Q. Left eye starts watering when I see bright light. Why is it?

Answered by
Dr. Anand Yattinamani
and medically reviewed by iCliniq medical review team.
This is a premium question & answer published on Jul 25, 2018 and last reviewed on: Oct 14, 2020

Hi doctor,

I am a 26 year old male. I have noticed over the past several months, that I have been favoring my right eye more (monocular vision). My right eye is my dominant eye. I have been leaning in that direction to read. I can still see out of my left eye but the focus is from my right. I have slight double vision with close objects of about 2 feet from my face but when I consciously try and focus with both eyes it disappears. Corneal light reflex shows slight deviation to the left of my left eye, approximately 1.5 mm. I went to the optometrist yesterday to get a prescription for reading glasses since I read a tremendous amount for school. All of my EOMI as well as my pupils were reactive to both direct and consensual light reflexes. Left pupil is slightly larger by 1 mm or so. I had a CT scan of my head last month due to a headache and acute anxiety. I have had four concussions and was worried about delayed symptoms from those. CAT scan came back clean with no noticeable lesions.

My dog scratched my eye around 6 months back or so and it felt as if it pulled slightly and I am worried that might have caused it out of alignment. There was no surface damage to the eye, but the left medial rectus becomes sore if I move it too often or try to focus. My left eye starts tearing up as well whenever I go into bright lights. Since all of the extra ocular muscles are intact, should I just wait and see if the prescription fixes the problem or should I have them checked out by an ophthalmologist? I have attached the pictures for your reference. Please suggest.



Welcome to

I have gone through the photographs (attachment removed to protect patient identity) of your eyes.

  • It looks absolutely normal. Your symptoms appear to be related to eye fatigue and tiredness due to continuous reading. 
  • Also there dominant eye can be changed with little effort (unless you have similar vision in both eyes and no glasses).
  • It is nothing related to your previous problems of dog scratch or head injuries.
  • Just take the prescription and try glasses. Wait and watch. You will be fine soon.
  • Also do some eye exercises like, eye rotation, focusing on tip of your thumb and moving it near and far for five minutes daily.

For further information consult an eye care ophthalmologist online -->

Hi doctor,

Thank you for the advice. My prescription glasses should be ready by the end of the week. The horizontal diplopia is very slight as well and hopefully will resolve with the glasses. My girlfriend noticed the other day that when I tried to concentrate with both eyes on close objects that my eyes shift back and forth slightly, as if trying to use monocular vision and figuring out which one to focus with. There is no nystagmus when looking one direction or the other, vertical or horizontal. Is this due to eye fatigue and continuous reading as well causing one eye to move laterally when trying to focus?



Welcome back to

I have gone through the photographs (attachment removed to protect patient identity) of your eyes.

  • As I explained earlier they look normal in all the gazes.
  •  It can be due to eye fatigue and tiredness due to continuous reading.
  • Just use the prescribed glasses correctly.
  • Do eye exercises like rotation and focusing on the tip of the thumb and moving it near and close for five minutes twice a day.
  • Also if you are using computer, keep brightness to the minimum, maintain the distance of about 40 cm and blink the eyes as frequently as possible.
  • Close your eyes for 10 to 15 seconds for every 5 minutes, this will relax your eyes and decrease the fatigue. Hope you will be fine soon.

For further information consult an eye care ophthalmologist online -->

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