Proportions with keratoconus in persons with Down syndrome (studies identified by literature review)
| n DS | n (%) KC | Location | CT | Patient group and age | |
| Walsh18 | 91 | 7 (8%) | Sweden | No | Institutionalised mentally retarded persons (5–60 years). |
| Wong and Ho19 | 140 | 0 (0%) | Hong Kong | No | Children (3 months–13 years) in hospital. |
| Van Allen et al29 | 38 | 6 (15.8%) | USA | No | Adults (30–68 years old) in residential centre. |
| Haugen et al15 | 47 | 5 (10.6%) | Norway | Yes | Case–control study (all ages) |
| Kim et al25 | 123 | 0 (0%) | Korea | No | Children (6 months–14 years), non-institutionalised. |
| Van Splunder et al30 | 409 | 36 (9%) | Netherlands | No | Cross-sectional survey. Adults (≥18 years) |
| Liza-Sharmini et al26 | 60 | 0 (0%) | Malaysia | No* | Children (1 month–17 years) in hospital. |
| Fimiani et al20 | 157 | 0 (0%) | Italy | No | Children (1 month–18 years) in hospital. |
| Karlica et al24 | 153 | 2 (1.3%) | Split-Dalmatia | No | Children (0–18 years). |
| Fong et al21 | 91 | 1 (1%) | Hong Kong | No† | Cross-sectional survey. Adults (≥18 years) |
| Aslan et al16 | 27 | 21.1% (11 eyes) | Helsinki | Yes | Children (5–12 years). Clinical trial. Identified early subclinical keratoconus. |
| Li et al33 | 20 | 36.3% (12 eyes) | Hong Kong | Yes‡ | Adult patients scheduled for cataract surgery (tertiary eye hospital) |
| Real de Asua et al28 | 144 | 10 (7%) | Spain | Unknown | Retrospective review of medical records. Adults (17–65 years) |
| Alio et al13 | 59§ | 42 (71.3%) | Spain and Egypt | Yes | Multicentre case–control study. Age 3 months–60 years. |
| Marsack et al27 | 140 | 11.8%–20.8%¶ (26–46 eyes) | USA | Yes | Case–control study. Age 8–55 years |
| Hashemi et al22 | 226 | 28 (12.4%) | Iran | Yes | Population-based cohort study. Age 10–30 years. |
| Imbornoni et al23 | 31 | 10 (32%) | USA | Yes | Children/young adults (4–24 years) in hospital. |
| Mathan et al32 | 98 | 30 (30.6%) ** | New Zealand | Yes | Screening of paralympics athletes (age 15–53 years) |
| Bermudez et al31 | 1207 | 331 (27.2%) | Brazil | Yes‡ | Retrospective review of medical records. Adults (all ages) |
| Kristianslund and Drolsum34 | 4342 | 238 (5.5%) | Norway | Yes†† | Population-based register study. All ages. |
*Placido disc used to detect keratoconus.
†Corneal thickness measured.
‡when KC suspected and the patient cooperated.
§Number of patients that cooperated with eye examination.
¶Proportion above threshold on detection metric (two types used).
**Presents several numbers.
††Performed in many cases when indicated and the patient cooperated, however, proportion unknown.
CT, corneal topography/tomography; DS, Down Syndrome; KC, keratoconus; n, number.