What was the first method employed for soft lenses?

What was the first method employed for soft lenses?

• A. Molding
• B. Injection Molding
• C. Hydration
• D. Spin Casting

Answer: (D)

Spin casting was the pioneering way to make the very first soft contact lenses. In this method, a liquid monomer solution is placed on a rotating mold and polymerized while spinning. The centrifugal force helps shape the liquid into a uniform, smooth hydrogel lens with consistent thickness, which was crucial for comfort and good optics. This approach, developed by Wichterle and Lipot, produced the first practical soft lenses from hydrogel polymers like HEMA. Hydration refers to the lens absorbing water after polymerization, not how it was formed; molding and injection molding describe other production routes or contexts, not the initial technique used for soft lenses.

Spin casting was the pioneering way to make the very first soft contact lenses. In this method, a liquid monomer solution is placed on a rotating mold and polymerized while spinning. The centrifugal force helps shape the liquid into a uniform, smooth hydrogel lens with consistent thickness, which was crucial for comfort and good optics. This approach, developed by Wichterle and Lipot, produced the first practical soft lenses from hydrogel polymers like HEMA. Hydration refers to the lens absorbing water after polymerization, not how it was formed; molding and injection molding describe other production routes or contexts, not the initial technique used for soft lenses.