Compared with the corneal curve, base curves for hydrogel soft lenses are typically

Compared with the corneal curve, base curves for hydrogel soft lenses are typically

• A. Flat
• B. Steep
• C. The same
• D. Irregular

Answer: (A)

Soft hydrogel lenses are designed to sit on the tear film over the cornea with a gentle, even fit. The base curve of these lenses is typically flatter than the central corneal curvature, meaning it has a larger radius. This flatter curve allows the lens to rest smoothly on the cornea, move a bit with blinking, and distribute pressure evenly. A steeper base curve would press more onto the cornea, creating discomfort and limiting movement, while a base curve that matched the cornea too closely or was irregular would be less forgiving across different eye shapes. So, the common pattern is a flatter base curve relative to the corneal curve.

Soft hydrogel lenses are designed to sit on the tear film over the cornea with a gentle, even fit. The base curve of these lenses is typically flatter than the central corneal curvature, meaning it has a larger radius. This flatter curve allows the lens to rest smoothly on the cornea, move a bit with blinking, and distribute pressure evenly. A steeper base curve would press more onto the cornea, creating discomfort and limiting movement, while a base curve that matched the cornea too closely or was irregular would be less forgiving across different eye shapes. So, the common pattern is a flatter base curve relative to the corneal curve.