There is an interesting article presented for publication in Ophthalmology titled: Effect of Preoperative Pupil Size on Quality of Vision after Wavefront-Guided LASIK by Annie Chan MD and Edward E. Manche MD out of Stanford University. This paper studies what I have noticed for a long time: pre operative pupil size does not effect quality of vision in wavefront guided LASIK.
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. There is no doubt that with first generation lasers, pupil size was an important factor in determining night vision issues,. However, I soon noticed that this was not the case when I upgraded to the Allegretto laser over 5 years ago. This study supports my observations.
The study evaluated the effect of pupil size on quality of vision after wavefront-guided LASIK in a study of 51 patients undergoing the procedure for mild to moderate myopia or astigmatism. Pupil size was divided into 3 groups:
- 31 small pupils (up to 5.5 mm)
- 36 medium pupils (5.4-6.4 mm)
- 32 large pupils (at least 6.5 mm)
Night time glare, haze, and halo scores were increased for all pupil sizes in the first month, but improved over the folowing months. There was no significant differences among the 3 groups. Visual clarity at night and day improved from baseline at all visits, and there was no association between pupil size and these measurements.
The authors conclude:
A number of previous studies found a strong correlation between the level of attempted correction and visual symptoms, particularly glare, after refractive surgery. 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.
This paper supports what I have been telling my patients for a long time: although it has been reported in the past that night vision issues may be related to pupil size, I do not see it with the Allegretto laser, in fact, I more commonly see an improvement in night vision as compared to glasses or contact lenses.
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