Provided are: a lacrimal oily layer stabilizer that is appropriate for ameliorating, relieving or treating evaporation-sthenic type dry eye caused by meibomian gland dysfunction, said stabilizer being capable of stabilizing lacrimal oily layer and allowing the lacrimal oily layer to sufficiently spread over the corneal surface to thereby prevent the transpiration of the lacrimal watery layer on the corneal surface eye drops comprising the lacrimal oily layer stabilizer and a method for stabilizing lacrimal oily layer. The lacrimal oily layer stabilizer comprises a copolymer which has a weight-average molecular weight of 10,000-5,000,000 and contains 10-90 mol% of structural unit (A) based on 2-(meth)acryloyloxyethyl phosphorylcholine and 90-10 mol% of structural unit (B) based on an alkyl group-containing (meth)acrylic monomer.本發明提供一種適用於因瞼板腺功能障礙而導致的蒸發加重型乾眼症的改善、緩和、或治療的淚液油層穩定劑、摻和有淚液油層穩定劑的滴眼劑及淚液油層穩定化方法,淚液油層穩定劑通過使淚液油層穩定,且使淚液油層在角膜表面上充分地伸展,從而防止角膜表面上的淚液水層的蒸發。淚液油層穩定劑含有重均分子量為10,000~5,000,000的共聚物,共聚物含有10~90莫耳%的以2-(甲基)丙烯醯氧乙基磷醯膽鹼為基礎的結構單元(A)、及90~10莫耳%的以含烷基的(甲基)丙烯酸類單體為基礎的結構單元(B)。
