Cornea. 2006 May;25(4):388-403.
Klein SR, Epstein RJ, Randleman JB, Stulting RD.
From the *Cornea Service, Department of Ophthalmology, Rush University Medical Center, Chicago, IL; and the Department of Ophthalmology, Emory University Medical School, Atlanta, GA.
PURPOSE:: To evaluate patients who developed ectasia with no apparent preoperative risk factors.
METHODS:: Potential cases of patients who developed ectasia without apparent risk factors were identified by contacting participants in the Kera-Net (n = 580), ASCRS-Net (n = 450), and ISRS/AAO ISRS-Net (n = 525) internet bulletin boards from April to October 2003. Cases were included if ectasia developed after laser in situ keratomileusis in the absence of apparent preoperative risk factors. Reported cases were excluded for the following reasons: (1) calculated residual stromal bed less than 250 mum, (2) preoperative central pachymetry less than 500 mum, (3) any keratometry reading greater than 47.2 diopters (D), (4) a calculated inferior-superior value greater than 1.4, (5) more than 2 retreatments, (6) attempted initial correction greater than -12.00 D, (7) an Orbscan II "posterior float" (if obtained) greater than 50 mum, and (8) surgical/flap complications.
RESULTS:: A total of 27 eyes of 25 patients were submitted for consideration. Eight eyes (8 patients) met our inclusion criteria. Mean age was 27.7 years (range, 18-41 years). Preoperative manifest refraction spherical equivalent was -4.61 D (range, -2.00 to -8.00 D); steepest keratometric reading was 43.86 D (range, 42.50-46.40 D); keratometric astigmatism was 0.93 D (range, 0.25-1.90 D); and preoperative central pachymetry was 537 mum (range, 505-560 mum). The mean calculated ablation depth was 82.8 mum (range, 21-125.4 mum), and mean calculated residual stromal bed was 299.5 mum (range, 254-373 mum). Mean time to recognition of ectasia onset was 14.2 months (range, 3-27 months) postoperatively. At the time of ectasia diagnosis, the mean manifest refraction spherical equivalent was -1.23 D (range, +0.125 to -3.00) with a mean of 2.72 D (range, 0.75-4.00 D) of astigmatism.
CONCLUSIONS:: Ectasia can occur after an otherwise uncomplicated laser in situ keratomileusis procedure, even in the absence of apparent preoperative risk factors.