Amsler grid test: diagnostic accuracy assessed
Ophthalmologists have relied on Amsler grid test accuracy regarding AMD diagnosis. But a new study is shaking up long-standing knowledge on this.
International meta-analysis reviews the Amsler grid test
A team of international researchers has conducted a systematic review of various AMD studies. Globally, age-related macular degeneration (AMD) is responsible for around 8.7% of cases of blindness. The aim of this review was to examine the diagnostic accuracy of the Amsler grid test in the diagnosis of neovascular AMD. A total of 12 databases were searched for relevant titles on this topic. The study selection included the following groups:
- Eyes with neovascular AMD.
- Eyes with non-neovascular AMD.
- Healthy eye2
Of the total 523 records screened, only 10 studies with a total of 1,890 eyes were selected for the meta-analysis. The mean age of the participants ranged from 62 to 83 years. When patients with neovascular AMD were compared with healthy control participants, the sensitivity for the diagnosis of neovascular AMD was 67%. In contrast, the specificity for this group comparison was 99%. The situation was different when patients with neovascular AMD were compared with patients with non-neovascular AMD.
Here, the sensitivity was 71% and the specificity 63%. The international research team came to the following conclusion: Even though the Amsler grid test is a simple and inexpensive method for detecting metamorphopsia, the sensitivity is at a rather low level. Normally, methods with such a level are not recommended for surveillance. Regular ophthalmological examinations are currently the only reliable method to detect neovascular AMD (nAMD) in time.2
"EDNA" study tests non-invasive diagnostics in nAMD
The accuracy of previously used tests for the detection of neovascular AMD had also been the subject of the recently published "EDNA diagnostic accuracy study". The aim of the study was to determine the diagnostic monitoring performance of non-invasive tests for nAMD in the second eye of patients with unilateral nAMD. The research team also wanted their study to identify predictive factors for the development of neovascular age-related macular degeneration. Index tests included the Amsler grid test, visual self-testing, clinical examination of the back of the eye, optical coherence tomography (OCT) and visual acuity. Fluorescein angiography was used as the reference standard.3
In a multicentre, prospective, cohort-based, comparative study, the researchers investigated diagnostic accuracy over a 3-year period. A total of 552 out of 578 consenting patients from 24 NHS hospitals (UK) took part in the study. The study participants had an age range of 50 to 95 years. The average age was 77.4 years. Patients were included in the study if they had been diagnosed with nAMD in one eye within 6 weeks prior to study inclusion. The prerequisite was that no nAMD was present in the other, second (study) eye of the participants. Baseline visual acuity in the nAMD study eye was ≥ 68 ETDRS letters (ETDRS: Early Treatment Diabetic Retinopathy Study). The majority of study participants were female (57.2%).3
Optical Coherence Tomography: highest sensitivity among non-invasive diagnostic methods
Neovascular age-related macular degeneration was detected in a total of 120 of the 464 patients examined by fluorescence angiography. Compared to the non-invasive diagnostic methods, the following sensitivity and specificity could be determined:
- Optical coherence tomography 91.7% and 87.8%
- Clinical funduscopic examination 53.8% and 97.6%
- Amsler grid test 33.7% and 81.4%
- Visual acuity 30% and 66.3%
- Self-reported vision 4.2% and 97.0%3
Compared to the results of the meta-analysis by Bjerager J. et al, the sensitivity and specificity of the Amsler grid test in the "EDNA diagnostic accuracy study" was at an even lower level.2,3
- Surabhi Ruia; Evan J. Kaufman. Macular Degeneration. StatPearls 2022.
- Bjerager J. et al. (2023). Diagnostic Accuracy of the Amsler Grid Test for Detecting Neovascular Age-Related Macular Degeneration, JAMA Ophthalmology.
- Banister K. et al. Non-invasive testing for early detection of neovascular macular degeneration in unaffected second eyes of older adults: EDNA diagnostic accuracy study. Health Technology Assessment Volume: 26, Issue: 8.