Mix 1 teaspoon of activated charcoal powder into ¼ cup of distilled or filtered water. Store the solution in a glass jar. Use 1-2 drops of the resulting solution in your eyes twice a day.
Do not use a crushed up tablet to make this solution, only use a fine powder.
It is also not recommended to use the contents of an activated charcoal gel cap. These products will have additives in them that may not be suitable to put into your eyes. Look for activated charcoal powder that has no other ingredients.