The retinal alterations caused by both diseases affect the central retina (the macula) and its periphery.
The macular edema caused by diabetes mellitus or retinal vein obstruction results in increasingly declining visual acuity and distorted vision. Both laser and injections (Lucentis, Eylea, Ozurdex, Iluvien) are important treatment methods.
The alterations of the peripheral retina results in ophthalmic veins disorder which can not only cause minor retinal haemorrhages but also major haemorrhages combined with a loss of eyesight (usually temporary). The laser eye treatment can prevent major haemorrhages, but in most late-stage cases an operation will be necessary.