Pilot Randomized Clinical Trial Comparing Subthreshold Laser Treatment Versus Threshold Laser Treatment for Retinal Arterial Macroaneurysm

The treatment of RAM is controversial and at present there is no general consensus about the best approach. Spontaneous obliteration of RAM may occur over the follow-up, but the long persistence of blood or subretinal fluid may lead to progressive photoreceptor damage, with consequent irreversible visual impairment. More specifically, the presence of subretinal hemorrhage beneath the fovea leads to a diminished visual function.

Treatment is generally indicated for RAM associated with exudative manifestations involving the fovea which do not tend to resolve spontaneously. The most commonly employed approach is direct or indirect laser photocoagulation with visible end-point. Nevertheless, several complications may be associated with conventional threshold laser for macular lesions, including enlargement of laser scar, choroidal neovascularization, and subretinal fibrosis. In addition to these complications, arteriolar obliteration, increased retinal exudation and scarring, with possible retinal traction, have also been reported as possible sequelae of the laser photocoagulation of RAM.

Another approach for the treatment of RAM is based on the use of subthreshold laser treatment.

Subthreshold laser treatment has been proposed in an attempt to minimize the negative aspects of conventional grid laser photocoagulation and has achieved encouraging results, especially in macular oedema secondary to diabetic retinopathy, proliferative diabetic retinopathy, and branch retinal vein occlusion. The concept underlying the use of subthreshold laser treatment is to decrease the laser damage by reducing the duration of laser exposure and by using a subvisible clinical end point. A micropulse diode laser releases low energy micropulses in order to confine the energy to the RPE cells, with limited protein denaturation, avoiding lateral thermal spreading.

Aim of the study is to compare the effects of subthreshold laser treatment to those of threshold laser treatment in patients affected by symptomatic retinal arterial macroaneurysm.