Subthreshold Laser Treatment Versus Threshold Laser Treatment for Symptomatic Retinal Arterial Macroaneurysm

Purpose To compare the effects of subthreshold laser treatment (STLT) with threshold laser treatment (TLT) in patients affected by symptomatic retinal arterial macroaneurism (RAM). Methods The trial was registered at Clinicaltrail.gov (number NCT01301326 ). 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: Changes in central point thickness (CPT) at the end of the follow-up. Secondary outcome measures: Changes in mean BCVA at the end of the follow-up, and identification of post-laser alterations. Results In this single centre, randomized, clinical trial, 12 patients were randomized to STLT and 13 to TLT. CPT at baseline was 332μm and 341μm, changing to 249μm and 226μm at the 12-month examination, in STLT and TLT, respectively, with a statistically significant difference (p<0.001). BCVA changed from 0.72 to 0.28 LogMAR in the STLT subgroup and from 0.76 to 0.26 LogMAR in the TLT subgroup with a statistically significant difference (p<0.001). Three eyes (23%) treated with TLT developed an epiretinal membrane with subjective metamorphopsia. Conclusions This pilot randomized clinical trial shows that similar improvements in BCVA and CPT can be obtained with both laser approaches. The inferior laser energy delivered by STLT can reduce the complication rate.