Posterior lamellar interventions for Fuchs’ dystrophy and bullous keratopathy such as DMEK and DSEK can restore the corneal anatomy to a nearly normal state. While both of these procedures greatly improve the contrast sensitivity and color vision of Fuchs’ patients, studies suggest that DMEK results in better post-op contrast sensitivity than DALK and DSEK. In a recent study, researchers examined the pre- and post-op contrast sensitivities with DMEK to analyze the influence of corneal anatomy on the outcome and found that corneal thickening plays an important role.

The prospective study included 50 pseudophakic eyes of 50 DMEK patients in Berlin. A team measured contrast sensitivity at spatial frequencies of 1.5, three, six, 12 and 18 cycles per degree in photopic and mesopic light with and without glare.

Additionally, the researchers also measured central corneal thickness (CCT) and anterior and posterior corneal aberrations. They noted that corneal aberrations are common in patients with posterior corneal endothelial diseases such as Fuchs’. DMEK procedures alter the corneal aberrations, which is thought to influence contrast sensitivity.

Postoperatively, the researchers found that BCVA and contrast sensitivity improved significantly while CCT decreased significantly. They noted that pre-op CCT correlated significantly with pre-op photopic contrast sensitivity and that post-op total anterior aberrations correlated with post-op photopic contrast sensitivity.

“Before surgery, we found a significant correlation between contrast sensitivity and CCT, but no correlation between contrast sensitivity and anterior or posterior aberrations,” the researchers wrote in their paper. “After DMEK surgery, anterior corneal aberrations correlated to contrast sensitivities, but there’s no correlation between postoperative corneal aberrations and contrast sensitivities.”

They concluded that both photopic and mesopic contrast sensitivities are impaired in Fuchs’ and bullous keratopathy patients, especially when glare is present. They added that the extent of corneal thickening seems to influence contrast sensitivity and that DMEK significantly improves it. “Higher postoperative anterior corneal aberrations limit the postoperative contrast sensitivities,” they noted.

Gundlach E, Pilger D, Brockmann T, et al. Recovery of contrast sensitivity after descemet membrane endothelial keratoplasty. Cornea. February 10, 2021. [Epub ahead of print].