Initially I thought what he means by 'overlapping vision' could be a case of serious astigmatism (散光). I came across a lot of people saying they see double but actually it is just blurred.
I carried on with my investigation and found out that he has lateral rectus palsy. Lateral Rectus is one of the muscle inside the eye causing one of his eye unable to look to one side, causing his double vision.
As it is a sudden onset and he is in his 40's so I referred him to the hospital for further evaluation of the nervous system. I reassured him of the treatment options and if there's nothing they can do at hospital level, I will need to prescribe him with prism glasses.
For your information, each of our eyeball is surrounded by six muscles, and each has different function. Trust me, this topic is one of the toughest in uni. All six muscles are differently controlled by third, fourth and sixth cranial nerve, connected to the brain. Commonly lateral rectus palsy is caused by birth trauma as it is controlled by the sixth nerve, located near the side of our head. It's palsy causes esotropia, in-turned of the eye. Eye muscles of both eyes must be balanced in order to see 3-D vision, no double vision, and good depth perception. If you need more information about muscles of the eye, drop me an email. If you have real life story, share with me!
In routine optometric practice, the most problems and symptoms are easily solved by giving a pair of glasses. When there's challenging cases like my patient today, it really boost my passion and anticipation. Solving a complicated eye condition is just the same as the joy of solving a difficult mathematics question!
I declare that I have never regret to start on this route as an optometrist. Once I started university in Glasgow, I have never look back since. Call me an eye freak! Haha!
The health of your eyes is my main concern.
Till then! xoxo