[Visual acuity testing of three-year-old children using Landolt ring and picture targets].

Visual acuity testing using Landolt ring and picture targets (silhouettes of butterfly, fish, bird and tulip), was performed on 184 three-year-old subjects who had received secondary ophthalmic examination at the age of 3 years and 1-3 months, and the results were evaluated. The examinations were feasible on 83.1% of the subjects for the picture test and 76.1% for the Landolt ring test; the picture test being significantly higher. However, when the level was set at 0.5, namely, 0.5 or more were judged as "passing" and less than 0.5 judged as "failing", the Landolt ring test showed a significantly higher rate than the picture test in the number "passing". Specificity and sensitivity were calculated with reference to the clinical findings. Results suggest that the Landolt ring test has a better validity than the picture test and the Landolt ring test could differentiate between good and poor vision. The silhouette of the bird was particularly poor. When using picture targets for testing, the necessity of proper selection of the kind of pictures used is indicated. In the case of use of the Landolt ring, reexamination at the age of 3 years and 6 months or later, or postponement of the examination until age 3 years and 6 months or later would appear to be beneficial for enhancing the feasibility of the test.