Diurnal variations in sensitivity to deprivation myopia or near work in chickens and humans

Abstract

Purpose. In chickens, changes in retinal image quality are translated into changes m axial eye growth with time constants of several hours. We have tested whether the time of the day at which the changes m visual experience occur is important for myopia development. If this would be true, near work could be differently myopigenic at different times of the day also in children Methods 18 chickens were binocularly deprived with translucent occluders from day 7 to 12 Occluders were removed each day either in the morning (A) or in the evening (B) for 40 minutes, or were continuously worn (C). Diurnal growth rhythms were recorded by A-scan ultrasound, refractions by automated infrared photoretinoscopy. 180 children of both sexes aged 7, 9, and 12 years in a single grade school were randomly selected. Cycioplegic refraction, ultrasound biometry, and a diary to document nearwork activities were administered every 2 to 3 months. This 24-hr diaries quantified reading, writing, computer use, and outdoor activities at half hourly intervals. Results In chickens. normal vision in the evening suppressed deprivation myopia more efficiently (refractions +1 74 + 1.04D (B) vs -60+1.20 (C)) than in the morning (-1 56+4.05D (1); (A) vs (B): p