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

Investigating the impact of OCT imaging of the crystalline lens on the accuracy and precision of cataract assessment

Purpose: To determine if supplementing standard clinical assessments with Optical Coherence Tomography (OCT) imaging of the crystalline lens improves the accuracy and precision of lens opacity assessment and associated clinical management decisions by optometrists. Methods: Fifty optometrists registered in the UK or Éire undertook a clinical vignette study where participants graded lens opacities and made associated clinical management decisions based on the image(s)/information displayed. Three forms of vignettes were presented: (1) Slit‐lamp (SL) images of the lens, (2) SL and OCT images and (3) SL, OCT and visual function measures. Vignettes were constructed using anonymised data from 50 patients with varying cataract severity, each vignette being presented twice in a randomised order (total vignette presentations = 300). The accuracy of opacity and management decisions were evaluated using descriptive statistics and non‐parametric Bland–Altman analysis where assessments from experienced clinicians were the reference. The precision of assessments was examined for each vignette form using non‐parametric Bland–Altman analysis. Results: All (n = 50) participants completed the study, with 36 working in primary eyecare (primary eyecare) settings and 14 in hospital eyecare services (HES). Agreement was highest where vignettes contained all clinical data (i.e., SL, OCT and visual function data—grading: 51.0%, management: 50.5%), and systematically reduced with decreasing vignette content (p &lt; 0.001). A larger number of vignettes containing imaging and visual function measures exhibited below reference (i.e., less conservative) grading compared with vignettes containing imaging data alone (all p &lt; 0.05). HES‐based optometrists were more likely to grade lens opacities lower than clinicians working in primary eyecare (p &lt; 0.001). Good measurement precision was evident for all vignettes, with a mean bias close to zero and limits of agreement below one grading step for all conditions. Conclusions: The addition of anterior segment OCT to SL images improved the accuracy of lens opacity grading. Structural assessment alone yielded more conservative decision making, which reversed once visual functional data was available

Global estimates on the number of people blind or visually impaired by Uncorrected Refractive Error: A meta-analysis from 2000 to 2020

BackgroundUncorrected refractive error (URE) is a readily treatable cause of visual impairment (VI). This study provides updated estimates of global and regional vision loss due to URE, presenting temporal change for VISION 2020MethodsData from population-based eye disease surveys from 1980–2018 were collected. Hierarchical models estimated prevalence (95% uncertainty intervals [UI]) of blindness (presenting visual acuity (VA) &lt; 3/60) and moderate-to-severe vision impairment (MSVI; 3/60 ≤ presenting VA &lt; 6/18) caused by URE, stratified by age, sex, region, and year. Near VI prevalence from uncorrected presbyopia was defined as presenting near VA &lt; N6/N8 at 40 cm when best-corrected distance (VA ≥ 6/12).ResultsIn 2020, 3.7 million people (95%UI 3.10–4.29) were blind and 157 million (140–176) had MSVI due to URE, a 21.8% increase in blindness and 72.0% increase in MSVI since 2000. Age-standardised prevalence of URE blindness and MSVI decreased by 30.5% (30.7–30.3) and 2.4% (2.6–2.2) respectively during this time. In 2020, South Asia GBD super-region had the highest 50+ years age-standardised URE blindness (0.33% (0.26–0.40%)) and MSVI (10.3% (8.82–12.10%)) rates. The age-standardized ratio of women to men for URE blindness was 1.05:1.00 in 2020 and 1.03:1.00 in 2000. An estimated 419 million (295–562) people 50+ had near VI from uncorrected presbyopia, a +75.3% (74.6–76.0) increase from 2000ConclusionsThe number of cases of VI from URE substantively grew, even as age-standardised prevalence fell, since 2000, with a continued disproportionate burden by region and sex. Global population ageing will increase this burden, highlighting urgent need for novel approaches to refractive service delivery