بسم الله الرحمن الرحيم
If during the cataract operation (eye surgery) blood comes out of the pupil but it remains inside of the eye and does not reach the eyelashes or the outside corner of the eye, the wudhu will not break.
If this blood comes out of the pupil of the eye and it touches the eyelashes or it goes to the outside corner of the eye, the wudhu will break.
أفضل التطبيق العصري على مسائل القدوري
للمفتي محمد أشرف الاشاعتي
Vol.1 Pg.108