April 2014
Volume 55, Issue 13
Free
ARVO Annual Meeting Abstract  |   April 2014
Detecting early keratoconus in Down's syndrome
Author Affiliations & Notes
  • Stephanie Campbell
    School of Optometry and Vision Sciences, Cardiff University, Cardiff, United Kingdom
    Cardiff Centre for Vision Sciences, Cardiff University, Cardiff, United Kingdom
  • J. M Woodhouse
    School of Optometry and Vision Sciences, Cardiff University, Cardiff, United Kingdom
  • Keith M Meek
    Cardiff Centre for Vision Sciences, Cardiff University, Cardiff, United Kingdom
  • Footnotes
    Commercial Relationships Stephanie Campbell, None; J. Woodhouse, None; Keith Meek, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science April 2014, Vol.55, 4203. doi:https://doi.org/
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    • Get Citation

      Stephanie Campbell, J. M Woodhouse, Keith M Meek; Detecting early keratoconus in Down's syndrome. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4203. doi: https://doi.org/.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract
 
Purpose
 

Keratoconus is significantly more prevalent in young people with Down's syndrome (DS) than in the typical aged-matched population. However, patients who have DS are unlikely to report early changes in vision both because of their communicative limitations, and because the DS visual system is inherently less sensitive than that in typically developing young people. As a result, presenting disease is commonly moderate to advanced, creating challenges for contact lens fitting and corneal grafting. Early diagnosis is a priority for young people with DS, so that they can benefit from interventions such as corneal cross-linking, but this diagnosis is difficult owing to a naturally steeper, thinner cornea, which is present even in healthy individuals with DS. The current study evaluates corneal and visual norms of young people with DS and suggests indicators which should raise suspicion of keratoconus during screening in this population.

 
Methods
 

A case-control study was conducted involving 56 eyes of 31 subjects (17 male, 14 female) with DS. The age range was 7 to 26 years (mean±SD 18.19±5.12). The subjects underwent corneal examination including slit lamp biomicroscopy, corneal tomography analysis using Pentacam (Oculus GmbH, Wetzlar, Germany) and biomechanical evaluation using Ocular Response Analyzer (Reichert, Buffalo, NY). Optometric data including best corrected spectacle visual acuity, contrast sensitivity, binocular status and spectacle refraction were obtained. Subjects were classified using a modified Amsler-Krumeich approach prior to statistical analysis.

 
Results
 

The current cohort of young people with DS have a lower corneal resistance factor (mean±SD 8.7±2.2) than has been noted in typical subjects of a similar age in other published studies. In the non-keratoconic eyes examined, a minimum corneal thickness of as little as 378μm was noted (range 378μm to 575μm), whilst the maximum corneal power was 47.7D (range 42.6D to 27.7D). The range of regular corneal astigmatism was 0.1D to 1.6D. Corneal astigmatism >1.60D and corneal power >50D are each significant risk factors for keratoconus in DS.

 
Conclusions
 

Young people with DS, even without keratoconus, display an altered biomechanical status. Standard topographical and pachymetric indices for the identification of keratoconus in DS, are on their own, inappropriate, and this carries implications for monitoring and diagnosis in primary and secondary care.

 
Keywords: 574 keratoconus • 479 cornea: clinical science  
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