An alkyl ether derivative represented by thefollowing general formula [1](see formula 1)or its salt: wherein R1 and R2 represent each asubstituent such as hydrogen, halogeno or alkyl； R3represents alkylamino, amino or hydroxyl； the ring Arepresents a 5- or 6-membered aromatic heterocycle or abenzene ring； m and n are each an integer of from 1 to6； and p is an integer of from 1 to 3； shows an effectof protecting retinal nerve cells and, therefore, isuseful as a preventive and/or a remedy for retinalnerve diseases such as glaucoma, diabetic retinopathy,retinal artery obstruction, retinal venous obstruction,macular degeneration and retinopathy of prematurity.
