Pupil size has little effect on patient satisfaction one year after LASIK for high myopia, says study
July 28, 2008
It stands to reason that the size of a person's pupils may play a part in their visual outcome and satisfaction after LASIK surgery. If a person's pupils are larger than the laser treatment area, it's likely that visual disturbances will occur.
Pupil size especially comes into play when driving at night or during other activities in low light, when our pupils dilate to allow more light to enter the eye.
To determine whether pupil size does in fact influence visual performance and patient satisfaction after LASIK, researchers in Denmark recently conducted a study that examined the influence of pupil size on highly myopic patients' self-reported ratings of the quality of their vision in daytime and nighttime conditions.
Study design and methods
The researchers selected 40 highly nearsighted patients to have LASIK performed in both eyes. The average amount of myopia among patient sin the study was -8.71 diopters (D), with a range of -6.31 D to -12.00 D.
Prior to surgery, pupil sizes were measured using a semi-automated infrared pupillometer.
At approximately one year after LASIK, patients completed a questionnaire to report their feelings about the quality of their vision before and after LASIK.
Results
Results of the study included these findings:
- Binocular uncorrected visual acuity (UCVA) after LASIK among this highly myopic patient population was between 20/30 and 20/40, with a range from 20/16 to 20/200.
- One year after LASIK, 72% of the patients reported to agree or partly agree with being "very satisfied" with the results of their surgery.
- LASIK caused no significant changes in self-reported quality of vision during daylight conditions.
- 64% of the patients reported their night vision was worse after LASIK.
- A significant number of patients reported an increase in glare, halos and other visual disturbances under low-light conditions.
- 66% of the patients reported an increased susceptibility to "blinding" glare from oncoming headlights when driving at night.
- Patients with larger-than-normal pupil sizes were more likely to report nighttime glare problems.
High overall satisfaction scores were correlated with good post-operative UCVA, whereas the patients' self-reported quality assessments of their daytime and night vision did not significantly affect their overall satisfaction with LASIK.
Conclusions
Based on the findings of the study, the researchers concluded:
- One year after LASIK for high myopia, night vision disturbances are common.
- Large pupils increase the risk of significant glare in low-light conditions.
But surprisingly, night vision disturbances had little impact on the self-reported overall satisfaction this group of patients had with the outcome of their LASIK surgery. Overall satisfaction was solely dependent on the level of uncorrected visual acuity attained (UCVA) after the procedure.