Hello Malika,

Firstly you should know the VISUAL STANDARDS FOR INDIAN NAVY are as follows -

1. Uncorrected without glass 6/12

2. Corrected with glass 6/6

3. Limits of Myopia -1.5

4. Limits of Hypermetropia +1.5

5. Binocular vision Ill 

6. Limits of Colour Perception

You will get many opportunities after 12th science stream to apply for the NAVY.

NDA Entry:- UPSC Conducts NDA Exam for 12th Pass and Appearing Students, twice a year. You need to keep the track of Notification on http://www.upsc.gov.in/

10+2 B.TECH ENTRY:- This Entry also come twice a year and is a technical Entry, so if you have good PCM Percentage and/or good JEE Score, you can get shortlisted for SSB Call Up.

Hope this helps. 

All the best.

hey, You will have to crack the NDA entrance conducted by UPSC twice a year April and September. The candidates joining Indian Naval Academy would undergo 4 years B.Tech Course and would be given a chance to join the Executive and Technical Branch of the Navy.

I hope this helped.

Best wishes