Which option represents the average HVID used with GP lens fittings?

Which option represents the average HVID used with GP lens fittings?

• A. 8.9 mm
• B. 7.5 mm
• C. 10.2 mm
• D. 9.6 mm

Answer: (D)

The main idea here is how horizontal visible iris diameter (HVID) guides the initial sizing of corneal gas-permeable lenses. In GP fitting, the diameter of the lens is chosen to align with the corneal surface and lid behavior, using HVID as a practical reference point for what an average eye’s visible iris width looks like. The value around 9.6 mm is a commonly cited baseline for the average HVID in adults, which translates into a typical starting GP lens diameter around the mid-to-upper 9 mm range. That’s why 9.6 mm is considered the representative average HVID used in GP fittings. The other options are outside this standard starting point: they’re smaller or larger than the usual baseline and wouldn’t reflect the common starting reference used for an average eye.

The main idea here is how horizontal visible iris diameter (HVID) guides the initial sizing of corneal gas-permeable lenses. In GP fitting, the diameter of the lens is chosen to align with the corneal surface and lid behavior, using HVID as a practical reference point for what an average eye’s visible iris width looks like. The value around 9.6 mm is a commonly cited baseline for the average HVID in adults, which translates into a typical starting GP lens diameter around the mid-to-upper 9 mm range. That’s why 9.6 mm is considered the representative average HVID used in GP fittings. The other options are outside this standard starting point: they’re smaller or larger than the usual baseline and wouldn’t reflect the common starting reference used for an average eye.