The damaging effect of various intensities of light on retinal function in pigmented rats

• Published in: Acta ophthalmologica (Oxford, England) Vol. 87; no. s244
• Main Authors: BARYLUK, A, THALER, S, REJDAK, R, BOLZ, S, ZRENNER, E, ZARNOWSKI, T
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.09.2009
• ISSN: 1755-375X; 1755-3768
• DOI: 10.1111/j.1755-3768.2009.367.x

Purpose To investigate the functional retinal damage following the short term (6h) light exposure in pigmented rats. Methods One group of dark adapted Brown‐Norway rats was exposed for 6 h to 10 klux without mydriasis. Five groups of rats were exposed to different intensities of light (10, 5, 3.4, 2.7 and 1.7 klux) for 6 h with pupil dilatation. Electroretinography (ERG) was recorded prior to, and at 1st and 7th day after light damage (LD). ERG protocol enabled quantification of scotopic sensitivity parameters (Vmax‐saturated b‐wave amplitude and k‐ luminance to reach Vmax/2),photopic cone response and oscillatory potentials(OPs). Results The exposure to 10 klux without mydriasis did not result in significant retinal injury. In groups subjected to mydriasis, the light of 1.7 klux resulted in nonsignificant (ns) decrease of ERG response. However, the severe loss of retinal function was reported after exposure to higher intensities. The value of Vmax at 1st day after LD was reduced respectively to 90±25%(ns), 19±5%, 7±4%, 4±1% and 3±0.3% of baseline value (p<0.05).No significant improvement was recorded during the following 7 days. The parallel decrease was observed in scotopic mixed (rod+cone) a‐ and b‐wave amplitude,in photopic response and in OPs. The scotopic threshold luminance increased gradually together with the damaging light intensity, while the value of parameter k was only narrowly altered (p>0.05) after LD in all animal groups. Conclusion Our results show, that a few hours' illumination with the light of even moderate intensity may result in severe functional retinal impairment in pigmented rats. Presented model may be useful to study the cell degenerations in pigmented retinas.