Heterochromia and Eye Freckles??

[Tsiyeria]

I did not know this was a thing. And I have it too! The heterochromia, not the eye freckle. Mine change, though. Sometimes they're green, sometimes brown, sometimes something else (I can't remember what atm). I'm pretty sure I always have that ring, though. Weird!

[Seshat]

My questions are:

1) How could I have gotten green/brown central heterochromia?
2) What causes eye freckles?
3) What are the chances of a person having 2 rare eye conditions (one a rarity of a rarity) at the same time?

1) Despite the fact that we simplify genetics into 'recessive' and 'dominant', it's actually a lot more complex than that.
For instance, with melanin (body pigment) alone, humans have both 'red melanin' and 'brown melanin'.
Red hair/green eyes is associated with red melanin.
Brown hair/brown eyes is associated with brown melanin.
Blonde hair/blue eyes has low levels of brown melanin.
Strawberry blonde hair/hazel eyes has low levels of both red and brown.
Dark red or auburn hair/dark brown or black eyes is high levels of both red and brown.
Black hair/black eyes can be very high levels of either, or of both.

BUT: even melanin isn't limited to two genes, one for red and one for brown. You probably have a particularly funky set of melanin genes, especially for the placement of melanin in the eyes.
No, I don't know exactly what sort of 'funky', but it's unusual, beautiful and (since your optical specialists don't seem to think you have an eye disease) harmless. So it sounds like a good sort of 'funky' to me.

2) If you have had it since birth, it's probably part of your unusual iris genetics. Your childhood imagination could be correct: your iris leaked.
More precisely, a few cells that would normally be part of the white of the eye instead got RNA instructions to collect melanin, like the iris would. They may even be functional iris cells, just not connected to the iris muscles.
NOTE: this is speculation, based on my knowledge of how infants develop in the womb. If you want an answer that you can rely on, please ask a specialist in eyes or a specialist in embryo/foetal development.
NOTE II: If it developed since birth, I can only answer with 'I'm not sure, I'd have to look it up'.

3) Clearly, at least one in six billion.
Actually, I'm not sure. I'd have to look it up.

[Eisa]

I have no idea, but you have a pretty eye, and I want to see the other one.

[Kisa]

I have central heterochromia in both eyes. Green outside and brown inside. Also, in my right eye, I have a single eye freckle.

I've always noticed my freckle (when I was little, I thought the color in my iris was leaking out ), but never knew what it was until I switched Optimologists and my new doctor told me I had eye freckles and astigmatism. Apparently, eye freckles are very rare and normally(when presented) there are multiple freckles. I only have one.

When I got home that day, I looked at my eye really close for about 10 minutes and was surprised to see that I had a ring of green in my iris. I looked it up online and found out what it was called. However, it was today that I started to wonder how it happens. I took AP Biology and learned all about genetics and eye color, but I can't recall learning about heterochromia.

I looked it up and every site I clicked on said it is either genetics, injury or disease. I have bad eyesight and need glasses, but many people in my family wear glasses. I have no other symptoms that could cause this, no other family members have heterochromia, and I've never had and injuries near my head.
As for eye freckles, I can't seem to find anywhere what causes eye freckles. No family members have eye freckles either.

My questions are:

1) How could I have gotten green/brown central heterochromia?
2) What causes eye freckles?
3) What are the chances of a person having 2 rare eye conditions (one a rarity of a rarity) at the same time?

For referance, here is a picture of my right eye. The brown is near the pupil, the green is outside, and the freckle is that brown spot in the upper right corner near my iris.