Hello dear,
From the information you shared it seems like your father may be suffering from high intraocular pressure that's why the I was paining and was red and most possibly the surgery was done for that only. As you said now the eyes small it means it has become pthysical and now nothing can be done at this stage to restore the vision.
Next Steps
Share with me the case file which you have so that we can see assess the condition of the Other eye also.
Health Tips
Take six monthly eye consultation from a competent ophthalmologist.