Eye lightening drops are potentially permanent

[Imretarded?]

patients withdrawn from latanoprost treatment suggest that the increased iridial pigmentation is irreversible while changes in eyelash and periocular skin pigmentation are reversible after cessation of therapy

All available evidence from in vitro, in vivo, and clinical studies suggests that latanoprost does not induce melanocyte proliferation

Based on this study, it appears that the upgrading of melanogenesis via drugs permanently up regulates the synthesis of melanin. Ie a new equilibrium is established after a period of use. My hypothesis is that the inverse works the same way, downregulating the production of pheomelanin over 1-5 years should result in local melanocytes becoming less active forever.

Latanoprost and pigmentation - PubMed

Latanoprost is a prostaglandin analogue with well-established efficacy in the treatment of open-angle glaucoma and ocular hypertension. Once-daily administration of this drug for up to 5 years is generally well tolerated both locally and systemically. While most reported side effects have been...

pubmed.ncbi.nlm.nih.gov