High Order Aberrations In Dmek: The Relationship Between The Anterior And Posterior Surfaces

To analyze corneal higher-order aberrations (HOA) following Descemet membrane endothelial keratoplasty (DMEK), with focus on the relationship between the anterior and posterior surfaces.

 Ophthalmology Department, São José Local Health Unit, Lisbon, Portugal

Eighteen patients (18 eyes) who underwent DMEK surgery and twenty pseudophakic patients (20 eyes) in a control group were retrospectively evaluated. Corneal anterior and posterior surface HOA were measured with Scheimpflug imaging at 6 months post-operatively. Best corrected visual acuity (BCVA) and total, anterior and posterior HOA, expressed as root mean square (RMS) values deviation from a best fit sphere reference surface at 6-mm optical zone were assessed. Total HOA/Anterior HOA (T/AHOA) and Posterior HOA/Anterior HOA (P/AHOA) ratios were also calculated to assess the parallelism between both surfaces.

In patients submitted to DMEK, mean BCVA improved from 0,79±0,55 logMAR before surgery to 0,11±0,15 logMAR (p<0,001).Compared with controls, the RMS of total corneal aberrations (p=0,041), HOA (p=0,017), , trefoil (p=0,009) and tetrafoil (p<0,001) were significantly higher in DMEK patient’s group.

The posterior corneal surface had significantly higher total aberrations (p=0,045), HOA (p=0,012), SA (p<0,01) and tetrafoil (p=0,001) in patients that underwent DMEK. 

Relevant correlation was found between total and posterior corneal surfaces HOA in the control group (r=0,559; p=0,01), but the same was not found in transplanted patients (r=0,114; p<0,001).

There was no statistical significance in P/A HOA or T/A HOA between groups.

Despite higher total cornea aberrations and higher cornea front total aberrations DMEK has an outstanding improvement in visual acuity. One of the factors that seems to contribute is an improved parallelism between the graft, shown by the absence of significant differences in P/A HOA and T/A HOA between groups.