Prevalence of Keratoconus in Persons With Down Syndrome in a National Registry in Norway

Abstract

This cross-sectional study evaluates the association of keratoconus with Down syndrome by estimation of the prevalence of keratoconus in persons with Down syndrome in Norway.

Prevalence of keratoconus in persons with Down syndrome: a review

“…15 Several studies from general populations have found a male predominance for keratoconus, 3 6 40 54-56 although this finding has not been consistent. 2 5 39 57 In this literature review, we identified one publication that found a similar gender distribution among persons with Down syndrome and keratoconus, 22 which is consistent with our recent publication, 34 otherwise, the gender distribution does not seem to have been in focus. There seem to be slightly more male than female persons with Down syndrome.…”

“…16 23 26 28 29 33 Thus, a total of 19 articles met the inclusion criteria for the review. In addition, we have included results from our recently published nationwide register study of the keratoconus prevalence in persons with Down syndrome 34 As shown in table 1, the reported rates in these publications ranged from 0% to 71%. Another three studies were considered relevant, although they did not quantify the rate of keratoconus: one study found a high proportion of astigmatism and myopia in persons with Down syndrome 14 ; another found a steeper corneal curvature on topography in persons with Down syndrome compared with controls 35 and a third showed that corneal topographic changes in persons with Down syndrome were more similar to mild keratoconus than in controls.…”

“…13 15 16 18-30 Only one study reported nationwide numbers, estimating a keratoconus prevalence of 5.5% among persons with Down syndrome. 34 Most previous studies have estimated a keratoconus prevalence in the range of 17.5-86 per 100 000 in general populations. 2 38-42 However, markedly higher numbers have been reported in some recent studies of general populations, with an estimated prevalence of 0.2% in Norway, 4 0.3% in the Netherlands 3 and 1.2% in a younger population in Australia.…”

“…This review identified rates in the range of 10.6%-71.3% in studies that included corneal topography as part of the examination of mainly adult patients (table 1). 13 15 16 22 23 27 31 32 In a study from Norway, we reported a national prevalence of keratoconus in persons with Down syndrome using data from a nationwide patient registry, 34 thereby avoiding the risk of selection bias. We found a keratoconus rate of 5.5% in this subgroup, which is 30 times the estimated keratoconus prevalence in the general Norwegian population.…”

“…13 15 16 22 23 27 31 32 Our recently published study was the only one that included the whole population of a country. 34 Still, its quality of evidence was limited by the lack of detailed clinical data. Two studies were screened for keratoconus in selected samples of the population with Down syndrome, 22 32 otherwise, we identified no large population-based screening studies.…”