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Action spectrum for photobleaching of human lenses by short wavelength visible irradiation.

Kessel L, Larsen M - PLoS ONE (2015)

Bottom Line: For a 75 year old lens an effect corresponding to elimination of 15 years or more of optical ageing was obtained.This study of the spectral characteristics and intensity needed to bleach the human lens with single-photon laser effects found an action-spectrum peak at 420 nm tailing gradually off toward longer wavelengths and more steeply toward shorter wavelengths.The results may be used to guide experiments with two-photon bleaching.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, Glostrup Hospital, Glostrup, Denmark.

ABSTRACT

Purpose: Cataract is the world-leading cause of blindness. In search for a new treatment of cataract we have found that the yellow discolouration of aged human lenses can be photobleached using a non-invasive, infra-red, femtosecond laser treatment. These results were presented in an earlier PlosOne publication. The objective of the study was to characterize the single-photon photobleaching action spectrum of the aged human lens in vitro.

Methods: Ninety-one human donor lenses were irradiated with continuous wave laser light at 375, 405, 420, 445, 457 or 473 nm. Photobleaching was monitored by photography and transmission measurements.

Results: The action spectrum peaked at 420 nm followed by, in order of decreasing effect, 445, 457, 473, 405 and 375 nm. Younger and less absorbent lenses showed smaller changes than older and more absorbent lenses. There was a dose-dependent increase in lens transmission with increasing laser irradiation.

Conclusions: For a 75 year old lens an effect corresponding to elimination of 15 years or more of optical ageing was obtained. This study of the spectral characteristics and intensity needed to bleach the human lens with single-photon laser effects found an action-spectrum peak at 420 nm tailing gradually off toward longer wavelengths and more steeply toward shorter wavelengths. The results may be used to guide experiments with two-photon bleaching.

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Related in: MedlinePlus

Effect of irradiation wavelength on optical lens rejuvenation for a standard 75 year old lens.The photobleaching effect for each irradiation wavelength was calculated using the formulas presented in Table 1 using an irradiation dose of 4000 J/cm2. The photobleaching effect was transformed into a clinically interpretable factor by calculating the apparent lens age after photobleaching using Eq 1. The numbers on the y-axis present the difference between the apparent lens age before and after irradiation. The photobleaching effect is presented as mean value (thick line), upper and lower 95% confidence intervals (thin hatched lines).
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pone.0123732.g005: Effect of irradiation wavelength on optical lens rejuvenation for a standard 75 year old lens.The photobleaching effect for each irradiation wavelength was calculated using the formulas presented in Table 1 using an irradiation dose of 4000 J/cm2. The photobleaching effect was transformed into a clinically interpretable factor by calculating the apparent lens age after photobleaching using Eq 1. The numbers on the y-axis present the difference between the apparent lens age before and after irradiation. The photobleaching effect is presented as mean value (thick line), upper and lower 95% confidence intervals (thin hatched lines).

Mentions: To define a parameter of clinical relevance, the effect of photobleaching was expressed as the change in the apparent age of the lens as judged on the basis of its optical characteristics. For this purpose, transmission of blue light as a function of age in untreated lenses (Transblue) was modelled by Eq 1 (adjusted R2 = 0.58, p<0.001):Transblue=1.017−0.00991×Age(1)To compare photobleaching efficiency between different wavelengths, an apparent lens age was calculated before and after irradiation for a model 75 year old lens using Eq 1. After an irradiation dose of 4000 J/cm2 the mean reduction in apparent lens age was 6.8, 9.7, 15.6, 10.1, 10.2 or 9.0 years for 375, 405, 420, 445, 457 or 473 nm, respectively, see also Fig 5.


Action spectrum for photobleaching of human lenses by short wavelength visible irradiation.

Kessel L, Larsen M - PLoS ONE (2015)

Effect of irradiation wavelength on optical lens rejuvenation for a standard 75 year old lens.The photobleaching effect for each irradiation wavelength was calculated using the formulas presented in Table 1 using an irradiation dose of 4000 J/cm2. The photobleaching effect was transformed into a clinically interpretable factor by calculating the apparent lens age after photobleaching using Eq 1. The numbers on the y-axis present the difference between the apparent lens age before and after irradiation. The photobleaching effect is presented as mean value (thick line), upper and lower 95% confidence intervals (thin hatched lines).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4401553&req=5

pone.0123732.g005: Effect of irradiation wavelength on optical lens rejuvenation for a standard 75 year old lens.The photobleaching effect for each irradiation wavelength was calculated using the formulas presented in Table 1 using an irradiation dose of 4000 J/cm2. The photobleaching effect was transformed into a clinically interpretable factor by calculating the apparent lens age after photobleaching using Eq 1. The numbers on the y-axis present the difference between the apparent lens age before and after irradiation. The photobleaching effect is presented as mean value (thick line), upper and lower 95% confidence intervals (thin hatched lines).
Mentions: To define a parameter of clinical relevance, the effect of photobleaching was expressed as the change in the apparent age of the lens as judged on the basis of its optical characteristics. For this purpose, transmission of blue light as a function of age in untreated lenses (Transblue) was modelled by Eq 1 (adjusted R2 = 0.58, p<0.001):Transblue=1.017−0.00991×Age(1)To compare photobleaching efficiency between different wavelengths, an apparent lens age was calculated before and after irradiation for a model 75 year old lens using Eq 1. After an irradiation dose of 4000 J/cm2 the mean reduction in apparent lens age was 6.8, 9.7, 15.6, 10.1, 10.2 or 9.0 years for 375, 405, 420, 445, 457 or 473 nm, respectively, see also Fig 5.

Bottom Line: For a 75 year old lens an effect corresponding to elimination of 15 years or more of optical ageing was obtained.This study of the spectral characteristics and intensity needed to bleach the human lens with single-photon laser effects found an action-spectrum peak at 420 nm tailing gradually off toward longer wavelengths and more steeply toward shorter wavelengths.The results may be used to guide experiments with two-photon bleaching.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, Glostrup Hospital, Glostrup, Denmark.

ABSTRACT

Purpose: Cataract is the world-leading cause of blindness. In search for a new treatment of cataract we have found that the yellow discolouration of aged human lenses can be photobleached using a non-invasive, infra-red, femtosecond laser treatment. These results were presented in an earlier PlosOne publication. The objective of the study was to characterize the single-photon photobleaching action spectrum of the aged human lens in vitro.

Methods: Ninety-one human donor lenses were irradiated with continuous wave laser light at 375, 405, 420, 445, 457 or 473 nm. Photobleaching was monitored by photography and transmission measurements.

Results: The action spectrum peaked at 420 nm followed by, in order of decreasing effect, 445, 457, 473, 405 and 375 nm. Younger and less absorbent lenses showed smaller changes than older and more absorbent lenses. There was a dose-dependent increase in lens transmission with increasing laser irradiation.

Conclusions: For a 75 year old lens an effect corresponding to elimination of 15 years or more of optical ageing was obtained. This study of the spectral characteristics and intensity needed to bleach the human lens with single-photon laser effects found an action-spectrum peak at 420 nm tailing gradually off toward longer wavelengths and more steeply toward shorter wavelengths. The results may be used to guide experiments with two-photon bleaching.

Show MeSH
Related in: MedlinePlus