Changing indications for keratoplasty: monocentric analysis of the past two decades.

PURPOSE: Over the past two decades, lamellar keratoplasty procedures, such as Descemet's Stripping Automated Endothelial Keratoplasty (DSAEK) and Descemet's Membrane Endothelial Keratoplasty (DMEK) as well as Deep Anterior Lamellar Keratoplasty (DALK), have become an integral part of clinical practice. With advances in contact lens fitting for keratoconus management and the implementation of UVA-Riboflavin Crosslinking (CXL), the landscape of keratoplasty indications is undergoing changes. Procedures and indications in a single tertiary care center over the past two decades are reviewed in this retrospective analysis. METHODS: Retrospective analysis utilized anonymized electronic data from the LIONS cornea bank Baden-Württemberg, Eye Center Freiburg, spanning from beginning of 2004 to end of 2023. The primary focus was on surgical procedures and indications for keratoplasty. RESULTS: The study encompassed a comprehensive analysis of 7130 corneal transplants. Penetrating keratoplasty (PK) exhibited a significant decline from 95% (n = 206, 2004) to 11% (n = 46, 2023), while DMEK increased from 48% (n = 157, 2012) to 82% (n = 347, 2023). Fuchs endothelial dystrophy (FED) emerged as the dominant indication, witnessing a significant increase from 24% (2004, n = 39) to 72% (2023, n = 288). Conversely, keratoconus (KC) showed a reciprocal change from 25% (2004, n = 40) to 4% (2023, n = 17). PK demonstrated a noteworthy indication shift in descending order from Bullous Keratopathy (BK), FED, and KC in 2004 to KC, graft failure, corneal scars, and ulcers in 2023. Repeat keratoplasty following DMEK remained rare, but a discernible upward trend was observed for PK. CONCLUSION: This retrospective analysis highlights significant changes in both keratoplasty indications and techniques over the past two decades. DMEK has emerged as a successful intervention for treating endothelial diseases, while PK retains its qualitative indispensability for a wide range of indications. Modern corneal banks are urged to maintain a robust supply of grafts for all surgical techniques in anticipation of potential increased demand in the future, particularly for repeat keratoplasties. KEY MESSAGES: What is known • Over the past two decades, lamellar keratoplasty procedures such as DSAEK and DMEK have increasingly replaced penetrating keratoplasty (PK) in clinical practice due to their improved outcomes and reduced complications for certain indications. New Findings • Our study reveals a significant shift in keratoplasty indications, with Fuchs endothelial dystrophy (FED) emerging as the predominant indication, increasing from 24% in 2004 to 72% in 2023, while keratoconus (KC) declined from 25 to 4% during the same period. • Penetrating keratoplasty (PK) has shown a marked decline in use, dropping from 95% of keratoplasties in 2004 to 11% in 2023, whereas DMEK has grown to represent 82% of procedures in 2023. • Despite the rise of DMEK, PK remains vital for a broad spectrum of indications, highlighting the necessity for corneal banks to maintain a versatile supply of grafts to meet diverse clinical needs, particularly in cases of repeat keratoplasties.

A duality based 2-approximation algorithm for maximum agreement forest.

We give a 2-approximation algorithm for the Maximum Agreement Forest problem on two rooted binary trees. This NP-hard problem has been studied extensively in the past two decades, since it can be used to compute the rooted Subtree Prune-and-Regraft (rSPR) distance between two phylogenetic trees. Our algorithm is combinatorial and its running time is quadratic in the input size. To prove the approximation guarantee, we construct a feasible dual solution for a novel exponential-size linear programming formulation. In addition, we show this linear program has a smaller integrality gap than previously known formulations, and we give an equivalent compact formulation, showing that it can be solved in polynomial time.

Repeat corneal transplantation: indication, surgical technique, and early graft failures trends in France from 2004 to 2019.

PURPOSE: To investigate the repeat corneal transplantation trend in France from 2004 to 2019. METHODS: Review of the prospectively compiled French Biomedicine Agency electronic database containing all corneal transplantation records from 2004 to 2019. The surgical technique, demographic characteristics, diagnosis, and previous graft data were retrieved and analyzed using the Cochran-Armitage trend test. RESULTS: A total of 66,584 corneal transplantations were performed, 51,260 of which were first grafts and 15,324 (23%) were regrafts. For regrafts, 77% were penetrating keratoplasties (PK) and 19.6% were lamellar keratoplasties (LK). Age, hypertonia, glaucoma, trauma, lens surgery, immune disorders, diameter > 8.5 mm, and neovessels in > 2 quadrants were associated with a higher rate of repeat keratoplasty. Keratoconus, secondary endothelial dystrophy, and Fuchs' dystrophy were the principal indications for regrafting. When a previous graft failed, it occurred earlier for patients with LK (4.6 years, median = 2, SD = 7.54) than PK (8.48 years, median = 5, SD = 9.51). Failure within a year was the reason why 28.3% of the LK regrafts and 12.5% of PK regrafts were performed, while for failure within two years these values were 49.9% and 27.8%, respectively. Graft survival decreased with the number of repeat keratoplasty, being more pronounced after a second LK regraft and after a first PK regraft. CONCLUSION: The number of LK regrafts increased continuously, and 1/3 were performed for failure within the year. This rate increased until 2015, after which it stabilized until 2019, probably due to the better mastery of the technique.

Lost in space? Generalising subtree prune and regraft to spaces of phylogenetic networks.

Over the last fifteen years, phylogenetic networks have become a popular tool to analyse relationships between species whose past includes reticulation events such as hybridisation or horizontal gene transfer. However, the space of phylogenetic networks is significantly larger than that of phylogenetic trees, and how to analyse and search this enlarged space remains a poorly understood problem. Inspired by the widely-used rooted subtree prune and regraft (rSPR) operation on rooted phylogenetic trees, we propose a new operation-called subnet prune and regraft (SNPR)-that induces a metric on the space of all rooted phylogenetic networks on a fixed set of leaves. We show that the spaces of several popular classes of rooted phylogenetic networks (e.g. tree child, reticulation visible, and tree based) are connected under SNPR and that connectedness remains for the subclasses of these networks with a fixed number of reticulations. Lastly, we bound the distance between two rooted phylogenetic networks under the SNPR operation, show that it is computationally hard to compute this distance exactly, and analyse how the SNPR-distance between two such networks relates to the rSPR-distance between rooted phylogenetic trees that are embedded in these networks.

Quantifying MCMC exploration of phylogenetic tree space.

In order to gain an understanding of the effectiveness of phylogenetic Markov chain Monte Carlo (MCMC), it is important to understand how quickly the empirical distribution of the MCMC converges to the posterior distribution. In this article, we investigate this problem on phylogenetic tree topologies with a metric that is especially well suited to the task: the subtree prune-and-regraft (SPR) metric. This metric directly corresponds to the minimum number of MCMC rearrangements required to move between trees in common phylogenetic MCMC implementations. We develop a novel graph-based approach to analyze tree posteriors and find that the SPR metric is much more informative than simpler metrics that are unrelated to MCMC moves. In doing so, we show conclusively that topological peaks do occur in Bayesian phylogenetic posteriors from real data sets as sampled with standard MCMC approaches, investigate the efficiency of Metropolis-coupled MCMC (MCMCMC) in traversing the valleys between peaks, and show that conditional clade distribution (CCD) can have systematic problems when there are multiple peaks.

Median quartet tree search algorithms using optimal subtree prune and regraft.

Gene trees can be different from the species tree due to biological processes and inference errors. One way to obtain a species tree is to find one that maximizes some measure of similarity to a set of gene trees. The number of shared quartets between a potential species tree and gene trees provides a statistically justifiable score; if maximized properly, it could result in a statistically consistent estimator of the species tree under several statistical models of discordance. However, finding the median quartet score tree, one that maximizes this score, is NP-Hard, motivating several existing heuristic algorithms. These heuristics do not follow the hill-climbing paradigm used extensively in phylogenetics. In this paper, we make theoretical contributions that enable an efficient hill-climbing approach. Specifically, we show that a subtree of size m can be placed optimally on a tree of size n in quasi-linear time with respect to n and (almost) independently of m. This result enables us to perform subtree prune and regraft (SPR) rearrangements as part of a hill-climbing search. We show that this approach can slightly improve upon the results of widely-used methods such as ASTRAL in terms of the optimization score but not necessarily accuracy.

Incidence of Complications Related to Corneal Graft in a Group of 758 Patients.

Purpose: this study aimed to assess the frequency of complications related to corneal grafts, including epithelialization disorders, wound dehiscence, infectious keratitis, recurrence of herpetic keratitis, graft rejection, late graft failure, and infectious and noninfectious corneal melting, while also considering risk factors, particularly indications. Methods: this retrospective analysis of corneal graft failure included a chart review of the hospital records of patients who underwent penetrating keratoplasty (PK) between January 2016 and December 2020 at the Department of Ophthalmology of the District Railway Hospital, Katowice, Poland. Results: Between 2016 and 2020, a total of 758 PK procedures were carried out at the ophthalmology department. Bullous keratopathy (20.58%), keratoconus (18.07%), and corneal perforation (13.32%) were the primary indications for keratoplasty. Secondary glaucoma was diagnosed in 99 patients (13.06%). The success rate of PK was 72.43% (494). The most frequent treatment complication was secondary glaucoma (13.06%), followed by late endothelial failure, perforation (4.1%), and bacterial keratitis (3.23%). Patients in the high-risk group were 4.65 times more likely to develop complications than those in the low-risk group. Multivariate regression analysis showed that concomitant ophthalmic diseases (odds ratio (OR): 3.12, confidence interval (CI): 1.60−6.08, p = 0.00) and connective tissue diseases (OR: 7.76, CI: 2.40−25.05, p = 0.00) were significant factors associated with the occurrence of complications. Diabetes, dermatological diseases, primary glaucoma, and sex were not associated with corneal graft failure (p > 0.05). Conclusion: Chronic loss of the endothelium was the primary cause of graft failure in individuals who underwent PK. The high-risk transplant has up to 4.65 times higher risk of complications compared to the indications with a good prognosis.

Descemet Membrane Endothelial Keratoplasty versus Descemet Stripping Automated Keratoplasty - Outcome of One Single Surgeon's More Than 200 Initial Consecutive Cases.

PURPOSE: To compare clinical outcome and complications of Descemet stripping automated keratoplasty (DSAEK) and Descemet membrane endothelial keratoplasty (DMEK). METHODS: This is a retrospective study of the first consecutive cases of DSAEK and DMEK performed by a single surgeon at a tertiary referral centre. Best-corrected visual acuity (BCVA), postoperative complications, rate of rebubbling and regraft were the main outcome measures. RESULTS: The study included 241 eyes, 116 subjected to DSAEK and 125 to DMEK. Fuchs endothelial dystrophy (FED) was the predominant diagnosis in both groups. Mean BCVA at all follow-ups up to 2 years was in favour of DMEK. Median BCVA (decimal) at 1 year was 0.4 (0.13-0.60; interquartile range) for the DSAEK and 0.8 (0.6-1.0) for the DMEK group, p<0.001. Preoperative BCVA in the DSAEK group was lower than in DMEK. There was no significant difference in visual improvement between groups at 1 year postoperatively. The most common postoperative complication in both groups was a pupillary block with high intraocular pressure, 27% and 34% respectively. This was not affected by the presence of an iridectomy/iridotomy. In the DMEK group, gas provided significantly better adherence than air (p=0.020). Rebubbling for partial/total detachment was performed in 7% (DSAEK) and 11% (DMEK) of cases, p=0.361. Regraft within 2 years was performed in 13% of eyes in the DSAEK and 17% in the DMEK group, p=0.450. No case of graft rejection occurred. CONCLUSION: Both DSAEK and DMEK provide overall satisfying outcome and the two techniques do not differ significantly in postoperative pupillary block, detachment rate, early graft failure or graft rejection. However, differences at baseline may have influenced or obscured potential differences. In DMEK procedures, gas seems to facilitate early graft adherence.

Roadblocked monotonic paths and the enumeration of coalescent histories for non-matching caterpillar gene trees and species trees.

Given a gene tree topology and a species tree topology, a coalescent history represents a possible mapping of the list of gene tree coalescences to associated branches of a species tree on which those coalescences take place. Enumerative properties of coalescent histories have been of interest in the analysis of relationships between gene trees and species trees. The simplest enumerative result identifies a bijection between coalescent histories for a matching caterpillar gene tree and species tree with monotonic paths that do not cross the diagonal of a square lattice, establishing that the associated number of coalescent histories for n-taxon matching caterpillar trees (n ⩾ 2) is the Catalan number C n - 1 = 1 n ( 2 n - 2 n - 1 ) . Here, we show that a similar bijection applies for non-matching caterpillars, connecting coalescent histories for a non-matching caterpillar gene tree and species tree to a class of roadblocked monotonic paths. The result provides a simplified algorithm for enumerating coalescent histories in the non-matching caterpillar case. It enables a rapid proof of a known result that given a caterpillar species tree, no non-matching caterpillar gene tree has a number of coalescent histories exceeding that of the matching gene tree. Additional results on coalescent histories can be obtained by a bijection between permissible roadblocked monotonic paths and Dyck paths. We study the number of coalescent histories for non-matching caterpillar gene trees that differ from the species tree by nearest-neighbor-interchange and subtree-prune-and-regraft moves, characterizing the non-matching caterpillar with the largest number of coalescent histories. We discuss the implications of the results for the study of the combinatorics of gene trees and species trees.

[Analysis of clinical effects in the treatment of single-segment lumbar degenerative disease by lamina osteotomy and former vertebral plates regraft].

OBJECTIVE: To compare the clinical effect between the lamina osteotomy and former vertebral plates regraft method and total laminectomy and interbody fusion method in treating single-segment lumbar degenerative disease. METHODS: The clinical data of 167 patients with single-segment lumbar degenerative disease underwent surgical treatment from January 2010 to December 2014 were retrospectively analyzed. There were 92 males and 75 females, aged from 45 to 75 years old with an average of (59.6±12.4) years. The patients were divided into lamina osteotomy and former vertebral plates regraft group(82 cases) and total laminectomy and interbody fusion group(85 cases) according to the different surgical methods used. The general conditions and clinical effects were compared between two groups. General conditions included the operation time, intraoperative blood loss, postoperative drainage, hospitalization time and the clinical effects included the visual analogue scale (VAS), Japanese Orthopaedic Association(JOA), Oswestry Dability Index(ODI), MacNab results, epidural fibrosis (EF), the incidence of adjacent segment degeneration (ASD). RESULTS: All the patients were followed for 18 to 36 months with an average of (24.8±5.7) months, furthermore, there was no significant difference in the follow-up time between two groups. There was no significant difference in general conditions such as operation time, intraoperative blood loss, postoperative drainage, or hospitalization time between two groups. At final follow-up, the VAS, ODI, JOA, of all patients were significantly improved (P<0.05);and the three factors above in the lamina osteotomy and former vertebral plates regraft group respectively were(2.0±1.1) points, (24.0±1.8) %, (19.8±8.2) point, while the results of total laminectomy and interbody fusion group were(2.5±1.6) points, (23.3±2.0)%, and(22.5±8.5) point;there was statistical difference between two groups(P<0.05). According to the standard of MacNab, 59 cases obtained excellent results, 20 good, 3 fair results in the lamina osteotomy and former vertebral plates regraft group;while 47 cases got excellent results, 26 good, and 12 fair results in the total laminectomy and interbody fusion group;there was significant difference between two groups(P<0.05). Sixteen patients(19.51%) with EF and 20 patients(24.39%) with ASD were found in lamina osteotomy and former vertebral plates regraft group;and 30 patients(35.29%) with EF and 37 patients(43.53%) with ASD were found in total laminectomy and interbody fusion group; there was significant difference between two groups(P<0.05). CONCLUSIONS: Both two methods can achieve the ideal effects for the treatment of single-segment lumbar degenerative disease, but the lamina osteotomy and former vertebral plates regraft method can reserve the integrity of posterior ligamentous complex, reducing the incidence of EF and ASD, and is a better surgical method.

Wound-healing improvement by resurfacing split-thickness skin donor sites with thin split-thickness grafting.

INTRODUCTION: Split-thickness skin graft (STSG) donor site dressing has been controversial until now. Our study aimed to assess the patient comfort and wound-healing efficacy with the application of thin split-thickness skin grafts regrafting on STSG donor sites. METHODS: One hundred ninety-two consecutive patients undergoing split-thickness skin grafting were included in the study, and the participants were randomly divided into the following three groups: group A was regrafted with thin STSGs and groups B and C were covered with occlusive hydrocellular dressing and paraffin gauze, respectively. The participants were compared according to the epithelialization time, pain and scar formation. RESULTS: The average time of epithelialization was 6.2 ± 1.1 days in group A, 11.1 ± 2.1 days in group B and 13.5 ± 2.5 days in group C. The pain scores on days 2 and 5 after operation were 2.3 ± 0.8 and 1.9 ± 0.8 in group A, 2.5 ± 1.1 and 3.9 ± 1.3 in group B, and 3.8 ± 1.4 and 5.9 ± 2.1 in group C. The scar scores at half a year and one year after operation were 4.3 ± 0.6 and 2.50 ± 0.6 in group A, 7.4 ± 0.6 and 6.2 ± 0.6 in group B, and 11.8 ± 0.4 and 10.9 ± 1.0 in group C, separately. The difference in the three groups was significant. CONCLUSION: Utilizing thin STSGs regrafting on donor sites could significantly shorten the epithelialization time, reduce pain and prevent hyperplastic scar formulation.