Question

What happens if the lachrymal glands are absent in our eyes

Answer 1

As we know that, the lacrimal glands secrete tears which act to lubricate and protect the cornea and eyeball from injury which may result from small particles such as dust. 
 If the lacrimal gland were absent the eyes would not be able to lubricate and secrete tears to protect the cornea from injuries

Answer 2

our eyes completely fills with dust it avoid the entry of dust