Grating Discs: a simplified method of testing vision in infants and young children

We have developed a simple new method of evaluating visual function in young children about 15 to 36 months of age. Our Grating Discs system consists of six discs with a striped pattern and one homogeneous disc. One striped disc and the homogeneous disc are presented simultaneously, and the examiner observes whether the subject can discriminate between the two. The patterned discs have vertical stripes of different widths from 16 to 0.5 mm. At a testing distance of 57 cm, the visual resolution required for discriminating the grating ranges from 96 min of arc (0.01) to 3 min of arc (0.33) in one-octave steps; at a testing distance of 114 cm the required resolution ranges from 48 min (0.02) to 1.5 min (0.67). Using this system, we evaluated the visual acuity of normal infants and young children. Their ability to discriminate the finer gratings improved with increasing age, and more than 90% of the normal subjects in the 36-month group tested at 0.67. We also examined young children with known ocular pathologies and compared the results with acuity measurements obtained with the preferential looking test. The latter method gave acuities slightly better than those from the Grating Disc system, but the finding with the two techniques were generally in good agreement. Grating Discs are a simple, compact, effective tool for rapid assessment of visual function in young children.