MacuGuard Ocular Support

My 13 year-old, 16lbs, Poodle toy is on the Royal Canin Satiety Support, as recommended by her vet, because she’s a little overweight. She is also taking Dasuquin with MSM (by Nutramax), Canine Plus Senior (by Vetri-Science), and Omega 3 6 9 (by Vetri-Science), as recommended by a different vet. For the past years we noticed her eyes were getting cloudy, we took her to the vet and she said it was a normal aging condition, no signs of cataract, and that there was nothing we could do to reverse this. But after an online search, I started giving her MacuGuard with Astaxanthin (by Life Extension), a supplement for humans that seemed to also help dogs. Since I started giving my dog the MacuGuard (1 softgel per day), we noticed her eyes are not as cloudy as they used to be, and we assumed the supplement was working. But now I’ve came across some conflicting information. Some people say that black currants may be toxic to dogs. Researching online, I found out something like “American currants are raisings and thu, toxic, while European currants are berries and actually very healthy to a dog.” Indeed, I found that some dry foods have black currant in their formulas. Is this accurate? I didn’t want to stop giving her the supplement as I noticed an improvement in the color of her eyes, but I am afraid the supplement, which uses European black currant extract, may cause her any harm. Also, the dosage I am giving (one softgel a day for a 16lbs dog) may be too much?
Thanks in advance, below you can find the supplement facts:

MacuGuard™ Ocular Support with Astaxanthin

http://www.lef.org/Vitamins-Supplements/Item01886/MacuGuard-Ocular-Support-with-Astaxanthin.html?source=search&key=macuguard

Supplement Facts
Serving Size 1 softgel
Servings Per Container 60
Amount Per Serving

MacuGuard™ Carotenoid Phospholipid Blend Phospholipids, marigold extract (flower) [providing 10 mg free lutein, 4 mg meso-zeaxanthin & trans-zeaxanthin]
145 mg

Natural Astaxanthin (from CO2 extract of Haematococcus pluvialis algae)
6 mg

C3G (Cyanidin-3-glucoside) [from European black currant extract (fruit)]
2.2 mg

Other ingredients: soy lecithin, gelatin, safflower oil, extra virgin olive oil, glycerin, sunflower oil, soy fatty acids, purified water, beeswax, potato maltodextrin, annatto color.