Name

Visualisation in-vivo du rainbow-glare en microscopie confocale et son traitement à l’aide d’une photoablation sur la face postérieure du capot

Rainbow glare is a rare optical side effect of femtosecond laser-assisted LASIK where patients complain of postoperative rainbow-like effects when exposed to a polychromatic light source. The presumed hypothesis is that it is caused by a grating pattern of geometrically-aligned, regularly-spaced femtosecond laser impacts which can be seen on confocal microscopy of the cornea.  Often transient, no consensus exists regarding management of persistent rainbow glare, which can have a high impact on quality of life. A 16-mm planar photoablation of the undersurface of the flap was described as a successful treatment, effectively smoothening the grating pattern of the femtosecond laser. Surgeons should be however particularly careful regarding the remaining thickness of residual flap after treatment in order to avoid complications

Description of a 33-year-old patient suffering from rainbow glare after myopic LASIK correction of the right eye (Wavelight FS-200 / EX-500), initial and follow-up investigations after therapeutic undersurface photoablation.

Unaided visual correction was 20/12.5 in the right eye after the first myopic correction, but subjective vision was drastically impaired because of the rainbow glare. Initial investigations reveal the characteristic grating pattern of regularly aligned femtosecond impacts on confocal microscopy, and raster pattern of impacts after flap and interface creation on the right eye exclusively. A 10-mm undersurface photoablation was performed and resulted in a major subjective and objective improvement but remained slightly insufficient. After a year, the patient asked for completion of treatment, and another 10-mm undersurface photoablation was performed, with complete resolution of symptoms, and disappearing of the grating pattern of impacts on confocal microcopy.

Rainbow glare is a benign and often transient optical side effect of femtosecond laser, which rarely causes dramatic life impairment. The grating pattern of hyperreflective dots of femtosecond laser impacts can be seen on confocal microscopy and their disappearance correlate with the disappearance of the symptoms after undersurface photoablation.

This further strengthens the hypothesis that rainbow glare is caused by diffraction of polychromatic light through regularly aligned femtosecond impacts in a grating pattern on the posterior aspect of the flap. Undersurface flap photoablation can be performed to treat rainbow glare and should be of at least 15-20 mm thick for efficacy.