Quality of Vision Issues after LASER Vision Correction


Quality of Vision ISSUES after LASER Vision Correction
Halo, Glare, Starbursting and Reduced Contrast Sensitivity

When the excimer laser is used to improve the optical characteristics of the eye it does so by the pre programmed application of Ultraviolet light energy (UV-C) in short bursts. The application of this light results in the vaporization of collagen in the cornea in a pattern that provides for improved focusing. The higher the prescription treated, the more laser energy needs to be applied and thus more corneal tissue will be inevitably removed.

Approximately 1% of patients treated with excimer laser ablations will experience what I like to refer to as quality of vision issues. Patients in this 1% group can experience problems with night vision widely described as glare. This is most notably composed of haloes and starburst phenomena when viewing point sources of light at night. Affected individuals can also experience mild doubling of vision and poor contrast sensitivity, or a desaturation of clarity during daytime visual tasks. In the early days of Laser Vision Correction fully 15-20% of patients treated over a wide range of refractive errors could experience this unwanted side effect. With the recent development of custom wavefront laser treatments and the use of Femtosecond lasers in creation of LASIK flaps the incidence of quality of vision issues has dropped to roughly 1% of treated patients with most of these treated for the highest of refractive errors still in range for laser vision correction.

While most patients can expect to experience minor amounts of glare due to tissue swelling in the post operative period this can be expected to clear in the vast majority of patients.

Why Does Glare Develop?

As with all surgical procedures we are dependent upon a predictable corneal response to the application. In the vast majority of those treated outcomes producing excellence in visual function over the full range of lighting environments are achieved, however, in a small group comprising approximately 1% of our patients micro-irregularity can occur after treatment. Light passing through the cornea can find these pockets of irregularity resulting in some divergence of light rays producing the glare symptoms. These changes are much more likely encountered when higher prescriptions are treated, i.e.greater than -9.00. The reason for this is two fold: First, higher prescriptions require the removal of more corneal tissue thus increasing the chances of irregular areas in the cornea and, second, removal of larger amounts of corneal tissue can create a situation where the corneal shape is excessively modified from its original native morphology. For these reasons we will recommend ICL (implantable contact lens) as a treatment alternative to those patients with the highest of prescriptions.

How Are Quality of Vision Issues be Treated?

If such symptoms occur our first response is to wait for complete healing of the eye over 3-6 months. We have observed that fully 30% of patients with quality of vision issues will improve through the natural healing process. For those that do not improve we will recommend a LASIK refinement procedure. Making use of Wave Scan technology, the source of irregularity can be identified and treated with a secondary laser application. Fully 95% of those requiring such a custom refinement procedure can expect to have their symptoms improved or eliminated.
Article by
New York Ophthalmologist