Microwave irradiation and soft contact lens parameters

Area of Science:

• Ophthalmology
• Materials Science
• Biomedical Engineering

Background:

• Soft contact lenses (SCLs) require regular disinfection.
• Microwave disinfection is a potential alternative method for SCL sterilization.
• The impact of microwave irradiation on SCL material properties is not fully understood.

Purpose of the Study:

• To evaluate the effects of repeated microwave irradiation on key parameters of soft contact lenses.
• To determine if microwave disinfection causes clinically significant alterations in SCL polymers or dimensions.
• To assess the safety and efficacy of microwave disinfection for unworn SCLs.

Main Methods:

• Ten factory-sealed SCLs from each of the four FDA categories were used.
• Lenses were disinfected using repeated 5-minute cycles in a standard microwave oven.
• Key lens parameters (power, radius, diameter, thickness, water content) were measured before and after irradiation over 200 cycles.

Main Results:

• Statistically significant changes were observed in multiple SCL parameters after microwave irradiation.
• However, the magnitude of these changes was small, with few reaching clinical significance.
• The study simulated over six months of daily disinfection for unworn lenses.

Conclusions:

• Microwave disinfection does not appear to have a clinically significant impact on the parameters of most unworn soft contact lenses.
• The findings suggest microwave irradiation is a potentially viable disinfection method for SCLs.
• Further investigation is necessary to understand the long-term effects on worn soft contact lenses.