Dog with a scratched Cornea. (please help quite worried)

ok about 5 weeks ago my grandams cat came over to my property and
attacked my dog as we were leaving that Morning. When we got home
that late afternoon. I noticed my dogs eye was tearing realy bad. He
could open it about halfway. That night I went to the first aid
homeopathic websight under eye injuries and I choose Arnica. Here the
websight for anyone that wants to see it
http://www.simillimum.com/education/first-aid-room/index.php.... His
looked like a semi deep paper cut. on the Irisof his eye. not on his
pupil. Anyway so I started giving him Arnica internally and a drop in
his eye. It healed with in a day or two with only a dot of the
scratch being left and his eye wasent watering or anything. so I gave
him a dose. and it seemed to disappear. well here we are 5 week later
I just happen to look at his eye and there it was again like I had
never touched it. His eye isent tearing or anything.. but why is it
back?? same scratch same place. and now I'm freaked because I've read
that it can lead to scaring which can lead to blindness..Where do I
go from here?? the next one on that websight that I would choose
under eye injuries is Hypericum. Its says its for old eye
injuries..Am I going down the right path?? Dilly just turned 10. Does
his age have something to do with it?? or did it heal too fast that
it broke open again??


Thanks,
April