Aside from the technical benefits that came along with femtosecond lasers, there were new side effects that arose with the technology that are now better understood.
The formation of a bubble layer occurs along the cutting plane, which in some cases leads to an escape of some bubbles into deeper stroma with the formation of an OBL (Figure 6). These deeper bubbles may take a few hours to disappear, and if severe, may impair the aim of the eye tracker during surgery. This is less common with a softer docking (applanation) pressure, lower energy and faster repetition rate devices. Gentle scraping of the surface with a spatula may lessen the density of the OBL prior to laser treatment.
In the optical coherence tomography analysis, it is possible to visualize that the opaque bubble layer is present to a depth of 261 µm, much deeper than the flap plane.
Interface haze is also a possible complication, with an increased risk when making very thin flaps (<100 µm) (Figure 7).
Dense interface haze.
Transient light-sensitivity syndrome is characterized by photophobia and mild pain that can appear days after surgery and can persist for weeks. Rainbow glare is an optical effect due to light scattering from the perfect array of laser spots remaining on the back surface of the flap. It can create a spectral pattern (Figure 8) whose visual impact is clinically inconsequential in the majority of patients. Both of these situations are predominately related to earlier, femtosecond laser devices with higher raster energy and lower numerical aperture optics.[19,20]
Spectral pattern in the clinical presentation of rainbow glare.
Expert Rev Ophthalmol. 2011;6(1):55-65. © 2011 Expert Reviews Ltd.
Cite this: Comparison of Commercially Available Femtosecond Lasers in Refractive Surgery - Medscape - Feb 01, 2011.