Compensation wise you should see strong support for $300K+ starting salaries in private practices, more in rural areas. The highest I've placed someone with was a $450K base in a rural midwest, physician-owned practice. You can eventually make high 6 figures, maybe 7 if you're a partner and have a very busy clinic.
Jobs can be a little harder to find:
You've indicated you would likely want to stop doing cataract surgery. In my opinion, that's the best option if you choose to go medical retina. You can be 100% retina and focus solely on that. You should be open-minded about seeing some comprehensive/routine patients in the clinic starting out if you're not in a retina-only group. If you do decide you want to do surgery, this can create a tricky practice pattern. If you're willing to go to a rural/semi-rural area, this pattern can actually work great. If you're in a large metro, you'll likely need to join a large multi-specialty practice that can feed you retina patients internally. It will be harder to get retina patients from other ophthalmologists given you do cataract surgery as well.
If you do decide to do retina-only, you can seek out retina-only groups. This will be hit or miss, some retina-only groups love having a med. retina doc to ease the patient load. Some do not because you cannot fully be on the call schedule due to not doing surgery. I've seen this be a non-starter with retina groups. However, again, if you're willing to go rural/semi-rural these groups generally don't care.
If you have an interest in retina, I would encourage you to do a surgical retina fellowship. However, I realize these two specialties can have vastly different lifestyles. From a job market perspective, there are many more jobs, base pay is higher, and total career income will likely be higher due to an ability to buy into a surgery center.
Happy to have a more in-depth discussion with you sometime.