Growth of the visual system in the African cichlid fish, Haplochromis burtoni. Accommodation.

We have both measured directly and computed the amplitude of accommodation as a function of fish size to discover how the accommodative process changes during growth in the African cichlid fish, Haplochromis burtoni. We found that accommodation is achieved by lens movement in the pupillary plane along the naso-temporal axis. Accommodative lens movement is thereby directed toward a region of retinal specialization characterized by higher density of all cell types (except rods) in H. burtoni. When relaxed, the temporal retina is focused for near vision and active accommodation through lens movement adjusts the focus in the temporal retina for far vision. As the animal grows, the near and far focus points change appropriately for the fish size.