Cao 2021a.

Study characteristics
Patient Sampling	Single‐centre, retrospective, case‐control study. The data collection was conducted at the Royal Victorian Eye and Ear Hospital in Australia from between 2007 and 2019.
Patient characteristics and setting	Subclinical keratoconus group: subjects were defined as those eyes with abnormal corneal tomography, including I‐S localized steepening or an asymmetric bowtie pattern, but without detectable clinical signs on slit‐lamp biomicroscopy and retinoscopy examination. The control group consisted of eyes that had no known history of any corneal disorder, but may have presented with another ocular condition that did not introduce a corneal change.
Index tests	Random forest‐based model trained using a modest number (15) of components derived from a reduced dimensionality representation of complete Pentacam system parameters.
Target condition and reference standard(s)	The diagnosis was made by an experienced optometrist together with > 1 cornea specialist, using Pentacam corneal tomography system; cases were classified before the inclusion.
Flow and timing	All cases were included in reference standard and index. All data were included in a 2 × 2 table.
Comparative	Not applicable
Notes	This study was supported by the Australian National Health and Medical Research Council (NHMRC) project Ideas grant APP1187763 and Senior Research Fellowship (1138585 to PNB), Lions Eye Donation Service (SS), Angior Family Foundation (SS), Perpetual Impact Philanthropy grant (SS), and Keratoconus Australia Funding (SS). The Centre for Eye Research Australia (CERA) receives Operational Infrastructure Support from the Victorian Government. The sponsor or funding organizations had no role in the design or conduct of this research.
Methodological quality
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient selection
Was a consecutive or random sample of patients enrolled?	Unclear
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?	No
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?	Yes
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?		Low 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