Abstract
Purpose :
The onset and progression of keratoconus is considered to be a complex interplay of genetic and environmental factors, with the 'cause or effect' role of eye rubbing remaining particularly elusive. Keratoconus has much greater prevelence in the Down's syndrome (DS) population, and is largely attributed to eye-rubbing in scientific literature, but has not yet been investigated experimentally. This prospective, case-control observational study explored the associations of eye rubbing, atopy and keratoconus in DS. We hypothesise that significant eye rubbing corresponds to a higher level of atopy and keratoconus in DS.
Methods :
Forty-six subjects were recruited from the Cardiff University Down's syndrome cohort (range 7.5 - 27.8 years, 28 male, 18 female). A diagnosis of keratoconus was made using Scheimflug tomography (Pentacam, Oculus, Germany) in combination with clinical indicators of visual function and slit lamp biomicroscopy. Eyes with previous ocular surgery or co-morbidity were excluded from analysis. Structured questionnaires with graded responses were used to elicit the history of atopy and eye rubbing from family or care team members over a two-week period. Statistical analysis of the correlation between variables was carried out using the Chi-squared test (with Yates’ correction where appropriate) in SPSS (Version 20.0, IBM Corp.).
Results :
In contrast to the hypothesis, and in contrast to what is observed in the non-DS population, there was no significant associations between the prescence of keratoconus and eye rubbing (p = 0.786), keratoconus and atopic dermatitis (p = 0.876) or keratoconus and atopy as a whole (p = 0.734). Of forty-six subjects, two had blepharitis that required intervention, neither had keratoconus nor were observed to rub their eyes.
Conclusions :
These results do not support the hypothesis that keratoconus is associated with eye rubbing nor atopy in this cohort. Keratoconus in the DS cohort may be attributable to an underlying biomechanical weakness or collagen abnormality, and such a group may represent a useful model for further targeted genetic investigations of keratoconus. The majority of subjects with DS were observed not to rub their eyes significantly. Therefore, presumed eye rubbing due to intellectual disability alone should not be a contraindication to contact lenses, collagen cross-linking or corneal grafting in DS.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.