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Rationale: Dextro-transposition of the great arteries (D-TGA) is a severe congenital heart defect which affects approximately 1 in 4,000 live births. While there are several reports of D-TGA patients with rare variants in individual genes, the majority of D-TGA cases remain genetically elusive. Familial recurrence patterns and the observation that most cases with D-TGA are sporadic suggest a polygenic inheritance for the disorder, yet this remains unexplored. Objective: We sought to study the role of common single nucleotide polymorphisms (SNPs) in risk for D-TGA. Methods and Results: We conducted a genome-wide association study in an international set of 1,237 patients with D-TGA and identified a genome-wide significant susceptibility locus on chromosome 3p14.3, which was subsequently replicated in an independent case-control set (rs56219800, meta-analysis P=8.6x10 -10 , OR=0.69 per C allele). SNP-based heritability analysis showed that 25% of variance in susceptibility to D-TGA may be explained by common variants. A genome-wide polygenic risk score derived from the discovery set was significantly associated to D-TGA in the replication set (P=4x10 -5 ). The genome-wide significant locus (3p14.3) co-localizes with a putative regulatory element that interacts with the promoter of WNT5A , which encodes the Wnt Family Member 5A protein known for its role in cardiac development in mice. We show that this element drives reporter gene activity in the developing heart of mice and zebrafish and is bound by the developmental transcription factor TBX20. We further demonstrate that TBX20 attenuates Wnt5a expression levels in the developing mouse heart. Conclusions: This work provides support for a polygenic architecture in D-TGA and identifies a susceptibility locus on chromosome 3p14.3 near WNT5A . Genomic and functional data support a causal role of WNT5A at the locus.

To evaluate the relationship between penetrating keratoplasty (PK) and postoperative PRA level and number of unacceptable antigens.A cross-sectionalstudy was performed on patients with history of PK. Patients with prior solid organ transplantation, pregnancy, or blood transfusion were excluded. These findings were combined with a retrospective review. Patients were grouped by single or multiple PKs. The primary outcome was postoperative PRA level.Incidence of postoperative PRA elevation and mean peak PRA was higher in the multiple PK group (p = .08 and p = .010, respectively). Mean number of unacceptable antigens was elevated in the multiple PK group (p = .024). There was a moderately positive correlation between number of PK grafts and PRA level (r = 0.629, p = .0002).PRA level may be influenced by PKs, with higher PRA associated with increased prior PKs. Further studies are necessary to determine the potential prognostic value.

Objective To describe the steps, hurdles, and recommendations for the implementation of ISBCS evidence-based protocol at a high-volume Canadian tertiary care centre. Design Quality improvement study Participants A total of 406 patients who underwent ISBCS from July 2020 to December 2020. Patients were selected based on specific inclusion and exclusion criteria including psychosocial factors, refractive error and consent. This initiative impacted staff at all levels involved with cataract surgery. Methods The Model of Improvement framework was used and involved numerous discussions with multidisciplinary teams of ophthalmologists, nursing and support staff, management, pharmacists, and medical device reprocessing teams. This initiative was created and refined via a thorough review of the literature and current best practices. It was implemented in July 2020 after a nursing “huddle”. Any adverse outcomes and overall impact were collected from various levels of staff involved. Results Each eye was treated as a separate surgery with a “double time out” per bilateral case. Additional measures were taken to ensure different lot numbers for medications, equipment and materials. This practice increased surgical volume approximately by 25% and reduced the number of patient visits by 50%, reducing potential COVID-19 exposure. Conclusions The resulting protocol from our study may be useful to other centres wishing to integrate ISBCS, as one example of successful implementation. Of the 406 cases of ISBCS performed, we report zero cases of TASS or endophthalmitis. In times of decreased elective surgeries, ISBCS is a safe and effective option to supplement surgical volume and provide significant patient benefits.

Purpose To describe the outcomes of allograft ocular surface stem cell transplantation (OSST) and the complication profile of systemic immunosuppression (SI) in pediatric patients with limbal stem cell deficiency. Methods This was a retrospective interventional case series from a single tertiary referral institution of 20 eyes from 13 patients who 1) underwent allograft OSST surgery, 2) were 18 years or less at time of OSST, and 3) received SI with 4) a minimum of 12-months follow-up. The main outcome measures were ocular surface stability, visual acuity, and SI adverse events. Results The mean age of patients was 15.1 ± 3.2 years (range 9-18 years). The mean follow-up was 5.6 ± 5.0 years after OSST. At the last follow-up, 15 eyes (75%) had a stable ocular surface, 1 eye (5%) developed partial failure, and 4 eyes (20%) developed total surface failure. Preoperative mean logarithm of the minimum angle of resolution visual acuity 1.5 improved to 1.1 at the last follow-up (P = 0.1); when 4 eyes of 3 nonadherent patients were excluded, the results were more pronounced and statistically significant (1.5 improved to 1.0, P = 0.002). SI was tolerated well by all patients with minimal adverse events. Conclusions OSST provides a stable ocular surface and is a successful treatment option for pediatric patients with limbal stem cell deficiency. SI is well-tolerated with a minimal complication profile.

Objective To describe a new/modified technique to manage posterior vitreous pressure (PVP) during penetrating keratoplasty (PKP) and report a small series. Design Retrospective interventional case series and technique description. Participants PKP eyes necessitating mattress suture placement owing to PVP. Methods Retrospective chart review from 2016 to 2019 was undertaken. Placed prophylactically (before trephination) or after trephination, the mattress suture is placed limbus-to-limbus across the anterior chamber. A second mattress suture can be placed in the opposite meridian (perpendicularly) for added support (safety basket configuration). Variations of suture technique are described based on lens status (i.e., phakic, pseudophakic, aphakic) and intraoperative timing. Parameters assessed included demographics, lens status, suture indications, intraoperative technique details, successful PKP completion, and presence of primary failure. Results There were 6 phakic eyes (5 patients) and 9 pseudophakic/aphakic eyes (8 patients). Indications for the phakic subgroup were obesity (83%), poor scleral rigidity (83%), repeated iris prolapse (67%), dense mature cataract (33%), and planned large-diameter PKP (33%). Indications for pseudophakic/aphakic eyes included intraocular lens/iris prolapse (100%), pre-existing iris defects (67%), and planned large-diameter PKP (33%). Successful PKP was performed in all cases. Whereas one case had residual corneal edema in the setting of a persistent epithelial defect owing to limbal stem cell deficiency, all other cases demonstrated no primary graft failure. Conclusions Although increased PVP can present a stressful and challenging situation, it is important to have multiple options for management. This simple mattress suture technique normalizes the lens-iris complex behaviour and appears safe for the donor graft.

Purpose To compare the long-term outcomes of living-related conjunctival limbal allograft (lr-CLAL) with keratolimbal allograft (KLAL) in patients with limbal stem cell deficiency. Methods A retrospective, comparative, interventional cohort of patients with bilateral total limbal stem cell deficiency who underwent surgical treatment with a KLAL or lr-CLAL procedure alone (not combined with any other ocular surface stem cell transplantation procedures) with a minimum follow-up of 1 year and who received systemic immunosuppression. Ocular surface stability, best-corrected visual acuity (BCVA), and postoperative complications at the last follow-up were the main outcome measures. Results There were 224 eyes that underwent KLAL alone and 63 eyes that underwent lr-CLAL alone, with a mean follow-up time for all eyes of 7.2 years (range 1.0-16.0 years). For lr-CLAL eyes, 82.5% maintained a stable ocular surface compared with 64.7% of KLAL eyes at the last follow-up. Only 6.3% of lr-CLAL eyes demonstrated a failed ocular surface compared with 15.6% of KLAL eyes. The mean BCVA was 20/158 for KLAL eyes compared with 20/100 for lr-CLAL eyes at the last follow-up. A smaller proportion of lr-CLAL eyes (30.2% compared with 43.3%) developed an episode of acute rejection, and a higher proportion of these episodes resolved with treatment in the lr-CLAL group (79.0% compared with 53.6%). Conclusions lr-CLAL demonstrates lower rejection rates, improved graft survival, and better BCVA compared with KLAL. Both careful preoperative donor selection and triple-agent systemic immunosuppression (including tapered systemic corticosteroids) are critical to optimizing the ocular surface stem cell transplantation outcomes.

Objective To study indications for penetrating keratoplasty (PK) at a single site. The trends in the causative organisms for infectious keratitis requiring surgery were also evaluated. Design Retrospective observational study. Participants A total of 1181 eyes of 935 patients undergoing PK between January 2000 and December 2015 in Northern Alberta, Canada. Methods Indications for PK were evaluated over the 16-year study period, and the trends in these indications were compared over 5-year intervals. The microbiology of infectious keratitis cases requiring surgery was similarly evaluated. Results The most common indications for PK from 2000 to 2015 were keratoconus (23%), re-graft (22%), and corneal scar (12%). There was a decline in the percent of total surgeries done for Fuchs’ dystrophy (p = 1.1 × 10−3) and pseudophakic bullous keratopathy (p = 5.6 × 10−5), whereas a corresponding increase in keratoconus (p = 3.2 × 10−5), trauma (p = 2.1 × 10−3), and infectious keratitis cases (p = 0.010) was observed. The most common causes for infectious keratitis cases were viral (45%), bacterial (18%), parasitic (11%), and fungal (9%). There was a significant increase in the percent of infectious keratitis cases due to a viral etiology from 2005 to 2010 (p = 6.4 × 10−3). Conclusions The indications for PK are comparable with other centres in North America. Nearly half of all infectious keratitis cases requiring surgery are viral. The increase in viral cases requiring surgery may reflect improved diagnostics or recurrent cases.

To describe the rate, clinical/microbiological characteristics, and outcomes of infectious keratitis in eyes with limbal stem cell deficiency after ocular surface stem cell transplantation (OSST).In this retrospective chart review of 278 eyes that underwent OSST between January 2006 and December 2016, eyes treated for previous infectious keratitis (bacterial, fungal, or viral) were included. Demographics, risk factors, course, microbiological characteristics, and outcomes were assessed.A total of 52 eyes (18.7%) of 48 patients (28 men and 20 women) developed 75 episodes (culture-proven or presumed) of infectious keratitis (range 1-4 episodes) with mean follow-up of 5.3 ± 3.6 years after OSST. The most common limbal stem cell deficiency etiologies included chemical/thermal (27 episodes), Stevens-Johnson syndrome (19 episodes), aniridia (8 episodes), and mucous membrane pemphigoid (8 episodes). There were 44 (58.7%) bacterial keratitis episodes, 24 (32%) fungal keratitis episodes, and 7 (9.3%) HSV keratitis episodes. Gram-positive bacteria (79%) and Candida species (73%) were the most common bacterial and fungal pathogens. Before infection, 33% had an epithelial defect, 69% had a bandage contact lens, 91% were on systemic immunosuppression, and 25% recently had undergone ocular surgery (3 months). Although 75% resolved with antimicrobial treatment, 25% required a therapeutic keratoplasty (TPK; 2 cases needed multiple TPK).Despite successful OSST surgery, infectious keratitis is relatively common, and aggressive medical/surgical therapy is warranted. Prophylactic topical antibiotics and a cicatrizing conjunctivitis diagnosis may account for the high proportion of fungal keratitis in this population.