Accommodation and convergence in the absence of retinal images

Abstract The behaviour of accommodation and convergence of the eyes in total darkness and in very low illumination has been studied by an objective method. Also the ability of subjects to accommodate and converge to the position of their own finger held up in darkness has been recorded. Simultaneous records show that both accommodation and convergence are active in darkness, but fluctuate without relation to one another. Results also show that the brain is unable to use the information from proprioceptor nerves of the hand and arm to direct the eyes and control accommodation in darkness. The synergic relation between the innervations to accommodation and convergence still holds near the threshold, although the accommodation activity of night myopia is present, but when there is no retinal image the two mechanisms act independently.