The focal length of the fish eye lens and visual acuity.
D000818:Animals; D005399:Fishes / Q000033:anatomy & histology*; D007908:Lens, Crystalline / Q000033:anatomy & histology*; D055095:Optics and Photonics; D012029:Refraction, Ocular; D012160:Retina / Q000502:physiology; D013045:Species Specificity; D014792:Visual Acuity