What do we really want to determine with contact lens selection?

What do we really want to determine with contact lens selection?

• A. Sagittal height/depth
• B. Color
• C. Material
• D. Oxygen permeability

Answer: (A)

Sagittal height, or depth, is the key factor because it determines how the lens sits over the cornea—the fit, clearance, and centration are all driven by that relationship. The goal in lens selection is to match the lens’ sagittal profile to the eye so the lens rests with the right amount of tear reservoir, sits centered, and moves appropriately with blinking. If the sag is too shallow for the corneal curvature, the edges can lift and the lens won’t align properly; if the sag is too deep, the lens may bear on the cornea or feel tight and move poorly. Once the sagittal fit is correct, you can then choose a material with suitable oxygen permeability to protect the cornea, while other factors like color are mainly cosmetic.

Sagittal height, or depth, is the key factor because it determines how the lens sits over the cornea—the fit, clearance, and centration are all driven by that relationship. The goal in lens selection is to match the lens’ sagittal profile to the eye so the lens rests with the right amount of tear reservoir, sits centered, and moves appropriately with blinking. If the sag is too shallow for the corneal curvature, the edges can lift and the lens won’t align properly; if the sag is too deep, the lens may bear on the cornea or feel tight and move poorly. Once the sagittal fit is correct, you can then choose a material with suitable oxygen permeability to protect the cornea, while other factors like color are mainly cosmetic.