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Meta-Analysis
. 2020 May 28;5(5):CD012947.
doi: 10.1002/14651858.CD012947.pub2.

Non-contact tests for identifying people at risk of primary angle closure glaucoma

Anish Jindal  1 , Irene Ctori  1 , Gianni Virgili  2 , Ersilia Lucenteforte  3 , John G Lawrenson  4
Affiliations
Meta-Analysis

Non-contact tests for identifying people at risk of primary angle closure glaucoma

Anish Jindal et al. Cochrane Database Syst Rev. .

Abstract

Background: Primary angle closure glaucoma (PACG) accounts for 50% of glaucoma blindness worldwide. More than three-quarters of individuals with PACG reside in Asia. In these populations, PACG often develops insidiously leading to chronically raised intraocular pressure and optic nerve damage, which is often asymptomatic. Non-contact tests to identify people at risk of angle closure are relatively quick and can be carried out by appropriately trained healthcare professionals or technicians as a triage test. If the test is positive, the person will be referred for further specialist assessment.

Objectives: To determine the diagnostic accuracy of non-contact tests (limbal anterior chamber depth (LACD) (van Herick test); oblique flashlight test; scanning peripheral anterior chamber depth analyser (SPAC), Scheimpflug photography; anterior segment optical coherence tomography (AS-OCT), for identifying people with an occludable angle.

Search methods: We searched the following bibliographic databases 3 October 2019: CENTRAL; MEDLINE; Embase; BIOSIS; OpenGrey; ARIF and clinical trials registries. The searches were limited to remove case reports. There were no date or language restrictions in the searches.

Selection criteria: We included prospective and retrospective cross-sectional, cohort and case-control studies conducted in any setting that evaluated the accuracy of one or more index tests for identifying people with an occludable angle compared to a gonioscopic reference standard.

Data collection and analysis: Two review authors independently performed data extraction and quality assessment using QUADAS2 for each study. For each test, 2 x 2 tables were constructed and sensitivity and specificity were calculated. When four or more studies provided data at fixed thresholds for each test, we fitted a bivariate model using the METADAS macro in SAS to calculate pooled point estimates for sensitivity and specificity. For comparisons between index tests and subgroups, we performed a likelihood ratio test comparing the model with and without the covariate.

Main results: We included 47 studies involving 26,151 participants and analysing data from 23,440. Most studies were conducted in Asia (36, 76.6%). Twenty-seven studies assessed AS-OCT (analysing 15,580 participants), 17 studies LACD (7385 participants), nine studies Scheimpflug photography (1616 participants), six studies SPAC (5239 participants) and five studies evaluated the oblique flashlight test (998 participants). Regarding study quality, 36 of the included studies (76.6%) were judged to have a high risk of bias in at least one domain.The use of a case-control design (13 studies) or inappropriate exclusions (6 studies) raised patient selection concerns in 40.4% of studies and concerns in the index test domain in 59.6% of studies were due to lack of masking or post-hoc determination of optimal thresholds. Among studies that did not use a case-control design, 16 studies (20,599 participants) were conducted in a primary care/community setting and 18 studies (2590 participants) in secondary care settings, of which 15 investigated LACD. Summary estimates were calculated for commonly reported parameters and thresholds for each test; LACD ≤ 25% (16 studies, 7540 eyes): sensitivity 0.83 (95% confidence interval (CI) 0.74, 0.90), specificity 0.88 (95% CI 0.84, 0.92) (moderate-certainty); flashlight (grade1) (5 studies, 1188 eyes): sensitivity 0.51 (95% CI 0.25, 0.76), specificity 0.92 (95% CI 0.70, 0.98) (low-certainty); SPAC (≤ 5 and/or S or P) (4 studies, 4677 eyes): sensitivity 0.83 (95% CI 0.70, 0.91), specificity 0.78 (95% CI 0.70, 0.83) (moderate-certainty); Scheimpflug photography (central ACD) (9 studies, 1698 eyes): sensitivity 0.92 (95% CI 0.84, 0.96), specificity 0.86 (95% CI 0.76, 0.93) (moderate-certainty); AS-OCT (subjective opinion of occludability) (13 studies, 9242 eyes): sensitivity 0.85 (95% CI 0.76, 0.91); specificity 0.71 (95% CI 0.62, 0.78) (moderate-certainty). For comparisons of sensitivity and specificity between index tests we used LACD (≤ 25%) as the reference category. The flashlight test (grade 1 threshold) showed a statistically significant lower sensitivity than LACD (≤ 25%), whereas AS-OCT (subjective judgement) had a statistically significant lower specificity. There were no statistically significant differences for the other index test comparisons. A subgroup analysis was conducted for LACD (≤ 25%), comparing community (7 studies, 14.4% prevalence) vs secondary care (7 studies, 42% prevalence) settings. We found no evidence of a statistically significant difference in test performance according to setting. Performing LACD on 1000 people at risk of angle closure with a prevalence of occludable angles of 10%, LACD would miss about 17 cases out of the 100 with occludable angles and incorrectly classify 108 out of 900 without angle closure.

Authors' conclusions: The finding that LACD performed as well as index tests that use sophisticated imaging technologies, confirms the potential for this test for case-detection of occludable angles in high-risk populations. However, methodological issues across studies may have led to our estimates of test accuracy being higher than would be expected in standard clinical practice. There is still a need for high-quality studies to evaluate the performance of non-invasive tests for angle assessment in both community-based and secondary care settings.

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Conflict of interest statement

AJ: Received funding for a PhD studentship from the College of Optometrists and a doctoral progress award from City, University of London, there are no conflicts of interest in publishing this review. IC: None known GV: None known ESL: None known JL: Recieved grant income from NIHR, IGA and the College of Optometrists for projects outside the submitted review.

Figures

1
1
Clinical Pathway
2
2
Study flow diagram.
3
3
Risk of bias and applicability concerns graph: review authors' judgements about each domain presented as percentages across included studies
4
4
Risk of bias and applicability concerns summary: review authors' judgements about each domain for each included study
5
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Summary ROC Plot of LACD with thresholds of 0%, ≤5%, ≤15%, ≤ 25% or <25%, ≤40%, >25% to ≤50%. Summary point estimate and confidence region shown for LACD ≤ 25%.
6
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Summary ROC Plot of the flashlight test with thresholds of grade 1 and grade 2. Summary point estimate and confidence region shown for flashlight grade 1.
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Summary ROC Plot of SPAC with thresholds of S or P, S, ≤ 4, ≤ 5, ≤ 5 and or S or P, ≤ 6, ≤ 6 and or S or P.
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Summary ROC Plot of Scheimpflug photography with thresholds of ACV, ACD (central), ACA. and ACD (peripheral). Summary point estimate and confidence region shown for ACD (central).
9
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Summary ROC Plot of AS‐OCT with thresholds of subjective judgement), AOD 500 temporal, AOD 500 nasal, AOD 750 temporal, TISA 500 temporal, TISA 500 nasal, TISA 750 temporal, TISA 750 nasal, ACA angle, ACA area, ACD, ACV, ARA 500 average, ARA 750 average, ARA 750 nasal and LV. Summary point estimate and confidence region shown for AS‐OCT (subjective judgement).
10
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Summary ROC of tests: 4 Direct comparison: LACD ≤ 25% or <25%, 20 Direct comparison: AS‐OCT (subjective judgement).
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Summary ROC Plot of tests: 4 Direct comparison: LACD ≤ 25% or < 25%, 17 Direct comparison: Scheimpflug photography ACD (central).
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Summary ROC Plot of tests: 4 Direct comparison: LACD ≤ 25% or < 25%, 7 Direct comparison: Flashlight grade 1.
1
1. Test
LACD 0%
2
2. Test
LACD ≤ 5%
3
3. Test
LACD ≤ 15%
4
4. Test
LACD ≤ 25% or <25%
5
5. Test
LACD ≤ 40%
6
6. Test
LACD > 25% to ≤ 50%
7
7. Test
Flashlight grade 1
8
8. Test
Flashlight grade 2
9
9. Test
SPAC S or P
10
10. Test
SPAC S
11
11. Test
SPAC ≤ 4
12
12. Test
SPAC ≤ 5
13
13. Test
SPAC ≤ 5 and or S or P
14
14. Test
SPAC ≤6
15
15. Test
SPAC ≤ 6 and or S or P
16
16. Test
Scheimpflug photography ACV
17
17. Test
Scheimpflug photography ACD (central)
18
18. Test
Scheimpflug photography ACA
19
19. Test
Scheimpflug photography ACD (peripheral)
20
20. Test
AS‐OCT (subjective judgement)
21
21. Test
AS‐OCT AOD 500 temporal
22
22. Test
AS‐OCT AOD 500 nasal
23
23. Test
AS‐OCT AOD 750 temporal
24
24. Test
AS‐OCT AOD 750 nasal
25
25. Test
AS‐OCT AOD 500 average
26
26. Test
AS‐OCT TISA 500 temporal
27
27. Test
AS‐OCT TISA 500 nasal
28
28. Test
AS‐OCT TISA 500 average
29
29. Test
AS‐OCT TISA 750 temporal
30
30. Test
AS‐OCT TISA 750 nasal
31
31. Test
AS‐OCT TISA 750 average
32
32. Test
AS‐OCT ACA
33
33. Test
AS‐OCT ACA area
34
34. Test
AS‐OCT ACD
35
35. Test
AS‐OCT ACV
36
36. Test
AS‐OCT ARA 500 average
37
37. Test
AS‐OCT ARA 750 nasal
38
38. Test
AS‐OCT ARA750 temporal
39
39. Test
AS‐OCT ARA 750 average
40
40. Test
AS‐OCT ITC index ≥35%
41
41. Test
AS‐OCT ITC index ≥50%
42
42. Test
AS‐OCT ITC index ≥70%
43
43. Test
AS‐OCT ITC index ≥75%
44
44. Test
AS‐OCT LV
See this image and copyright information in PMC

Update of

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References to studies excluded from this review

Addepalli 2019 {published data only}
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Annoh 2019 {published data only}
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Baskaran 2015 {published data only}
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Foo 2012 {published data only}
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Forsius 1991 {published data only}
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Guo 2015 {published data only}
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Hadziahmetovic 2014 {published data only}
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He 2012 {published data only}
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Kalev‐landoy 2007 {published data only}
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Khalil 1975 {published data only}
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Kim 2012 {published data only}
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Liu 2011 {published data only}
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Lu 1980 {published data only}
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Matonti 2011 {published data only}
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Narayanaswamy 2013 {published data only}
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Nongpiur 2010 {published data only}
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Nongpiur 2013 {published data only}
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Nongpiur 2014 {published data only}
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Nongpiur 2017 {published data only}
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Nuriyah 2010 {published data only}
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Pekmezci 2009 {published data only}
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Rojananuangnit 2016 {published data only}
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Sah 2007 {published data only}
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Sasikumar 2011 {published data only}
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Scalamogna 2002 {published data only}
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Zhang 2008 {published data only}
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Zhang 2010 {published data only}
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