Figure 1. The protective effects of rosemary and zinc oxide on retinal light damage in dark-reared rats exposed to intense visible light. A: Rats were treated with various doses of rosemary powder extract (R) and or aqueous zinc oxide (Z) given 1 h before light exposure of 4 h duration and then dark maintained for 2 weeks before rhodopsin and photoreceptor cell DNA analysis. At doses of rosemary greater than 17 mg/kg and zinc oxide above 1.3 mg/kg, visual cell survival was significantly higher than for vehicle treatment, with no significant difference between the individual components and combined treatment (R+Z). At 8.5 mg/kg rosemary and 0.65 mg/kg zinc oxide, intermediate levels of visual cell rhodopsin and DNA were found for rosemary and zinc alone. These values were significantly higher than for vehicle but significantly lower than for combined rosemary plus zinc. At lower doses, neither rosemary nor zinc was effective. (*) Average rhodopsin and DNA values were combined for the 1% Tween-80/10% ethanol and acidified water vehicles. (**) Average values for rhodopsin and DNA measurements following treatment of rats with a combination of 0.32 mg/kg zinc oxide and 8.5 mg/kg rosemary powder extract. No LD represents data for rats unexposed to intense light. Results correspond to n=4-8 rats per treatment, ±standard deviation. B: The protective efficacy for pretreatment of rats with rosemary and zinc following exposure to intense visible light. Efficacy was calculated from the average values for rhodopsin and DNA in panel A (n=4-8) and plotted as average % for various doses of zinc oxide (blue diamond), rosemary extract (red square), and zinc plus rosemary (Z+R; green triangle). Efficacy was greater for the combined treatments than for either treatment alone over the entire dosing range. In this figure, and as described [21], percent efficacy was calculated using the following formula: 100x (nutrient treated - vehicle treated and light exposed) / (unexposed control - vehicle treated and light exposed).