Cataract Development by Exposure to Ultraviolet and Blue Visible Light in Porcine Lenses

Abstract

Background and Objectives: Cataract is still the leading cause of blindness. Its development is well researched for UV radiation. Modern light sources like LEDs and displays tend to emit blue light. The effect of blue light on the retina is called blue light hazard and is studied extensively. However, its impact on the lens is not investigated so far. Aim: Investigation of the impact of the blue visible light in porcine lens compared to UVA and UVB radiation. Materials and Methods: In this ex-vivo experiment, porcine lenses are irradiated with a dosage of 6 kJ/cm² at wavelengths of 311 nm (UVB), 370 nm (UVA), and 460 nm (blue light). Lens transmission measurements before and after irradiation give insight into the impact of the radiation. Furthermore, dark field images are taken from every lens before and after irradiation. Cataract development is illustrated by histogram linearization as well as faults coloring of recorded dark field images. By segmenting the lens in the background's original image, the lens condition before and after irradiation could be compared. Results: All lenses irradiated with a 6 kJ/cm² reveal cataract development for radiation with 311 nm, 370 nm, and 460 nm. Both evaluations reveal that the 460 nm irradiation causes the most cataract. Conclusion: All investigated irradiation sources cause cataracts in porcine lenses-even blue visible light.

Keywords: UV radiation; UVA; UVB; blue light; cataract; porcine lens.

Figure 1

Schematic drawing of the custom-made dark field image setup. A ring light (6) illuminates the sample from below. The light that passes the sample in a straight line is not detected by the camera (1), whereas scattered light (2) from insight the sample is detected by the camera from above. With this setup, cataractogenic structures can be made visible.

Figure 2

Schematic drawing of the experimental setup. A closed box prohibits radiation reaching the outside of the experimental box. To prevent overheating of the lenses cold water circles ((1) and (6)) around the sample holder (3). The radiation source (2) irradiates the sample from above. With the height-adjustable stage (4), the distance between lenses and radiation source is regulated. The control group (5) is located under a box shielded from irradiation.

Figure 3

The mean transmission data and the corresponding standard error of the mean (SEM) of porcine lenses are given in the visible spectrum from 380 nm to 780 nm for irradiation with UVB (black curve), UVA (violet curve), 460 nm (blue curve), and the control group (red curve). Before irradiation, measurements are displayed with solid lines, whereas measurements after irradiation are displayed with dashed lines.

Figure 4

The mean quotient Q_T of the transmission after and before irradiation is illustrated with the standard error of the mean (SEM) for lenses irradiated with UVB (black curve), UVA (violet curve), and 460 nm (blue curve), as well as for the control group (red curve).

Figure 5

The pictures illustrate some lenses, which developed different kinds of cataracts due to irradiation. In the upper part of each paired picture, the unedited grey images are illustrated. Below there are the false color pictures. All pictures include a circular-shaped red line around the lens, which symbolizes the area Matlab detected as the lens. The upper pictures (a–e) are taken directly after lens extraction from the eye. The lenses (f–j) are irradiated. The pictures in (a) present a lens before UVB irradiation leading to the pictures in (f) after UVB irradiation. An example for a UVA irradiated lens is presented in (b,g) before and after irradiation, respectively. Lenses before 460 nm irradiation can be seen in (c,d), whereas (h,i) represent the irradiated ones. The lens (e,j) represents the control group.

Figure 6

This diagram represents the quotients describing the calculated change from the dark field images for each irradiation and control group. The lower the value the more cataract development was detected. The closer the quotient to one, the less change occurred to the lens. Hence, the control group has the least change with a quotient of 0.82. In the UVB irradiated lenses with a quotient value of 0.78, the least cataractogenic effect was detected, followed by the quotient of the UVA irradiated lenses with 0.78 as a quotient. The 460 nm-irradiated lenses with a quotient of 0.69 reveal the greatest cataractogenic effect. The error bars indicate the standard error of the mean.