Declared Medically Unfit in pre employment Medical examination

I have been selected for a post of Chief Manager-Mechanical at a ship building PSU. The post of is for ship/submarine construction, refits, modernization, in any relevant fields of planning / design / procurement/ fabrication / berth / outfitting / quality assurance / tests & trials. I have very low vision in my left eye as per guideline of physical disability it is 30% disability. After premedical examination, company has declared me medically unfit for the post on the grounds that my left eye is not healthy. There is no mention of any medical standards in advertisement. Can I fight Legally.