Loosing vision at the age 30 yrs,there is many causes ,if eye examination is normal& there is no optic nerve &retina problem, you should consult neurologist because there may be due to some lesions in brain because ultimate Vision center lies in the occipital lobe which lies back side of head.

Hello there.  I can understand your concern.  When eye doctors examine the patients, they also check for any defects inside the eye ball or defect in the nerves. So consult a ophthalmologist at a good hospital near you for further evaluation and management.  He will be able to help you further. Best regards. Dr. Anil kumar jain. Bangalore.