Adding parsley and dill to the diet can help with maintaining good eye conditions. Also, euphrasia officinalis can be used internally. It can be given as an infusion by steeping teaspoon of the herb in 1 cup of boiling water. Strain and cool. The same dosages as for the euphrasia infusion would apply.
Nutritional supplements can also aid in keeping the eyes healthy.
Vitamin A given as cod-liver oil will help. Give cats teaspoon a day, medium dogs 1 teaspoon and larger dogs 2 teaspoons a day. Vitamin C is another excellent supplement to give. Dosage should be raised up to bowel tolerance. Of note, is that Vitamin B complex including niacin and pantothenic acid can be helpful, but only if the formula does not contain yeast as it can cause eye allergies.