Please don't feed spinach daily...that binds to the calcium and they then can't absorb it. Last thing someone needs is a vit A and calcium issues!
When my wood turtle had Vitamin A defficancy my vet told me to give her lots of yellow and orange veggies. Yellow squash, carrots etc. Find fresh pesticide free stuff and wash it. Don't go with any fish pellets or anything else, over doseing is just as bad as under doseing. Feed the veggies daily for a few weeks. Then go back to a normal diet.
Also what I do with all of mine, on advice from someone who has been dealing with turtles and tortoises since the 60's and has won several awards for conservation etc, use human centrum vitamins. You can get the store brand it has the same thing in it. Crush one tablet and sprinkle it on the food you give the tortoise one a week...spred the tablet out, or give it all on one day doesn't matter but one tablet a week for a russian.That will make sure it gets the vitamins and minerals it needs without over dosing. Give the veggies also. After a few weeks the eye issues should clear. Tortoise metabolism is slower then ours and it will take a few weeks before it goes away, but with the right stuff it will get there.