There are several reasons why a patient might develop glare and / or halos after laser eye surgery:
If you have been ‘under-corrected’ (i.e. if the shape of your cornea has not been changed enough during your procedure), you may still be slightly short or long-sighted and/or still have a minor astigmatism.
A minor enhancement procedure can usually address this. For the small minority of patients who are not candidates for an enhancement, wearing glasses can generally get rid of any troublesome symptoms.
The size of your pupils can be another cause of glare and halos. If a patient’s pupils dilate (open) beyond the area of the cornea that has been treated during laser eye surgery, this can cause glare and halos in low light conditions. The risk of this can be mitigated by accurately measuring your dilated pupil size before surgery. The surgeon can determine whether or not they can effectively treat a large enough area of your cornea with the laser, and if this is not possible then the surgeon should decide not to treat you. Frequently Asked Questions
If you do have glare and halos at night because of your pupil size, there are a few techniques that can help. Some patients find that keeping the overhead light on inside their car when driving stops their pupils dilating so much that it affects their vision. There are also medicated eye drops that stop the pupil from dilating fully, and some patients find that these fully alleviate the problem. Alternatively, clinics with access to an excimer laser that includes a topography-guided treatment option can perform a second treatment that can reduce these symptoms.
Finally, glare and halos can be caused if the area of your cornea treated by the laser is off to one side (known as ‘off-centred ablation’ or ‘decentration’). Choosing a properly qualified and experienced surgeon can help to minimise the risk of this serious complication. Specialist clinics will be able to perform a topography-guided treatment to re-center the treated zone and improve the quality of vision.
In general, using advanced wavefront technology can significantly reduce the risk of glare, halos and night vision difficulties resulting from surgery (see Technology section for further detail).