There is a limit for NDA and the limit states that that the student must have 6/6 vision in the good eye and 6/9 vision on the worst eye at least with glasses or without glasses. For the Myopia, the spectacles should have glasses above 2.5D and for Hypermetropia the spectacles shouldn't have glasses above 3.5D including Astigmatism.

So if you have - power, then it must be less than 2.5 and if you have + power then it must be less than 3.5. If you satisfy this conditions then you are eligible.

For more information regarding NDA consider the link below:

https://competition.careers360.com/exams/nda

I hope this helps. Wish you a great day!