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**softy54534** · 10-07-2009, 02:15 PM

However, for the first few years, I saw big "halos" (like a ring of hazy light) around any light source that I looked at in darkness. For example, incoming car headlights at night, or lit signs for stores, etc. This is because the circle they cut the flap out of is as wide as possible without going too deep, which is wide enough to be larger in diameter than the iris during daylight conditions, but as your iris opens up for low-light in dark conditions, it becomes wide enough that it's now included the ripple in the surface of the cornea, which is the "dip" from where the flap was cut. This causes light refraction. Which is what causes the halo thingy. Rather interesting, though kind of annoying, but it lessened after maybe three years, and now I don't even notice it anymore; a combination of my eye smoothing out over time, and now it's pretty much so close to completely gone I don't notice it.

That used to be a common side-effect, and as you point out it's a mismatch between the ablation zone (cutting area) of the laser and your pupil's dilated size. I was well aware of this when I checked out the procedure, and when the doctor measured my dilated pupil at 7 mm with an ablation zone of 6.5 and told me I would have no night vision troubles, I ran away.

Modern machines now have larger ablation zones so it's not so much an issue. But I'm still very nervous about the procedure, especially after being lied to by a doctor at what was supposedly a very reputable clinic.

10-07-2009, 02:15 PM	#26
softy54534 Join Date Apr 2007 Posts 5,457 Senior Member	However, for the first few years, I saw big "halos" (like a ring of hazy light) around any light source that I looked at in darkness. For example, incoming car headlights at night, or lit signs for stores, etc. This is because the circle they cut the flap out of is as wide as possible without going too deep, which is wide enough to be larger in diameter than the iris during daylight conditions, but as your iris opens up for low-light in dark conditions, it becomes wide enough that it's now included the ripple in the surface of the cornea, which is the "dip" from where the flap was cut. This causes light refraction. Which is what causes the halo thingy. Rather interesting, though kind of annoying, but it lessened after maybe three years, and now I don't even notice it anymore; a combination of my eye smoothing out over time, and now it's pretty much so close to completely gone I don't notice it. That used to be a common side-effect, and as you point out it's a mismatch between the ablation zone (cutting area) of the laser and your pupil's dilated size. I was well aware of this when I checked out the procedure, and when the doctor measured my dilated pupil at 7 mm with an ablation zone of 6.5 and told me I would have no night vision troubles, I ran away. Modern machines now have larger ablation zones so it's not so much an issue. But I'm still very nervous about the procedure, especially after being lied to by a doctor at what was supposedly a very reputable clinic.
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