From what little I've read (not much available in OVID or PubMed) the last group of studies hypothesized that
a) the subjects were predisposed to cataract formation,
b) were Vitamin C and/or E deficient (which has been show in cataract formation in general). Metabolites of DNP have been shown to deplete Vitamin C levels and increase oxidative stress on the eyes. Even the risk increase found was in very large doses. The sample group and incidence of cataracts shows a 0.01-.1 chance of cataracts. Among the subjects who did have cataracts, the average length of time on the drug was
11 MONTHS continuously and the average dose during that 11mos was a whopping
73 GRAMS.
My wife doing 250mg per day x 30 days results in a 7.5g total ingestion roughly 10x less of a dose and 10 x less duration. Also of note, dietary antioxidants were barely know to science and supplementation was unheard of at the time.
The article is scanned in so reading it is a pain but it's journal-published peer reviewed science by an Ophthalmologist M.D.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1315023/?page=18