It is possible that you may have what is called a refractory error. This means that light is not entering your eye at the right angel and hence does not get to the retina. My suggestion would be to get your eyesight checked as the more you strain the higher your chances of worsening whatever is causing the error.
Makobu commented on :
Allergic reactions are as a result of a rejection of something by the immune system. People can have allergy to dust, smoke etc.
In the case of protein allergy, when one egests a protein, it is broken down to increasingly smaller particles. Some of this microscopic protein molecules can trigger and immune reaction form the host. The result of this would be development of an allergy to that and any similar protein molecules. Since the immune system has ‘memory’, the next time it encounters that molecule the reaction is even faster and stronger.