Accommodation deficit in children with Down syndrome: Practical considerations for the Optometrist.

Julie-Anne Little School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, UKAbstract: Down syndrome is the most common cause of intellectual impairment, and life expectancy in this group has increased in recent decades, meaning that health care is increasingly focused on quality of life and the management of treatable illnesses. There are frequent problems associated with vision in Down syndrome, including refractive errors, strabismus, reduced vision, and reduced accommodative ability. This review will discuss the importance of accommodative ability; describe the prevalence and nature of accommodative deficits in Down syndrome, which are found in approximately 55%–76% of individuals; discuss the management of this deficit with the prescription of bifocal correction; and summarize the possible etiologies of hypoaccommodation in Down syndrome. Finally, the review will consider practical considerations for the optometrist managing accommodative deficits in patients with Down syndrome. Keywords: Down syndrome, accommodation, accommodative deficits, dynamic retinoscopy, bifocals, refractive erro

Trying to see, failing to focus:near visual impairment in Down syndrome

The majority of individuals with Down syndrome (DS) do not exhibit accurate accommodation, with the aetiology of this deficit unknown. This study examines the mechanism underlying hypoaccommodation in DS by simultaneously investigating the ‘near triad’ – accommodation, vergence and pupillary response. An objective photorefraction system measured accommodation, pupil size and gaze position (vergence) under binocular conditions while participants viewed an animated movie at 50, 33, 25 and 20 cm. Participants were aged 6–16 years (DS = 41, controls = 76). Measures were obtained from 59% of participants with DS and 99% of controls. Accommodative response was significantly less in DS (p < 0.001) and greater accommodative deficits were associated with worsening visual acuity (p = 0.02). Vergence responses were as accurate in DS as in controls (p = 0.90). Habitual pupil diameter did not differ between groups (p = 0.24) but reduced significantly with increasing accommodative demand in both participants with and without DS (p < 0.0001). This study is the first to report simultaneous binocular measurement of the near triad in DS demonstrating that hypoaccommodation is linked to poor visual acuity. Vergence responses were accurate indicating that hypoaccommodation cannot be dismissed as a failure to visually engage with near targets, but rather is a consequence of underlying neurological or physiological deficits