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Web site created by
Berney Design
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Night driving problems
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Night driving problems, also called night vision disturbances (NVDs), are common after refractive surgery. The cause of problems with vision at night range from residual refractive errors to a small, or misplaced optical zone (resulting in GASH), to an uneven corneal surface (irregular astigmatism). Night vision problems after refractive surgery range from mildly annoying, but fully functional vision, to an inability to function at night.
Most commonly, night vision problems (GASH) appear when the lasered optical zone is either too small, or off center. This doesn't usually cause a problem during the day because when there is a lot of light the pupil stays small. But at night, the pupil gets bigger to allow more light to enter the eye. When the pupil becomes bigger than the optical zone, GASH is the result.
If the night vision problems are caused by simple refractive error or regular astigmatism, they can be reduced or eliminated with glasses, contact lenses and/or additional surgery. Additional surgery usually comes with a risk level similar to the original surgery.
If the night vision problems are caused by a too-small or misplaced optical zone, glasses and/or soft contacts cannot usually mask the GASH. Rigid gas permeable contact lenses (“RGPs,” aka “hard lenses”) are the only option to mask GASH from some surgical results. Fitting RGPs after refractive surgery can be challenging (due to the changed curvature of the cornea) and not everyone is able to wear these lenses successfully. Surgical options to fix these problems are not yet reliable and must be approached with caution, although technology continues to advance. Additional surgery usually comes with a risk level similar to the original surgery.
Another approach that works for some is the use of prescription eye drops that constrict the pupil. This method works when the constricted pupil is the same size or smaller than the optical zone created by refractive surgery.
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back to visual-optical complications
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back to handbook
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