These occasional, but intermittent and sharp pains as well as the light sensitivity are very often the result of dry eyes. I noticed that you have already tried eye drops, but let me explain a couple of things and suggest a regimen for them.
There are many different reasons why you can have dry eyes, including not making enough of your own tears, having inflammation in your eyelids, and even allergies. If the actual cause(s) of the dry eye are not treated properly, then sometimes using artificial tears doesn't always help. This evaluation should be done by an ophthalmologist who can examine you and determine what kinds of problems are factoring into the dry eyes.
However, using artificial tears is always a good place to start, no matter what kind of dry eyes you have. In order for them to help, however, they must be used regularly for a few weeks. Usually a good regimen is 3-4x/day for 4 weeks and then slowly tapering to see if your eyes feel better. When you have dry eyes and you use tears only when you feel like you need them, they only work for 30 seconds and then do no good to hydrate the eyes overall.
The products like Naphcon A are good for brief intermittent use, but their chronic use tends to irritate the eyes progressively more, and also tends to habituate the eyes to their effects, such that you need progressively more and more of the drop to keep the eyes from getting red, and then they still are red.
I would suggest stopping any tear product that says "get the red out" or "redness reliever" and switch to an artificial tear without this chemical. Any other tear should work well, just find one that you like the best. Drops that come in a bottle have preservatives in them and therefore shouldn't be used more than 4-5x/day or the preservatives themselves will start to irritate your eyes. If you plan on using them more than 4-5x/day, buy preservative free drops. If you don't plan to use them more than that, preserved drops are just fine.
Does this address your concerns?
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My opinion is solely informative and does not constitute a formal medical opinion or recommendation. For a formal medical opinion and/or recommendation you must be examined by your doctor.