1.   For some, particularly those with large pupils, Lasik can result in nighttime glare and blurry halos around street lamps.

2.   In people with especially large pupils that dilate widely at night, the rings may obstruct vision on the periphery.

3.   People with large pupils and extreme astigmatisms, like Ferro, are also more likely to have postsurgical problems.

4.   Those with abnormally large pupils or dry eyes can also be considered poor LASIK candidates.

5.   Those with unusually large pupils are poor candidates because they will see around the edge of the treated cornea at night, causing them to see halos around lights.

6.   Unsuitable candidates can include those with large pupils, retinal problems, corneal scars or severe astigmatisms.