From the FDA website, “When is LASIK not for me?”
"Large pupils. Make sure this evaluation is done in a dark room. Although anyone may have large pupils, younger patients and patients on certain medications may be particularly prone to having large pupils under dim lighting conditions. This can cause symptoms such as glare, halos, starbursts, and ghost images (double vision) after surgery. In some patients these symptoms may be debilitating. For example, a patient may no longer be able to drive a car at night or in certain weather conditions, such as fog." Link
From the American Academy of Ophthalmology website:
"In determining suitability, a baseline eye evaluation should include: Measurement of scotopic pupil size" Link (Update: 12/11/2011 - The text at this link has changed).
From the ASCRS Eye Surgery Education Council website, LASIK Patient Screening Guidelines:
"Measurement of pupil size in dim and room light. Pupil size is an important factor in counseling a candidate about night vision and planning the appropriate laser vision correction strategy." Link
From the Ophthalmic Mutual Insurance Company (OMIC) website:
"As part of the independent evaluation, the surgeon must personally examine the patient’s eyes and ocular adnexa, perform a slit lamp exam, and carefully review topographies, pupil size, pachymetry, refractive stability, eye health history, and prior records." Link
From the Federal Trade Commission website:
"You may be rejected if your pupils are too large." Link (Update: 12/11/2011 - The text at this link has changed).