Astyanax mexicanus has two morphs; a surface, eyed morph (A) and a blind, cave morph (B) whose nonfunctional optic capsules are buried deep beneath the integument. At birth, cavefish have eyes and respond to light, but soon after, the eye degenerates. At 16–21 dpf, both the surface (C) and the cavefish larvae (D) have eyes. However, while the eye capsule and retina of the surface larvae (E) are well suited for vision, the eye capsule of the cavefish (F) has degenerated, the lens has undergone apoptosis, the outer nuclear layer of the retina is not completely differentiated, and there are essentially no photoreceptors. Cavefish larvae may detect light and darkness at this stage, but they lack central visual acuity and are thus blind to form perception. The scale in the right column is the same for the left column.