I've been through that with my mother. When she had the first detached retina, she didn't say anything about it for a couple of days. By the time they did the surgery, it wouldn't stay in place. She had 4 surgeries to repair it, and while it is now held in place with a silicone band, the drops adversely affected the cornea. The cornea is now shot so all she can see is a tiny bit of light through that eye.
Then she fell at a local hospital and suffered a detached retina in the other eye. They did some type of
red reflex test and got the reading they wanted but never asked her any questions on whether she could see. She also contracted MYRSA from the fall which went to that eye clouding it inside so the eye doctors couldn't see inside. Nine days later when the cloudiness started to dissipate, they saw the detached retina. They did the surgery right away. She still has the oil bubble in her eye holding the retina in place. Since the retina was detached for 9 days (the retina was deprived of receiving blood all those 9 days), it left her with loss of vision. She is legally blind in that eye too although she can read some large print.
Good luck with your dad's surgery. Yes, it's a lot of work to be sure he gets his drops regularly and follows protocol (sleeping in a certain position and not bending forward for x amount of days). And be sure to keep watch of his cornea. Those retina drops are very hard on the corneas. My mom almost had to have a corneal transplant when she suffered the detached retina in the second eye. Her eye stopped making fluid. The cornea doctor had to do a corneal scraping (scrape off the surface of the cornea and put placenta on it to try and force the healing to start again). Fortunately it worked, but she will be on eye drops for the rest of her life.
Just be sure you address any and all concerns you have to the eye doctors. Good luck with your dad's surgery. Perhaps work on some staged photography inside while you are there helping your dad. You will need a break once in a while.
