The duration of normal visual exposure necessary to prevent form deprivation myopia in chicks

• Published in: Vision research (Oxford) Vol. 35; no. 9; pp. 1337 - 1344
• Main Authors: Napper, Genevieve A., Brennan, Noel A., Barrington, Michelle, Squires, Margaret A., Vessey, Glenn A., Vingrys, Algis J.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.05.1995
• Subjects: Animals; Anterior Chamber - pathology; Biometry; Chickens; Chicks; Eye - pathology; Myopia - etiology; Myopia - pathology; Occlusion induced myopia; Refractive error; Retina - pathology; Sensory Deprivation - physiology; Space life sciences; Time Factors; Translucent occlusion; Vision, Ocular - physiology; Translucent occlusion; Chicks; Occlusion induced myopia; Refractive error
• ISSN: 0042-6989; 1878-5646
• DOI: 10.1016/0042-6989(94)00226-C

The aim of this study was to determine the minimum daily period of exposure to normal visual stimulation required to prevent occlusion induced myopia in chicks. Chicks were treated with monocular translucent occlusion in a 12 hr light/12 hr dark cycle. Occluders were removed for 0 (constant occlusion), 15, 20, 30, 40, 60, 75, 90, 120, 150, 240 or 720 (no occlusion) minutes each day for either 2 or 3 weeks. Fellow eyes and the eyes of normal chicks (bilaterally unoccluded) were used as controls. Occlusion-induced myopia and axial elongation were found to decrease significantly ( P<0.01) with increasing daily exposure to normal visual stimulation. Application of a time series equation to the data estimates that 30 and 130 min of normal visual exposure per day reduces myopia by 50 and 95% respectively. This study demonstrates that the regulation of ocular growth is affected strongly by short periods of normal visual stimulation in the presence of long periods of abnormal stimulation.