Too much chlorine. This is a common occurence in over-chlorinated pools, especially if you don't wear goggles. The chlorine irritates and dries out the cornea, causing the stinging and halo effect. This is basically a mild chemical burn. With time and frequent artificial tear use, the eye will heal. It can take up to a day to recover. If not better within this time, please see an eye doctor.
Blurred vision. Are your eyes blurry all the time, or just after swimming? Halos are common after being in water for some time, and should clear up in a few minutes after you come out. If they don't, it would be a good idea to have an eye exam. Wearing goggles when you are swimming would probably prevent the halos.
My eyes are blurry, and I'm seeing a glow around everything after being in a swimming pool for only an hour?
Corneal swelling. You likely are experiencing some swelling in your cornea, the clear front portion of your eye, from exposure to the chlorine and salts in the pool water. If you open your eyes while in the pool and are not wearing a swimming mask or swimming goggles, this is more likely to happen. Your cornea is likely experiencing an osmotic accumulation of pool water from the corneal exposure to the chlorine.