While I would prefer to leave the Legal aspects of your situation/issue to members who are much better in legal aspects, I shall focus on the practicalities of the situation.
While your line "I feel that as the position is Managerial and I can perform all the activities as a normal person I should be given opportunity to work", AS A GENERAL RULE, is quite logical & realistic & actionable, vis-a-vis YOUR situation, I DON'T think it would be so.
Had your job role & responsibilities involved just a desk job with not much of movements-related activities, then the disability in your eyesight MAY NOT be a valid argument to keep you off the position.
You are into an area where the work would involve a high level of movement, especially in a ship/submarine, where movements are in constricted locations as also the flights of steps most movements involve.....you know what I mean. And, in general, any movements under such environment/topology would need an eyesight that enables at least a 120 deg view.......something that's the norm of a normal eyesight.
Added to this would also be the typical lighting scenario of such nooks & corners, where lighting would be far less than a typical office environment.
The reason, as far as I can see, why the above aspects become important in your case is due to the fact that you are into Engineering function & NOT any other function that doesn't need getting into the nitty-gritty of how the ship/submarine is built & resolving the engineering problems including integration/installation issues. Had it been any SCM or Design position, then the stand of the PSU can surely be faulted with.
The days of ONLY the lower-end staff handling the hands-on work AND the Manager or senior management controlling ONLY the paperwork [and possibly the credits too] IS GONE.
I am basing the above views on my experience in a Defence Project @ MDL/Mumbai.
Suggest pl wait for other members to respond too.