Blind calfs

Its been a crappy start to our calfing season. Found 1 dead this morning from a 1st calf heifer no idea why, and my grandfather had his 2nd one born blind in 3 years. He only has 8 or 9 cows and to have 2 blind out of such a small group is worrisome to me. He doesnt really keep mineral out or salt. I use to keep mineral out for them when I was in high school (out of my pocket) but have quit since buying my own herd. Other then vitamin a deficiency what could cause this.

On the upside did have a nice calf this morning