I've been seeing Dr. XX in the ophthalmology department.
Dr. XX in the ophthalmology department has been taking care of me.
この場合、次のような言い方ができますよ。
ーI've been seeing Dr. XX in the ophthalmology department.
「眼科のXX先生に診てもらっています」
ーDr. XX in the ophthalmology department has been taking care of me.
「眼科のXX先生が診てくれています」
in the ophthalmology department で「眼科」と言えます。
ご参考まで！
カナダ 
