MyVisionTest News Archive
Jan 15, 2009
Blue-light-filtering implants may impair vision
A new study reports that color perception and contrast sensitivity by be impaired by blue-light-filtering intraocular lens implants.
Intraocular lens implants (IOLs) are placed in the eye following cataract surgery. They correct vision by focusing light in much the same way as eyeglasses or contact lenses do, but because they are located within the eye, the vision is more natural. Because it is hypothesized that blue light may contribute to the development of age-related macular degeneration (AMD), many eye surgeons will use an implant that filters out potentially harmful blue light in addition to ultra-viotet radiation. Implants are also available that only block UV but allows blue light into the eye, as well as implants that do not contain any filter.
This study included 48 eyes of 24 consecutive patients with age-related cataract. Each patient had standard cataract surgery with IOL implantation. Patients received a blue-light-filtering IOL in one eye and a UV-filtering IOL in their other eye. Contrast acuity, color vision, and blue/yellow foveal threshold was tested on each eye following the surgery. The subjective visual impression of patients was also evaluated using a questionnaire.
The investigators found that blue-light-filtering IOLs had worse contrast acuity and lower foveal thresholds compared with the UV-filtering IOLs. Color vision tests and high-contrast visual acuity did not show any statistically significant differences between IOLs. On questioning, only 3 of 24 patients noticed a difference in the quality of their vision between their eyes.
The researchers conclude that blue-light-filtering IOLs negatively affect contrast acuity and blue/yellow foveal threshold when compared with UV-filtering IOLs. They acknowledge that the differences they found were small, and that some previous studies have failed to find any significant difference in vision between blue-filtering and UV-filtering implants. Nonetheless, they suggest that the same type of IOL be used in both eyes of patients to avoid potential vision disturbances, especially in patients with high demands in color vision.
WHAT IT MEANS TO YOU: Intended as a way to decrease the risk of AMD following cataract surgery, the negative consequences of blue-blocking IOLs may out weight any theoretical advantage. First, it is important to recognize that there is no clinical or experimental proof that normal sunlight exposure causes AMD. Some studies have found an association between AMD and cataract surgery, but others have not. The Centers for Medicare and Medicaid Services concluded that "the relationship between blue light and AMD is speculative and not proven by available evidence." Furthermore, sunlight is important in setting the body's internal clock, known as the circadian rhythm. Insufficient sunlight exposure may result in insomnia, daytime sleepiness, depression, and poor concentration due to circadian dysfunction. The ideal IOL for circadian health should transmit as much blue light as possible. Blue-blocking IOLs provide 27% to 38% less circadian sensitivity than UV-blocking IOLs. Now, the current study indicates that blue-blocking IOLs may impair visual function in some patients. Unless stronger evidence emerges linking sunlight exposure to AMD, blue-blocking IOLs may not be such a great idea.
Read more...
Ophthalmology. 2009 Jan;116(1):39-45
A new study reports that color perception and contrast sensitivity by be impaired by blue-light-filtering intraocular lens implants. Intraocular lens implants (IOLs) are placed in the eye following cataract surgery. They correct vision by focusing light in much the same way as eyeglasses or contact lenses do, but because they are located within the eye, the vision is more natural. Because it is hypothesized that blue light may contribute to the development of age-related macular degeneration (AMD), many eye surgeons will use an implant that filters out potentially harmful blue light in addition to ultra-viotet radiation. Implants are also available that only block UV but allows blue light into the eye, as well as implants that do not contain any filter.
The investigators found that blue-light-filtering IOLs had worse contrast acuity and lower foveal thresholds compared with the UV-filtering IOLs. Color vision tests and high-contrast visual acuity did not show any statistically significant differences between IOLs. On questioning, only 3 of 24 patients noticed a difference in the quality of their vision between their eyes.
The researchers conclude that blue-light-filtering IOLs negatively affect contrast acuity and blue/yellow foveal threshold when compared with UV-filtering IOLs. They acknowledge that the differences they found were small, and that some previous studies have failed to find any significant difference in vision between blue-filtering and UV-filtering implants. Nonetheless, they suggest that the same type of IOL be used in both eyes of patients to avoid potential vision disturbances, especially in patients with high demands in color vision.
WHAT IT MEANS TO YOU: Intended as a way to decrease the risk of AMD following cataract surgery, the negative consequences of blue-blocking IOLs may out weight any theoretical advantage. First, it is important to recognize that there is no clinical or experimental proof that normal sunlight exposure causes AMD. Some studies have found an association between AMD and cataract surgery, but others have not. The Centers for Medicare and Medicaid Services concluded that "the relationship between blue light and AMD is speculative and not proven by available evidence." Furthermore, sunlight is important in setting the body's internal clock, known as the circadian rhythm. Insufficient sunlight exposure may result in insomnia, daytime sleepiness, depression, and poor concentration due to circadian dysfunction. The ideal IOL for circadian health should transmit as much blue light as possible. Blue-blocking IOLs provide 27% to 38% less circadian sensitivity than UV-blocking IOLs. Now, the current study indicates that blue-blocking IOLs may impair visual function in some patients. Unless stronger evidence emerges linking sunlight exposure to AMD, blue-blocking IOLs may not be such a great idea.
Read more...
Ophthalmology. 2009 Jan;116(1):39-45
