The purpose of this study is to compare visual acuity outcomes of two types of endothelial keratoplasty: 1) Ultrathin Descemet's Stripping Endothelial Keratoplasty (DSAEK) or 2) Descemet's Membrane Endothelial Keratoplasty (DMEK). Half of the participants will be randomized to have DSAEK and the other half will have DMEK.
Corneal transplantation has evolved rapidly in recent years. Lamellar keratoplasty to replace diseased endothelium has led to faster recovery times, fewer complications, and better visual acuity outcomes. Currently, Descemet's Stripping Endothelial Keratoplasty (DSAEK) is the most common procedure because of its relative ease and good outcomes. Newer techniques such as Descemet's Membrane Endothelial Keratoplasty (DMEK), where Descemet's membrane alone is transplanted, has the potential to further improve visual acuity outcomes, produce fewer higher-order corneal aberrations and decrease rejection rates. However, donor preparation, increased intra-operative times, and problems with donor attachment in DMEK are all important limitations. There are three potential mechanisms by which DMEK may provide better visual acuity outcomes than DSAEK; graft thickness, interface haze and corneal higher-order aberrations. Graft thickness has been correlated with best spectacle corrected visual acuity (BSCVA) outcomes among thinner grafts. One retrospective case series found that 71% of thin endothelial grafts (defined as \<131μm) had BSCVA of 20/25 or better while only 50% of thick grafts (defined as ≥131) achieved this. In addition, higher-order aberrations, in particular of the posterior cornea, are increased after DSAEK. Theoretically, given the decreased tissue transplanted after DMEK this would be lessened, however, one retrospective series looking at higher order aberrations in DMEK compared with DSAEK found no difference in posterior aberrations of the central 4.0 mm zone between the two groups. Finally, interface haze may be increased in DSAEK and has been correlated with BSCVA. Ultrathin DSAEK involves donor preparation with a deep microkeratome pass to produce donor grafts less than 100 um thick. This procedure may have similar results to DMEK but without the technical difficulties. Several large prospective series show similar visual outcome results and rates of immunologic rejection between ultrathin DSAEK and DMEK, however comparisons are difficult. This comparative effectiveness clinical trial could directly address these important issues. The investigators also anticipate that secondary analyses of the trial data will allow us to address several more.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
38
The Endoserter, a corneal endothelium device, is an approved FDA device. This will be used to insert and position the graft into the anterior chamber during endothelial replacement surgery. It is a sterile, single-use instrument.
Byers Eye Institute, Stanford University
Palo Alto, California, United States
F. I. Proctor Foundation, University of California, San Francisco
San Francisco, California, United States
Casey Eye Institute, Oregon Health & Science University
Portland, Oregon, United States
Best Spectacle-Corrected Visual Acuity
The BSCVA was recorded at 4 meters by a masked refractionist certified for the study using a protocol adapted from the Age-Related Eye Disease Study using Early Treatment Diabetic Retinopathy Study charts: chart R(2110), chart 1(2111), and chart 2(2112) (Precision Vision, Woodstock, IL).
Time frame: 6 months
Best Spectacle-Corrected Visual Acuity
The BSCVA was recorded at 4 meters by a masked refractionist certified for the study using a protocol adapted from the Age-Related Eye Disease Study using Early Treatment Diabetic Retinopathy Study charts: chart R(2110), chart 1(2111), and chart 2(2112) (Precision Vision, Woodstock, IL).
Time frame: 3 and 12 months
Best Spectacle-Corrected Visual Acuity
The BSCVA was recorded at 4 meters by a masked refractionist certified for the study using a protocol adapted from the Age-Related Eye Disease Study using Early Treatment Diabetic Retinopathy Study charts: chart R(2110), chart 1(2111), and chart 2(2112) (Precision Vision, Woodstock, IL).
Time frame: 24 Months
Endothelial Cell Count
Time frame: 3, 6, 12 months
Endothelial Cell Count
Time frame: 24 months
Corneal Higher-Order Aberrations
Corneal anterior and posterior surface higher-order aberrations (HOA) were measured with Scheimpflug imaging (Pentacam) before surgery and at 3, 6, and 12 months post-operatively. Zernike orders 3-8 were calculated at 4.0- and 6.0-mm-diameter optical zones. The results reported here represent total HOA (Sum of Zernike orders 3-8). Note a single observation was not available for one eye in the DMEK group at 6 months, this was analyzed with last observation carried forward.
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Prednisolone is a corticosteroid used to alleviate swelling post-surgery.
Ofloxacin is an antibiotic used to treat bacterial infections of the eye.
Tropicamide is a prescription drug used to dilate pupils during an eye exam.
Phenylephrine is a prescription drug used to dilate pupils during an eye exam.
The Jones Tube will be used to insert the graft into a 3.5 mm corneal incision during endothelial replacement surgery.
Time frame: 3, 6, 12 months
Corneal Higher-Order Aberrations
As measured by Pentacam
Time frame: 24 months
Interface Haze
As measured by Pentacam densitometry
Time frame: 3, 6, 12 months
Interface Haze
As measured by Pentacam densitometry
Time frame: 24 months
National Eye Institute - Visual Functioning Questionnaire (NEI-VFQ)
The National Eye Institute has developed the validated Visual Functioning Questionnaire (NEI-VFQ) to assess the effect of ocular conditions and vision on patient quality of life. The answers to the questionnaire are transformed into sub-scales, including: general health, general vision, ocular pain, near activities, distance activities, social functioning, mental health, role difficulties, dependency, driving, color vision, peripheral vision. Participants are assigned a numerical value for each sub-scale based on their answers between 0-100, where higher numbers indicate better visual function. These sub-scales are then combined according to National Eye Institute guidelines into an overall composite score for each participant. This overall composite score is also on a scale of 0-100, where higher numbers indicate better visual function. Composite score based on National Eye Institute guidelines.
Time frame: Baseline, 12 months
Graft Failure/Graft Rejection
Time frame: Baseline 12 months
Graft Failure/Graft Rejection
Time frame: Baseline to 24 months