Are floaters normal after an eye injection?

What's normal

There are two different things people call floaters after an injection, and telling them apart is the whole point of this answer. The first is the injection itself. A small amount of air can go in with the medicine, and the NEI says you may see floating air bubbles which look similar to floaters, listing this among the short-term effects that usually resolve within a day or two. These typically look like one or a few dark round dots that sink or move when you move your eye, and they are noticeable immediately or within the first hours.

The AAO also notes that you may see spots in your vision after an injection, that they may be more noticeable in certain lighting or when you look certain ways, and that they usually do not affect vision. Expected bubbles appear at the start and shrink away over hours to a couple of days.

Injection air bubbles show up immediately and usually clear within 1 to 2 days. Floaters that begin after day 1 or arrive as a sudden shower need a call.

When it stops being normal

The second kind is the one to report. The ASRS specifically lists increased floaters after the first day as a symptom that should prompt you to contact your retina specialist. Floaters that appear or multiply after day 1, rather than fading from day 1, do not fit the air bubble pattern.

A sudden shower of many new floaters at once, with or without flashes of light, is a retinal detachment or retinal tear warning. The AAO says noticing many new floaters at once, seeing sudden flashing lights, a shadow in your side vision or a gray curtain over part of your vision all need an ophthalmologist right away, and that you should call immediately. Increased floaters together with pain and worsening vision in the first week can also point to infection inside the eye.