The 1961 movie certainly had Triffids Disolving with Salt water in the Lighthouse... The Book didnt come up with a cure.. One of the reasons Bills' Group were invited to Cokers' Island.. so he could take part in research to find a way to wipe em out... They had to flee Shirning Farm earlier than planned due to the appearance of the red headed soldier/standover man/thug, Torrence.
SPOILER ALERT DAY OF THE TRIFFIDS 09... and a bit on the cure in WWZ..............
The 09 Remake of DOTT. was awful. Triffids turned into powerful monsters that could get through just about any building / vehicle to reach thier prey. Ms Durrant morphed into a Nun that had a "deal" going with the local triffids.. they would leave her Church alone if she sent out a sacrifice every now and then.. Bills father was working on a way to wipe out the triffids by sending out sterile spores (so their seed couldnt germinate or some such)... and had a female plant inside an iron cell... of course.. it got him....
In the battle royale at the end of the show (involving Torrence (whose name comes from the London street in which his jet crashes), Bill remembered being in Africa as a child and being attacked by triffids there.... the local tribesmen poured triffid venom into his eyes so the plants couldnt see him... So he and Jo do the same thing IE pour triff poison into thier eyes throygh the same wooden mask the tribesmen had used when he was a child.. and live happily ever after.. invisible from their foes.... maybe they shack up in the same neighbourhood as Brad Pitt

..... it did have some good special effects... the comet scenes were pretty good I thought.
Pretty sure "Blindness" has been reviewed here... people start going blind. and the government isolates them in a crappy institution incase its catching.. they are given food and thats about it... film covers the fall of society inside thier prison. which degenerates into mob rule. one woman who remains sighted goes into the blind prison with her partner.. to care for him. when they finally break out.. they find the rest of the city has also fallen blind... at the end.. one of the group regains her sight...