How can three and nine o'clock staining in GP lenses be best eliminated?

Three and nine o'clock staining is a phenomenon typically associated with GP (gas permeable) lenses and occurs due to the interaction between the lens and the tear film, often leading to accumulation of deposits or staining in those areas of the lens. Reducing center and edge thickness directly influences the fit of the lens on the eye and can enhance how the lens interacts with the tear film.

When the center thickness is reduced, the lens may become more comfortable and may promote better tear exchange underneath the lens, which can help to clear away debris and prevent the build-up that leads to staining. Similarly, reducing edge thickness can improve the lens's edge chemistry, making it less likely for the lens to trap tears or foreign material along the edges where staining commonly occurs. Overall, addressing the thickness helps in achieving a better overall fit and promoting tear exchange, which is critical in preventing staining.

In contrast, changing the lens material might not specifically target the problem encountered with staining, and while improving lens care solutions could be beneficial, it wouldn't directly address the relationship between lens fit and the staining phenomenon. Changing the lens fitting technique may also influence the situation but is less direct in its impact on the specific issue of three and nine o'clock staining compared to adjusting lens thickness.