Provided is a method of treating or preventing age-related macular degeneration (AMD) or Stargardts disease in a patient subject to, or symptomatic of the disease, whereby normal lysosomal pH (pHL) of compromised retinal pigment epithelium (RPE) cells of the eye is restored, or abnormally elevated pHL is reacidified, thus decreasing or preventing damaging accumulations of lipofuscin debris or photoreceptor waste products. Further provided is a method for restoring photoreceptors to the eye of a patient subject to, or symptomatic of reduced photoreceptor activity or lipofuscin accumulation in RPE cells. By these methods D5 dopamine receptor (D5DR) agonists are administered to stimulate D5DR activity of compromised RPE cells, thereby regulating and reacidifying lysosomal pH (pHL) by a D5 dopamine receptor-(D5DR)-mediated pathway, without altering baseline maintenance.
