When doing fundus laser treatment, the pupil must be dilated, otherwise the laser can not be hit into. But after the pupil dilation pupil does not contract, may also be related to several reasons: 1, with the pupil dilation drugs are not the same, may be the use of long-acting pupil dilation agent, the pupil will be two weeks or even longer, can not be completely or can not be restored to the original as the same small pupil. 2, due to the dilation of the pupil in the process of the eye caused by the elevation of intraocular pressure, pupil enlargement, this time should be measured intraocular pressure. 3, some people have diabetes or other diseases, the pupil sphincter lost its contraction function, the pupil will not come back after dilation, the pupil dilation, the pupil dilated. 3, some people have diabetes or other diseases, the pupil sphincter has lost its contraction function, the pupil will not come back after dilation, should be used to shrink the pupil.