Commonly used self-test for AMD found to be inaccurate

AMD is one of the most prevalent eye diseases. In its late stage, newly formed blood vessels in the retina alter its structure, which leads to blurry and distorted vision. This condition (neovascular or wet AMD) is a leading cause of vision loss among the elderly, but the changes in vision can be subtle in the beginning with slow, gradual worsening of symptoms.  Realizing that one needs an eye examination is not always easy. 

Because timely diagnosis and treatment of wet AMD is crucial to saving vision, health professionals widely recommend the use of the Amsler grid test as a method of self-test for detection of wet AMD. The Amsler grid, developed by Swiss ophthalmologist Marc Amsler in the 1940s, is a grid of vertical and horizontal lines with a dot in the center. The user looks at the grid with each eye separately and focuses on the dot. This method allows the viewer to see a distorted grid in one eye, which otherwise can be difficult to observe.   

In theory, the Amsler grid is a great test. It is easy to use and is very inexpensive. A recent study by European researchers suggests, however, that theory may not match practice. In a recent meta-analysis study published in JAMA Ophthalmology, researchers evaluated how well the test actually detected wet AMD. (A meta-analysis is a statistical analysis that combines the results of multiple scientific studies.) They collected data from 10 studies with data from a total of 425 eyes with wet AMD and 1,262 eyes at risk of wet AMD (early/dry AMD). When performed under supervision and in the best possible conditions, the Amsler grid was positive in 2 of 3 cases with wet AMD. In patients at risk of wet AMD (early/dry AMD), it was positive in 1 of 3. In other words, this was far from being a perfect tool as it misses some cases of wet AMD and wrongly suggests wet AMD in others.  

The researchers recommend to health care professionals that if they prescribe the Amsler grid for patients, they should also allocate 5–10 minutes to ensure that it is used correctly. Patients should also be made aware of vision irregularities and seek an eye examination upon any visual decline regardless of the Amsler grid.  

Medical Xpress, February 27, 2023; see source article, DOI: 10.1001/jamaophthalmol.2022.6396