The present invention relates to a compound represented by the following formula (I):5-uagcaccauuugaaaucaguguucc-P-ggaacacugauuucaaauggugcuauu-3 (I)(SEQ ID NO: 1)(Wherein-P-represents a group represented by the following formula (Ia): Below. ), And a therapeutic agent for corneal diseases such as ocular surface diseases and the like, which comprises the single-stranded nucleic acid molecule as an active ingredient.本発明は、下記式(I):5’-uagcaccauuugaaaucaguguucc-P-ggaacacugauuucaaauggugcuauu-3’ (I)(配列番号1)(式中、-P-は、下記式(Ia):で表されるプロリン誘導体リンカーを示す。)で表される一本鎖核酸分子、並びに、該一本鎖核酸分子を有効成分とする、眼表面疾患等の角膜疾患の治療剤を提供する。