I had standard LASIK about 10 weeks ago with the VISX S4, which creates a 6.5mm optical zone with no transition zone. Unfortunately, my pupils appear to dilate to around 8mm in low-light conditions, resulting in night myopia and glare/ghosting.

My surgeon suggested a wavefront enhancement procedure to address this. He contends that the reason for my problems is more likely HOAs, which wavefront can treat. And from what I've been able to determine, even just introducing a transition zone would help reduce any effects caused by the sharp transition between treated and untreated cornea. But for obvious reasons I'd still like my optical zone to be as large as possible.

According to information available at:

http://www.allaboutvision.com/visionsurgery/lasik_laser_3.htm

the VISX S4 Wavefront procedure is capable of treating an optical zone up to 9.0mm with a transition zone up to 9.5mm. However, the standard wavefront treatment uses a 6.5mm optical zone with a transition zone to 8mm.

Have any doctors here used the VISX in a wavefront procedure with an optical zone greater than 6mm? Other than the standard concern of more tissue per diopter, is there anything to recommend against larger treatment zones with this technology? By my calculations I should be able to increase my optical zone to at least 7mm with a transition of 8.5mm or more while preserving a residual cornea bed of 300 microns.

Is there any reason to prefer other lasers to the VISX for this purpose? I'd prefer to use the VISX for the enhancement if possible since this is the laser my surgeon has the most experience with.