Light Damage – White Light Damage

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By Experimentica on July 2, 2020
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Summary: Bright light retinal damage in rodents remains one of the most widely used models mimicking human retinal degenerations such as retinitis pigmentosa (RP) and age-related macular degeneration (AMD).

Model Description

Retinal damage induced by bright light in laboratory rodents has remained one of the most widely used models mimicking human retinal degenerations such as retinitis pigmentosa (RP) and age-related macular degeneration (AMD) for more than five decades.

The model is induced by exposing rodents to bright light (2.500-10.000 lux). The exposure to bright light (BLE) induces the apoptosis of photoreceptors and retinal pigment epithelium1-3. Our previous studies have shown that the total retinal thickness in decreases with aging, as seen in 7 month-old vs 3.5 month-old BALB/c mice. Moreover, the BLE exacerbates the retinal damage in aged mice when compared to young mice.

Animal speciesMice
Method of inductionExposure to bright light
Follow-up periodUp to 7 days
Route of compound administrationTopical (e.g. eye drops), subretinal, intravitreal, systemic
Read-outs1. In vivo imaging: spectral-domain optical coherence tomography (SD-OCT),
2. In vivo functional assessment,
3. Morphological assessment,
4. Molecular biology (ELISA, Western blotting, qPCR)

Read-outs

Figure 1. Sample images of the SD-OCT scans taken at baseline and 7 days after BLE.
Figure 1. Sample images of the SD-OCT scans taken at baseline and 7 days after BLE in 3.5 months old and 7 months old mice raised under normal light and under darkness.
Figure 2. Heat maps depicting the retinal thickness measured from the SD-OCT scans.
Figure 2. Heat maps depicting the retinal thickness measured from the SD-OCT scans. 7-month-old mice already had a thinner retina at baseline than 3.5-month-old mice. There was a statistically significant decrease in total retinal thickness in young mice exposed to 10 klux light (t-test, P<0.05) as compared to retinal thickness measured before BLE. Aged mice exposed to 10 klux light suffered a dramatic decrease in ONL thickness when compared to the young 10 klux group (t-test, P<0.05). There were no differences in retinal thickness between young mice which were raised in darkness and young control mice after BLE. However aged mice which were kept in darkness were slightly more resistant to intense light exposure than age-matched control mice. Data was analyzed by One-Way ANOVA followed by Tukey’s post-hoc test. S: Superior; T: Temporal; N: Nasal; I: Inferior; X: optic nerve head.
Figure 3. fERG results in young and old mice at baseline and seven days after BLE.
Figure 3. fERG results in young and old mice at baseline and seven days after BLE. a and b-wave amplitudes decreased after BLE in young and aged groups. Moreover, the level of decrease in the response was similar for the dark and light raised animals. The aged animals grown in darkness maintained the fERG responses as the young ones, while the ones grown in light presented decreased responses.

References

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