This invention concerns the acquisition of diagnosis information data effective for diagnosing eye disease independently of the eye state. An image processing apparatus for processing a tomogram of an eye includes a unit configured to determine an eye feature based on the tomogram and thus determine the eye state, a unit configured to detect, from the tomogram, a detection target to be used to calculate diagnosis information data quantitatively representing the determined eye state, and a unit configured to calculate the diagnosis information data using position information of the detection target. In accordance with the eye state, the detection unit changes the detection target or an algorithm to be used to detect the detection target.
