To evaluate the effects of Trientine Hydrochloride in prevention of post-laser (pan-retinal photocoagulation) macular edema in the eyes for subjects with diabetic retinopathy. Trientine hydrochloride can limit secondary inflammatory damage to retinal vessels following the administration of pan-retinal photocoagulation therapy for severe non-proliferative diabetic retinopathy or retinal neovascularization due to diabetic retinopathy, resulting in less macular edema and improved visual outcomes.