Higher-order aberrations in eyes with irregular corneas after laser refractive surgery.
OBJECTIVE
To investigate the distribution of the eye's higher-order aberrations in postoperative laser refractive surgery patients with visual complaints and highly irregular corneal shapes.


METHODS
Retrospective case-control study.


METHODS
Thirty-three symptomatic postoperative LASIK and/or photorefractive keratectomy eyes with subjective visual complaints not corrected by spectacles more than 6 months after surgery are compared with 46 normal preoperative and 46 asymptomatic successful postoperative conventional LASIK eyes.


METHODS
Postoperative wave aberrations were measured for each patient using a Shack-Hartmann wavefront sensor (Zywave, Bausch & Lomb, Rochester, NY) over a 6-mm pupil. These measurements were averaged across patients with similar corneal topographic diagnoses (central islands, decentered ablations, a new group termed baby bowties, and irregularly irregular corneas).


METHODS
Higher-order aberrations and corneal topography.


RESULTS
The average (+/-1 standard deviation) higher-order root-mean-square (rms) wavefront error values (third, fourth, and fifth orders) for the symptomatic patients was 1.31+/-0.58 microm. This was an average of 3.46 times greater than the average magnitude of normal preoperative eyes (mean rms, 0.38+/-0.14 microm), and an average of 2.3 times greater than the average magnitude of asymptomatic successful postoperative conventional LASIK eyes (mean rms, 0.58+/-0.21 microm) over a 6-mm pupil. Higher-order rms wavefront error increased with pupil size, roughly doubling for every millimeter of increasing pupil diameter. On average, eyes with central islands (n = 6) had the most vertical coma (Z3(-1); mean, -1.35+/-0.43 microm). Eyes with central islands and decentered ablations (n = 2) also had elevated amounts of spherical aberration (Z4(0); means of 0.83+/-0.11 microm and 0.69+/-0.29 microm, respectively) compared with successful postoperative LASIK eyes (mean of 0.42+/-0.20 microm). Eyes with a topographic central baby bowtie demonstrated the most secondary astigmatism (Z4(2) and Z4(-2); mean rms, 0.56+/-0.17 microm; n = 3), despite the lowest average higher-order rms (mean, 0.84+/-0.05 microm) among symptomatic topographic subgroups. Eyes with irregularly irregular corneas had a mean higher-order rms of 1.10+/-0.39 mum.


CONCLUSIONS
Symptomatic postoperative laser refractive surgery patients with irregular corneas have higher-order aberrations that are 2.3 to 3.5 times greater than asymptomatic postoperative LASIK and normal preoperative eyes, respectively. The higher-order aberrations seem to correlate with corneal topography.
McCormick
Gregory J
GJ
Department of Ophthalmology, University of Rochester, Rochester, New York, USA.
Porter
Jason
J
Cox
Ian G
IG
MacRae
Scott
S
D000328:Adult; D001251:Astigmatism / Q000209:etiology* / Q000503:physiopathology; D016022:Case-Control Studies; D003315:Cornea / Q000473:pathology*; D019781:Corneal Topography; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000009:adverse effects*; D008875:Middle Aged; D011183:Postoperative Complications; D011680:Pupil / Q000502:physiology; D012029:Refraction, Ocular / Q000502:physiology; D012030:Refractive Errors / Q000503:physiopathology; D054140:Refractive Surgical Procedures; D012189:Retrospective Studies; D014786:Vision Disorders / Q000209:etiology* / Q000503:physiopathology; D014792:Visual Acuity / Q000502:physiology