Low-Contrast Acuity Measurement: Does It Add Value in the Visual Assessment of Down Syndrome and Cerebral Palsy Populations?

Abstract

PURPOSE. Children with Down syndrome (DS) and cerebral palsy (CP) often have reduced visual acuity (VA). This study assessed VA and low-contrast acuity (LCA) with Lea symbols in DS and CP populations to explore whether LCA measures provide useful additional information about visual performance. VA and LCA were also measured in a large group of typically developing young people.METHODS. High-contrast VA and LCA performance was measured monocularly using crowded Lea symbols with 45 young people with CP (mean age 11.8 -4 years), 44 with DS (mean age 10.5 -3 years), and 211 controls (mean age 11.4 -3 years). Refractive status was confirmed with cycloplegic retinoscopy.RESULTS. DS and CP groups had significantly lower acuities than controls at all contrasts (P < 0.001). Mean (-SD) high-contrast VA was as follows: DS ¼þ0.39 -0.2 logMAR; CP ¼þ0.18 -0.2 logMAR; controls ¼À0.04 -0.1 logMAR. Mean 2.5% LCA was as follows: DS ¼þ0.73 -0.2 logMAR; CP ¼þ0.50 -0.2 logMAR; controls ¼ þ0.37 -0.1 logMAR. For controls, the mean difference between VA and 2.5% LCA was 0.40 logMAR (95% limits of agreement, -0.22 logMAR). While there was a positive relation between VA and 2.5% LCA scores (linear regressions, P < 0.0001), considerable variation existed, with VA explaining only 36% of the variance in LCA performance for control data.CONCLUSIONS. VA and LCA performance was significantly poorer in DS and CP groups than in controls, and high-contrast VA did not reliably predict low-contrast performance. Therefore both high-and low-contrast acuity assessment are valuable to fully describe an individual's visual function, and this may be particularly relevant in DS and CP in cases in which patients are unable to articulate visual difficulties. Age-specific reference data from a large sample of typically developing young people across a broad age range are presented for clinicians using high-and low-contrast Lea symbols. (Invest Ophthalmol Vis Sci. 2013;54:251-257)

Effects of bifocals on visual acuity in children with Down syndrome: a randomized controlled trial

“…Compared to other children, many ocular findings in DS occur more frequently and in a more severe form (Creavin & Brown 2009;Little et al 2009b, Afifi et al 2013Aslan et al 2014;Watt et al 2015). In literature, the following prevalences have been reported: reduced visual acuity (poorer than 0.3 LogMar) in 80-100% and poor contrast sensitivity in almost all DS children (John et al 2004;Morton 2011;Little et al 2013;Watt et al 2015;Zahidi et al 2018). Accommodation deficit occurs in 50-90% of the children with DS (Woodhouse et al 1993(Woodhouse et al , 1996(Woodhouse et al , 2000Cregg et al 2001;Nandakumar & Leat 2009Anderson et al 2011;Doyle et al 2016Doyle et al , 2017.…”

Simulated Keratometry Repeatability in Subjects with and without Down Syndrome

“…There are two reasons one would expect more variation in topography measurements in DS eyes: 1) they are likely to have more astigmatic and possibly more distorted corneas than the general population and 2) they may have less cooperation for measurements than the general population –related either to behavioral difficulties in cooperation due to intellectual disability, or related to reduced visual acuity 13–15 (a common finding in this population) creating difficulty with fixation. Therefore the purpose of this study is to evaluate the repeatability of simulated keratometry values from topography measurements in DS eyes in comparison with age-matched individuals without DS.…”

Accommodation deficit in children with Down syndrome: practical considerations for the optometrist

“…Along with an understanding of the refractive error profile in Down syndrome, it is worth noting that VA is often reduced, even with optimal refractive correction. Children with Down syndrome rarely achieve "6/6" or "20/20" levels of VA. Figure 3 illustrates this with data from Little et al 54 This figure demonstrates VA (plotted against age) measured with the Lea symbols VA chart in a group of children with Down syndrome aged 6-16 years. These were compared with normative data from age-matched typically developing children, indicated by the black solid and dashed lines in Figure 3.…”