Assessment: Measuring metamorphopsia using the D-Chart test

The D Chart is a new clinical test that has been developed by researchers in Glasgow to assess the degree and location of metamorphopsia (distortion) and field loss in the central visual field. Currently, the most common method of detecting and monitoring changes in central visual field function is the Amsler chart. However, this method is not quantitative and largely relies upon subjective responses and the interpretative skills of the practitioner. Other clinical tests that measure metamorphopsia can be expensive, have limitations in terms of patient level of visual acuity and do not always provide reliable and accurate mapping of visual distortions within the central visual field. The lack of information regarding the central visual field leads to difficulties for clinicians in deciding whether macular disease is progressive, and whether or not surgical or medical intervention is required.