Study ID

First author, year of publication

Clinical features and settings

Previous testing and results.
Setting: community/school/clinic (office) setting.

Referral route/selection.

Participants

Sample size.

Socio‐demographic items: age, gender, ethnicity, frequency of ocular abnormalities (i.e. media opacities, which would affect test results/technical failure rates), geographic region.

Study design

Selection: as single group/as separate group with/without target condition.
Enrolment: consecutive series.
Identification: prospective/retrospective.
If more than one test: how were tests allocated to individuals, did each individual receive all tests?

Target condition

Constant and intermittent manifest strabismus (esotropia, exotropia, vertical tropia, microtropia), including the prevalence of the target condition in the sample.

Reference standard

Test definition and description, i.e. cover test; 'comprehensive eye examination' (visual acuity, cover test, cycloplegic refraction).
Test operator(s).
Timing of reference standard.

Index tests

Test definition and description.
Criteria for positive test result.
Details of test operators.
Timing.
Manufacturer.
Technical characteristics.

Follow‐up

How many participants were lost to follow‐up: unknown.
How many have missing or uninterpretable test results: unknown.
Adverse events noted that could be caused by the test: none reported.

Notes

Sources of funding.

Abbreviations.

Anything else of relevance.

Domain

Yes

No

Unclear

PATIENT SELECTION

Describe methods of patient selection: Describe included patients (prior testing, presentation, intended use of index test and setting)

Was a consecutive or random sample of patients enrolled?

Consecutive sampling or random sampling of children according to inclusion criteria.

Non‐random sampling or sampling based on volunteering or referral.

Unclear whether consecutive or random sampling used.

Was a case‐control design avoided?

Yes for all studies since case‐control studies are excluded unless nested in cohort studies.

N/A

N/A

Did the study avoid inappropriate exclusions?

Exclusions are detailed and felt to be appropriate (systemic disease causing strabismus).

Children with known strabismus can be excluded.

Inappropriate exclusions are reported e.g. of children in whom strabismus has been suspected in primary care but not confirmed by trained professionals.

Exclusions are not detailed (pending contact with study authors).

Risk of bias: could the selection of patients have introduced bias?

‐ 

 ‐

 ‐

Concerns regarding applicability: are there concerns that the included patients do not match the review question?

Inclusion of children in community settings, such as school or screening settings, with no previous diagnosis of any eye disease.

Inclusion of children over the age of 6 years, referred to clinical settings, referred to eye professionals for suspect eye disease, or assessed in commercial settings on a volunteer basis; or previous diagnosis of failed screening test or strabismus.

Unclear inclusion criteria.

INDEX TEST 

Describe the index test and how it was conducted and interpreted

Were the index test results interpreted without knowledge of the results of the reference standard?

Test performed "blinded" or "independently and without knowledge of" reference standard results are sufficient and full details of the blinding procedure are not required; or clear temporal pattern to the order of testing that precludes the need for formal blinding.

Reference standard results available to those who conducted or interpreted the index tests.

Unclear whether results are interpreted independently.

If a threshold was used, was it pre‐specified?

Many included index tests are based on continuous measures (e.g. eye deviation, stereopsis, refractive error, visual acuity); the study authors declare that the selected cut‐off used to dichotomise data was specified a priori, or a protocol is available with this information.

A study is classified at higher risk of bias if the authors define the optimal cut‐off post hoc based on their own study data.

No information on pre‐selection of index test cut‐off values.

Risk of bias: could the conduct or interpretation of the index test have introduced bias?

‐ 

 ‐

‐ 

Concerns regarding applicability: are there concerns that the index test, its conduct, or interpretation differ from the review question?

Tests used and testing procedure clearly reported and tests executed by personnel with sufficient training.

Tests used are not validated or study personnel is insufficiently trained.

Unclear tests (e.g. stereopsis‐based tests but does not mention if a validated test is used) or unclear study personnel profile, background and training.

REFERENCE STANDARD

Describe the reference standard and how it was conducted and interpreted

Is the reference standard likely to correctly classify the target condition?

Cover‒uncover test performed by trained professionals, e.g. ophthalmologists, optometrists, orthoptists.

Complete eye examination with cover‒uncover test used as reference standard but not only the cover‒uncover test used to judge on strabismus (e.g. visual acuity measure also used).

Complete eye examination used but unclear whether cover‐uncover test used.

Were the reference standard results interpreted without knowledge of the results of the index test?

Reference standard performed "blinded" or "independently and without knowledge of" index test results are sufficient and full details of the blinding procedure are not required; or clear temporal pattern to the order of testing that precludes the need for formal blinding.

Index test results available to those who conducted the reference standard; or the index test is part of the reference standard (e.g. visual acuity within a compete ophthalmic examination used as reference standard and visual acuity is also the index test analysed ‒ this will be specific of each analysis).

Unclear whether results are interpreted independently.

Risk of bias: could the reference standard, its conduct, or its interpretation have introduced bias?

Concerns regarding applicability: are there concerns that the target condition as defined by the reference standard does not match the review question?

Cover‒uncover test used and testing procedure  executed by personnel with sufficient training.

Cover‒uncover test used  by personnel with inappropriate profile or insufficient training.

Unclear study personnel profile, background and training.

FLOW AND TIMING

Describe any patients who did not receive the index test(s) and/or reference standard or who were excluded from the 2×2 table (refer to flow diagram): describe the time interval and any interventions between index test(s) and reference standard

Was there an appropriate interval between index test(s) and reference standard?

No more than three months between index and reference test execution, and no corrective intervention between assessments.

More than three months between index and reference test execution.

Unclear whether test results are executed within three months.

Did all patients receive a reference standard?

The verification rate of index test‐positive children is definitely higher than that of negative children (the opposite is unlikely).

All children receiving the index test are verified with the reference standard.

Unclear whether all children receiving the index test are verified with the reference standard.

Did all patients receive the same reference standard?

All children are verified with the cover‒uncover test by trained professionals.

Some children, i.e. positive children, are verified with the cover‒uncover test by specialised personnel, while the others are verified by personnel with lower level of training.

Unclear whether all children are verified with the cover‒uncover test by trained professionals.

Were all patients included in the analysis?

The number of children included in the study does not match the number in analyses or children with undefined or borderline test results are excluded. However, children in whom one or more index tests are not performed because they are poorly cooperative can be excluded.

The number of children included in the study does not match the number in analyses and children with undefined or borderline test results are excluded from the analyses.

The number of children analysed, but not that included in the study, are reported; or unclear if there were inappropriate exclusions.

Risk of bias: could the patient flow have introduced bias? 

 ‐

 ‐

 ‐

COMPARATIVE STUDIES (MULTIPLE INDEX TESTS)

Were all tests performed on all patients, or randomly assigned?

All children received all index tests, or tests were randomly assigned.

Not all children received all index tests and the assignment criterion was opportunistic or non‐random (e.g. depending on test availability or type of professional).

Not all children received all index tests and the assignment criterion was unclear.

Could the order in which the index tests were used affect the target condition or the interpretation of the alternative tests? 

The order of presentation of the index test was random or alternate to avoid fatigue effects; or clear that no fatigue effect can arise.

Several tests are delivered in a fixed order which can cause children to be less compliant with the second or later test.

Unclear order of test presentation.

Test type categories

Tests included

Output measure

Threshold to extract data

1) Tests which identify ocular misalignment

1.1) Corneal reflections tests: Hirschberg, Krimsky (prism reflection test).
1.2) Fundus reflections test: Brückner.

Prism dioptres (PD).

8 PD for horizontal deviations; 1 PD for vertical deviations (no published threshold identified).

2) Test of binocular function: stereopsis

Stereoacuity tests such as contour and random dot stereotests.

Seconds of arc.

400 seconds of arc.

3) Tests designed to detect reduced ventral vision

3.1) Visual acuity tests, e.g. HOTV, LEA symbols, Keeler (previously Glasgow) crowded logMAR, Sonksen crowded logMAR, crowded Kay picture test.

3.2) Suppression tests.
3.3) Blur test.

LogMAR or

logMAR equivalent.

0.2 logMAR.

4) Automated refraction devices designed to report ocular misalignment

‐

Millimetres of asymmetry or corneal reflections.

No published threshold identified.