Five years' experience with the Grating disc. A simplified method of evaluating vision in young children

The Grating Disc (GD) is a simplified visual test designed for children 18 months to 4 approximately 5 years. Two hundred pediatric patients (103 males, 97 females; aged 5 months to > 6 years) participated in this study to determined how the GD visual acuity (VA) correlates with the Preferential Looking (PL) VA. Forty-six percent of the patients had varying degrees of retinopathy of prematurity. The PL acuity was determined using the up-and-down staircase procedure. To measure GD acuity, six GDs with vertical gratings equivalent to acuities of 20/1920 to 20/60 were used. The examiner presented one GD simultaneously with the homogeneous disc from 57 cm. The VA was determined by the finest GD that the child could differentiate from the homogeneous disc. The overall correlation between the PL and the GD acuities was very high (R2 = 0.861). One hundred twenty-eight patients (64.0%) had an acuity agreement within 0.5 octave and 178 (89.0%) patients were within 1.0 octave. When the PL acuity was > or = 20/100, the GD and PL acuities showed good agreement. When the PL acuity was poorer, the GD acuity was poorer than the PL acuity. Although the GD acuity tended to be lower than the PL acuity in severely visually impaired patients, the GD acuity agreed with the PL in most visual assessments of young children. GD testing could be a useful alternative when sophisticated assessment systems such as the PL are unavailable.