Determining the relative contribution of retinal disparity and blur cues to ocular accommodation in Down syndrome

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Individuals with Down syndrome (DS) often exhibit hypoaccommodation alongside accurate vergence. This study investigates the sensitivity of the two systems to retinal disparity and blur cues, establishing the relationship between the two in terms of accommodative-convergence to accommodation (AC/A) and convergence-accommodation to convergence (CA/C) ratios. An objective photorefraction system measured accommodation and vergence under binocular conditions and when retinal disparity and blur cues were removed. Participants were aged 6-16 years (DS n = 41, controls n = 76). Measures were obtained from 65.9% of participants with DS and 100% of controls. Accommodative and vergence responses were reduced with the removal of one or both cues in controls (p <0.007). For participants with DS, removal of blur was less detrimental to accommodative responses than removal of disparity; accommodative responses being significantly better when all cues were available or when blur was removed in comparison to when proximity was the only available cue. AC/A ratios were larger and CA/C ratios smaller in participants with DS (p <0.00001). This study demonstrates that retinal disparity is the main driver to both systems in DS and illustrates the diminished influence of retinal blur. High AC/A and low CA/C ratios in combination with disparity-driven responses suggest prioritisation of vergence over accurate accommodation.
Original languageEnglish
Article number39860
Number of pages8
JournalScientific Reports
Publication statusPublished - 10 Jan 2017

Bibliographical note

Reference text: 1. Bharadwaj, S. R. & Candy, T. R. Cues for control of ocular accommodation and vergence during postnatal human development.
J Vis. 8, 14, 1–16 (2008).
2. Horwood, A. M. & Riddell, P. M. The use of cues to convergence and accommodation in naive, uninstructed participants. Vis Res.
48, 1613–1624 (2008).
3. Horwood, A. M. & Riddell, P. M. Accommodation and vergence response gains to different near cues characterize specific
esotropias. Strabismus. 21, 155–164 (2013).
4. Woodhouse, J. M., Meades, J. S., Leat, S. J. & Saunders, K. J. Reduced accommodation in children with Down syndrome. Invest
Ophthalmol Vis Sci. 34, 2382–2387 (1993).
5. Woodhouse, J. M. Visual acuity and accommodation in infants and young children with Down’s syndrome. J Intellect Disabil Res. 40,
49–55 (1996).
6. Woodhouse, J. M. et al. The effect of age, size of target, and cognitive factors on accommodative responses of children with Down
syndrome. Invest Ophthalmol Vis Sci. 41, 2479–2485 (2000).
7. Cregg, M. et al. Accommodation and refractive error in children with Down syndrome: cross-sectional and longitudinal studies.
Invest Ophthalmol Vis Sci. 42, 55–63 (2001).
8. Haugen, O. H. & Høvding, G. Strabismus and binocular function in children with Down syndrome. A population-based,
longitudinal study. Acta Ophthalmol Scand. 79, 133–139 (2001).
9. Stewart, R. E., Woodhouse, J. M., Cregg, M. & Pakeman, V. H. Association between accommodative accuracy, hypermetropia, and
strabismus in children with Down’s syndrome. Optom Vis Sci. 84, 149–155 (2007).
10. Nandakumar, K. & Leat, L. Bifocals in Down Syndrome Study (BiDS): design and baseline visual function. Optom Vis Sci. 86,
196–207 (2009).
11. Anderson, H. A., Manny, R. E., Glasser, A. & Stuebing, K. K. Static and dynamic measurements of accommodation in individuals
with Down syndrome. Invest Ophthalmol Vis Sci. 52, 310–317 (2011).
12. Doyle, L., Saunders, K. J. & Little, J. A. Trying to see, failing to focus: near visual impairment in Down syndrome. Sci Rep. 6, 20444,
doi: 10.1038/srep20444 (2016).
13. Bharadwaj, S. R. et al. Empirical variability in the calibration of slope-based eccentric photorefraction. J Opt Soc Am. 30, 923–931
14. Bharadwaj, S. R. & Candy, T. R. Accommodative and vergence responses to conflicting blur and disparity stimuli during
development. J Vis. 9, 4, 1–18 (2009).
15. Horwood, A. M. & Riddell, P. M. A novel experimental method for measuring vergence and accommodation responses to the main
near visual cues in typical and atypical groups. Strabismus. 17, 9–15 (2009).
16. Blade, P. J. & Candy, T. R. Validation of the PowerRefractor for measuring human infant refraction. Optom Vis Sci. 83, 346–353
17. Bharadwaj, S. R. & Candy, T. R. The effect of lens-induced anisometropia on accommodation and vergence during human visual
development. Invest Ophthalmol Vis Sci. 52, 3593–3603 (2011).
18. Phillips, S. & Stark, L. Blur: a sufficient accommodative stimulus. Doc Ophthalmol. 43, 1, 65–89 (1977).
19. Hung, G. K., Semmlow, J. L. & Ciuffreda, K. J. Identification of accommodative vergence contribution to the near response using
response variance. Invest Ophthalmol Vis Sci. 24, 6, 772–7 (1983).
20. Horwood, A. M. & Riddell, P. M. Differences between naive and expert observers’ vergence and accommodative responses to a range
of targets. Ophthalmic Physiol Opt. 30, 152–159 (2010).
21. Horwood, A. M. & Riddell, P. M. Disparity-driven vs blur-driven models of accommodation and convergence in binocular vision
and intermittent strabismus. J AAPOS. 18, 576–83 (2014).
22. Courage, M. L., Adams, R. J., Reyno, S. & Kwa, P. G. Visual acuity in infants and children with Down syndrome. Dev Med Child
Neurol. 36, 586–593 (1994).
23. Woodhouse, J. M. et al. Refractive errors in young children with Down syndrome. Optom Vis Sci. 74, 844–851 (1997).
24. Cregg, M. et al. Development of refractive error and strabismus in children with Down syndrome. Invest Ophthalmol Vis Sci. 44,
1023–1030 (2003).
25. Tondel, G. M. & Candy, T. R. Accommodation and vergence latencies in human infants. Vis Res. 48, 564–76 (2008).
26. Stewart, R. E., Woodhouse, M. J. & Trojanowska, L. D. In focus: the use of bifocal spectacles with children with Down’s syndrome.
Ophthalmic Physiol Opt. 25, 514–522 (2005).
27. Al-Bagdady, M., Stewart, R. E., Watts, P., Murphy, P. J. & Woodhouse, J. M. Bifocals and Down’s syndrome: correction or treatment?
Ophthalmic Physiol Opt. 29, 416–421 (2009).


  • Down syndrome
  • accommodation
  • convergence


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