Castro‐Luna 2020.

Study characteristics
Patient Sampling	Retrospective single‐centre case‐control study in 60 eyes from 60 people from the Department of keratoconus of INVISION Ophthalmology clinic in Almería, Spain
Patient characteristics and setting	Participants were divided into the following 2 groups depending on their preliminary diagnosis based on the classical topographic criteria. Control group without topographic alteration (30 eyes) Keratoconus group (30 eyes). The keratoconus group included people with asymmetric bow tie in the topographic image and ≥ 1 sign of keratoconus in the examination with the slit lamp, such as stromal thinning, conical protrusion of the cornea at the apex, Fleischer's ring, Vogt's striae, or anterior stromal scar. Grade 4 keratoconus with excessively distorted corneal topography was excluded. All cases were examined using the CSO topography system (CSO, Firenze, Italy).
Index tests	Bayesian network classifier for keratoconus identification that uses previously developed topographic indices, calculated directly from the digital analysis of the Placido ring images.
Target condition and reference standard(s)	It is unclear who performed the selection and classification. However, cases were classified before inclusion.
Flow and timing	All cases were included in the reference standard and index. All data were included in a 2 × 2 table.
Comparative	Not applicable
Notes	This research was partially supported by the Andalucian regional government (grant PIN‐0530‐2017). Research of A.M.‐F. and D.R.‐L. was also supported in part by the Spanish Government – European Regional Development Fund (grant MTM2017‐89941‐P), the Andalucian regional government (research group FQM‐229), and the University of Almería (Campus de Excelencia Internacional del Mar CEIMAR). A.M.‐F. acknowledges an additional support from the Carlos I Institute of Theoretical and Computational Physics, while D.R.‐L. thanks the support from CDTIME (Center for Development and Transfer of Mathematical Research to Industry, University of Almería).
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?	No
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?			Unclear
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?	Yes
Were all patients included in the analysis?	Yes
Could the patient flow have introduced bias?		Low risk
DOMAIN 5: Comparative