Visual demands in primary school classrooms

Purpose To quantify the visual function requirements to perform in a primary school classroom setting. Methods 33 classrooms of Years 5 and 6 (children aged 10-12 years) from 8 schools were included. The classroom activities undertaken for a full day (9am-3pm) were observed and a range of measurements recorded; text size and contrast of learning materials, habitual working distances (distance and near) and time spent performing various classroom tasks. These measures were used to calculate demands for distance and near visual acuity, contrast and sustained use of accommodation and vergence. Results The minimum resolution requirements for distance and near were 0.3±0.1 and 0.7±0.1 logMAR (using maximum viewing distances and smallest target sizes). Mean contrast levels of learning materials at distance and near were >70% (an average contrast reserve of 25:1). Near tasks (47%) dominated the academic tasks performed in the classroom followed by distance (29%), distance to near (15%) and computer-based (9%). On average, children maintained continuous near fixation for 23.2±4.7 minutes at a time and during distance-near tasks performed fixation changes 10±0.9 times per minute. The mean habitual near working distance was 22.9±1.3 cm, which corresponds to a 4.4±0.2 D accommodative demand and the vergence demand was 0.9±0.1Δ at distance and 21.9±1.1 Δ at near assuming an average pupillary distance of 56 mm. Conclusions The visual demands placed on children in modern classrooms were greater than those reported for traditional classrooms, likely due to inclusion of modern technologies. Relatively high levels of visual acuity, contrast processing and sustained accommodative-convergence are required to perform optimally in the classroom environment. These findings are important for determining evidence-based prescribing guidelines and developing paediatric vision screening protocols and referral criterion.