FAO Footlong

Any tissue that operates on electrical signals will have lots of ion channels - holes in the cell membranes - that move charged ions. Both cardiac tissue and retinal tissue have lots and lots of these ion channels, because both rely heavily on electrical activity to do their jobs.

I assume that the drug you will be taking to target (specifically, to inhibit) certain cardiac ion channels is "leaking" and also targetting retinal ion channels (maybe they are similar types of ion channels?). Wiki says that "luminous phenomena" is the most likely problem. My own interpretation of this is that the type of channel being targetted in your heart is similar to a channel in the retina required to dampen visual signals. If you inhibit the channel in the heart, you inhibit this channel in the retina, and thus perceive excessive brightness in your visual field.

Wiki also says that the phenomenon is completely reversible. That matches what would be my intuition/knowledge on such ion channels.

I read that as living with "sparkly tights".

ho hum...!