Small Paracentral Acute Middle Maculopathy Lesions as Biomarker of Vascular Morbidity: Natural Course

Background: To evaluate the incidence rate of small paracentral acute middle maculopathy (PAMM) lesions in healthy fellow eyes of patients with retinal vein occlusions (RVO). Methods: Patients with unilateral branch RVO or central RVO who were followed up for at least one year were included. Fellow healthy eyes were examined with 6 mm optical coherence tomography angiography scans at baseline and at the end of the follow-up. Small resolved PAMM lesions were displayed using structural en face projections of the slab between two segmentation lines of the outer plexiform layer with 0 µm and −9 µm offset. New lesions were identified by overlaying baseline and final structural en face projections. Results: A total of 41 eyes of 41 patients (12 females and 29 males, mean age 63.5 ± 10.1 years) were included. The mean follow-up was 23.6 ± 11.4 months. Among all RVO patients, small resolved PAMM lesions in healthy fellow eyes were found in 39 patients (95.1%). In the whole cohort, the median number of PAMM lesions was 5.5 (95% CI 3.0 to 8.0) (mean 6.5 ± 5.7) at baseline, which increased statistically significantly to 5.5 (95% CI 3.8 to 8.2) (mean 6.7 ± 5.7) at the end of the follow-up period (p = 0.03). Eight (19.5%) patients demonstrated new lesions, with a median number of new lesions of 1 (ranged 1 to 2). Conclusions: Small PAMM lesions seem to be a slowly progressing retinal vascular biomarker.