Aberration-sensing and wavefront-guided laser in situ keratomileusis: management of decentered ablation.
OBJECTIVE
To clarify the feasibility of aberration-sensing and wavefront-guided laser in situ keratomileusis (LASIK) to manage grossly decentered ablation and to discuss the limitations of the technology.


METHODS
Three patients with previous decentrations of the ablation zone between 1.5 to 2.0 mm were scheduled for wavefront-guided LASIK. All patients reported monocular diplopia and halos. Wavefront aberrations were measured with a Tscherning-type aberrometer. Laser ablation was done with a WaveLight Allegretto in a one-step procedure with ablation profiles calculated only from the individual wavefront map. Decentrations were determined from corneal topography.


RESULTS
Three months after surgery, patient WM and patient SU had gained uncorrected and best spectacle-corrected visual acuity. The root mean square-wavefront error decreased up to 61% and 33%, respectively, for total and higher order aberrations (Zernike modes of 3rd order and higher). There was significant enlargement of the optical zone determined by corneal topography, and both patients no longer reported diplopia and halos at 3 months postoperatively. The optical aberration of the third patient (RE), after a 5.00-D overcorrection with a 2-mm decentration, was too high for aberration-sensing; retinal images obtained from the wavefront device were too smeared and not of sufficient contrast. In addition, this patient had a residual corneal thickness of 416 microm and thus wavefront-guided LASIK was not done.


CONCLUSIONS
Wavefront-guided LASIK offers a new way of managing grossly decentered laser ablations. Unfortunately, there are still patients who have aberrations too large for wavefront sensing or with other clinical limitations such as a residual corneal thickness too thin for further treatment.
Mrochen
Michael
M
University of Zurich, Dept of Ophthalmology, Switzerland. Michael.Mrochen@aug.usz.ch
Krueger
Ronald R
RR
Bueeler
Michael
M
Seiler
Theo
T
D000328:Adult; D003315:Cornea / Q000473:pathology / Q000601:surgery*; D019781:Corneal Topography / Q000379:methods*; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000295:instrumentation / Q000379:methods*; D054018:Lasers, Excimer; D018903:Photorefractive Keratectomy / Q000009:adverse effects; D011183:Postoperative Complications / Q000601:surgery*; D012030:Refractive Errors / Q000209:etiology; D054140:Refractive Surgical Procedures; D012086:Reoperation; D016896:Treatment Outcome; D014792:Visual Acuity