I am a head cashier in a bank. Whenever I am reading or doing something stressful job, I am having a slight stiffness in upper neck and below the head. After few minutes I am suffering from a blurry vision along with slight headache. During this condition I cannot focus on the number/ text weather near or far. Also I am experiencing a white bright light in front of the out of focussed eyes and hence concentrate on the job. Kindly help me to diagnose & cure the problem. Thanks