Pupil size was much more relevant prior to “custom” LASIK surgery.  Small ablation patterns in patients with large pupil commonly created problems under “scotopic” or dimly lit situations.  Now, with larger and so called “custom” ablation patterns, pupil size is less relevant.  Patients who have significant problems with vision at night using their best correction prior to surgery are more likely to experience some of these same symptoms after surgery.  Patients experiencing new problems after surgery are most likely related to residual refractive error that is frequently correctable. 

The Stanford group looks at the effect of preoperative pupil size on quality of vision after wavefront-guided LASIK.

Ophthalmology.  2011; 118(4):736-41 (ISSN: 1549-4713)

Chan A; Manche EE
Department of Ophthalmology, Stanford University School of Medicine, Stanford, California 94305, USA.

PURPOSE: To evaluate the effect of preoperative pupil size on quality of vision after wavefront-guided LASIK.

DESIGN: Prospective study.

PARTICIPANTS: One hundred two eyes.

INTERVENTION: LASIK for mild to moderate myopia or astigmatism (preoperative manifest spherical equivalent, -3.99±1.42 diopters).

MAIN OUTCOME MEASURES: Questionnaires evaluating specific visual symptoms before and after surgery. Each eye was evaluated before surgery, and 1 week and 1, 3, 6, and 12 months postoperatively. Pupils were stratified according to size: small (≤5.5 mm), medium (5.6-6.4 mm), or large (≥6.5 mm). Mesopic pupil size and preoperative and postoperative variables were evaluated using an analysis of variance. A regression model was also performed to determine the correlation between mean spherical equivalent and cylinder and visual symptoms.

RESULTS: In the early postoperative period, there was no difference between the 3 groups with regard to any of the symptoms. At the final 12-month postoperative visit, patients with medium pupils experienced less glare at night than small pupils (P = 0.02), medium pupils had less halos than small or large pupils (P = 0.001 and P = 0.02, respectively), and medium pupils experienced greater satisfaction in visual improvement than small pupils (P = 0.014).

CONCLUSIONS: Twelve months after wavefront-guided LASIK surgery, large pupil size does not positively correlate with any postoperative visual symptoms.