GUWonder

30+ hour trip without regular freezer availability during any part of the trip? Then those eye drops are not going to stay anywhere as close to as cold as in a freezer unless you have something else in mind to replace/replenish the freezer/ice/frozen cooling gel packs (or their "power") during the trip. If it's critical to take those eye drops and have them stored at such cold temperatures for so long, then consider breaking up the journey so as en route you have long enough freezer access or some other means to effectively replace/replenish the cooling implements for them.

I've seen frozen breast milk and other "war on water" "exempted" "keep cold" stuff transported on long journeys -- going from rural places in the US to rural places in Asia with road trips on both sides of the journey and multi-flight connections domestically on both ends as well as for the international section has meant such long trips -- but then it's very important to have a plan for that without counting on airlines' fridge/freezer to be useful in this regard. Counting on the airlines and not having a plan to boost the cooling power of the accessories en-route would mean you could be facing the potential for "keep cold" stuff to be spoiled before the journey is over.

For any important medicine, people should really consider what they would do to replace such stuff while at their destination(s) if they were to find out that their supply is missing/stolen/gets spoiled/whatever during the course of a long trip and related stay abroad. For something that sounds as customized as what you're mentioning, returning "home" may have to be in the plan if the unfortunate happens.