Regulatory Calculations Using the Spectral Evaluation Function: Evaluating Spectacle Lenses as Specified by JIS T7333

Importance of Topic

Accurate measurement of spectral transmittance in spectacle lenses is essential to ensure consumer protection against harmful ultraviolet radiation and to meet regulatory requirements. Spectral sum-of-products evaluations with user-specified weighting factors enable compliance with diverse safety standards.

Study Objectives and Overview

The study demonstrates how Shimadzu’s UV-2600i spectrophotometer, combined with LabSolutions UV-Vis software, can measure transmittance of clear spectacle lenses and compute four JIS T7333 criteria. It highlights the customization of weighting factors for UV-A, UV-B, and visible light ranges to quantify lens performance.

Used Instrumentation

• UV-2600i UV-Vis spectrophotometer
• MPC-2600A multipurpose large sample compartment
• LabSolutions UV-Vis software with optional Daylight or UPF modules

Methodology

Four uncoated clear lenses (A1, A2, B1, C1) were measured in triplicate. Measurement parameters: 280–780 nm wavelength range, 1 nm data interval, medium scan speed, 5 nm slit width, light source switch at 315 nm. Custom weighting factors were defined in a CSV file and loaded into the spectral evaluation function to calculate weighted mean transmittance values via equation (1) in JIS T7333.

Key Results and Discussion

All lenses blocked most wavelengths below 400 nm, with C1 transmitting up to 0.1 % in the 310–370 nm UV-A region. Computed criteria (τSUVA, τSUVB, τV, τUVA) revealed protection ranking B1 > A1 > A2 > C1 for solar UV-A, and τSUVB ≤ 0.1 % for all lenses, indicating effective UV-B blocking. Visible transmittance (380–780 nm) exceeded 91.6 %, placing all samples in category 0 (transparent).

Benefits and Practical Applications

• Provides quantitative assessment of UV protection and visible light transmission in spectacle lenses.
• Enables compliance with JIS T7333 and other regulations by defining custom weighting factors.
• Supports informed selection of eyewear for cataract prevention and visual clarity.

Future Trends and Potential Applications

Emerging developments include real-time integration of regulatory updates, expansion to tinted and polarized lenses (Q and P value calculations), and broader application of spectral evaluation in material certification, product development, and quality control across optical industries.

Conclusion

The spectral evaluation function in LabSolutions UV-Vis, combined with Shimadzu UV-2600i instrumentation, allows precise calculation of weighted transmittance criteria per JIS T7333. This approach ensures reliable quantification of UV protection and visible light performance in spectacle lenses.