BLOG: Violet light filtration
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As presbyopia-correcting IOLs continue to evolve, it is exciting to see lens manufacturers find additional ways to improve the optical performance of these lenses.
A great example is the introduction of the first presbyopia-correcting IOLs with a violet light filter, the Tecnis Symfony OptiBlue (ZXR00V/DXR00V and ZXWDXW series) and Tecnis Synergy (ZFR00V/DFR00V and ZFW/DFW series) IOLs (Johnson & Johnson Vision). Both feature the InteliLight triad of technologies that includes high-resolution lathing to reduce halo intensity and light scatter, achromatic technology to enhance image contrast, and violet light filtration.
All IOLs filter nonvisible ultraviolet light that is harmful to the retina. The shorter wavelengths of high-energy light at the blue-violet end of the visible light spectrum are often grouped together, but there are important differences. Violet light, at wavelengths less than 450 nm, is associated with a higher degree of light scatter and may have phototoxic effects that increase the risk for retinal disease. Blue light in the 450 nm to 500 nm range has some potential benefits for low-light (mesopic and scotopic) contrast acuity. Selectively filtering just the shortest wavelengths preserves the benefits of blue light while filtering out the violet light that is most likely to be detrimental.
Unfortunately, environmental exposure to short-wavelength light has been increasing due to the proliferation of light emitting diode (LED) bulbs. While LED light is brighter, more efficient and longer lasting than conventional alternatives, it also scatters more. This is particularly of concern for drivers facing oncoming LED highlights at night. Transportation researchers have found a linear relationship between short-wavelength light output from LED headlights and discomfort glare. Blocking high-energy ultraviolet and violet wavelengths may improve night driving vision.
We conducted an informal pilot series in our practice in which one eye of each patient was implanted with a Symfony OptiBlue lens and the fellow eye implanted with a legacy Symfony IOL without violet filtration. Patients reported less dysphotopsias and, in particular, a reduction in starbursts with the newer violet-filtering lens. Based on this experience, we now regularly utilize violet light-filtering lenses. I still counsel patients to expect to notice starbursts, but they seem to find dysphotopsia symptoms less bothersome even when they do notice them.
My anecdotal findings mirror those reported by Daniel Chang, MD, and colleagues at the 2022 ASCRS meeting. They found a 45% reduction in dysphotopsia complaints, a 72% reduction in time spent in postoperative counseling about dysphotopsia, and fewer secondary interventions and postoperative visits with the violet-filtering lens compared with a clear IOL from the same platform, even though both offered the same level of visual acuity. This may be due to a reduction in veiling luminance and enhancement in contrast vision under challenging light conditions with violet light filters, Dr. Chang reported.
Violet filtration is an important step in improving quality of vision under low-light conditions, including night driving, and improving low-light reading performance, which we have not observed with other forms of presbyopia correction to date. I hope that violet light filters, which are currently only available on the two lenses discussed here, will be utilized in monofocal and monofocal toric lenses, as well as other manufacturers’ lens platforms, in the future.
References:
- Canovas C, et al. Invest Ophthalmol Vis Sci. 2019;60:3717.
- Chang D, et al. J Ophthalmic Stud. 2020;doi:10.16966/2639-152X.119.
- Chang DH. Symposium 2: Hot and happening: The case for EDOF technologies. Presented at: American Society of Cataract and Refractive Surgery meeting; April 23, 2022; Washington.
- Chang DH, et al. The effect of violet light filtration and manufacturing improvements on the clinical performance of an extended depth of focus IOL. Presented at: American Society of Cataract and Refractive Surgery meeting; April 25, 2022; Washington.
- Sivak M, et al. Blue content of LED headlamps and discomfort glare. https://deepblue.lib.umich.edu/bitstream/handle/2027.42/57444/98625.pdf.Published February 2005.
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