Visual Acuity Testing With Preferential Looking in Mental Retardation

Abstract

Twenty-six mentally retarded children and young adults, most of them with severe neurological deficits, in the age range 5-24 years, were examined ophthalmologically, and their binocular visual acuities were tested with 'operant preferential looking' according to the technique of Mayer & Dobson (1980). Five of the subjects did not co-operate sufficiently for visual testing, although 3 had no ocular abnormalities that would affect binocular acuity. The visual acuity levels determined with 'preferential looking' ranged from 1.29 to 0.03 in the 21 subjects that could be tested. Two children with high myopia showed substantial increase in acuity with appropriate correction (from 0.1 to 1.06 in one child and from 0.05 to 0.31 in the other). Inability to fixate light or objects was found in subjects, who at acuity testing showed values of 0.15 or less. In patients with suspected or definite optic atrophy, visual acuities 0.28 or less were obtained. In general there was a good correlation between ophthalmological abnormalities (in fixation, pupil reactions to light, ocular motility, fundus appearance and refraction) and poor visual acuity. It is therefore concluded that visual acuity testing with 'preferential looking' techniques can give valid information on central visual function in mentally retarded children and young adults.

Assessment of visual acuity in adult patients with strabismic amblyopia: A comparison between the preferential looking method and different acuity charts

“…The same holds for testing with single optotypes. With these limitations PL is a valuable method in clinical practice in patients where no other tests can be performed due to age, mental capacity (Lennerstrand et al 1983;Mayer et al 1983;Mohn & van Hof-van Duin 1983;Hertz 1987), and various disorders of the eye and the visual system (Rydberg 1989;Katz & Sireteanu 1990;Fielder et al 1992).…”

Two years' clinical experience with the preferential looking technique for visual acuity determination in infants and young children

“…The operant preferential looking method was found suitable for children with psychomotor retardation of different causes, also over the age of 3 years. Many of the retarded children were unable to co-operate in ordinary acuity testing (cf also Lennerstrand et al 1983). To guide rehabilitation efforts in these children, it is of interest to demonstrate either the presence of form vision rudiments or total absence of responses to visual stimulation.…”

“…During the observation period (29 months) 229 tests were performed on 93 patients. Observations on 34 of these have been reported by Lennerstrand et al (1983Lennerstrand et al ( , 1986. The remaining 59 patients (male 35; female 24) were tested on 131 occasions.…”