Nope, this is definitely a retinal surgery. Sub-retinal injections are actually done through the inside of the eye.

Your eyeball is filled with vitreous humour which although technically a fluid is really like a thick layer of gelatine, surgical instruments can't navigate that.

Before a needle is able to reach that retinal area, the surgeon must perform what is known as a Vitrectomy which is basically a chop and suction of that gelatine in order to have a good visual and be able to accurately manipulate surgical instruments.

Source: worked in embedded software for ophthalmic surgery equipment.