Incidence of ocular surface squamous neoplasia in pterygium specimens.

OBJECTIVE: Pterygium and ocular surface squamous neoplasia (OSSN) have been recognized as likely related conditions and share similar risk factors such as ultraviolet radiation and chronic inflammation. The purpose of this study is to review the incidence of OSSN in pathology specimens sent as pterygium at a single tertiary centre between 2010 and 2022. METHODS: This is a retrospective chart review of patients operated on for pterygium between 2010 and 2022 at the University of Montreal Health Centre. Data collected include baseline demographics, results of pathology specimen, and clinical information for cases diagnosed as OSSN on pathology. RESULTS: A total of 1559 patients were operated on for a clinical diagnosis of pterygium between 2010 and 2022, of which 854 patients (55%) were male. A total of 1142 specimens had available pathology reports, and most of the specimens were consistent with pterygium on pathology (1105 of 1142; 97%). There was an unexpected finding of 3 cases of OSSN (3 of 1142; 0.3%). Other diagnosis besides pterygium were seen in 3% of specimens (34 of 1142), including nevus (n = 12), spheroidal degeneration (n = 3), pyogenic granuloma (n = 3), and lymphangiectasia (n = 2). The 3 cases of OSSN included an 81-year-old male of French-Canadian background, a 52-year-old male of South Asian background, and a 59-year-old female of French-Canadian background. The pathology was diagnosed as conjunctival intraepithelial neoplasia (CIN) grade 3, CIN grade 2, and CIN grade 2, respectively. CONCLUSION: The finding of OSSN in pterygium is rare in our population but can be clinically difficult to distinguish. It is important to send all pterygium specimens for pathology.

Survey: Preferred practice patterns in the diagnosis of mucous membrane pemphigoid amongst cornea specialists.

PURPOSE: To evaluate preferred diagnostic tools and treatment decision-making factors in cases suspicious of mucous membrane pemphigoid (MMP) amongst ophthalmologists and cornea specialists. METHODS: Web-based survey, consisting of 14 multiple choice questions, posted to the Cornea Society Listserv Keranet, the Canadian Ophthalmological Society Cornea Listserv, and the Bowman Club Listserv. RESULTS: One hundred and thirty-eight ophthalmologists participated in the survey. Eighty-six percent (86%) of respondents were cornea trained and practiced in either North America or Europe (83%). Most respondents (72%) routinely perform conjunctival biopsies for all suspicious cases of MMP. For those who do not, fear that biopsy will exacerbate inflammation was the most common reason to defer investigation (47%). Seventy-one percent (71%) performed biopsies from perilesional sites. Ninety-seven percent (97%) ask for direct (DIF) studies and 60% for histopathology in formalin. Most do not recommend biopsy at other non-ocular sites (75%), nor do they perform indirect immunofluorescence for serum autoantibodies (68%). Immune-modulatory therapy is started following positive biopsy results for most (66%), albeit most (62%) would not let a negative DIF influence the choice of starting treatment should there be clinical suspicion of MMP. Differences in practice patterns as they relate to level of experience and geographical location are contrasted to the most up-to-date available guidelines. CONCLUSION: Responses to the survey suggest that there is heterogeneity in certain practice patterns for MMP. Biopsy remains an area of controversy in dictating treatment plans. Identified areas of need should be targeted in future research.

Probing mechanisms and improving management of glaucoma following Boston keratoprosthesis surgery.

Corneal blindness is a leading cause of visual impairment worldwide. The most common treatment is to replace the diseased cornea with standard corneal transplantation. In eyes at high risk of graft failure, the Boston keratoprosthesis type 1 (KPro) can be used to restore vision and is currently the most frequently used artificial cornea in the world. However, glaucoma is a well-known complication of KPro surgery and is the most important threat to vision in KPro-implanted eyes. This chronic disease is influenced by elevated intraocular pressure (IOP) and damages the optic nerve, leading to progressive vision loss. In KPro patients, glaucoma is highly prevalent and extremely challenging to manage, yet its exact cause remains unknown.

Success of the Canadian Ophthalmological Society's first virtual meeting amid COVID-19 pandemic.

OBJECTIVE: To assess participant attendance and engagement for an in-person Canadian Ophthalmological Society (COS) annual meeting (2019) compared with a virtual COS annual meeting (2020). DESIGN: Retrospective case-control study of key event metrics of the 2019 and 2020 COS meetings as well as Twitter activity. METHODS: Key annual meeting metrics were collected retrospectively for 2020 virtual meeting and compared with the most recent in-person annual meeting cohort from 2019. Metrics collected included attendance by ophthalmology specialist, geographic distribution of attendees, postevent survey rate, and social media engagement (Twitter). RESULTS: Overall, there was a 7% (n = 60) increase in the number of registrants between 2019 and 2020. The largest change noted was the increase in registrants from British Columbia (n = 78). More ophthalmologists registered for the 2020 meeting than for 2019 meeting (627 versus 592). Of those who registered for the meeting, meeting participation (defined as checking in for the 2019 and logging in for the 2020 meetings) increased from 70% in 2019 to 79% in 2020. There was a 158% (n = 15 000) increase in tweet impressions in 2020 compared with 2019. CONCLUSION: The first COS virtual meeting attracted more participants and was available to a geographically wider audience. Indeed, more professionals from provinces that are geographically further from the traditional COS meeting locations were able to participate in the event. Meeting engagement on a social media platform increased in the virtual meeting in 2020 relative to the in-person meeting in 2019, and possible enablers for increased engagement should be sought and incorporated into future meetings.

Probing mechanisms and improving management of glaucoma following Boston keratoprosthesis surgery.

ENGLISH SUMMARY: Corneal blindness is a leading cause of visual impairment worldwide. The most common treatment is to replace the diseased cornea by standard corneal transplantation. In eyes at high risk of graft failure, the Boston keratoprosthesis type 1 (KPro) can be used to restore vision and is currently the most frequently used artificial cornea in the world. However, glaucoma is a well-known complication of KPro surgery and is the most important threat to vision in KPro-implanted eyes (paper I). This chronic disease is influenced by elevated intraocular pressure (IOP) and damages the optic nerve, leading to progressive vision loss. In KPro patients, glaucoma is highly prevalent and extremely challenging to manage, yet its exact cause remains unknown. The overall purpose of this PhD Thesis (Geoffrion, 2021) was to better understand the mechanisms and how to improve management of glaucoma after KPro implantation. The approaches used in this thesis included investigating one of the largest KPro patient cohorts in North America, with a total of 157 operated patients at that time, as well as studying KPro surgery and outcomes in mice. The first objective was to identify risk factors for glaucoma development and progression after KPro implantation (paper II). Multivariate logistic regression revealed that high preoperative IOP signals a higher risk for both glaucoma development and progression. Stromal and endothelial corneal disorders were less associated with glaucoma progression, while autoimmune and ocular surface diseases precipitated glaucoma development. Second, there is no objective evidence that indicates the best order for glaucoma surgeries and KPro implantation. By comparing medical and surgical management in KPro eyes with either preexisting or de novo glaucoma (paper III), we showed that glaucoma surgery may be performed before or at the time of KPro in eyes with preexisting glaucoma to limit progression without increasing complications. In eyes with de novo glaucoma, glaucoma surgery did not increase complications compared with medications. Third, among glaucoma surgery interventions, the two most frequently implanted glaucoma drainage devices were compared in KPro patients (paper IV). Compared with the Ahmed glaucoma valve, the Baerveldt glaucoma implant was associated with lower failure rates, without increased postoperative complications. Fourth, even with aggressive management, many KPro patients suffer from progressive optic nerve damage, sometimes despite normal IOP. Inflammatory cytokines play an important role in glaucomatous optic neuropathy, but their role in KPro-associated glaucoma is still unknown. By analysing tear fluid of KPro patients by multiplex bead immunoassay (paper V), we identified that cytokines TNF-a, IL-1b, FGF-basic and IFN-g were elevated in KPro patients with glaucoma compared to those without. These cytokines correlated with optic nerve excavation and IOP. For the first time in humans, these results concorded with the elevations of TNF-a and IL-1b documented in the mouse KPro model. Ocular surface inflammation may thus reflect the inflammatory processes that perpetuate glaucoma damage years after KPro surgery. Fifth, we determined that miniaturized mouse KPro implantation requires extensive practice to be used as a reproducible model of glaucoma post-KPro (paper VI). KPro animal models with larger eyes and a full-thickness, 360-degree corneal excision should be prioritized to best validate human outcomes. In conclusion, glaucoma in KPro eyes is a long-lasting and multifactorial process. Most probable mechanisms combine IOP-independent inflammation mediated by TNF-a and IL-1b that prolong glaucoma damage, together with post-surgical angle closure elevating the IOP. Altogether, our results inform glaucoma risk profiling of transplant recipients, improvement of surgical management of KPro patients with glaucoma and development of targeted treatments to minimize glaucomatous damage after KPro. Ultimately, this work has the potential to preserve the vision of thousands of patients who undergo KPro surgery every year worldwide and to provide insight for the role of inflammation in other diseases involving neuronal damage. RÉSUMÉ (FRENCH SUMMARY): La cécité cornéenne est l'une des causes les plus importantes de déficience visuelle dans le monde. Le traitement usuel est de remplacer la cornée malade par une greffe de cornée traditionnelle. Dans les yeux à haut risque d'échec de greffe, la kératoprothèse de Boston de type 1 (KPro) peut rétablir la vision et est la cornée artificielle la plus utilisée au monde. Cependant, le glaucome est une complication importante de la KPro (papier I). Cette maladie chronique est influencée par une pression intraoculaire (PIO) élevée et endommage le nerf optique, menant à une perte de vision. Chez les patients avec KPro, le glaucome est fréquent et difficile à contrôler, mais sa cause exacte demeure inconnue. L'objectif principal de cette thèse est de découvrir les mécanismes et d'optimiser la prise en charge du glaucome après l'implantation de la KPro. Pour ce faire, nous avons investigué l'une des plus grandes cohortes de patients KPro en Amérique du Nord avec un total de 157 patients, ainsi qu'un groupe de souris ayant reçu une implantation de kératoprothèse. Le premier but était d'identifier les facteurs de risque pour le développement et la progression du glaucome après la KPro (papier II). Par régression logistique multivariée, nous avons démontré qu'une PIO préopératoire élevée mène à un plus grand risque de développement et de progression du glaucome. Les maladies cornéennes stromales ou endothéliales sont moins associées à une progression, alors que les maladies autoimmunes ou de la surface oculaire précipitent le développement du glaucome. Deuxièmement, il n'existe aucune donnée objective pour indiquer le meilleur ordre des chirurgies de glaucome et de KPro. En comparant les traitements médicaux et chirurgicaux des yeux KPro avec glaucome (papier III), nous avons démontré que les chirurgies de glaucome peuvent limiter la progression en étant effectuées avant ou pendant l'implantation de KPro dans les yeux avec glaucome préexistant, sans augmenter les complications. Dans le glaucome de novo, les chirurgies de glaucome n'augmentent pas les complications en comparaison aux médicaments. Troisièmement, les deux implants de glaucome les plus communs ont été étudiés chez les patients KPro (papier IV). Comparé à la valve Ahmed, l'implant Baerveldt est associé à des taux d'échec plus bas, sans augmentation des complications. Quatrièmement, même avec une prise en charge agressive, plusieurs patients KPro souffrent de glaucome qui progresse, parfois sans PIO élevée. Les cytokines inflammatoires jouent un rôle dans la pathophysiologie du glaucome, mais leur rôle dans le glaucome associé à la KPro est inconnu. En analysant les larmes de patients KPro (papier V), nous avons identifié que les cytokines TNF-a, IL-1b, FGF-basic et IFN-g sont élevées chez les patients KPro avec glaucome comparé à ceux sans glaucome. Ces cytokines corrèlent avec l'excavation du nerf optique et la PIO. Pour la première fois chez les humains, ces résultats concordent avec les niveaux élevés de TNF-a et IL-1b documentés dans le modèle murin de KPro. L'inflammation de la surface oculaire pourrait donc refléter les processus inflammatoires qui perpétuent le dommage glaucomateux. Cinquièmement, nous avons déterminé que l'implantation de la KPro miniature chez la souris requiert beaucoup de pratique pour être utilisé comme modèle de glaucome post-KPro (papier VI). Des modèles animaux avec des yeux plus larges et une excision cornéenne de pleine épaisseur sur 360 degrés devraient être priorisés pour valider les résultats chez l'humain. En conclusion, le glaucome associé à la KPro est un processus multifactoriel qui persiste à long terme. Les mécanismes probables combinent l'inflammation médiée par TNF-a et IL-1b et une fermeture de l'angle qui augmente la PIO. Nos résultats contribuent à établir les facteurs de risque de glaucome pour les receveurs de KPro, à améliorer leur prise en charge et à développer des thérapies ciblées. Ce travail a le potentiel de préserver la vision de milliers de patients recevant une KPro chaque année dans le monde et d'aider à mieux comprendre le rôle de l'inflammation dans d'autres maladies avec atteinte neuronale.

Hypo-osmolar accelerated corneal crosslinking on resultant sub-400 µm topography-guided excimer regularized keratoconus corneas.

PURPOSE: To investigate the efficacy and safety of phototherapeutic keratectomy (PTK) with topography-guided photorefractive keratectomy (T-PRK) corneal regularization followed by sequential hypo-osmolar riboflavin accelerated corneal crosslinking (CXL) in keratoconic (KC) eyes with <400 µm stromal bed thickness after excimer ablation. SETTING: Multisurgeon multicenter standardized protocol practice. DESIGN: Retrospective multicenter case series. METHODS: This study included progressive KC eyes that underwent PTK and T-PRK combined with accelerated CXL and had a corneal stromal bed thickness of <400 µm after excimer ablation before administration of hypo-osmolar riboflavin. Demographics and clinical measures were reviewed at baseline and every follow-up visit. RESULTS: 61 consecutive eyes had a mean corneal stromal bed thickness of 367 ± 21 µm after excimer laser normalization. Postoperatively, uncorrected distance visual acuity (UDVA) improved by 0.29 logMAR ( P < .0001), corrected distance visual acuity (CDVA) improved by 0.07 logMAR ( P = .0012), and maximum keratometry (Kmax) decreased by 4.67 diopters ( P < .0001). The safety index was favorable (1.29 ± 0.56), with stable manifest astigmatism, Kmax, and pachymetry at 12 months. 2 eyes (3%) showed evidence of keratometric progression on topography. CONCLUSIONS: In KC corneas thinner than 400 µm after excimer ablation, PTK epithelial removal followed by T-PRK and hypo-osmolar accelerated CXL decreases manifest astigmatism and Kmax, improves UDVA and CDVA, and halted disease progression in 97% of eyes at 12 months. These outcomes are comparable with thicker ablated corneas not requiring hypo-osmolar stromal swelling.

Mid-term prognosis of type I Boston keratoprosthesis reimplantation.

AIM: To examine the mid-term visual and anatomical prognosis of patients who require reimplantation of a second Boston keratoprosthesis type 1 (B-KPro). METHODS: Retrospective observational case series of 122 patients (141 eyes) who received a B-KPro at a single institution were reviewed. Eyes that underwent a second B-KPro were included in the study. Primary endpoints were B-KPro retention, final visual acuity 20/200 and loss of light perception. Secondary endpoints included the occurrence of postoperative complications. RESULTS: Seventeen eyes (12%) required a B-KPro reimplantation. Corneal melt was the most common indication for replacement (88%). Mean follow-up time after the second B-KPro was 4.4±2.1 years. The Kaplan-Meier analysis estimated the second B-KPro retention rate at 79% over 8 years. Retroprosthetic membrane (RPM, 53%) was the most common complication. Forty-one per cent of the eyes suffered from corneal melt following their second B-KPro. One year after the second B-KPro, 47% of the patients retained a vision 20/200. Seven eyes (41.2%) lost light perception, which was secondary to an inoperable retinal detachment in five cases. Four eyes (24%) developed phthisis following inoperable retinal detachment (n=3) or endophthalmitis (n=1). CONCLUSION: B-KPro reimplantation is a potentially sight- and globe-saving procedure for eyes with B-KPro failure, but the prognosis is guarded. B-KPro reimplantation can salvage ambulatory vision in a third of patients while another third of patients progress to loss of light perception. RPM and retinal detachment were important obstacles to visual rehabilitation while recurrent corneal melt was responsible for most cases of anatomical failure.

Cost-effectiveness analysis : fibrin glue versus sutures for conjonctival fixation during pterygion surgery.

OBJECTIVE: Pterygium surgery requires the removal of pterygium tissue and repair of the conjunctiva with either sutures or fibrin glue. The literature suggests that the cost of fibrin glue could be compensated by reducing procedure time and be more cost-effective. However, to our knowledge, no formal studies have examined this hypothesis. METHOD: Retrospective chart review of patients who received pterygium surgery with only sutures between January 2008 and January 2010, and those whose surgeons used fibrin glue with or without sutures, between April 2017 and November 2018. Equipment cost, operating room (OR) maintenance, and surgeon's remuneration were compared between the groups. RESULTS: A total of 164 eyes were included. Three different procedure methods were noted: use of sutures only, combination of sutures and fibrin glue, or application of fibrin glue alone. The equipment cost was $97, $169.50, and $152.10 for the suture group, dual method, and fibrin-only method. Average procedure time was 35.8 minutes for the sutures-only group, 21.1 minutes for the dual method, and 25.6 minutes for the method using only glue. OR maintenance cost was $51.20 CAD per minute. The total cost for the method using only sutures was $2528.90, whereas the average cost for the protocol using only fibrin glue was $2063. CONCLUSION: Although using fibrin glue for conjunctival graft adhesion increases the equipment cost, it significantly decreases procedure time, which allows a reduction of the total surgery cost. Therefore, fibrin glue is a more cost-effective approach than sutures alone.

Long-term outcomes following primary versus secondary Boston keratoprosthesis type 1 implantation.

BACKGROUND/AIMS: To compare long-term outcomes of primary versus secondary (postgraft failure) Boston keratoprosthesis type 1 (KPro) implantation. METHODS: Medical records of patients at the Centre hospitalier de l'Université de Montréal having undergone KPro implantation between 2008 and 2017 were reviewed and included if they had a preoperative Snellen best-corrected visual acuity (BCVA) of 20/100 or worse and a minimum of 5 years of follow-up. Eighty-two eyes were separated into two cohorts (40 primary, 42 secondary KPro) and BCVA, complications and device retention were evaluated between groups. RESULTS: BCVA improved from baseline in both groups at each year; this was significant at all five postoperative years in the primary group and the first 3 years in the secondary group (p<0.05). Mean BCVA was similar between groups at 5 years (logarithm of minimal angle resolution 1.3±0.8 in the primary group vs 1.5±0.8 p<0.05). Idiopathic vitritis, choroidal detachment and new glaucoma occurred more after primary KPro (n=7, 17.5% vs n=1, 2.4%; n=11, 27.5% vs n=3, 7.14% and n=14, 35% vs n=6, 14%, respectively; p<0.05). Primary KPro had lower retention (n=28, 70% vs n=38, 91%, p<0.05) at final follow-up. There was more aniridia in the primary group (n=19, 48% vs n=6, 14%, p<0.01). Within each group, 50% of removals occurred in aniridic eyes. CONCLUSION: Primary KPro yielded favourable long-term visual outcomes but had more complications and lower retention rates than secondary KPro, likely explained by preoperative indications. Primary device implantation represents a favourable option for patients for whom grafts are likely to fail.

Time to achieve best postoperative visual acuity following Boston keratoprosthesis surgery.

BACKGROUND/AIMS: To evaluate the time needed for patients with Boston type 1 keratoprosthesis (KPro) to reach their best-corrected visual acuity (BCVA) and all contributing factors. METHODS: We retrospectively reviewed 137 consecutive eyes from 118 patients, measured how long they needed to reach their BCVA and looked at factors that might affect this time duration including patient demographics, ocular comorbidities and postoperative complications. RESULTS: The mean follow-up was 5.49 years. The median time to BCVA postoperatively was 6 months, with 47% of patients achieving their BCVA by 3 months. The mean best achieved logMAR visual acuity was 0.71, representing a gain of 6 lines on the Snellen visual acuity chart. Postoperative glaucoma, retroprosthetic membrane (RPM) and endophthalmitis prolonged this duration. We found no correlation between the following factors and time to BCVA: gender, age, indication for KPro surgery, primary versus secondary KPro, number of previous penetrating keratoplasties, previous retinal surgery, intraoperative anterior vitrectomy and preoperative glaucoma. CONCLUSION: In our retrospective cohort, the majority of subjects reached their BCVA between 3 and 6 months after KPro implantation. This duration was significantly prolonged by the development of postoperative glaucoma, RPM and endophthalmitis.

Frozen versus fresh corneal graft carriers in Boston keratoprosthesis surgery: 10-year outcomes.

OBJECTIVE: To compare 10-year clinical outcomes of frozen versus fresh corneal graft carriers for the Boston Keratoprosthesis type 1 (KPro). DESIGN: Prospective, non-masked randomized controlled trial. PARTICIPANTS: Nineteen eyes of 19 patients having undergone Boston KPro type 1 implantation using a fresh or frozen graft carrier. METHODS: All patients that underwent Boston KPro type 1 implantation by a single experienced surgeon using an allograft carrier between October 2008 and March 2010 at the Centre Hospitalier de l'Université de Montréal were considered. Patients were excluded if they had a history of prior KPro implantation in the same eye. A subset of the patient cohort enrolled in the initial study protocol of 24 months continued follow-up to 120 months. Participants were randomized to receive either a fresh or frozen corneal graft carrier depending on tissue availability from the eye bank on the day of KPro implantation. RESULTS: Nineteen eyes of 19 patients were included, with 11 in the fresh group and 8 in the frozen group. At 10 years, in the fresh and frozen groups respectively, device retention was 91% and 75%; mean best corrected visual acuity increased from counting fingers preoperatively to 20/300 and 20/125; and incidence of complications per patient was 2.36 and 2.37. There were no statistically significant differences between groups for any of these outcome measures (p > 0.05 for all analyses). CONCLUSIONS: Fresh and frozen corneal graft carriers offer similar clinical outcomes for KPro implantation in terms of device retention, change in visual acuity, and rate of complications at 10 years.

Assessment of the Role and Timing of Glaucoma Surgery in Boston Keratoprosthesis Type 1 Patients.

PURPOSE: To determine the role and optimal timing of glaucoma surgery in relation to Boston keratoprosthesis type 1 (KPro) implantation. DESIGN: Retrospective, comparative, nonrandomized clinical study. METHODS: Single-center study of a total of 100 eyes (100 patients) implanted with a KPro between 2008 and 2017, and diagnosed with glaucoma before or after KPro. Patients were separated into 2 groups: those with preexisting glaucoma and those who developed de novo glaucoma after KPro. Groups were then divided based on whether patients were medically or surgically managed. Glaucoma surgery included glaucoma drainage device (GDD) implantation, trabeculectomy, and cyclophotocoagulation (CPC). Primary outcomes included best-corrected visual acuity (BCVA), glaucoma progression, and complications. Differences in outcomes were compared using parametric and nonparametric tests, as well as log-rank test to compare time-to-outcome events. RESULTS: Among 72 eyes with preexisting glaucoma, 27 (38%) had glaucoma surgery before KPro (18 GDD), whereas 45 (62%) were medically managed only. Among the latter, 19 (42%) needed glaucoma surgery post-KPro (16 GDD). Among 28 eyes with de novo glaucoma, 12 (43%) had glaucoma surgery post-KPro (9 GDD). For eyes with preexisting glaucoma, glaucoma progression was greater with glaucoma surgery performed post-KPro (100%) compared with pre-KPro (74%, P = .016) and to medical management (54%, P = .002). No increase in complications were observed with glaucoma surgery compared to medications only (P > .05), whereas fewer eyes maintained a BCVA of 20/200 or better over time with medical management (P = .013). Eyes with de novo glaucoma had similar progression, BCVA, and complications between medical and surgical care (P > .05). CONCLUSIONS: Glaucoma surgery should be performed before or at the same time as KPro implantation in eyes with preexisting glaucoma. Complication rates are not increased when glaucoma surgery is performed in KPro eyes with either preexisting or de novo glaucoma. To ensure optimal glaucoma control, glaucoma surgery should be performed as early as possible in KPro eyes with good visual potential.

Comparison of outcomes in patients with and without soft contact lens wear following Boston keratoprosthesis type 1.

OBJECTIVE: To compare the rate of long-term complications in Boston keratoprosthesis type 1 (KPro) patients with and without soft contact lens wear (SCL). METHODS: A chart review was performed on patients who underwent KPro type 1 surgery from January 2008 to June 2018 performed by a single surgeon at the University of Montreal Hospital Centre. Ninety-nine KPro patients (114 eyes) were separated into group 1 (patients with SCL) and group 2 (patients without SCL) at 1 and 5 years. Survival at 1- and 5-year follow-ups is defined as the absence of complications: corneal melts, leaks, retroprosthetic membrane, infectious keratitis, sterile vitritis, endophthalmitis, and KPro extrusion. RESULTS: The mean SCL retention duration was 3.17 years. Overall, the survival distribution of both groups was not significantly different. At 1 year, group 1 achieved a higher KPro survival rate (75.11%) than group 2 (61.39%; p = 0.248). At 5 years, group 1 had a lower survival rate (49.11%) than group 2 (65.22%; p = 0.127). Although not statistically significant, the percentage of individual complications was higher in group 2 at 1 year (p = 0.3040) and lower in group 2 at 5 years (p = 0.6089) compared with group 1. CONCLUSION: The mean SCL retention duration in our study was longer than previously reported. Long-term SCL does not significantly decrease the rate of complications. A prospective study is warranted to further examine the outcomes of long-term SCL wear.

Vitreoretinal Complications in Boston Keratoprosthesis Type 1.

PURPOSE: To evaluate the incidence of vitreoretinal complications, treatment modalities, and the visual outcomes in a large cohort of eyes that underwent Boston Keratoprosthesis (KPro) implantation. DESIGN: Retrospective, interventional case series. METHODS: 132 eyes of 114 patients who underwent KPro implantation at the Centre Hospitalier de l'Université de Montréal from 2008 to 2017 were included with at least 1 year follow-up. Charts were reviewed and data was collected, including demographics, initial corneal indication for surgery, posterior segment complications, preoperative and postoperative visual acuity. RESULTS: Mean follow-up was 68.2 months and 61.4% of eyes developed postoperative vitreoretinal complications (VRC). The most common VRC was RPM formation (38.6%, n=51) followed by RD (15.2%, n=20), CME (12.1%, n=16), ERM (9.8%, n=13), endophthalmitis (9.1%, n=12), sterile vitritis (7.6%, n=10), vitreous hemorrhage (6.8%, n=9), choroidal detachment (3.0%, n=4) and central retinal vein occlusion (0.7%, n=1). BCVA improved in the no VRC group from 1.74 ± 0.33 logMAR to 1.33±0.83 logMAR and in the VRC group from 1.74±0.36 logMAR to 1.52±0.83 logMAR, without any statistically significant intergroup differences (p=0.231). RD was the only significant complication associated with poorer visual outcomes (p=0.001). CONCLUSION: Potentially blinding secondary complications occur in the majority of patients and frequent monitoring is necessary, specifically in the early and intermediate postoperative periods. This study evidenced significant improvements in visual outcomes of KPro eyes, including those that developed postoperative vitreoretinal complications.

Perspectives for preclinical mouse models of glaucoma after Boston keratoprosthesis type 1.

Animal models of the Boston keratoprosthesis type 1 (KPro) are needed to study glaucoma damage after KPro implantation to control for confounding comorbidities common in human KPro recipients. The purpose of this study was to determine the feasibility of establishing a reproducible mouse model of glaucoma after KPro surgery, specifically that of a miniaturized mouse model of KPro (mKPro). In the present study, a total of 20 corneas of donor C57BL/6 mice (n = 10) were implanted in one eye of each recipient BALB/C mouse (n = 20), assembled as part of the mKPro, either with or without intraoperative lensectomy. Main feasibility outcomes consisted in incidence rates of loss of tone, capsule nicking, and lens extrusion, as well as acquisition of posterior segment optical coherence tomography (OCT) images. With lensectomy (n = 10), loss of ocular tone and retinal detachment occurred in 100% of mice. Without lensectomy (n = 10), capsule nicking and opening, as well as lens extrusion, occurred in 80% of mice. Causes of these complications included the large proportion of intraocular volume occupied by the lens, the shallow anterior chamber, and thus the lack of available intraocular volume to implant the KPro if the lens remains present. Successful mouse KPro surgery may require a great deal of practice to be useful as a reproducible model. Animal KPro models ought to be pursued further by research teams in future studies.