Two Techniques to Evaluate Visual Acuity from the Age of 18 Months

Abstract

Two methods to measure visual acuity in children aged 18 months and upwards are described, the Kolt-test and the O-test. The validity of the tests was evaluated. These new tests are based on the ability of small children to identify symbols of increasing complexity as they grow older. Thus, a circle is recognized at 12 months, and a cross at about 24 months, while recognition of a triangle and a square comes in between. Correct performance is rewarded. Simplified procedures permit testing children with visual acuity below 0.1 (6/60, 20/200). The tests may also be used in mentally retarded persons if conventional methods fail.

Prevalence of amblyopia with anisometropia or strabismus among schoolchildren in the Sultanate of Oman

“…The VA for the pupils in Grade 1 was performed with the Kolt-test (Lithander 1996;1997) using a testing distance of 3 metres. The symbols used were squares, crosses, circles and triangles printed in rows according to Snellen's principle with correct responses on matching symbols being rewarded with music.…”

“…Equipment made available for Group 1 included: ô For Grade 6, Snellen's E chart, testing distance 6 m. ô For Grade 1, the Kolt-test (Lithander 1996) testing distance 3 m. Group 2 was involved in screening for externally visible eye diseases in the school classrooms, and was composed of medical students under the supervision of a senior eye doctor. Trachoma, conjunctivitis and allergies were registered and treated on the spot, whereas all other pathology, including strabismus, was referred to the paediatric ophthalmologist.…”

Prevalence of myopia in school children in the Sultanate of Oman, A nation‐wide study of 6292 randomly selected children

“…The screening was undertaken by trained medical students involved in their 6th year of study at Sultan Qaboos University, with the assistance of supervisors. The 6-year-olds were tested for VA at a distance of 3 meters with the Kolt-test (Lithander 1996(Lithander , 1998, while the 12-year-olds were tested with the linear E-chart at 6 meters. If VA was found to be less than 0.5 in one or both eyes, they were referred to the paediatric ophthalmologist for a more detailed examination involving a complete eye examination which included cycloplegic retinoscopy in a specially prepared, darkened room.…”

The dynamics of practice effects in an optotype acuity task

“…It will be interesting to investigate whether practice effects with other optotype categories, such as letters or digits, are larger or smaller, and whether the confusion matrix [56], i.e., the probabilities that certain letter pairs are confused, changes with practice. Qualitative data reported by Cavazos et al [7] and Rassow et al [8] suggest that similar practice effects can be expected with letter optotypes and with the Kolt test [57], and improvements in the contrast threshold in peripheral letter recognition in noise have been reported [58]. Due to the heterogeneity of letter optotypes, there may be more potential for improvement with letters than with Landolt Cs, although one may argue that the every-day reading practice should have caused letter acuity to reach a ceiling.…”