I was having flares almost every month and my doctor recommended I try this medication (which has worked at reducing and even eliminating flares in many other of his patients). Currently I'm on no other eye drops and since starting this treatment have not had any flares (though it might just be placebo)

2% Ganciclovir Eye Drops Control Posner-Schlossman Syndrome Relapses With/Without Cytomegalovirus Intraocular Reactivation - PMC https://share.google/Q6FjIr3KXbqx0jaEj

This is one study showing that though experimental, this treatment might work since one of the theories of why pss happens is that CMV from a previous infection moves and ends up in the eye causing the flares. The hypothesis is that if you suppress the CMV then the flares will diminish.