McLaren 2009.

Methods	Study design: Prospective, randomised clinical trial Number randomised (total and per group): Total 28 eyes of 25 patients; 13 eyes in the deep lamellar endothelial keratoplasty (DLEK) group and 15 eyes in the penetrating keratoplasty (PK) group Number analysed (total and per group): Total 27 eyes; 12 eyes in the DLEK group and 15 eyes in the PK group Exclusions and loss to follow‐up: “One eye in the DLEK group required repeat surgery for graft failure after the 6‐month visit, and subsequent data for this eye were excluded from the analysis.” Study follow‐up: All patients were examined before surgery and at 1, 3, 6, 12, and 24 months after surgery.
Participants	Country: United States Age (mean ± SD, range): Not reported Gender: Not reported Inclusion criteria: participants with corneal oedema resulting from Fuchs dystrophy Exclusion criteria: Not reported
Interventions	Treatment or intervention 1: deep lamellar endothelial keratoplasty Control or intervention 2: penetrating keratoplasty General procedures: "Penetrating keratoplasty was performed by incising the host central cornea with a vacuum trephine system (Hanna Trephine; Moria, Antony, France) with a diameter of 7.5 or 7.75 mm (mean, 7.55 mm). Donor tissue was punched from the endothelial side by using a trephine with diameter of 7.5 or 7.75 mm (mean, 7.63 mm). The donor tissue was secured to the host by using a double‐running technique consisting of a 12‐bite running 10‐0 nylon suture and a 12‐bite running 11‐0 nylon suture over a viscoelastic‐filled anterior chamber." "Deep lamellar endothelial keratoplasty was performed by using a method similar to that described by Terry and Ousley through a 9‐ to 10‐mm scleral tunnel 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) with 300‐µm head depth for the last 2 eyes."
Outcomes	Primary outcome(s): High‐order aberrations (HOA) at months 1, 3, 12, and 24 Secondary outcome(s): best spectacle‐corrected, high‐contrast visual acuity (HCVA), mesopic and phtopic low‐contrast visual acuity (LCVA), and contrast sensitivity Measurements taken, and intervals at which outcomes assessed: “HOA was measured from the anterior corneal surface calculated from corneal topography and decomposed into Zernike polynomials to the sixth order, high‐ and low‐contrast visual acuity (VA), and contrast sensitivity.” “HCVA was measured by the electronic Early Treatment Diabetic Retinopathy Study protocol.” “LCVA was measured in a darkened room at a distance of 4 m from a backlit 10% Sloan Translucent Low Contrast Chart (Precision Vision, La Salle, Illinois, USA). Mesopic LCVA was measured first, by placing a neutral density (2 ND) filter in front of the low‐contrast chart (screen brightness, 1.1 cd/m2). Photopic LCVA was measured after removing the filter (screen brightness, 139 cd/m2).” “Contrast sensitivity was measured at 1.5, 3, 6, 12, and 18 cycles/degree by using the Functional Acuity Contrast Test (Vision Sciences Research Corporation, San Ramon, California, USA). 12 Subjects were asked to identify the orientation (right, left, or vertical) of bars of decreasing contrast until they could no longer identify the bars. This was repeated at each spatial frequency. Manual keratometry was measured by using a Bausch & Lomb Keratometer (Bausch & Lomb Inc, Rochester, New York, USA).” “All patients were examined before surgery and at 1, 3, 6, 12, and 24 months after surgery. At each visit, we measured contrast sensitivity, manual keratometry, VA, and corneal topography.” Unit of analysis (individual or eye): eye Other issues with outcome assessment (e.g., quality control for outcomes if any): None
Notes	Study dates: Not reported Funding source(s): Mayo Clinic Department of Ophthalmology and Dr Patel as an Olga Keith Wiess Scholar from Research to Prevent Blindness Inc, New York, New York; and the 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
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"Randomization was performed by using a web‐based dynamic randomisation process to stratify prospectively by age (< 70 years vs ≥ 70 years) and by best‐corrected visual acuity (VA) (< 20/80 Snellen equivalent vs ≥ 20/80 equivalent)."
Allocation concealment (selection bias)	Low risk	Same as above. It is likely a web‐based randomisation process includes allocation concealment
Blinding of participants (performance bias)	Unclear risk	Not specified
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	“All videokeratography maps of each cornea were examined by 1 masked observer (S.V.P.), and from each visit” Masking of other outcome assessors was not reported
Incomplete outcome data (attrition bias) All outcomes	Low risk	Only one eye was excluded in the final analysis
Selective reporting (reporting bias)	Unclear risk	This information was not available in the report
Other bias	Low risk	No other source of bias identified