Patel 2008.
| Methods | Study design: RCT Number randomised (total and per group): total: 31 eyes of 28 patients; DLEK group: 16 eyes of 14 patients; PKP group: 15 eyes of 14 patients Number analysed (total and per group): total: 28 eyes of 26 patients; DLEK group: 13 eyes of 12 patients; PKP group: 15 eyes of 14 patients Exclusions and loss to follow‐up: 3 eyes of DLEK group were converted to PKP intraoperatively for inadvertent perforation Study follow‐up: 12 months |
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| Participants | Country: United States Age (mean ± SD, range): 75 ± 8 years in the DLEK group (n = 12; range, 56 to 85 years); 74 ± 8 years in the PKP group (n = 14; range, 62 to 86 years) Gender: Not reported Inclusion criteria: corneal edema attributable to endothelial dysfunction, and were either pseudophakic or had a cataract requiring extraction, entrance BSCVA was 20/40 or worse (with the fellow eye better than the study eye) Exclusion criteria: central corneal scarring, as determined by slit‐lamp biomicroscopy, the presence of a filtering bleb or uncontrolled glaucoma, or a history of herpetic keratitis |
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| Interventions | Treatment or intervention 1: deep lamellar endothelial keratoplasty (DLEK) Control or intervention 2: penetrating keratoplasty (PKP) General procedures: “Deep lamellar endothelial keratoplasty was performed under general or local anesthesia by using a method similar to that described by Terry and Ousley. A 9 to 10 mm scleral tunnel incision was created superiorly using a guarded diamond blade set to a depth of 350 µm. In procedures combined with cataract surgery, phacoemulsification, and intraocular lens insertion was performed through a separate temporal clear corneal incision. The donor lenticule was prepared over an artificial anterior chamber by using a manual technique for the first 11 eyes, or by using a mechanical microkeratome (ALTK; Moria, Antony, France) with 300 µm head depth for the last two eyes.” “Penetrating keratoplasty was performed by using vacuum trephination of the host cornea (Hanna trephine; Moria, Antony, France) after marking the host with 12 equally spaced radial marks. In cases combined with cataract surgery, crystalline lens extraction, and intraocular lens insertion were performed via an open‐sky technique. A similar‐sized donor button was prepared by punching the tissue from the endothelial side and placing 12 equally spaced marks on the epithelial surface. The donor tissue was sutured to the host by using a double‐running technique (12 bites each of a 10‐0 and 11‐0 nylon suture) over a viscoelastic‐filled anterior chamber.” |
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| Outcomes | Primary outcome(s): high‐contrast visual acuity Secondary outcome(s): manifest refraction, keratometric astigmatism, contrast sensitivity, intraocular forward light scatter, and corneal backscatter Measurements taken, and intervals at which outcomes assessed: “Patients were examined before surgery and at one, three, six, and 12 months after surgery.” “High‐contrast visual acuity was measured by using the e‐ETDRS testing protocol.” “Contrast sensitivity was examined by using the Functional Acuity Contrast Test (FACT: Vision Sciences Research Corporation, San Ramon, California, USA) with best‐spectacle correction in place.” “Intraocular forward light scatter was measured with a stray light meter, which used the direct compensation method to measure stray light at the retina.” “Central corneal backscatter (haze) was measured by using a custom scatterometer.” Unit of analysis (individual or eye): eye Other issues with outcome assessment (e.g., quality control for outcomes if any): None |
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| Notes | Study dates: Not reported Funding source(s): Research to Prevent Blindness, Inc., New York, New York (Dr Patel as Olga Keith Wiess Scholar and an Unrestricted Grant to the Department of Ophthalmology at Mayo Clinic, Rochester, Minnesota) and Mayo Foundation, Rochester, Minnesota Declaration of interest: the authors indicated no financial conflict of interest involved in design and conduct of study Publication language: English |
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| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | “Eyes were then randomly assigned to either DLEK or PK.” |
| Allocation concealment (selection bias) | Unclear risk | Not specified |
| Blinding of participants (performance bias) | Unclear risk | Not specified |
| Blinding of outcome assessment (detection bias) All outcomes | Low risk | “At each examination, high‐contrast visual acuity, manifest refraction, keratometric astigmatism, contrast sensitivity, intraocular forward light scatter, and corneal backscatter were measured by observers masked as to which treatment was received.” Outcomes were measured by masked observers |
| Incomplete outcome data (attrition bias) All outcomes | High risk | 3 eyes of DLEK group were converted to PKP intraoperatively for inadvertent perforation. Not sure whether the analyses accounted for the crossover of treatments |
| Selective reporting (reporting bias) | Unclear risk | Protocol not available |
| Other bias | Low risk | No other sources of bias identified |
BCVA: best corrected visual acuity BSCVA: best spectacle‐corrected visual acuity DLEK: deep lamellar endothelial keratoplasty FED: Fuchs endothelial dystrophy FLEK: femtosecond laser‐assisted endothelial keratoplasty HCVA: high contrast visual acuity HOA: higher order aberration LCVA: low contrast visual acuity MDD: minimum detectable difference PKP: penetrating keratoplasty R: correlation coefficient RCT: randomised controlled trial UCVA: uncorrected visual acuity VA: visual acuity