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Preoperative pupil size does not affect quality of vision after LASIK

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) – Although large pupil size is viewed by some ophthalmologists as a relative contraindication to undergoing LASIK, preoperative pupil size does not affect quality of vision after wavefront-guided LASIK, two researchers from Stanford University in California report in the November 20th online issue of Ophthalmology.



“All patients should be advised that glare, halos, and night vision issues are a possible side effect of laser vision correction procedures regardless of pupil size,” co-author Dr. Edward E. Manche told Reuters Health in an email.



Dr. Manche and Dr. Annie Chan evaluated the effect of preoperative pupil size on quality of vision after wavefront-guided LASIK in a prospective study of 51 patients undergoing the procedure for mild to moderate myopia or astigmatism.



There were 31 small pupils (up to 5.5 mm), 36 medium pupils (5.4-6.4 mm), and 32 large pupils (at least 6.5 mm).



In the first postoperative month, night time glare, haze, and halo scores were increased for all pupil sizes, but these scores improved over the ensuing months. There were no significant differences among the 3 groups.



Clarity at night and during the day improved from baseline at all visits, and there was no association between pupil size and these measures.



Patient assessments of vision quality improved in all groups at all visits compared with baseline.



In linear regression analysis, larger pupil size tended to be associated with higher scores for vision, clarity at night, and glare at night, but none of these associations reached statistical significance.



At the final 12-month visit, patients with medium pupils had less glare at night than patients with small pupils, less halo than patients with small or large pupils, and greater satisfaction with visual improvement than patients with small pupils.



“A number of previous studies found a strong correlation between the level of attempted correction and visual symptoms, particularly glare, after refractive surgery,” the authors explain. “It is possible that the use of wavefront-guided ablations may play a role in reducing visual symptoms after refractive surgery, especially in eyes with higher levels of myopia and astigmatism.”



“Further comparative studies are needed to validate this hypothesis,” they conclude.



Reference:


Effect of Preoperative Pupil Size on Quality of Vision after Wavefront-Guided LASIK


Ophthalmology 2010.