| Study characteristics |
| Patient Sampling |
Participants were selected from 4 different hospitals: Department of Ophthalmology of the Ohio State University, Columbus, Ohio; Clinica de Oftalmologia de Cali, Pontificia Universidad Javeriana, Cali, Colombia; Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas; and Department of Ophthalmology, University Hospital of Bern, Inpelspital, Bern, Switzerland. |
| Patient characteristics and setting |
People with keratoconus were clinically identified by characteristic refractive and slit‐lamp signs (e.g. unstable refraction; oblique astigmatism; irregular retinoscopic and keratometry mires; and biomicroscopic signs such as Vogt's striae or Fleischer's ring) and no history of corneal surgery. Normal subjects had no documented history of corneal disease or corneal surgery. |
| Index tests |
Logistic regression. The algorithm included both anterior and posterior curvature maps; results were divided into 3 categories: normal (0–0.25), suspect (0.25–0.8), and keratoconus (0.8–1.0). |
| Target condition and reference standard(s) |
Tomography images from the Galilei Dual Scheimpflug‐Placido tomographer were used. It was unclear how the reference standard made the diagnosis; however, all cases were diagnosed before the index test analysed them. |
| Flow and timing |
It was unclear whether all participants received the same reference standard, but all cases were diagnosed before inclusion. |
| Comparative |
Not applicable |
| Notes |
No funding source mentioned. |
| Methodological quality |
| Item |
Authors' judgement |
Risk of bias |
Applicability concerns |
| DOMAIN 1: Patient selection |
| Was a consecutive or random sample of patients enrolled? |
No |
|
|
| Was a case‐control design avoided? |
No |
|
|
| Did the study avoid inappropriate exclusions? |
Unclear |
|
|
| Could the selection of patients have introduced bias? |
|
High risk |
|
| Are there concerns that the included patients and setting do not match the review question? |
|
|
High |
| DOMAIN 2: Index test (All tests) |
| Were the index test results interpreted without knowledge of the results of the reference standard? |
Unclear |
|
|
| If a threshold was used, was it pre‐specified? |
Unclear |
|
|
| Was the model designed in an appropriate manner? |
Yes |
|
|
| Could the conduct or interpretation of the index test have introduced bias? |
|
Unclear risk |
|
| Are there concerns that the index test, its conduct, or interpretation differ from the review question? |
|
|
Low concern |
| DOMAIN 3: Reference standard |
| Is the reference standard likely to correctly classify the target condition? |
Unclear |
|
|
| Were the reference standard results interpreted without knowledge of the results of the index tests? |
Yes |
|
|
| Could the reference standard, its conduct, or its interpretation have introduced bias? |
|
Unclear risk |
|
| Are there concerns that the target condition as defined by the reference standard does not match the question? |
|
|
Low concern |
| DOMAIN 4: Flow and timing |
| Did all patients receive the same reference standard? |
Unclear |
|
|
| Were all patients included in the analysis? |
Yes |
|
|
| Could the patient flow have introduced bias? |
|
Unclear risk |
|
| DOMAIN 5: Comparative |
