Please, be utterly careful when having vitamin A or anything injected into your turtle. An overdose of vitamin A can kill a turtle in a painful manner. It is hard to decide the medication dosages for turtles. It is done by weight, and a lot of a turtle's weight comes from the shell. A lot of people have become a lot more conservative in their treatments. There are MANY causes for swollen eyes, and vitamin A deficiency is only one cause. Soaking the turtle twice a day for 15 minutes in a separate container and using Saline Solution or Turtle Eye Clear will make the turtle more comfortable. You can start this immediately upon noticing the problem. Add a small amount of vitamins to his food every other day--I use bird vitamins and dust a piece of banana with it. Or you can feed Tender Vittels or another cat food with high vitamins once a week. Look for something that is relatively low in fat! If his eyes get worse or don't improve, you may need to apply some antibiotics. See a veterinarian first, so you use the appropriate cream. Vitamin A deficiency is caused by dietary problems. Swollen eyes can also be caused by dusty litter, especially if you are using shavings of any kind, or by a bacterial infection, which can come from a dirty enclosure, or as a symptom together with respiratory infections or colds. Don't assume automatically, that it is a vitamin deficiency, but make sure the condition is evaluated properly. If your turtle is sluggish, not eating, or shows any other symptoms together with the swollen eyes, see a veterinarian immediately. Your turtle has a serious health problem that needs treatment.