In this study, we attempted to enhance disulfiram (DSF) solubility using a 2-hydroxypropyl-β-cyclodextrin (HPβCD) and hydroxypropylmethylcellulose (HPMC). We also investigated the effect of an HPβCD solution containing DSF and HPMC (DSF eye drops) on cataract development in ICR/f rat. The solubility of DSF increased with increasing HPβCD concentration, and the solubility of DSF in HPβCD solution containing 0.1% HPMC was approximately 20% greater than that of DSF in HPβCD solution without HPMC. In in vivo transcorneal penetration experiments using rabbits, only diethyldithiocarbamate (DDC) was detected (DSF was not detected) in the aqueous humor. This DSF-DDC conversion in the cornea was inhibited by treatment with a sulfhydryl (SH) inhibitor, p-mercuribenzoate and N-ethylmaleimide, in in vitro transcorneal penetration experiments using rabbit corneas. On the other hand, the instillation of 0.25% and 0.5% DSF eye drops delayed cataract development in ICR/f rats, a recessive-type hereditary cataractous strain. The present study demonstrates that DSF in HPβCD solution with HPMC is converted to DDC by the catalysis of proteins containing SH residues in the cornea, and this DDC may cause the delay in cataract development in ICR/f rats.