Figure 2.

Four subtypes of morphological changes in the IRMAs. (1) Stable IRMA (yellow arrow). All IRMA lesions maintain their original structure, including branch count, vessel caliber, and the area of nonperfused tissue around them, without any changes. (2) Regression of IRMA (red arrow). At least one site of abnormal IRMA branches disappears or gradually integrates with the nearby normal capillary bed, resembling the typical pattern of healthy blood vessels (reperfusion). This occurs without an expansion of the surrounding NPA. (3) Obliteration of IRMA (green arrow). In at least one location, the IRMA structures begin to vanish, corresponding to the progression of nonperfused areas in the capillary bed. (4) Progression of IRMA (blue arrow). In at least one location, there is an increase in the branching of the abnormal IRMA blood vessels, accompanied by the possible emergence of new IRMA structures, sometimes with nonperfused areas around them increases. F/U, follow-ups.