| Study characteristics |
| Patient Sampling |
Prospective case‐control study, involving 50 eyes selected in a single centre in Belgium |
| Patient characteristics and setting |
Scheimpflug single‐image snapshots obtained with Corvis‐ST (Oculus, Germany) were analysed and grouped as follows.
Normal (25 eyes): intraocular pressure of 15–17 mmHg and corneal astigmatism < 0.75 D Keratoconus (25 eyes): various stages of keratoconus, including clear cornea, non‐severe corneal thinning, Fleischer's ring at the apex, and anterior or posterior corneal steepening
|
| Index tests |
The combination of central corneal thickness with microscopic parameters extracted from statistical modelling of light intensity distribution |
| Target condition and reference standard(s) |
The definition of keratoconus is unclear. The classification was performed by only 1 experienced ophthalmologist, before the index test. |
| Flow and timing |
All cases were included in the reference standard and index test. All data were included in a 2 × 2 table. |
| Comparative |
Not applicable. |
| Notes |
This project received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 779960 and support from the Statutory Funds of Wroclaw University of Science and Technology. MW received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 666295 and from the financial resources for science in the years 2016 to 2019 awarded by the Polish Ministry of Science and Higher Education for the implementation of an international co‐financed project. JJR received a grant from the Flemish Fund for Scientific Research (FWO‐TBM T000416N). |
| 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? |
No |
|
|
| 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? |
Yes |
|
|
| If a threshold was used, was it pre‐specified? |
Yes |
|
|
| Was the model designed in an appropriate manner? |
Yes |
|
|
| Could the conduct or interpretation of the index test have introduced bias? |
|
Low 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? |
No |
|
|
| 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? |
|
High 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? |
Yes |
|
|
| Were all patients included in the analysis? |
Yes |
|
|
| Could the patient flow have introduced bias? |
|
Low risk |
|
| DOMAIN 5: Comparative |
