A classic presentation of RGP contact lenses that ride too low is which staining pattern?

• A. 6 o'clock staining
• B. 3 and 9 o'clock staining
• C. Diffuse central staining
• D. Peripheral staining

Answer: (B)

Staining patterns with a contact lens reveal where the lens edge or other fitting issues irritate the corneal surface. When a rigid gas-permeable lens rides too low, the edge tends to sit closer to the central cornea in the horizontal plane. The lens edge then rubs against the mid-peripheral cornea at the 3 and 9 o'clock positions, creating linear, horizontal staining in those zones. This pattern is a classic sign of a low-riding lens and indicates that the fit needs to be adjusted to improve clearance, especially along the horizontal mid-periphery. Central or diffuse staining would point to different problems, such as surface issues or broader epithelial compromise, rather than targeted horizontal edge contact.