True about macula lutea is:

Near the centre of the retina there is a region 5-6 mm in diameter, which contains the macula lutea, an elliptical yellowish area, 2 mm horizontally and 1 mm veically. Its colour is due to the presence of xanthophyll derivatives. The macula lutea contains a central depression, the fovea centralis or foveola, with a diameter of 0.4 mm, where visual resolution is highest. Here, all elements except pigment epithelium cone photoreceptors are displaced laterally. The minute size of the foveola is the reason why the visual axes must be directed with great accuracy in order to achieve the most discriminative vision. Ref: Gray's anatomy 40th edition, Chapter 42