Fig. 10. Visual acuity with different levels of illumination. The curve for normal eyes represents theaverage of measurements taken from 10 eyes. The curves for strabismic amblyopia and organic disease represent individual cases. (Von Noorden GK, Burian HM. Visual acuity in normal and amblyopicpatients under reduced illumination. II. The visual acuity at various levels of illumination. Arch Ophthal-mol 62:396, 1959. Copyright 1959, American Medical Association.)