Chemical injuries affecting the eyes vary in severity, with widespread ocular surface disruption and loss of vision in severe cases. The damage relates to the rate of penetration of the ocular surface due to cell membrane disruption: ammonia > sodium hydroxide > potassium hydroxide > calcium hydroxide > lime > acid eg. sulphuric battery acid. Formation of calcium soaps (lime) or coagulated protein (acids) in the more superficial layers of the cornea can limit penetration.