Abstract
Purpose: :
To report the incidence of rainbow glare after LASIK flap creation with a 60 kHz femtosecond laser (IntraLase, Irvine, CA) and to investigate the factors associated with its occurrence.
Methods: :
260 consecutive IntraLASIK patients (479 eyes), treated by one surgeon (RK), were questioned about the occurrence of postoperative rainbow glare. Rainbow glare is an optical side effect of IntraLASIK that is created when light scatters off the back surface of the flap. Patients describe radiating colors around a white light source at night. IntraLase settings included: pulse frequency 60 kHz, flap thickness 90-110µm, and spot/line separation 8µm. Raster energy varied from 0.8 µJ (75% of eyes) to 1.0-1.1 µJ (25% of eyes). Excimer laser ablation was performed with either the Alcon LADAR 4000 or 6000 platforms using custom or conventional treatments. Patients were questioned during their postoperative exam or by telephone.
Results: :
256 patients (98.5%) were successfully contacted. 15 patients (28 eyes) experienced rainbow glare after their surgeries, for an incidence of 5.8%. Most patients first noticed mild symptoms within the first 3 months after surgery. Rainbow glare descriptions included anywhere from 4-12 bands of color around a white light source, with 6 bands being the most common. While the presence of the symptom did not correlate to refractive error, age, or gender, there was a statistically significant difference (confidence interval 95%) between the incidence of rainbow glare at 1.0 or 1.1 µJ raster energy (11.6%), compared to the incidence at 0.8 µJ (4.1%). The incidence also followed a bimodal distribution, with the first peak (7 patients) occurring just after installation of the 60 kHz upgrade, when due to poor performance the higher energies were necessary. This improved with a service call and replacement of optics. The second peak (5 patients) began two months before the second preventative service call. No additional cases of rainbow glare were reported after the second service call until the end of the study.
Conclusions: :
Rainbow glare represents a mild optical side effect of IntraLASIK. In this study higher raster energy levels and length of time between service calls were associated with the occurrence of rainbow glare.
Keywords: refractive surgery: LASIK • refractive surgery: optical quality • refractive surgery: complications