What is the typical lens diameter for soft contact lenses?

• A. 11.0 to 12.5 mm
• B. 6.0 to 18.0 mm
• C. 14.5 to 15.5 mm
• D. 13.8 to 15.0 mm

Answer: (D)

Diameter is the width of the lens across its opening, and for soft contact lenses this size is chosen to balance corneal coverage with comfortable interaction with the eyelids. The range 13.8 to 15.0 mm covers the vast majority of standard soft lenses, providing enough coverage of the cornea while leaving room for blinking without the lens lifting or causing excessive lid pressure. Lenses that are much smaller tend not to cover the cornea adequately and can move or displace easily, while ranges that are much larger are not typical for everyday corneal wear and can cause fit and handling issues. Because most soft lenses are manufactured within this 13.8–15.0 mm window, it represents the typical diameter range you’ll encounter in practice.