cecil’s take on the subject:
http://www.straightdope.com/classics/a971205.html
By the way, Cecil also had this to say about green eyes:
Eye color can change with age. When my sister was in high school, she had blue eyes. Now that she’s in her 50s, her eyes are more my color – gray-green-brown.
The “Afghan Girl”'s eyes faded with the years. The pictures of her at the two different ages really show the toll a hard life takes, and her luminous eyes certainly faded somewhat. I’ve seen blue eyes get more ‘washed out’ with age.
I had very dark brown eyes when I was younger. I’m in my thirties now and my eyes are hazel.
Medications can change eye color. My mom had medium brown eyes until she started taking medication for glaucoma. Her eyes are now extremely dark brown.
Mine have changed, almost certianly due to my inflamatory eye disease - uveitis - or the cortisone eye drops I have every day. I used to have dark hazel eyes - both the same. The uveitis is much more active in one eye and that one is now quite pale. The other is just paler than it was. They are now significantly different. It is obvious if I am looking into the light or wear green clothes.
There was a good chance i’d lose my sight, but eye drops seem to be holding it fairly steady. Losing the colour instead is fine by me!
Lynne
I have dark green eyes with a hint of brown. They have definitely become lighter, in fact someone said they looked blue. I know blue will get washed out, too.
Babies’ eye color changes, too. Both of my kids had blue eyes when they were born. Now one has gray/hazel eyes and one has brown eyes.
My niece had blue eyes as a baby (I believe all newborns’ are blue), which changed
to brown by the 12 month mark. Something to do with the melanin not coming in
until later.