A study of the crowding phenomenon using the Landolt Ring Crowded Card in normal adults and children

• Published in: JAPANESE ORTHOPTIC JOURNAL Vol. 27; pp. 241 - 245
• Main Authors: Matsumoto, Fumiko, Wakayama, Akemi, Ohmure, Kazuyo, Tanoue, Kyoko, Otori, Toshifumi, Kusube, Toru
• Format: Journal Article
• Language: English
• Published: JAPANESE ASSOCIATION OF CERTIFIED ORTHOPTISTS 1999
• Subjects: crowding phenomenon; Landolt Ring Crowded Card; normal adults; normal children
• ISSN: 0387-5172; 1883-9215
• DOI: 10.4263/jorthoptic.27.241

A study was made on the crowding phenomenon using the Landolt Ring Crowded Card which we developed. The subjects we tested were eight normal adults between the age of 20 and 30 years and ten normal children between the age of six and ten years. Their corrected vision was 20/20 or better. A Landolt Ring Crowded Card consisted of a Landolt ring with the 1 minute visual angle. The central ring was placed on a piece of octagonal paper measuring 8.2cm per side and either four of six Landolt rings were placed around the central Landolt ring. Distances between the central and outer Landolt rings were 0.2, 0.5, 1, 2, 3, 4, 5, and 6 times the diameter of the central ring. The Landolt Ring Crowded Card was tested at the distance of 5m. The examines were asked to distinguish the direction of the central Landolt ring. We first showed the Landolt Ring Crowded Card with the largest distance between the central Landolt ring and the outer Landolt rings. The results were evaluated by the Landolt Ring Crowded Card with the nearest outer rings when the examine correctly identified the Landolt ring as often as three times out of four presentations. Almost all of normal adults correctly identified the card with the rings 0.5 times the diameter apart from the central ring in both four and six Optotypes. Almost all of normal children also correctly identified the card with the rings 1 time the diameter apart from the central ring in both four and six Optotypes. It was thus concluded that our Landolt Ring Crowded Card was quite useful for the assessment of the crowding phenomenon.