Different visual development: norms for visual acuity in children with Down's syndrome.

BACKGROUND: Visual acuity is known to be poorer in children with Down's syndrome than in age-matched controls. However, to date, clinicians do not have access to norms for children with Down's syndrome that allow differential discrimination of healthy from anomalous visual development in this population. METHODS: The Down's Syndrome Vision Research Unit at Cardiff University has been monitoring visual development in a large cohort of children since 1992. Cross-sectional data on binocular visual acuity were retrospectively analysed for 159 children up to 12 years of age in order to establish binocular acuity norms. Longitudinal binocular acuity data were available for nine children who were seen regularly over the 12 years age-range. Monocular acuity was successfully recorded less often in the cohort, but analysis of scores for 69 children allowed assessment of inter-ocular acuity differences and binocular summation. RESULTS: In comparison with published norms for the various acuity tests used, binocular acuity was consistently poorer in children with Down's syndrome from the age of three years and stabilised at around 0.25 logMAR from the age of four years. Inter-ocular acuity difference and binocular summation were both 0.06 logMAR, which is similar to the reported values in children without Down's syndrome. CONCLUSIONS: The study provides eye-care practitioners with the expected values for binocular acuity in children with Down's syndrome and demonstrates the visual disadvantage that children with Down's syndrome have when compared with their typically developing peers. The results emphasise the responsibility that practitioners have to notify parents and educators of the relatively poor vision of children with Down's syndrome, and the need for classroom modifications.

Infantile nystagmus: an optometrist's perspective.

Infantile nystagmus (IN), previously known as congenital nystagmus, is an involuntary to-and-fro movement of the eyes that persists throughout life. IN is one of three types of early-onset nystagmus that begin in infancy, alongside fusion maldevelopment nystagmus syndrome and spasmus nutans syndrome. Optometrists may also encounter patients with acquired nystagmus. The features of IN overlap largely with those of fusion maldevelopment nystagmus syndrome, spasmus nutans syndrome, and acquired nystagmus, yet the management for each subtype is different. Therefore, the optometrist's role is to accurately discern IN from other forms of nystagmus and to manage accordingly. As IN is a lifelong condition, its presence not only affects the visual function of the individual but also their quality of life, both socially and psychologically. In this report, we focus on the approaches that involve optometrists in the investigation and management of patients with IN. Management includes the prescription of optical treatments, low-vision rehabilitation, and other interventions such as encouraging the use of the null zone and referral to support groups. Other treatments available via ophthalmologists are also briefly discussed in the article.