Spectacle Lens UV Selective Coating Myopia Control
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Solution Overview
Problem
Conventional spectacle lenses absorb light in the beneficial wavelength range for controlling eye growth, particularly in adolescents with myopia progression, leading to increased shielding of required radiation and exacerbating myopia, as they become thicker, creating a vicious cycle.
Innovation Solution
A spectacle lens with a base material containing a UV absorber or an antireflection coating that allows beneficial UV light to reach the eye by configuring the UV absorber or coating to achieve a band-stop filter effect for ultraviolet light, ensuring transmittance in the 355 nm to 390 nm range and reflectance in specific angular ranges to direct beneficial light into the eye while blocking harmful radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional spectacle lenses with UV absorbers are used to block harmful UV radiation, then eye protection from harmful UV is improved, but transmission of beneficial UV light (355-390 nm) for controlling eye growth is reduced
Solution Approach 1:
The UV spectrum is segmented into harmful ranges (below 355 nm) and beneficial ranges (355-390 nm). The coating is designed to selectively block different segments of UV radiation, allowing beneficial wavelengths to pass through while blocking harmful ones, thereby resolving the contradiction between protection and growth control.
Solution Approach 2:
The coating applies different optical properties to different wavelength ranges. Specifically, the coating has high reflectance for harmful UV wavelengths and low reflectance (high transmission) for beneficial UV wavelengths in the 355-390 nm range, creating local quality differentiation that simultaneously achieves protection and growth control.
2Manufacturing precision
If spectacle lenses are made thicker to correct higher myopia, then optical correction is improved, but shielding of beneficial radiation is increased, exacerbating myopia progression
Solution Approach 1:
The coating converts the harmful effect of thick lens material (blocking beneficial UV light) into a benefit by actively reflecting harmful UV radiation away from the eye. This compensates for the increased shielding effect of thicker lenses, allowing high myopia correction without exacerbating myopia progression through beneficial UV transmission.
Solution Approach 2:
The coating changes the optical parameters of the lens system by introducing angular-dependent reflectance properties. This modifies the overall transmission characteristics to ensure beneficial UV light reaches the eye regardless of lens thickness, thereby decoupling optical correction from harmful radiation shielding.
3Duration of action of stationary object
If UV absorbers are added to base materials to protect against UV degradation, then material durability is improved, but transmission of beneficial UV light (355-390 nm) is reduced
Solution Approach 1:
The harmful UV absorption function is extracted from the base material and relocated to the coating layer. This allows the base material to maintain durability through UV protection while the coating is engineered to selectively transmit beneficial UV wavelengths, separating the protection function from the growth control function.
Solution Approach 2:
The solution uses a composite structure combining UV-absorbing base material with a wavelength-selective coating. This composite approach allows simultaneous achievement of material durability (through UV absorption in the base) and beneficial UV transmission (through selective coating properties), resolving the contradiction between protection and growth control.
4Ease of manufacture
If conventional coatings are applied to reduce reflection, then antireflective performance is improved, but angular-dependent control of UV light reflection is lost
Solution Approach 1:
The coating introduces dynamic, angular-dependent optical properties to control UV light reflection. Rather than a static antireflective coating, the design varies reflectance based on angle of incidence and wavelength, enabling adaptive control that directs beneficial UV light into the eye while blocking harmful radiation at different angles.
Solution Approach 2:
The coating changes multiple optical parameters simultaneously: reflectance, transmittance, and angular dependence. By engineering these parameters to vary with wavelength and angle of incidence, the coating achieves both antireflective performance in visible light and selective UV control, maintaining ease of manufacture while adding versatility.
Data Source
AI summary
A spectacle lens has an object-side front surface and an eye-side rear surface and is made of a base material that includes an ultraviolet (UV) absorber, which functions as a band-stop filter for UV light. In a first variant, the band-stop filter has an upper cut-off wavelength between 325 nm and 360 with a transmittance of 2% for light which is incident on the front surface, transmitted through the spectacle lens, and emerges from the rear surface for each angle of incidence between 0° and 15°. Additionally or alternatively, in a second variant, the spectacle lens has an antireflective coating with a reflectance below 5% for UV light in a wavelength range between 280 nm and a threshold wavelength, which lies between 325 nm and 350 nm, and a reflectance of 5% at the threshold wavelength for each angle of incidence between 30° and 45°.