What is the average pH value of human tears?

Human tears generally have an average pH value of around 7.4, which is slightly alkaline. This pH level is important for maintaining the health of the ocular surface and the function of the tears, as it supports the stability of tear film and promotes the activity of enzymes that are present in tears, which help to fight infections and maintain the overall health of the eyes.

The slightly alkaline nature of tears helps in preventing discomfort and ensures that the eye maintains an optimal environment for vision and protection against pathogens. Understanding the pH of tears is essential for contact lens fitting and care, as products that are used with contact lenses need to have a compatible pH to avoid irritation.

In the context of the other options, values such as 6.6 would be slightly more acidic than normal tear pH and could lead to discomfort or poor tear stability, while a pH of 7.8 would be more alkaline than typical, which might indicate some pathological condition or affect tear stability. A pH of 10.0 would be highly alkaline and likely harmful to the ocular surface, resulting in severe irritation and damage to the eye.

Overall, recognizing this pH level is crucial in optometry practice, particularly in managing and recommending the