Amsler Grid Test Not Recommended for Early AMD Detection

Age-related macular degeneration (AMD) in its early stages was not as readily detected by using the Amsler grid test compared with other methods, according to a study published in JAMA Ophthalmology. Researchers determined that patients attempting to assess their risk of developing neovascular AMD would be better served with alternative methods.

The Amsler grid is recommended by health professionals to detect central vision metamorphopsia and relative scotoma. Patients can self-assess using the grid to enable early detection of neovascular AMD. However, researchers found that patients often feel the grid appears normal, which puts off a trip to the ophthalmologist and, therefore, timely treatment. This review aimed to assess the overall accuracy of the Amsler grid in diagnosing neovascular AMD.

Studies that evaluated eyes with neovascular AMD, healthy eyes, and eyes with nonneovascular AMD were considered. Healthy eyes were defined as those without retinal abnormalities outside of subtypes of AMD. Studies that used the Amsler grid test were considered, and eligible studies included data on diagnostic test accuracy calculation. Eligible studies also had to have an ophthalmic examination or had a diagnosis from a previous examination.

The researchers used PubMed, Embase, Cochrane Central, ClinicalTrials.gov, Web of Science Core Collection, BIOSIS Previews, Current Contents Connect, Data Citation Index, Derwent Innovations Index, KCI Korean Journal Database, Russian Science Citation Index, and SciELO Citation Index to search for studies on May 7, 2022. Data on study design, population characteristics, methodological details, and results were all extracted from the studies.

There were 10 studies that were included in the review, which included data on 2524 eyes that used the Amsler grid. All of the studies were conducted between 2003 and 2015, with the studies originating from Germany, the United States, Brazil, Israel, and Poland, and 1 international collaboration study. All but 1 study were cross-sectional and all but 1 study were prospective.

There were 425 eyes with neovascular AMD, 1262 eyes with nonneovascular AMD, and 203 healthy eyes, with mean age of the participants ranging from 62 to 83 years and women making up 40% to 68% of each study sample. A reference test was defined as a clinical exam; the index test was defined as the Amsler grid test.

When evaluating the prevalence of metamorphopsia in macular diseases, a study found that metamorphosia in neovascular AMD was centrally located in the Amsler grid, with other types of AMD less likely to lead to metamorphopsia.

There were 3 studies that found that the preferential hyperacuity perimeter (PHP) for detecting neovascular AMD was more sensitive than the Amsler grid for detection. There was 1 study that found that the Amsler grid was more accurate in detecting intermediate AMD and classic choroidal neovascularization (CNV) compared with PHP, which was more accurate in detecting occult CNV. Studies also found that both methods had similar diagnostic accuracy and revealed metamorphopsia, and that earlier stages of AMD had positive Amsler grid or PHP findings.

A study that compared diagnostic accuracy of non-PHP modalities compared with the Amsler grid found that the Amsler grid had a higher sensitivity. M-charts were found to have a higher sensitivity than Amsler grids in 1 study, and a 3-dimensional computer automated threshold Amsler grid was able to detect cases of dry and neovascular AMD that weren’t detected by the standard Amsler grid.

Differences in disease definition across studies could have been caused by the adoption of ocular coherence tomography in the time span of the selected studies. The Amsler grid test was performed with supervision in the selected studies, which may not accurately reflect self-assessment. Retrospective studies could have selection, ascertainment, or information biases. Differences across studies could be explained through the different distributions of CNV.

The researchers concluded that caution should be applied when using the Amsler grid test to detect neovascular AMD in at-risk patients, as its performance is not sufficient for monitoring when patients have signs of early or dry AMD.

Reference

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