Flanagan JG, Hudson C, et al.,IOVS 2001;42:S694:
The HRT edema maps are in good agreement with clinical assessment.
§15 of 16 eyes with DME that converted to clinically significant DME showed significant increase in HRT edema map values either at the same time of, or before, conversion to clinically significant DME.
§HRT edema map analysis provides a non-invasive, objective technique for the topographic quantification of retinal edema and to monitor change of DME over time§§
 

HRT scan may be easier for the patient than angiography
Laszlo Dosa