4 month old pupil size

My daughter does track items and follow me across a room so I know she can see well.  However, I've noticed at times when I am feeding her, her pupils will quickly change size from large to small.  I am sitting in the same spot with her, not moving around the room.  Her eyes are looking all around the room so I don't know if that has anything to do with it.  Both pupils will change size at the same rate.  I don't know if it is something to worry about or not.  I thought that when you are in a room with equal lighting that your pupil size would remain the same.

[Forum-OD-MP]

that is totally normal.  it is not anything to worry about.  your daughter is likely kind of "experimenting" with focusing her eyes.  the amount of light present in the room is only one of the factors that influences her pupil size.  when she looks at something farther away her pupils will get a little larger.  when she looks at something closer to her, her pupils will get much smaller.  that is called MIOSIS.  pupils can also constrict and dilate based on emotion (sympathetic nervous response, for example) and hormones.

as long as both pupils get larger or smaller at the same rate as each other, and as long as the pupils are the same size as each other, she is totally fine.

[Linda'smom]

Thank you so much for putting my mind at ease.  This is our first child and everything worries me.