Zeaxanthin, a natural carotenoid, can improve and increase the ability of enzyme inhibitors that can slow down certain enzymes that are contributing to toxic metabolite accumulation in people who suffer from Stargardt's disease or other lipofuscin disorders. Such enzyme inhibitors include retinoid analogs such as isotretinoin, commonly known by the trademark, ACCUTANE. This drug binds to and inhibits at least two retinal enzymes, known as RPE65 and short chain dehydrogenase, which create surplus metabolites that feed into a pathway that eventually creates toxic metabolites in people with Stargardt's disease. However, isotretinoin treatment alone is not highly effective; therefore, use of zeaxanthin as an adjunctive treatment can improve the efficacy and outcomes of such treatments.