Keratoplasty Outcomes: Are We Making Advances?
2014; Elsevier BV; Volume: 121; Issue: 5 Linguagem: Inglês
10.1016/j.ophtha.2014.01.029
ISSN1549-4713
AutoresSanjay V. Patel, W. John Armitage, Margareta Claesson,
Tópico(s)Glaucoma and retinal disorders
ResumoOver the last 15 years, there has been a progressive trend away from penetrating keratoplasty (PK) toward lamellar procedures, predominantly endothelial keratoplasty (EK) but also deep anterior lamellar keratoplasty.1Eye Bank Association of America. 2012 Eye Banking Statistical Report. Washington DC: Eye Bank Association of America; 2013.Google Scholar Successful selective tissue transplantation is broadly accepted as a scientifically logical and clinically desirable destination. This goal is fueled by a drive to improve outcomes, but as the techniques for keratoplasty rapidly change, how do we know whether better outcomes are really being achieved? Two major outcome indicators for most keratoplasty procedures are graft failure and vision. Yet, there have been few carefully designed studies directly comparing graft survival and vision between different keratoplasty techniques, despite some techniques evolving in pursuit of better vision. Randomized controlled trials (RCTs) comparing deep anterior lamellar keratoplasty with PK have had small sample sizes and short follow-up periods,2Cheng Y.Y. Visser N. Schouten J.S. et al.Endothelial cell loss and visual outcome of deep anterior lamellar keratoplasty versus penetrating keratoplasty: a randomized multicenter clinical trial.Ophthalmology. 2011; 118: 302-309Abstract Full Text Full Text PDF PubMed Scopus (114) Google Scholar, 3Shimazaki J. Shimmura S. Ishioka M. Tsubota K. Randomized clinical trial of deep lamellar keratoplasty vs penetrating keratoplasty.Am J Ophthalmol. 2002; 134: 159-165Abstract Full Text Full Text PDF PubMed Scopus (257) Google Scholar and 1 RCT comparing EK with PK encountered incomplete enrollment as techniques rapidly changed from deep lamellar endothelial keratoplasty in favor of Descemet's stripping endothelial keratoplasty (DSEK).4Patel S.V. McLaren J.W. Hodge D.O. Baratz K.H. Scattered light and visual function in a randomized trial of deep lamellar endothelial keratoplasty and penetrating keratoplasty.Am J Ophthalmol. 2008; 145: 97-105Abstract Full Text Full Text PDF PubMed Scopus (58) Google Scholar Currently, although many surgeons comfortably acknowledge DSEK as the standard of care for treating corneal endothelial disease, others are beginning to transition toward Descemet's membrane endothelial keratoplasty because it has been reported to offer improved visual outcomes and a lower risk of rejection.5Price M.O. Giebel A.W. Fairchild K.M. Price F.W. Descemet's membrane endothelial keratoplasty: prospective multicenter study of visual and refractive outcomes and endothelial survival.Ophthalmology. 2009; 116: 2361-2368Abstract Full Text Full Text PDF PubMed Scopus (531) Google Scholar, 6van Dijk K. Ham L. Tse W.H. et al.Near complete visual recovery and refractive stability in modern corneal transplantation: Descemet membrane endothelial keratoplasty (DMEK).Cont Lens Anterior Eye. 2013; 36: 13-21Abstract Full Text Full Text PDF PubMed Scopus (96) Google Scholar, 7Anshu A. Price M.O. Price Jr., F.W. Risk of corneal transplant rejection significantly reduced with Descemet's membrane endothelial keratoplasty.Ophthalmology. 2012; 119: 536-540Abstract Full Text Full Text PDF PubMed Scopus (430) Google Scholar Newer techniques may well be associated with better outcomes than their predecessors, but most current evidence is from noncomparative observational series by a few experienced surgeons, and these data should be extrapolated cautiously by other surgeons to their individual practices. Furthermore, interpreting and comparing outcomes between different studies can be difficult when outcome definitions vary, preoperative characteristics of cohorts are not well defined, and assessments of outcomes are not standardized. In the current issue, Coster et al8Coster D.J. Lowe M.T. Keane M.C. Williams K.A. A comparison of lamellar and penetrating keratoplasty outcomes: a registry study.Ophthalmology. 2014; 121: 979-987Abstract Full Text Full Text PDF PubMed Scopus (180) Google Scholar (see page 979) report the outcomes of lamellar keratoplasty from the Australian Corneal Graft Registry. The registry was established in 1985 for collecting outcomes data from a large number of subjects undergoing corneal transplantation and has proved to be highly successful for advancing our understanding of the factors that affect keratoplasty outcomes.9Williams KA, Lowe MT, Keane MC, Jones VJ, Loh RS, Coster DJ. The Australian Corneal Graft Registry 2012 Report. Adelaide, Australia: Printing S; 2012.Google Scholar Coster et al8Coster D.J. Lowe M.T. Keane M.C. Williams K.A. A comparison of lamellar and penetrating keratoplasty outcomes: a registry study.Ophthalmology. 2014; 121: 979-987Abstract Full Text Full Text PDF PubMed Scopus (180) Google Scholar found that lamellar procedures, whether endothelial or deep anterior, were associated with worse graft survival and visual acuity compared with PK for the same indication and over the same period. These outcomes are contrary to those that have become widely accepted for newer keratoplasty techniques, and the authors attribute this, at least in part, to the difference between "real-world" registry data from multiple surgeons versus data from a few single-center surgeons in "optimal conditions." The difference is important and should not be ignored, especially when donor corneas are not readily available in many parts of the world, the threshold for surgical intervention is being lowered because of presumed improvements in outcomes, and repeat grafts are known to have worse outcomes than primary grafts. The authors concluded by appropriately recommending that all practitioners should be aware of their own outcomes and carefully consider the evidence for new surgical procedures. Coster et al8Coster D.J. Lowe M.T. Keane M.C. Williams K.A. A comparison of lamellar and penetrating keratoplasty outcomes: a registry study.Ophthalmology. 2014; 121: 979-987Abstract Full Text Full Text PDF PubMed Scopus (180) Google Scholar refer to the different levels of evidence used for evaluating clinical outcomes, which, on the basis of the US Preventive Services Task Force methodology (www.uspreventiveservicestaskforce.org), range from well-designed RCTs (level I evidence) to opinions based on clinical experience, descriptive studies, or reports of expert committees (level III evidence). Level II evidence includes nonrandomized trials, cohort and case-control studies, multiple time series, and dramatic results from uncontrolled studies. Although level I evidence is assumed to be the gold standard, for logistic, clinical, and ethical reasons, RCTs may not always be feasible or achievable within a reasonable time frame. It may also be difficult to generalize from an RCT with strictly defined inclusion/exclusion criteria to the typical case mix and range of clinical conditions faced by ophthalmologists when deciding the best treatment option for their individual patients. The adoption of new techniques is often driven by single-center studies reporting the outcomes from specialist units. Longitudinal, observational data collected on large numbers of patients in national registries, such as those in Australia,9Williams KA, Lowe MT, Keane MC, Jones VJ, Loh RS, Coster DJ. The Australian Corneal Graft Registry 2012 Report. Adelaide, Australia: Printing S; 2012.Google Scholar the United Kingdom,10Jones M.N.A. Armitage W.J. Ayliffe W. et al.Penetrating and deep anterior lamellar keratoplasty for keratoconus: a comparison of graft outcomes in the United Kingdom.Invest Ophthalmol Vis Sci. 2009; 50: 5625-5629Crossref PubMed Scopus (104) Google Scholar and Sweden,11Claesson M. Armitage W.J. Fagerholm P. Stenevi U. Visual outcome in corneal grafts: a preliminary analysis of the Swedish Corneal Transplant Register.Br J Ophthalmol. 2002; 86: 174-180Crossref PubMed Scopus (139) Google Scholar provide invaluable information to detail the rate of uptake of new techniques and the outcomes across multiple centers. As shown by Coster et al,8Coster D.J. Lowe M.T. Keane M.C. Williams K.A. A comparison of lamellar and penetrating keratoplasty outcomes: a registry study.Ophthalmology. 2014; 121: 979-987Abstract Full Text Full Text PDF PubMed Scopus (180) Google Scholar the wider picture revealed by registry data does not necessarily reflect the optimism generated by the excellent results from single-center studies. Coster et al also address the "learning curve," which is often blamed for poor outcomes in the early stages of implementation of a new technique. For experienced corneal transplant surgeons, there seems to be little evidence of a learning curve, with the likelihood of EK failure appearing to be unrelated to the number of EKs performed. Pitfalls in gathering evidence at whatever level include selection bias and not collecting data on factors that may influence outcome (e.g., the stage of disease at keratoplasty, in the event that earlier intervention is associated with improved outcomes). Registries rely on large data sets to reduce selection bias, but they have to balance the amount and type of data collected for each patient against the willingness, ability, and resources required to provide the data. The Swedish registries (www.eyenetsweden.se) are web-based, and surgeons directly enter their data, which reduces time, improves accuracy, and enables them to compare their individual results with national outcomes. This year, the American Academy of Ophthalmology launched a similar efficient and effective data-collection initiative, the Intelligent Research in Sight Registry (www.aao.org/iris-registry), which will gather data directly from electronic medical records. In addition to contributing substantive, evidence-based data for the evaluation of the efficacy of new techniques, registries also may provide preliminary data for initiating RCTs. Registries are not without pitfalls, and changes in practice over time, such as patient selection or widely varying numbers of transplants between different hospitals, are factors that can influence the data. It is apparent that data from multiple sources should be considered when interpreting the outcomes of new procedures. We are indebted to the immense contributions of the pioneering surgeons who have spearheaded the evolution of keratoplasty and shared their pearls and pitfalls to help others learn new techniques. Their foresight to collect and report their outcomes has been instrumental and without which there would be little cause to pursue new endeavors. Most surgeons would agree with the anatomic advantages and rationale for lamellar surgery over PK and that further exploration of the bounds of keratoplasty is warranted. The results from the Australian Corneal Graft Registry emphasize the importance of measuring outcomes of newer techniques on a broad scale, so that we can ensure that advances in techniques translate to overall improvements in outcome. Indeed, we will garner 3-year standardized graft survival data after DSEK from the multicenter Cornea Preservation Time Study, and this will provide another opportunity to compare outcomes with after PK in the Cornea Donor Study.12Mannis M.J. Holland E.J. Gal R.L. et al.The effect of donor age on penetrating keratoplasty for endothelial disease: graft survival after 10 years in the cornea donor study.Ophthalmology. 2013; 120s: 2419-2427Abstract Full Text Full Text PDF Scopus (69) Google Scholar However, comparing visual outcomes of different techniques will not be as easy and may require carefully designed RCTs. The seemingly poorer outcomes of the lamellar techniques compared with PK reported by Coster et al8Coster D.J. Lowe M.T. Keane M.C. Williams K.A. A comparison of lamellar and penetrating keratoplasty outcomes: a registry study.Ophthalmology. 2014; 121: 979-987Abstract Full Text Full Text PDF PubMed Scopus (180) Google Scholar and Jones et al10Jones M.N.A. Armitage W.J. Ayliffe W. et al.Penetrating and deep anterior lamellar keratoplasty for keratoconus: a comparison of graft outcomes in the United Kingdom.Invest Ophthalmol Vis Sci. 2009; 50: 5625-5629Crossref PubMed Scopus (104) Google Scholar are not necessarily an indictment of these newer techniques because excellent results can be achieved in single-center studies. Nevertheless, the registry data serve as a reminder that, for whatever reason, outcomes do vary between different hospitals and surgeons, and one would expect that this gap in outcomes would close over time. Are graft failure and vision the ideal outcome measures for keratoplasty? Graft failure has typically been the primary outcome in most large keratoplasty studies because of its relative ease of assessment. Although graft failure is associated with patient dissatisfaction, graft survival is not always representative of visual outcomes or amelioration of patient visual disability. Visual outcomes are becoming more important in the current era of EK, but assessing vision with rigor requires standardized refraction and testing protocols, and a defined minimum level of ability and experience in refracting patients. There also can be incongruence between visual outcomes and patient-reported outcomes. Perhaps we should be making a more concerted effort to relate patient-reported outcomes to clinical outcomes by using validated vision-related quality of life instruments. For example, Catquest-9SF,13Lundstrom M. Behndig A. Kugelberg M. Montan P. Stenevi U. Pesudovs K. The outcome of cataract surgery measured with the Catquest-9SF.Acta Ophthalmol. 2011; 89: 718-723Crossref PubMed Scopus (41) Google Scholar which was developed for evaluating patient-reported visual disability after cataract surgery, is currently being validated for corneal transplantation and applied in an ancillary study to the Swedish Corneal Transplant Registry to compare clinical outcome with patient-reported outcome. Such tools could be simple to administer and could reveal a point of diminishing return in terms of patient-reported outcome in relation to vision and graft survival. With the changing health care environment ahead, it is imperative that we provide high long-term value for the total care that we deliver to our patients, and this will require defining and measuring the ideal outcomes in the most effective and meaningful manner. A Comparison of Lamellar and Penetrating Keratoplasty Outcomes: A Registry StudyOphthalmologyVol. 121Issue 5PreviewTo investigate changing patterns of practice of keratoplasty in Australia, graft survival, visual outcomes, the influence of experience, and the surgeon learning curve for endothelial keratoplasty. Full-Text PDF
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