A decentered ablation is a complication of LASIK eye surgery that occurs when the laser treatment is not properly centered over the pupil. Laser ablations that are off-center by as little as 0.5mm can cause visual symptoms, including glare and halos, ghost images, and blurred vision.
Significantly decentered laser ablations result in loss of best corrected visual acuity due to irregular astigmatism. This can cause symptoms such as glare, night vision difficulty, ghosting and diplopia. Possible causes of decentration include poor fixation due to poor patient instruction, anxiety, over-sedation, blurry vision due to high refractive error or the exposed stromal bed causing difficulty seeing the laser’s target. It can also be due to improper stabilization of the patient’s eye during the ablation procedure. In order to prevent decentration, careful preoperative and intraoperative instructions are key, especially with regard to the fixation target.
A patient with a decentered ablation generally presents with the following clinical signs and symptoms:
- A decentration of the ablation zone on corneal topography.
- Increased higher-order aberrations as measured using wavefront aberrometry, predominantly coma.
- The appearance of a tail on point spread function.
- Reduced best corrected visual acuity that improves only with gas permeable lenses.
- A cylinder measurement on autorefraction and wavefront that differs from manifest refraction.
- A history of reduced vision immediately after surgery that fails to improve with time.
Complications arising from Decentered Ablation zones can be very successfully countered with Laserfit scleral lenses. Particularly beneficial is the use of our custom wavefront guided optics that are ground into our lens surface at time of manufacture. This allows us to effectively counter specific aberrations, essentially eliminating vision disturbances for most patients.