Howard said that he was "seeing just a whole bunch of crazy stuff" when he closed his eyes and felt a "pulsating" sensation when they were open.
Retina damage, worst-case scenario. The "crazy stuff" he's talking about might be fluid leaking through the retina, and it looks like a bunch of very, very dim lights shaking vigorously when you close your eyes, and you can barely see them with your eyes open as well.
So, same situation as Amare, in a way. Amare's retina was detached severely, peeling...and Howard may have a tear, which will lead to Amare's situation.
Worst-case scenario, again...but if that's what happened, he's not playing for 2-3 weeks.
If that's the problem, a tear, doctors will use a freezing procedure to basically "scar over" the retina where the tear is, then inject a gas bubble into the eye, which will push against that location, keeping it in place and assisting it during the healing process.
If it's a detached retina, which is more severe, he'll have to have a surgery that removes any fluid and bleeding through the location, flatten the retina (and sometimes cut pieces out of it if it has folded), and then stick it in place and hold it there with a gas or oil bubble. That's a 3-4 week layoff.
Or he could be overreacting to what he was seeing, just floaters from light shining through/on irritated areas of the eye.
Just cross your fingers that he's overreacting.