Take-home message: A focus on functional vision outcomes in patients who had both DMEK and DSAEK procedures found that the DMEK procedure yielded quality of vision superior to that of DSAEK.
By Vanessa Caceres; Reviewed by Michael D. Straiko, MD
Portland, OR—Some surgeons may see only a slight advantage in performing Descemet membrane endothelial keratoplasty (DMEK) over Descemet stripping automated endothelial keratoplasty (DSAEK), with a Snellen visual acuity difference of only about a line.
However, that perspective does not consider functional vision outcomes, said Michael D. Straiko, MD, Devers Eye Institute, Portland, OR.
In a study led by Dr. Straiko, patients that had DMEK in one eye and DSAEK in the fellow eye had significantly better quality of vision in the DMEK eye as evidenced by patient preference and objective measurement of contrast sensitivity. The DMEK-treated eyes had contrast sensitivity that approached that of normal eyes that had no prior surgery.
The group had also previous published research on the topic of DSAEK versus DMEK outcomes.1
Results showed similar results in both groups except for slightly better visual acuity in the DMEK group. It got them wondering whether visual acuity tells the full story of visual results, particularly because Snellen visual acuity is usually measured under ideal lighting and high contrast conditions, unlike real life, Dr. Straiko said.
Dr. Straiko also has anecdotal reports of patients who favor their DMEK or DSAEK-treated eye, even if visual acuity is not as strong as their fellow untreated Fuchs’ dystrophy eye. He assumes that this must be explained by the quality of vision.
In the current study investigators identified 11 patients with DSAEK in one eye, DMEK in the fellow eye, and no visual limiting comorbidities. These patients then underwent further prospective visual quality testing with the Functional Visual analyzer. All patients had undergone a successful DMEK transplant in one eye and a successful DSAEK transplant in the fellow eye for Fuchs’ dystrophy. Patients had an average age of about 70 years old with similar preoperative visual acuity and central corneal thickness. Patients with dry eye with corneal staining or unstable tear film were not included.
Patients took part in an Institutional Review Board-approved study to test contrast sensitivity with the use of the Functional Vision Analyzer under varied, and precisely controlled, lighting conditions.
“Contrast sensitivity was evaluated at various levels of contrast and varied spatial frequencies,” the investigators reported in their abstract.
Patients also filled out a Quality of Vision (QoV) questionnaire to measure adverse visual symptoms in each eye.
In the 11 patients, investigators found that eyes with a DMEK transplant had significantly better contrast sensitivity than DSAEK-transplanted eyes.
“Patient scores from the QoV questionnaire indicate that the DMEK transplants trended toward lower frequency, severity, and less bothersome adverse visual symptoms than DSAEK transplanted eyes,” the investigators reported.
Investigators asked patients if they had an accident and could only keep one eye, which eye they would want to keep. Seventy-five percent would want to keep the DMEK eye.
“For others, it may have been an ocular dominance preference,” Dr. Straiko said.
Dr. Straiko and fellow investigators are expanding their equipment to conduct more contrast sensitivity testing in the future.
Surgeons should consider the advantages of improved functional vision in the real world provided by DMEK instead of just Snellen visual acuity measured in our exam lanes, Dr. Straiko believes. He speculates that the unique anatomic restoration achieved by DMEK is what accounts for the superior quality of vision over other keratoplasty procedures.
“And that’s in addition to the main advantage of a lower rejection rate with DMEK,” he said
1. Hamzaoglu E, Straiko MD, Mayko ZM, Sales CS, Terry MA. The first 100 eyes of standardized Descemet stripping automated endothelial keratoplasty versus standardized Descemet membrane endothelial keratoplasty. Ophthalmology. 2015;122:2193-2139.
Michael D. Straiko, MD
This article was adapted from Dr. Straiko’s presentation at the 2016 meeting of the American Society of Cataract and Refractive Surgery. Dr. Straiko did not indicate any financial interest in the subject matter.