Unmasking of subclinical keratoconus with Descemet membrane endothelial keratoplasty in Fuchs endothelial dystrophy

We report a case of Fuchs endothelial corneal dystrophy (FECD) with concurrent forme fruste keratoconus (KCN) that was unmasked with Descemet membrane endothelial keratoplasty (DMEK) in the right eye, but not with Descemet-stripping automated endothelial keratoplasty (DSAEK) in the left eye. The patient was a 65-year-old female with FECD who underwent uncomplicated combination cataract surgery and DMEK in the right eye. She subsequently developed intractable monocular diplopia associated with inferior displacement of the thinnest point of the cornea and subtle steepening noted on posterior corneal curvature on Scheimpflug tomography. The patient was diagnosed with forme fruste KCN. Altering the surgical plan to combine cataract surgery and DSAEK in the left eye successfully circumvented the development of symptomatic visual distortion. This is the first case providing comparable data from contralateral eyes in the same patient regarding the outcome of DMEK versus DSAEK in eyes with concurrent forme fruste KCN. DMEK appeared to unmask posterior corneal irregularities and resulted in visual distortion, whereas DSAEK did not. The additional stromal tissue in DSAEK grafts appears to help normalize alterations of the posterior corneal curvature and may be the preferred endothelial keratoplasty for patients with concurrent mild KCN.