Association between macular edema area on optical coherence tomography and Amsler grid sensitivity in diabetic macular edema: a cross-sectional study

Abstract Background Early detection of diabetic macular edema (DME) is essential to prevent vision loss through timely treatment. Optical coherence tomography (OCT) is the diagnostic gold standard but is not suitable for home monitoring. The Amsler grid represents a simple and inexpensive potential screening tool. This study aimed to determine the sensitivity of the Amsler grid for detecting DME and to assess its association with the size of foveal edema. Methods In this cross-sectional study, 1,444 eyes of 722 diabetic patients were examined using Spectralis OCT and the Amsler grid, and 90 eyes with DME were identified. A sensitivity analysis restricted to one eye per participant and excluding eyes with concomitant macular pathologies included 34 eyes with intrafoveal DME, in which the area of foveal edema was quantified. Results For very small DME (area ≤ 0.01 mm²), the sensitivity of the Amsler grid was 20.0% (1/5 eyes). For edema areas > 0.01 mm², the sensitivity increased to 62.1% (18/29 eyes), and for areas > 0.03 mm², it increased to 69.6% (16/23 eyes). Conclusion The Amsler grid demonstrated limited sensitivity for detecting DME, particularly for small edema areas (≤ 0.01 mm²). While it may serve as an adjunctive tool for home monitoring in diabetic patients, it cannot replace OCT-based examinations at recommended follow-up intervals.