Diagnostic Accuracy of Amsler Grid Test Moderate for AMD Detection

Article

A new analysis cautions against the use of the Amsler grid test, suggesting its performance is not at a level recommended for monitoring in a patient population with an a priori risk of nAMD.

Yousif Subhi, MD, PhD

Yousif Subhi, MD, PhD

Key Takeaways

What was the goal of the study?

  • A recent systematic review and meta-analysis investigated the diagnostic accuracy of the Amsler grid test for detecting nAMD, widely recommended due to its ease of use and low cost.

What did the study find?

  • In 10 studies, the sensitivity and specificity of the Amsler grid to diagnose nAMD versus non-neovascular AMD were reported as low and moderate, respectively.

What were the conclusions?

  • Physicians recommending the Amsler grid self-assessment should also encourage patients to undergo regular ophthalmic examination, regardless of Amsler grid results.

A recent systematic review and meta-analysis investigated the diagnostic accuracy of the Amsler grid test for detecting neovascular age-related macular degeneration (nAMD), widely recommended due to its ease of use and low cost.

Within the analysis, the findings suggest the accuracy of the Amsler grid test in eyes with a priori risk nAMD was moderate, indicating that while inexpensive, the actual performance is not at a level typically recommended for monitoring nAMD development.1

“Although the Amsler grid may perform well in some cases, it may also provide a false sense of security in others,” wrote investigators.1 “...Thus, physicians recommending the Amsler grid self-assessment should also encourage patients to undergo ophthalmic examination regularly, regardless of Amsler grid results.”

Healthcare professionals often recommend the Amsler grid to patients for self-assessment to facilitate early detection of nAMD, popularized in the 1940s as a tool to detect central vision metamorphopsia and relative scotoma. However, patients with AMD without neovascularization may report subjective changes to the Amsler grid, leading to unnecessary consultations and worry. A normal read on the Amsler grid may additionally convince patients to not visit an ophthalmologist in time and delay diagnosis or worsen visual outcomes.

A systematic literature review was performed by Yousif Subhi, MD, PhD, Department of Clinical Research, University of Southern Denmark in 12 databases for relevant titles from database inception until May 2022. The investigator team considered any study with 2 separate groups of eyes defined as having nAMD and either healthy eyes or eyes with non-neovascular AMD. Investigators defined healthy eyes or eyes with non-neovascular AMD as having no retinal abnormalities apart from other subtypes of AMD (early, intermediate, or late nonexudative AMD).

Eligible studies used the Amsler grid test as the index test and had to provide data qualified for diagnostic test accuracy calculation on the index test. Reference standards required studies to have performed an ophthalmic examination or have obtained a diagnosis of the ophthalmic condition from a previous exam.

Investigators extracted data regarding study design and characteristics, population characteristics, methodological details regarding index test and reference standard, and results regarding the diagnostic test accuracy of the Amsler grid (true-positive, false-positive, true-negative, false-negative) for detecting nAMD. The outcomes of interest were used to calculate sensitivity and specificity for detection in 2 settings: healthy control participants as the comparator and nonexudative AMD as the comparator.

The search identified 523 records and after the screening, 10 studies with a total of 1890 eyes were eligible for qualitative and quantitative review. Studies collectively included 425 eyes with nAMD, 1262 eyes with non-neovascular AMD, and 203 healthy control eyes. The studies were conducted between 2003 and 2015 and the mean participant age ranged from 62 to 83 years.

Investigators summarized the diagnostic test accuracy of the Amsler grid for the detection of nAMD in 2 identified scenarios. In the first, the comparator or control participants were those without retinal pathology. After analysis, investigators calculated a summary estimate of the diagnostic test accuracy to be 67% sensitivity (95% confidence interval [CI], 51% – 79%) and 99% specificity (95% CI, 85% – 100%).

In the second scenario, the comparator or control participants were those with non-neovascular AMD. The calculations suggest a summary estimate of the diagnostic test accuracy to be 71% (95% CI, 60% - 80%) and 63% (95% CI, 49% - 51%), for sensitivity and specificity, respectively.

Based on the findings, investigators noted fluorescein angiography and OCT angiography remain the best methods for detecting nAMD, as newer methods for evaluation of metamorphopsia remain in an early stage.

“From a screening perspective, increasing access to OCT alone can be expected to provide a significant improvement in detection of nAMD,” they wrote.1

References

1. Bjerager J, Schneider M, Potapenko I, et al. Diagnostic Accuracy of the Amsler Grid Test for Detecting Neovascular Age-Related Macular Degeneration: A Systematic Review and Meta-analysis. JAMA Ophthalmol. Published online February 16, 2023. doi:10.1001/jamaophthalmol.2022.6396

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