Ultraviolet and Visible Transmittance of Soft Contact Lenses with and without Ultraviolet Blockers

SIGNIFICANCE Ultraviolet (UV) and visible light transmittance of soft contact lenses (SCLs) was measured. A significant difference in UV transmittance has been found between SCLs with a positive and negative back vertex power (BVP). It can be shown that thicker SCLs absorb more UV radiation. PURPOSE This study aimed to determine UV and visible light transmittance of different SCLs with and without UV protection filters. METHODS Twenty-one lens brands were investigated in the BVP range of -12.00 to +6.00 D. Three SCLs were measured per BVP 25 times. Three hundred thirty-nine SCLs with UV filter (stenfilcon A, somofilcon A, narafilcon A, senofilcon A, senofilcon C, etafilcon A, nesofilcon A) and 489 SCLs without UV filter (delefilcon A, lotrafilcon A, lotrafilcon B, comfilcon A, balafilcon A, samfilcon A, asmofilcon A, nelfilcon A, omafilcon A, hilafilcon B, ocufilcon D, hioxifilcon A, omafilcon B) have been examined. The measurement setup was created according to ISO 18369-3. RESULTS All UV-absorbing labeled test SCLs meet UV protection class 2. senofilcon A, senofilcon C, and narafilcon A meet the higher UV protection class 1 level. A statistically significant difference in UV transmittance (280 to 380 nm) has been found between SCLs with a positive BVP (+1.00 to +6.00 D) and SCLs with a negative BVP (-1.00 to -12.00 D), both without (P = .04) and with UV filters (P = .02). CONCLUSIONS With the ISO-conforming, diopter-independent measurement setup, the UV-absorbing test contact lenses that meet the current international standards, regardless of their BVP, were identified. Lenses with increased center thickness absorb more UV radiation. Further studies may use a modified measurement setup with a larger aperture than 10 mm. It would also be worthwhile to examine the UV absorption of the contact lens over the complete corneal area and limbal area because UV radiation may damage inner ocular tissues like the crystalline lens as well as limbal stem cells.

Automated summary

Thicker soft contact lenses were found to absorb more UV radiation. Some soft contact lenses meet international standards for UV protection, and there is a significant difference in UV transmittance between lenses with positive and negative back vertex power.