Related Experiment Video
Updated: Aug 7, 2026
Oxygen-Induced Retinopathy Model for Ischemic Retinal Diseases in Rodents
Published on: September 16, 2020
Light-induced retinopathy: comparing adult and juvenile rats
Sandrine Joly1, Vincent Pernet, Allison L Dorfman
1Department of Biological Sciences, University of Montreal, and Department of Ophthalmology, McGill University-Montreal Children's Hospital Research Institute, Quebec, Canada.
Insights
The developing rat retina shows resistance to bright light damage, with this protection diminishing as the animal matures. Juvenile rats exposed to high light levels experience less severe retinal damage than adult rats.
Area of Science:
- Ophthalmology
- Developmental Biology
- Toxicology
Background:
- The developing retina's vulnerability to environmental factors is not fully understood.
- Bright light exposure can cause significant retinal damage (light-induced retinopathy - LIR).
Purpose of the Study:
- To investigate the impact of chronic bright light exposure on the developing rat retina.
- To compare the effects of light exposure on juvenile versus adult rat retinas.
Main Methods:
- Juvenile and adult Sprague-Dawley rats were exposed to 10,000 lux light.
- Exposure durations varied between postnatal day 14 and 34.
- Retinal structure and function were assessed using electroretinograms (ERGs) and histology.
Main Results:
- Retinal damage severity in juvenile rats was age-dependent, with earlier exposure causing less damage.
- Exposure between postnatal days 14-20 resulted in 50% outer nuclear layer thinning, versus 27% for days 28-34.
- Adult-like damage was observed only in rats exposed after postnatal day 28.
Conclusions:
- The developing retina is relatively protected against bright light-induced damage compared to the mature retina.
- This protective window narrows as the rat approaches one month of age.
- Age is a critical factor in determining susceptibility to light-induced retinopathy.
Purpose:
To investigate the effect of chronic exposure to a bright, luminous environment, starting at the opening of the eyes, on the retinal structure and function of the suckling rat.
Methods:
Juvenile Sprague-Dawley rats were exposed to 10,000 lux, for varying lengths of time between postnatal day (P)14 and P34. Results were compared with those obtained from adult rats exposed to the same light intensity and for the same duration. Electroretinograms (ERGs) were recorded at 1 month and 2 months of age, after which the retinas were harvested for histologic analysis.
Results:
In juvenile rats, the severity of light-induced retinopathy (LIR) depended not only on the duration of the exposure but, more important, on the age of the rat at the onset of exposure. For example, in adult rats, 6-day exposure reduced the thickness of the outer nuclear layer (ONL) to less than 18% of normal, whereas in juvenile rats, 6-day exposure between P14 and P20 reduced it to 50% compared with 27% after exposure between P28 and P34. An adultlike effect could only be evidenced in rats exposed at the end of the first postnatal month (P28-P34). A similar age-dependent effect was also noted on the electroretinogram.
Conclusions:
These results show that, compared with the mature retina, the developing retina appears to be relatively preserved from the devastating consequences of exposure to bright light. This window of resistance to light damage gradually weakens as the juvenile rat approaches its 1-month anniversary.
