A novel blunt dissection technique to treat modified deep anterior lamellar keratoplasty (DALK)-associated high astigmatism

Objectives To describe a new surgical technique to correct a high astigmatism following modified deep anterior lamellar keratoplasty (DALK) and to evaluate the associated clinical outcomes. Methods Retrospective interventional case series included eyes with high astigmatism following modified DALK performed between July 2012 and June 2016. The prevalence of keratometric astigmatism (KA) higher than 4.5 diopters (D) was evaluated after complete suture removal. Surgical correction was obtained by opening the surgical wound at the steeper meridian and carrying out a blunt dissection at the graft-host surface of contact under keratoscopic control. KA, Refractive astigmatism (RA), and best spectacle-corrected visual acuity (BSCVA) were measured preoperatively and at 1, 12, and 24 months postoperatively. Vector analysis of 1 year change in KA was performed. Results High astigmatism was found in 47 of 511 eyes (9.2%). KA (mean +/- standard deviation [SD]) decreased from 7.67 +/- 2.78 to 3.10 +/- 1.37 D at 1 month after astigmatic correction (p < 0.001) with no subsequent significant change. Vector analysis of 1 year change in KA: surgically induced astigmatism was 5.30 +/- 3.29 D and mean absolute angle of error was 6.97 +/- 4.25 degrees. BSCVA improved from 0.21 +/- 0.20 logMAR preoperatively to 0.11 +/- 0.13 logMAR (p < 0.001); RA decreased from 6.32 +/- 2.56 to 2.61 +/- 1.05 D (p < 0.001). No intra- or post-operative complications occurred. Conclusions High astigmatism is present in <10% of cases after modified DALK and can be effectively managed by means of blunt relaxing dissection at the graft-host junction.