Subthreshold laser treatment versus threshold laser treatment for symptomatic retinal arterial macroaneurysm.

PURPOSE: This study was designed to compare the effects of subthreshold laser treatment (STLT) with threshold laser treatment (TLT) in patients affected by symptomatic retinal arterial macroaneurism (RAM). METHODS: Patients affected by symptomatic RAM, characterized by exudative manifestations involving the fovea and best-corrected visual acuity (BCVA) worse than 20/80 Snellen equivalent, were recruited. Patients were randomly assigned to STLT or TLT and regularly followed up for 12 months. Primary outcome measures were changes in central point thickness (CPT) at the end of the follow-up. Secondary outcome measures were changes in mean BCVA at the end of the follow-up and identification of postlaser alterations. RESULTS: In this single center, randomized, clinical trial, 12 patients were randomized to STLT and 13 to TLT. CPT in STLT was 332 µm at baseline and changed to 249 µm at the 12-month examination. CPT in TLT was 341 µm and reduced to 226 µm at the end of the follow-up. BCVA in STLT changed from 0.72 logMAR to 0.28 logMAR. BCVA in TLT changed from 0.76 logMAR to 0.26 logMAR. The statistical analyses revealed a significant difference comparing the baseline values for both CPT and BCVA in each subgroup from the third month (P < 0.001). No difference was found comparing the two subgroups at any point in time. Three eyes (23%) treated with TLT developed an epiretinal membrane with subjective metamorphopsia. CONCLUSIONS: This pilot randomized clinical trial shows that both STLT and TLT can achieve similar improvements in BCVA and CPT. The lower laser energy delivered by STLT can reduce the complication rate.