Keratoplasty in the United States

Current Scenario and Future Perspectives of Porcine Corneal Xenotransplantation

ABSTRACT

Corneal diseases represent a significant cause of blindness worldwide, with corneal transplantation being an effective treatment to prevent vision loss. Despite substantial advances in transplantation techniques, the demand for donor corneas exceeds the available supply, particularly in developing countries. Cornea xenotransplantation has emerged as a promising strategy to address the worldwide scarcity, notably using porcine corneas. In addition to the inherent immune privilege of the cornea, the low cost of porcine breeding and the anatomical and physiological similarities between humans and pigs have made porcine corneas a viable alternative. Nonetheless, ethical concerns, specifically the risk of xenozoonotic transmission and the necessity for stringent biosafety measures, remain significant obstacles. Moreover, the success of xenotransplantation is compromised by innate and adaptive immune responses, which requires meticulous consideration and further studies. Despite these challenges, recent breakthroughs have further contributed to reducing immunogenicity while preserving the corneal architecture. Advances in genetic engineering, such as the use of CRISPR-Cas9 to eliminate critical porcine antigens, have shown promise for mitigating immune reactions. Additionally, new immunosuppressive protocols, such as have techniques like decellularization and the use of porcine-derived acellular matrices, have greatly increased graft survival in preclinical models. Future research must focus on refining immunomodulatory strategies and improving graft preparation techniques to ensure the long-term survival and safety of porcine corneal xenotransplantation in clinical trials in humans.

Predictors of Health Care Disparities in Fuchs Dystrophy Treatment Using the IRIS Registry

PURPOSE

To evaluate associations between sociodemographic factors and surgical management in patients with Fuchs Endothelial Corneal Dystrophy (FECD).

METHODS

Patients >40 years old with FECD diagnosis and subsequent corneal edema between 2007 and 2020 were identified from the American Academy of Ophthalmology IRIS Registry (Intelligent Research in Sight). Multivariable Cox proportional hazards models were fit to examine the relationships between sociodemographic variables and time from FECD diagnosis to penetrating keratoplasty (PK) and endothelial keratoplasty (EK)/PK.

RESULTS

A total of 20,366 patients with FECD diagnosis and subsequent corneal edema were identified. Of the 4313 patients who underwent either EK or PK (any surgery), 374 patients underwent PK, 4037 underwent EK, and 98 received both interventions. After controlling for age, sex, and insurance status, Black or African American patients were 1.48 times as likely (hazard ratio 1.48, 95% confidence intervals (CI), 1.06-2.07) to undergo PK as compared with White patients and were less likely to receive any surgery (HR 0.83, 95% CI, 0.74-0.94). Asian patients were less likely (HR: 0.57, 95% CI, 0.43-0.75) to undergo any surgery. Female patients were more likely to undergo PK and less likely to undergo any surgery than male patients, and older patients were less likely to undergo any surgery with each increasing decade of life. There were no significant differences when stratified by insurance type.

CONCLUSIONS

Age, sex, race and ethnicity, and insurance type are associated with varying rates of different surgical interventions for FECD.

Corneal Transplantation in Australia Over 29 Years: A Retrospective Analysis of Medicare Data from 1994 to 2022

PURPOSE

We aim to report the frequency and distribution of corneal transplantation, by age, sex, and state/territory, in Australia over a > 25-year period from 1994 to 2022, including during COVID-19 lockdowns.

METHODS

Using data from Medicare, Australia's Government-funded health insurance scheme, we retrospectively analysed corneal transplants performed from January 1994 to December 2022.

RESULTS

From 1994 to 2022, there were 27,536 corneal transplantation services processed by Medicare. Transplants tended to be more common in males in younger age groups (67.7% male in 15-24-year-olds), and in females in older age groups (59.2% female in 75-84-year-olds). Most transplants were performed in New South Wales (9,438 services, 34.3%), Queensland (7,722, 28.0%), and Victoria (5,209, 18.9%). Annual corneal transplantation rates in Australia tended to decrease from 1994 to 2006 (lowest rate during study period), falling by 31%, and then increased by 81%, from 2006 to 2022 (end of study period). Annual repeat corneal transplantation rates (i.e. second and subsequent transplants) increased from 2004 to 2022, rising 301%. During Australia's nationwide 2020 COVID-19 lockdown (from March to April), monthly transplantation rates decreased by 31%.

CONCLUSION

We performed a longitudinal analysis of corneal transplantation in Australia using a comprehensive, routinely collected, population-based data source. Prior studies examining corneal transplantation have interrogated data from the Australian Corneal Graft Registry, which relies on voluntary reporting. Corneal transplantation rates have increased during the last 15 years, likely as new corneal transplant techniques have evolved, with increasing demand for corneal donation and eye banking services.

Five Year Review of All Examined Corneal Tissue in a Tertiary Eye Care Center: Demographics and Surgical Indications

BACKGROUND

Corneal pathologies are among the most common reversible sight-threatening diseases globally. As such, corneal tissue transplantation (keratoplasty) techniques are evolving over time depending on the prevalence of different pathologies in each geographical area. We aim to provide a baseline information on the common keratoplasty procedures performed in our area in relation to prevalent corneal pathologies and to analyze common corneal surgical practice trends in our area. Other types of corneal tissue sampling (superficial keratectomy and corneal biopsy) indicated for therapeutic and diagnostic purposes are also included.

METHODS

This is a retrospective cohort study. All corneal tissue specimens, including those harvested for both therapeutic and diagnostic purposes, received for histopathological examination at our center over a period of 5 years were collected along with the respective demographic data, clinical diagnoses, and surgical indications. Descriptive analysis was used to elucidate important conclusions, and comparative analysis was used to highlight differences between different types of keratoplasty specimens in relation to the surgical indications.

RESULTS

A total of 347 patients' corneal tissue specimens were included. Males accounted for 52.45%. Full-thickness corneal buttons were the most common (n = 172), followed by partial-thickness corneal specimens (n = 75), and Descemet's membrane and endothelium samples (n = 63). Top surgical indications for keratoplasty were keratoconus (n = 149), followed by bullous keratopathy (n = 61), failed previous keratoplasty (n = 47), corneal ulceration (n = 33) and corneal dystrophies (n = 22). Patients undergoing penetrating or lamellar keratoplasty were significantly younger (p < 0.001). Superficial keratectomy and corneal biopsy for keratitis were significantly more common among male patients (p = 0.041), while failed endothelial keratoplasty was observed more among females (p = 0.026).

CONCLUSION

Our findings highlight the evolving landscape of corneal transplantation and the importance of tailoring surgical approaches to address the specific needs and risk profiles in different populations. Keratoconus is a leading cause for corneal grafting and seems to constitute a major treatable and visually disabling disease in Saudi Arabia, thus may require further screening and genetic studies with consideration for preventive measures.

Intraoperative Optical Coherence Tomography (OCT)-Guided Femtosecond Laser-Assisted Descemet Membrane Endothelial Keratoplasty (iFAD)

We describe retrospectively the indications and outcomes of nine patients who present with varying degrees of deep posterior stromal scarring or endothelial failure following deep anterior lamellar keratoplasty (DALK). These patients underwent a surgical strategy coined Intraoperative Optical Coherence Tomography Guided Femtosecond Laser-Assisted Descemet Membrane Endothelial Keratoplasty (iFAD). This strategy can be used to address suboptimal visual outcomes following primary DALK. Patients undergoing iFAD first had femtosecond laser-assisted trephination of the underlying posterior lamella using the liquid keratoplasty system on the Femto LDV Z8 platform (Zeimer Ophthalmic Systems AG, Port, Switzerland). A Descemet Membrane Endothelial Keratoplasty (DMEK) graft was subsequently transplanted in place of the removed lamella. Out of nine cases, major indications for seven included post-infective, blepharokeratoconjunctivitis (BKC) and deep stromal scarring related to stromal dystrophy. The remaining two had endothelial failure following primary DALK. The main benefits of this surgical approach are (1) Utilization of integrated real-time iOCT on the femtosecond laser platform allows for precise calibration of a wide range of vertical posterior trephination depths (96-329 microns) from the endothelial surface. (2) Femtosecond laser trephination utilizing a non-applanation liquid interface preserves trephination geometries and maximises precision-based surgical outcomes. (3) iFAD is a viable and straightforward technique for surgeons addressing patients who might otherwise require complex surgery to address residual deep stromal scars post-DALK.

Five years of emergency keratoplasty at a tertiary eye hospital

PURPOSE

The aim of this study is to present the results of patients who underwent emergency keratoplasty for tectonic or therapeutic reasons.

METHODS

Medical records of 33 patients who underwent tectonic or therapeutic keratoplasty at Ege University Department of Ophthalmology between January 2019 and January 2024 were retrospectively evaluated. Demographic characteristics, ocular and systemic findings, indications of keratoplasty, size of grafts, need for re-keratoplasty, preoperative treatment modalities, need for additional surgical interventions, and prognosis of the patients were investigated.

RESULTS

During this period, 450 penetrating keratoplasty (PK) surgeries were performed and 34 (7.55%) were emergency PK (34 eyes of 33 patients). The mean age of the patients was 65.30 ± 15.40 (40-91). Female to male ratio was 18/15. 17 (50.00%) emergency PKs were performed for tectonic and 17 (50.00%) were performed for therapeutic purposes. Mean follow up time was 24.85 ± 26.62 (2-120) months. A total of 20 (58.82%) eyes required additional surgery, 9 (26.47%) of which required re-keratoplasty with different indications during follow-up. Graft rejection or failure developed in 17 (50.00%) of the eyes in an average of 12.05 (1-45) months. Evisceration was needed in 2 (5.88%) eyes.

CONCLUSION

Despite limited access to donor cornea and high complication rate, emergency keratoplasty is one of the most important options that retain ocular integrity in the treatment of corneal infections and non-traumatic corneal perforations unresponsive to conventional treatment.

A bibliometric and citation network analysis of crosslinking

Purpose: Research on crosslinking has focused mainly on trying to slow the progression of keratoconus. The objective of this bibliometric analysis is to determine the relationships between the different publications and authors. As well as to identify the different areas of research on crosslinking. Methods: Web of Science (WOS) was the database for the search of publications for the period 1972 to December 2023, using the terms: crosslinking, cross-linking, ocular, vision, visual, cornea, ectasia AND Keratoconus. The analysis of the publication was performed using the CitNetExplorer, VOSviewer and CiteSpace software. Results: 7161 publications and 59415 citation networks were found. The year with the most publications is 2021, a total of 571 (7.97%) publications and 135 citation networks. The most cited publication was "Riboflavin/ultraviolet-a-induced collagen crosslinking for the treatment of keratoconus" published by Wollensak et al. in 2003, with a citation index of 1780. Using the Clustering function, five groups were found that cover the main research areas in this field: keratoconus, corneal transplantation, cataracts, corneal inflammation and axial growth. Conclusion: The treatment of keratoconus continues to be the topic of interest in this area of research. However, in recent years there has been an increase in research on how crosslinking helps to slow down axial growth.

Changing indications for and trends of keratoplasty in a tertiary comprehensive hospital in northern part of China from 2002 to 2021: a 20-year review

OBJECTIVE

To investigate indications and surgical procedures of keratoplasty in a tertiary comprehensive hospital in northern part of China over a 20-year period.

METHODS

All patients undergoing keratoplasty between January 1, 2002 to December 31, 2021 in a tertiary comprehensive hospital in northern part of China were retrospectively reviewed. The annual proportion of keratoplasty indications and surgical procedures was recorded and analyzed.

RESULTS

A total of 8266 keratoplasty procedures were included. Leading indications were keratoleukoma (n = 2108, 25.50%), followed by regraft (n = 1453 ,17.58%), corneal endothelial dysfunction (n = 1085, 13.13%), and keratoconus (n = 922,11.15%). A decreasing trend was observed for keratoleukoma (P < 0.01) and an increasing trend for corneal endothelial dysfunction (P < 0.01), regraft (P = 0.012), corneal limbal dermoids (P < 0.01) and congenital corneal opacity (P < 0.01). From 2002 to 2021, the proportion of penetrating keratoplasty (PK) had decreased from 73.95% (2002 to 2006) to 53.49% (2017 to 2021). On contrary, anterior lamellar keratoplasty (ALK) (459-705, 26.05-31.96%, P = 0.034) and endothelial keratoplasty (EK) (0-321, 0.00-14.55%, P < 0.01) became more prevalent from 2002 to 2021. For cases with corneal endothelial dysfunction, EK became the preferred technique (74.72%) in the recent 5 years.

CONCLUSION

Over the past 20 years, keratoleukoma and regraft have been the leading indications for keratoplasty. A noticeable shift in surgical preference from PK to DSAEK and ALK is evident, with key indications for keratoplasty including keratoleukoma, regraft, limbal dermoids, endothelial dysfunction, and keratoconus, respectively.

Evolving indications and surgical techniques for corneal transplantation at a tertiary eye care center in southern China

BACKGROUND

This retrospective study aimed to analyze the evolution of primary indications and surgical techniques for corneal transplantation in Southern China from 2012 to 2021.

METHODS

The medical charts of all patients who underwent keratoplasty between January 2012 and December 2021 at Zhongshan Ophthalmic Centre, Sun Yat-Sen University, Guangzhou, Southern China were reviewed. We collected and analyzed the primary indications for corneal transplantation and the surgical methods used in each keratoplasty.

RESULTS

The total number of corneal transplantations was 7,286 during this decade, increasing from 210 cases in 2012 to 1054 cases in 2021. The primary indications for keratoplasty included acquired nontraumatic corneal diseases (56.2%), congenital corneal abnormalities (16.4%), acquired traumatic corneal diseases (14.0%), and regraft (13.4%). Infectious keratitis was the leading indication among all keratoplasties (18.5%), followed by regraft (13.4%). Over the decade, the proportion of infectious keratitis gradually decreased (P = 0.013), while the proportion of regraft increased (P = 0.019). The predominant surgical technique was penetrating keratoplasty (PKP), accounting for 56.7%. However, the number of deep anterior lamellar keratoplasty (DALK) and endothelial keratoplasty (EK) significantly increased from 2012 to 2021 (P = 0.007 and P = 0.002).

CONCLUSIONS

The annual number of corneal transplants significantly increased from 2012 to 2021. In the past decade, infectious keratitis and regraft have become the leading primary indications for corneal transplantation. Although the use of customized lamellar techniques has dramatically increased, PKP remains the predominant surgical technique for keratoplasty.

Multi-dataset identification of innovative feature genes and molecular mechanisms in keratoconus

This study aimed to identify feature genes and explore the molecular mechanisms of keratoconus (KC). We downloaded data files from NCBI GEO public database. The Limma package was used for differential expression analysis of gene profiles. Lasso regression was used to identify the feature genes. The CIBERSORT algorithm was used to infer the proportion of immune-infiltrating cells and analyse the correlation between gene expression levels and immune cells. Related transcription factors and miRNAs of key genes were predicted using the Cistrome DB and Mircode databases. Analysis of expression differences in disease genes was based on the GeneCards database. The CMap was used to analyse targeted therapeutic drugs. IHC was performed to verify the expression levels of ATOH7 and MYRF in corneas. Exactly 593 upregulated and 473 downregulated genes were identified. Lasso regression analysis identified ATOH7, DBNDD1, RNF217-AS1, ARL11, MYRF and SNORA74B as feature genes for KC. All key genes were correlated with immune infiltration and the levels of activated memory CD4+ T cells and plasma cells were significantly increased. miRNA, IRF and STAT families were correlated to feature genes. The expression levels of key genes were significantly correlated to KC-related genes. Entinostat, ochratoxin-a, diphencyprone and GSK-3-inhibitor-II were predicted as potential KC medications. The expression of MYRF was significantly higher in the KC samples, contrary to the expression of ATOH7. KC is related to both immune infiltration and genetic factors. MYRF and ATOH7 were newly identified and verified feature genes of KC.

Andalusian Public Eye-Banks: a decade of continuous improvement

OBJECTIVES

To show donation data, number of keratoplasties and the changes in transplant indications and techniques that occurred in Andalusia in the period from 2013 to 2022.

MATERIALS AND METHODS

The present work is a retrospective and descriptive study that included all keratoplasties performed between January 2013 and December 2022 in Andalusia, as well as the evolution of the cornea donation and transplant activity of the public and private hospitals pertaining to the waiting list management system of the Public Health System of Andalusia. Transplants performed in private centers with corneas from outside Andalusia were excluded.

RESULTS

Cornea donation activity in Andalusia in the decade 2013-2022 has experienced a growth of more than 126%, while overall transplant activity has increased by 157% in public hospitals. Penetrating keratoplasty has decreased from 83% in 2013 to 43% in 2022, while lamellar techniques have increased from 17% to 57% in this same period. Since 2018, more lamellar transplants are performed than penetrating transplants. Regarding indications, endothelial conditions already represent the first cause of transplantation. In 2022 alone, the public Andalusian Eye Banks evaluated 1,054 corneas and prepared 281 endothelial grafts.

CONCLUSION

In the decade from 2013 to 2022 in Andalusia there has been an increase in donation activity and the number of keratoplasties. The public Eye Banks implementation in this period has played a key role in the widespread adoption of lamellar keratoplasty techniques and has enabled the transition to perform a greater number of lamellar keratoplasties compared to penetrating keratoplasty.

Outcomes of Corneal Transplantation for Herpetic Keratitis: A Narrative Review

Herpes simplex virus (HSV) is one of the most common etiologic agents of corneal disease and a significant cause of corneal blindness worldwide. Although most cases can be successfully managed with medical therapy, HSV keratitis associated with visually significant stromal scarring often requires corneal transplantation for visual rehabilitation. While penetrating keratoplasty (PK) represented the traditional keratoplasty technique, the past few decades have seen a shift towards lamellar keratoplasty procedures, including deep anterior lamellar keratoplasty and mushroom keratoplasty. This paper describes the current surgical techniques and perioperative antiviral prophylaxis regimen for herpetic keratitis and reviews their postoperative clinical outcomes.

Assessment of Corneal Graft Outcomes in a Murine Model of Endothelial Keratoplasty

Objectives: In this study, we establish a protocol for evaluating the outcomes of endothelial keratoplasty, including graft survival, rejection, or failure. Additionally, we also evaluate the alloimmune response in graft recipients. Methods: We performed EK using C57BL/6 (allogeneic) and BALB/c (syngeneic) as donors and BALB/c mice as recipients. Slit-lamp examination and optical coherence tomography were performed for clinical evaluations for 16 weeks post-procedure. Criteria for the assessment of corneal opacity were established and the animals were graded weekly. Additionally, we assessed corneal endothelial cell density by harvesting the corneas and staining with zonula occludens-1 (ZO-1). Lastly, lymph nodes were collected, and CD4+ T cells were MACS-sorted and co-cultured with syngeneic or allogeneic antigen-presenting cells (APCs) to assess the IFN-γ expression levels by alloreactive Th1 cells (ELISPOT) in response to the direct (donor) or indirect (host) pathways of sensitization. Results: We observed graft failure in four animals, including irreversible corneal opacity, graft detachment, and anterior synechiae in the first four weeks. The remaining animals were graded between 0 and 5 as per the established criteria. The total and graft corneal thickness and endothelial cell density progressively worsened with a higher grade of corneal opacity. The direct allosensitization of Th1 cells was significantly higher in mice with a higher grade of corneal opacity. At 16 weeks follow-up, the grafts remained stable with low opacity scores in syngeneic EK recipients; however, the opacity scores were higher and variable in allogeneic EK recipients. Conclusions: These findings establish a standardized protocol to assess the graft outcomes in a murine model of EK. Furthermore, we delineate the underlying immunological pathway that contributes to the immune-mediated rejection of grafts in this model.

Trends of Surgery, Patient, and Surgeon Characteristics for Corneal Transplants in the Medicare Population From 2011 to 2020

PURPOSE

The aim of this study was to describe recent trends in corneal transplants and patient and surgeon characteristics for corneal transplants that occurred in the Medicare population.

METHODS

This was a retrospective, cross-sectional study using Current Procedural Terminology codes. We identified Medicare Fee-For-Service (FFS) claims for different types of corneal transplant procedures performed on Medicare beneficiaries aged 65 years or older from 2011 to 2020. Number and types of corneal transplants performed each year and patient and surgeon demographics and characteristics were analyzed.

RESULTS

We analyzed 148,981 corneal transplants performed by 2972 surgeons within the study period. Most corneal transplants performed were endothelial keratoplasties (70.1%). Most patients were women (60.3%) and White (85.8%). 18.2% of patients lived in a rural area, whereas only 3.5% of transplants occurred in a rural area and 5% of surgeons practiced in a rural area. Male surgeons represented 77.8% of all surgeons and performed 84.9% of all corneal transplants in the study period. The proportion of corneal transplants performed by female surgeons gradually increased over time, from 12.1% in 2011 to 19.0% in 2020. The proportion of female surgeons also increased from 16.2% in 2011 to 23.8% in 2020. Most surgeons (67%) performed <6 corneal transplants per year.

CONCLUSIONS

Although the number of female corneal transplant surgeons has increased over time, women remain underrepresented in the surgical workforce. Further investigation should be conducted to identify the underlying reason and address the identified disparities within the landscape of corneal transplantation.

Descemet Membrane Endothelial Keratoplasty for Endothelial Failure in Primary Angle Closure Suspects

PURPOSE

To analyze the feasibility and outcome of Descemet membrane endothelial keratoplasty (DMEK) for treatment of endothelial failure in primary angle closure suspect (PACS) eyes.

METHODS

Retrospective, single-center case series of eyes treated by DMEK for endothelial failure caused by PACS. Main study parameters were success rate of DMEK, best-corrected visual acuity, anterior chamber depth, central corneal thickness, and endothelial cell density. Mean follow-up time was 16 ± 13 months.

RESULTS

Ten eyes of 9 patients receiving DMEK for the treatment of corneal endothelial failure because of PACS were included. Except for 2 eyes that had undergone cataract surgery, none of the eyes had previous ocular surgery. DMEK combined with cataract surgery was performed in 5 eyes, DMEK alone with second-step cataract surgery in 2 eyes. The eyes with corneal edema after cataract surgery received DMEK only. DMEK surgery was successful in nine out of 10 eyes, 1 patient required repeat DMEK because of primary graft failure. In the group of phakic eyes, mean preoperative internal anterior chamber depth was 1.74 ± 0.18 mm. In eyes with corneal edema, central corneal thickness was 849 ± 205 μm before DMEK surgery, and 517 ± 24 μm at the final postoperative visit (P = 0.002).

CONCLUSIONS

DMEK is a feasible option in eyes with endothelial failure because of primary angle closure. In case of advanced corneal edema, a second-step procedure (first DMEK, second cataract surgery) is a possible approach if visibility of the lens is too poor for simultaneous cataract surgery.

Design and Evaluation of an Eye Mountable AutoDALK Robot for Deep Anterior Lamellar Keratoplasty

Partial-thickness corneal transplants using a deep anterior lamellar keratoplasty (DALK) approach has demonstrated better patient outcomes than a full-thickness cornea transplant. However, despite better clinical outcomes from the DALK procedure, adoption of the technique has been limited because the accurate insertion of the needle into the deep stroma remains technically challenging. In this work, we present a novel hands-free eye mountable robot for automatic needle placement in the cornea, AutoDALK, that has the potential to simplify this critical step in the DALK procedure. The system integrates dual light-weight linear piezo motors, an OCT A-scan distance sensor, and a vacuum trephine-inspired design to enable the safe, consistent, and controllable insertion of a needle into the cornea for the pneumodissection of the anterior cornea from the deep posterior cornea and Descemet's membrane. AutoDALK was designed with feedback from expert corneal surgeons and performance was evaluated by finite element analysis simulation, benchtop testing, and ex vivo experiments to demonstrate the feasibility of the system for clinical applications. The mean open-loop positional deviation was 9.39 µm, while the system repeatability and accuracy were 39.48 µm and 43.18 µm, respectively. The maximum combined thrust of the system was found to be 1.72 N, which exceeds the clinical penetration force of the cornea. In a head-to-head ex vivo comparison against an expert surgeon using a freehand approach, AutoDALK achieved more consistent needle depth, which resulted in fewer perforations of Descemet's membrane and significantly deeper pneumodissection of the stromal tissue. The results of this study indicate that robotic needle insertion has the potential to simplify the most challenging task of the DALK procedure, enable more consistent surgical outcomes for patients, and standardize partial-thickness corneal transplants as the gold standard of care if demonstrated to be more safe and more effective than penetrating keratoplasty.

Long-Term Outcome After Bilateral Descemet Membrane Endothelial Keratoplasty for Fuchs Endothelial Corneal Dystrophy

PURPOSE

The aim of this study was to assess the long-term clinical outcome, complications, and graft survival of bilateral Descemet membrane endothelial keratoplasty (DMEK) in patients with Fuchs endothelial corneal dystrophy.

METHODS

This was a retrospective cohort study of 181 patients (362 eyes) with sequential bilateral DMEK for Fuchs endothelial corneal dystrophy. Clinical outcomes were assessed up to 5 years postoperatively. Outcome measures were best-corrected visual acuity, pachymetry, endothelial cell density, graft survival, and complication rates.

RESULTS

Contralateral DMEK was performed on average 15 ± 11 months (range: 2-60 months) after the first eye. From 1 until 5 years after DMEK, best-corrected visual acuity, pachymetry, endothelial cell density, and graft survival did not differ between the first and second eyes (all P > 0.05). Graft detachment occurred in 67 eyes (19% [18% first eyes, 19% second eyes], 6% bilateral), graft rejection in 9 eyes (3% [3% first eyes, 2% second eyes], 1% bilateral), glaucoma in 25 eyes (7% [8% first eyes, 6% second eyes], 2% bilateral), and graft failure in 22 eyes (6% [4% first eye, 8% second eye], 2% bilateral). All differences were not significant (all P > 0.05). Five-year graft survival rates were comparable for first and second eyes (0.95 and 0.92, respectively; P = 0.15).

CONCLUSIONS

Clinical outcomes after bilateral DMEK are similar in both eyes and sustainable in the longer term. Within the first 5 years, the same complication may rarely occur in the contralateral eye.

Infectious keratitis following corneal transplantation: A long-term cohort study

BACKGROUND

To assess the long-term incidence and risk factors for post-keratoplasty infectious keratitis (IK), associated ocular pathogens, and antibiotic resistance profiles.

METHODS

Cohort study including 2553 consecutive penetrating, endothelial, and anterior lamellar keratoplasties performed between 1992 and 2020. Medical and microbiological records of patients clinically diagnosed with IK were retrospectively reviewed.

MAIN OUTCOME MEASURES

cumulative incidence of IK, infectious agent species, and antibiotics resistance profiles.

RESULTS

The average follow-up time after transplantation was 112 ± 96 months. Eighty-nine IK episodes were recorded; microbiological tests were positive in 55/89 (62%). The cumulated incidence of postoperative IK was 5.50%/10.25% at 10/20 years. The occurrence of at least one episode of IK after transplantation was associated with lower graft survival in the long term (p < 0.0001). Rejection risk (adjusted Hazard Ratio, 2.29) and postoperative epithelial complications (HR, 3.44) were significantly and independently associated with a higher incidence of postoperative IK. Infectious agents included 41 bacteria, 10 HSV, 6 fungi, and 1 Acanthamoeba. The rate of antibiotic resistance was 0% for vancomycin, 13% for fluoroquinolones, 20% for rifamycin, 59% for aminoglycosides, and 73% for ticarcillin. In 41% of cases, patients were under prophylactic topical antibiotics before the infectious episode. Topical antibiotics were significantly associated with increased resistance to penicillin, carbapenems, and aminoglycosides.

CONCLUSION

IK (mainly bacterial) is a frequent complication of corneal transplantation in the long term. Vancomycin and fluoroquinolones can be considered as first-line treatments. Prolonged postoperative antibiotic preventive treatment is not advisable as it may increase antibiotic resistance.

Repeat corneal transplantation in Southern China: Indications, surgical technique, outcomes, and risk factors for repeat keratoplasty failure

PURPOSE

To report the indications, surgical techniques, and outcomes of repeat keratoplasty and evaluate the risk factors for graft failure in the Chinese population.

METHODS

The medical records of 216 patients (243 cases) who underwent at least two keratoplasties at a leading eye hospital in southern China between 2011 and 2020 were retrospectively reviewed. Indications and surgical procedures for repeat corneal transplantation were analyzed. Kaplan-Meier survival analysis was used to determine the graft survival rate after repeat keratoplasty. A multivariable survival model was used to assess the risk factors.

RESULTS

Repeated keratoplasties increased continuously from 2011 to 2020 (P = 0.002). The most common primary indication was infectious keratitis (38.7%), and the most common reason for repeat keratoplasty was graft rejection (30.04%). Regraft techniques included penetrating keratoplasty (PK) in 165 cases (67.9%), deep lamellar keratoplasty (DALK) in 52 cases (21.40%), and endothelial keratoplasty (EK) in 26 cases (10.7%). Median survival was 5.3, 6.8, and 6.4 years for PK, DALK, and EK, respectively. The 5-year survival rate was 53.5%, 66.6%, and 69.8% for PK, DALK, and EK, respectively. The median LogMAR visual acuity was 1.4 for PK, 0.75 for DALK, and 1.2 for EK at the end of the follow-up. Multivariate analysis revealed that graft rejection is a risk factor for repeat keratoplasty failure (P = 0.002).

CONCLUSIONS

DALK and EK may provide better outcomes than PK in treating graft failure. Preventing and treating postoperative graft rejection may be key to improving regraft survival. These findings will aid in the management of failed corneal grafts.

Replace or Regenerate? Diverse Approaches to Biomaterials for Treating Corneal Lesions

The inner structures of the eye are protected by the cornea, which is a transparent membrane exposed to the external environment and subjected to the risk of lesions and diseases, sometimes resulting in impaired vision and blindness. Several eye pathologies can be treated with a keratoplasty, a surgical procedure aimed at replacing the cornea with tissues from human donors. Even though the success rate is high (up to 90% for the first graft in low-risk patients at 5-year follow-up), this approach is limited by the insufficient number of donors and several clinically relevant drawbacks. Alternatively, keratoprosthesis can be applied in an attempt to restore minimal functions of the cornea: For this reason, it is used only for high-risk patients. Recently, many biomaterials of both natural and synthetic origin have been developed as corneal substitutes to restore and replace diseased or injured corneas in low-risk patients. After illustrating the traditional clinical approaches, the present paper aims to review the most innovative solutions that have been recently proposed to regenerate the cornea, avoiding the use of donor tissues. Finally, innovative approaches to biological tissue 3D printing and xenotransplantation will be mentioned.

Corneal blindness in the developing world: The role of prevention strategies

Corneal blindness is an important contributor to the burden of global blindness and has a greater prevalence in low-income countries of the developing world where resources and infrastructure are limited. The causes of corneal blindness too are different from high-income countries and include infectious keratitis, ocular trauma, and xerophthalmia. Persons with these indications tend to have unfavourable outcomes after corneal transplantation, limiting their chances of benefitting from this sight-saving procedure. However, most causes of corneal blindness in the developing world are preventable. This highlights the importance of understanding the unique challenges in these regions and the need for targeted interventions. This article discusses various prevention strategies, including primordial, primary, and secondary prevention, aimed at reducing the burden of corneal blindness in low-income countries. These include capacity building, training, and awareness campaigns to reduce the risk factors of ocular trauma, infectious keratitis, and to improve access to first aid. It is also important to promote safe eye practices and tackle nutritional deficiencies through public health interventions and policy changes. Providing the required training to general ophthalmologists in the management of basic corneal surgeries and diseases and enhancing the accessibility of eye care services in rural areas will ensure early treatment and prevent sequelae. Current treatment modalities belong to the tertiary level of prevention and are largely limited to corneal transplantation. In developing nations, there is a scarcity of donor corneal tissue necessitating an urgent expansion of eye banking services. Alternative approaches to corneal transplantation such as 3D printed corneas, cultured stem cells, and biomaterials should also be explored to meet this demand. Thus, there is a need for collaborative efforts between healthcare professionals, policymakers, and communities to implement effective prevention strategies and reduce the prevalence of corneal blindness in the developing world.

Effects of Autologous Serum and Platelet-Rich Plasma on Human Corneal Endothelial Cell Regeneration: A Comparative Study

OBJECTIVES

To investigate the effects of autologous serum (AS) and platelet-rich plasma (PRP) on human corneal endothelial cell (HCEC) proliferation and apoptosis in comparison to Y-27632 as the commonly studied Rho-associated kinase (ROCK) inhibitor.

METHODS

The human corneal endothelial primary cell line was used for this study. As the treatment groups, HCECs were incubated with AS, PRP, and Y-27632, whereas the control group received no treatment. Cell proliferation (measured by 5-bromo-2'-deoxyuridine [BrdU] incorporation) and apoptosis (based on the caspase-3 level) were compared between the control, Y-27632, AS, and PRP groups.

RESULTS

In the Y-27632, AS, and PRP groups, the ratios of BrdU-incorporated cells were significantly higher (115±0.2%, 125±0.2%, 122±0.4% at 24 hr, and 138±2.4%, 160±0.2%, 142±0.2% at 48 hr, respectively) than in the control group (100±18.4% at 24 hr, 100±1.1% at 48 hr) ( P <0.05 for all). Furthermore, AS provided a higher HCEC proliferation ratio compared with the Y-27632 group at 24 and 48 hr ( P <0.05 for all). Caspase-3 was significantly lower in the AS group (60.3±3.3%) than in the control (100±2.3%), Y-27632 (101.9±5.2%), and PRP (101±6.8%) groups ( P <0.05 for all).

CONCLUSIONS

The results of this study demonstrated for the first time that AS and PRP promoted HCEC proliferation and AS significantly decreased apoptosis in HCECs. A superior effect on HCEC proliferation was also observed with AS compared with Y-27632. Future "autologous" regenerative therapeutic options for corneal endothelial failure may involve the utilization of AS and PRP owing to their accessibility, simplicity in preparation, immunologic compatibility, and donor-free nature.

Descemet Endothelial Thickness Comparison Trial 1 (DETECT 1): outcome masked, placebo-controlled trial comparing two types of corneal transplant surgeries and effect of rho kinase inhibitors on endothelial cell loss protocol

BACKGROUND

It remains uncertain which endothelial keratoplasty (EK) technique yields the best outcomes while maintaining safety, particularly in eyes with coexisting ocular conditions. Moreover, the impact of endothelial cell loss (ECL) on long-term graft survival requires further investigation. Adjuvant ripasudil, a rho kinase inhibitor, may address the challenge of ECL in corneal transplantation. This paper presents the protocol for the Descemet Endothelial Thickness Comparison Trial 1 (DETECT 1), a multicentre, outcome-masked, randomised, placebo-controlled, four-arm clinical trial.

METHODS

A total of 160 eligible patients with endothelial dysfunction will be enrolled from five participating sites in the USA. The patients will be randomly assigned in a 2×2 factorial design to one of the following treatment groups: group 1-ultrathin Descemet stripping endothelial keratoplasty (UT-DSAEK) plus topical ripasudil 0.4%; group 2-UT-DSAEK plus topical placebo; group 3-Descemet membrane endothelial keratoplasty (DMEK) plus topical ripasudil 0.4% and group 4-DMEK plus topical placebo. Primary outcomes include the best spectacle-corrected visual acuity at 12 months and ECL at 12 months. Secondary outcomes include visual acuity at different time points, vision-related quality of life, endothelial cell morphology and cost-effectiveness.

RESULTS

The study outcomes will be analysed using mixed effects linear regression models, taking into account the treatment arms and relevant covariates. Adverse events, including rebubble procedures, graft failure and graft rejection, will be documented and analysed using appropriate statistical methods.

CONCLUSION

DETECT I aims to provide evidence on the comparative effectiveness of UT-DSAEK and DMEK, as well as the potential benefits of adjuvant topical ripasudil in reducing ECL. The results of this trial will contribute to optimising corneal transplantation techniques and improving long-term graft survival, while also exploring the cost-effectiveness of these interventions. Dissemination of findings through peer-reviewed publications and national/international meetings will facilitate knowledge translation and guide clinical practice in the field of corneal transplantation.

ETHICS AND DISSEMINATION

A data and safety monitoring committee (DSMC) has been empaneled by the NEI.All study protocols will be subject to review and approval by WCG IRB as the single IRB of record.This study will comply with the National Institute of Health (NIH) Data Sharing Policy and Policy on the Dissemination of NIH-Funded Clinical Trial Information and the Clinical Trials Registration and Results Information Submission rule. Data from the trial will be made available on reasonable request.

Review for special issue: Corneal lamellar surgery: Present outcomes and future perspectives

Since the establishment of the first eye bank in the 1940s, their role has evolved to face new challenges. With the recent development of lamellar keratoplasties, eye banks play an even bigger role in the selection and preparation of donor tissues. The increasing number of keratoplasty techniques and the high demand for "ready-to-use" tissues are challenging eye banks to improve and develop new preparation techniques. Besides necessary examinations, new approaches of tissue analysis in eye banks allow a better/optimized selection of corneal tissues. These new challenges in tissue preservation, preparation, and selection are propelling eye banks into a new era of modern eye banking.

Descemet membrane endothelial keratoplasty combined with presbyopia-correcting and toric intraocular lenses - a narrative review

Fuchs endothelial corneal dystrophy (FECD) is the leading indication for EK and may coexist with cataract and presbyopia. Notably, the outcomes of phacoemulsification in FECD patients are not as favorable as those in eyes without this condition. Historically, only monofocal intraocular lenses (IOLs) were recommended for these patients. However, recent reports have described the implantation of Premium-IOLs (such as Multifocal IOLs, Enhanced Depth of Focus IOLs, and Toric IOLs) in FECD eyes undergoing cataract surgery and Descemet membrane endothelial keratoplasty (DMEK). While the results are encouraging, they are not as optimal as those from unoperated eyes, especially when comparing simultaneous procedures to sequential ones. It's advised to perform the DMEK first to improve the accuracy of IOL calculations. Still, even successfully operated eyes may experience secondary graft failure or graft rejection after DMEK. The success rate of a secondary DMEK is typically lower than that of the initial procedure. Furthermore, if the postoperative thickness after DMEK is less than anticipated, laser enhancements might not be an option. There's a pressing need for more controlled and randomized clinical trials to ascertain the safety and effectiveness of Premium-IOLs for FECD eyes. This narrative review aims to collate evidence on the use of Premium IOL technologies in eyes receiving EK and to underscore key points for surgeons performing EK combined with cataract surgery.

New dawn for keratoconus treatment: potential strategies for corneal stromal regeneration

Keratoconus is a progressive, ectatic and blinding disorder of the cornea, characterized by thinning of corneal stroma. As a highly prevalent among adolescents, keratoconus has been a leading indication for corneal transplantation worldwide. However, the severe shortage of donor corneas is a global issue, and the traditional corneal transplantation surgeries may superinduce multiple complications, necessitating efforts to develop more effective strategies for keratoconus treatment. In this review, we summarized several strategies to promote corneal stromal regeneration or improve corneal stromal thickness, including cell-based therapies, biosynthetic alternatives for inducing corneal regeneration, minimally invasive intrastromal implantation and bioengineered tissues for implantation. These strategies provided more accessible but safer alternatives from various perspectives for keratoconus treatment, paving the way for arresting the keratoconus progression in its earlier stage. For the treatments of corneal ectatic diseases beyond keratoconus, these approaches will provide important references and widen the therapy options in a donor tissue-independent manner.

Descemet membrane endothelial keratoplasty compared with ultrathin Descemet stripping automated endothelial keratoplasty: a meta-analysis

AIMS

This study aims to compare the clinical outcome of Descemet membrane endothelial keratoplasty (DMEK) and ultrathin Descemet stripping automated endothelial keratoplasty (UT-DSAEK) in patients with corneal endothelial dysfunction due to Fuchs' endothelial dystrophy or pseudophakic bullous keratopathy.

METHODS

We conducted a meta-analysis using a literature search of Embase, PubMed, Cochrane CENTRAL, ClinicalTrials.gov and WHO ICTRP databases. We included randomised controlled trials (RCTs) and cohort studies that compared DMEK and UT-DSAEK (graft<130 µm), with a follow-up of ≥12 months, published until 20 February 2022. We used the Revised Cochrane risk-of-bias tool for RCTs and the Risk of Bias in Non-Randomised Studies-of Interventions system for cohort studies.

RESULTS

Out of 144 records, 8 studies (3 RCTs, 2 fellow-eye studies and 3 cohort studies) were included, encompassing 376 eyes, (N=187 DMEK vs N=189 UT-DSAEK). The 12-month logarithm of the minimum angle of resolution best-corrected visual acuity (BCVA) was better post-DMEK (mean difference -0.06 (95% CI -0.10 to -0.02)), but with higher rebubbling risk: OR 2.76 (95% CI 1.46 to 5.22). Heterogeneity was significant I2=57%. Findings were consistent when excluding retrospective studies, including only studies with low risk of bias or RCTs only. An analysis of studies with mean DSAEK grafts <70 µm showed no significant difference in BCVA between the procedures. Publication bias was found in the BCVA analysis (Egger's test p=0.023).

CONCLUSIONS

Post-DMEK BCVA is superior to post-UT-DSAEK when using <130 µm grafts. DSAEK grafts <70 µm may not significantly differ from DMEK. The higher risk of rebubbling with DMEK necessitates an appropriate selection of patients.

PROSPERO REGISTRATION NUMBER

CRD42022340805.

Keratoplasty in the United States: Trends and Indications From 2015 to 2020

PURPOSE

The aim of this study was to report trends in keratoplasty techniques and indications in the United States from 2015 to 2020.

METHODS

This retrospective review of annual reports from the Eye Bank Association of America assessed domestic corneal graft distribution and surgical indication data for various types of keratoplasty. Trends in procedure volume and indications from 2015 to 2020 were analyzed using the Cochran-Armitage test.

RESULTS

The total number of corneal transplants increased from 47,903 in 2015 to 49,143 in 2019, with a decline to 42,257 in 2020, most likely due to COVID-19. Penetrating keratoplasty (PK) volume decreased from 2015 to 2020 (19,160-15,402, 40% to 36.4%, P < 0.001), continuing a trend from the previous decade. Descemet membrane endothelial keratoplasty as a percentage of all keratoplasty procedures increased (9.8%-27.8%, P < 0.001), whereas Descemet stripping automated endothelial keratoplasty (47%-33.9%, P < 0.001) and anterior lamellar keratoplasty (ALK) decreased (2.3%-1.2%, P < 0.001).From 2017 to 2020, repeat corneal transplant was the most common specific indication for PK while ectasias/thinnings decreased in prevalence (15.6%-11.5%, P < 0.001). Ectasias/thinnings and endothelial dystrophy remained the leading indications for ALK and endothelial keratoplasty, respectively.

CONCLUSIONS

From 2015 to 2020, keratoplasty trends in the United States showed a continuation of the decrease in PK and increase in Descemet membrane endothelial keratoplasty observed in the previous decade. The most common domestic indications from 2017 to 2020 have been repeat corneal graft, endothelial dystrophy, and ectasias/thinnings for PK, EK, and ALK, respectively.

Effects of femtosecond laser-assisted minimally invasive lamellar keratoplasty (FL-MILK) on mild-to-moderate and advanced keratoconus

PURPOSE

To compare the outcomes of femtosecond laser-assisted minimally invasive lamellar keratoplasty (FL-MILK) for mild-to-moderate keratoconus (KC) and advanced KC.

METHODS

Prospective case series study. Sixty-three eyes of 56 patients with progressive KC underwent FL-MILK were divided into group 1 [mean keratometry (Kmean) ≤ 53D] and group 2 (Kmean > 53D). Best spectacle-corrected visual acuity (BSCVA), Kmean, maximum keratometry (Kmax), anterior central corneal elevation (ACE), stiffness parameter A1 (SP-A1) and deformation amplitude (DA) were evaluated preoperatively and up to 24 months postoperatively.

RESULTS

Mean BSCVA improved from 0.34 ± 0.13 logMAR preoperatively to 0.25 ± 0.13 logMAR at 24 months postoperatively in group 1 (F = 10.10, P < .0001), and from 0.54 ± 0.31 logMAR to 0.40 ± 0.26 logMAR (F = 9.06, P = .0002) in group 2. Group 2 showed an average Kmax reduction of 10.9 D and an average Kmean reduction of 3.9 D at 24 months postoperatively (both P < .0001), whereas no significant change was observed in group 1. Average ACE decreased from 19.2 ± 10.0 to 5.2 ± 8.4 at 24 months postoperatively in group 1 (F = 28.5, P < .0001), and from 46.2 ± 16.3 to 19.1 ± 9.0 (F = 49.6, P < .0001) in group 2; SP-A1 increased from 53.8 ± 12.7 mmHg/mm to 95.9 ± 20.2 mmHg/mm in group 1 (F = 70.0, P < .0001), and from 38.6 ± 13.4 mmHg/mm to 89.3 ± 18.2 mmHg/mm (F = 96.9, P < .0001) in group 2; DA decreased from 1.30 ± 0.14 mm to 1.17 ± 0.13 mm in group 1 (F = 14.0, P < .0001), and from 1.40 ± 0.16 mm to 1.18 ± 0.10 mm (F = 27.6, P < .0001) in group 2.

CONCLUSIONS

FL-MILK can stabilize progressive KC in mild-to-moderate cases and advanced cases at 24-month follow-up. Steeper corneas are more likely to undergo flattening after FL-MILK.

CLINICAL TRIAL

Date of registration: July 16, 2017. The title of the trail: www.

CLINICALTRIALS

gov Trial registration number: NCT03229239. The name of the trial registry: ClinicalTrials.gov.

2021 Survey of Keratoplasty Postoperative Steroid Management

PURPOSE

The aim of the study is to investigate US-based ophthalmologists' preferred corneal transplant techniques and postoperative steroid regimen.

METHODS

Ophthalmologists attending the 2021 Cornea and Eye Banking Forum and/or Cornea Subspecialty Day were surveyed in person.

RESULTS

Ninety-two ophthalmologists with a median of 13 years (range of 1-35; mean of 14.5; ±9.05 mean ± SD) of experience as attending clinicians were surveyed. One hundred percent of the surgeons performed penetrating keratoplasty, which was followed by 96.7% for Descemet stripping endothelial keratoplasty, 90.2% for Descemet membrane endothelial keratoplasty, and 72.8% for deep anterior lamellar keratoplasty. Prednisolone 1% for postoperative care was the preferred choice across all surveyed keratoplasty techniques and postsurgery time intervals. All surgeons reported steroid administration frequency of 4 times a day in the first month and once a day after 12 months postkeratoplasty. To manage ocular hypertension after corneal transplantation, the leading approach was adding a glaucoma medication (44.6%), and beta-adrenergic antagonists were ranked as the most preferred choice by 59 (66.3%) of the respondents. For graft rejection after corneal transplantation, topical steroids (79.8%) were the initial treatment of choice with hourly administration being the most common frequency prescribed (87.4%). Most surgeons either agreed or strongly agreed (78.4%) that a randomized clinical trial evaluating the safety and efficacy of different steroid regimens after corneal transplantation would influence their clinical decision making.

CONCLUSIONS

Prednisolone remains the predominantly used steroid across different keratoplasties. Steroid regimens are similar for non-high-risk penetrating keratoplasty, Descemet membrane endothelial keratoplasty, Descemet stripping endothelial keratoplasty, and deep anterior lamellar keratoplasty. To treat graft rejection, surgeons tend to initially add a glaucoma medication than to reduce the potency or frequency of the steroid.

Indications and types of keratoplasties: Trends in the past 10 years (2011-2020) in Eastern India

Purpose

To observe the trends of various types of keratoplasties in different etiologies over a period of 10 years (2011-2020) in a tertiary eye care center of eastern India.

Methods

A retrospective review of patients undergoing keratoplasties from 2011 to 2020 was performed in a tertiary eye care hospital situated in eastern part of India. Apart from demographic data, primary indication for each surgery and type of procedure carried out was recorded. For comparison, data were divided into two time periods: Group I: Jan 2011 to Dec 2015 and Group II: Jan 2016 to Dec 2020.

Results

Over a period of 10 years, a total of 2365 (Group I: 902, Group II: 1463) keratoplasties were performed. The average age of patients was 45.8 ± 19.9 and 46.9 ± 20.9 years in Group I and Group II, respectively. Among all the corneal grafts, 1747 (74%) surgeries were full-thickness. Although optical penetrating keratoplasty (OPK) was most the common indication for full-thickness keratoplasties, Descemet's stripping endothelial keratoplasty (DSEK) remained most performed lamellar keratoplasty. Keratitis, corneal scars, and bullous keratopathies remain to be most common indications in both groups. Number of lamellar keratoplasties increased significantly from Group I to Group II for corneal scars (P = 0.02), bullous keratopathies (P = 0.01), and endothelial dystrophies (P = 0.00).

Conclusion

With change in time, the indication and technique of keratoplasty has witnessed a changing trend from full-thickness keratoplasty to lamellar keratoplasty. There is rise in trend of lamellar keratoplasties over the period.

Why Are Corneal Specialists Resistant to Treating Patients Who Have Severe Ocular Surface Disease With Limbal Stem Cell Deficiency?

PURPOSE

To highlight the paucity of surgeons performing ocular surface stem cell transplantation with systemic immunosuppression (OSSTx with SI) for limbal stem cell deficiency (LSCD) patients, suboptimal treatments for LSCD, and obstacles to adoption.

METHODS

A review of the Eye Bank Association of America annual reports and the authors' case volume for OSSTx with SI was performed. Examination of the published literature on corneal surgeries, especially for LSCD, was completed. These findings were combined with our clinical observations to develop this editorial.

RESULTS

Despite techniques and protocols for OSSTx with SI published more than 30 years ago for the treatment of severe bilateral LSCD, only a small number of corneal specialists have adopted these techniques. There is a paucity of attention to this population of patients, with minimal publications to advance this area of our field. We are too often referred patients with LSCD and severe ocular surface disease that have had suboptimal treatments such as penetrating keratoplasties or primary keratoprostheses. Hesitancy for adopting OSSTx with SI is likely due to a lack of exposure to these procedures during training and fear of systemic immunosuppression. Corneal surgeons are likely unaware of the safety of systemic immunosuppression with appropriate monitoring especially when comanaging these patients with an organ transplant specialist.

CONCLUSION

There is a large unmet need for the treatment of corneal blindness secondary to conjunctival and LSCD. For the vast majority of patients, OSSTx should be the first surgical choice to treat these eyes. We hope major ophthalmology centers will meet this need by building programs, and groups of corneal surgeons should collaborate to create regional centers to make this treatment more accessible to help this population.

A 7-year review of clinical characteristics, predisposing factors and outcomes of post-keratoplasty infectious keratitis: the Nottingham infectious keratitis study

Background/objectives

Post-keratoplasty infectious keratitis (PKIK) is a unique sight-threatening clinical entity which often poses significant therapeutic challenges. This study aimed to examine the clinical presentation, risk factors, management, and clinical outcomes of PKIK.

Methods

This was a retrospective study of all patients who presented to the Queen's Medical Centre, Nottingham, with PKIK between September 2015 and August 2022 (a 7-year period). Relevant data on types of keratoplasty, clinical presentations, causative microorganisms, management, and outcome were analyzed.

Results

Forty-nine PKIK cases, including four cases of interface infectious keratitis, were identified during the study period. The most common graft indications for PKP, DALK and EK were failed grafts (9, 37.5%), keratoconus (6, 54.5%) and Fuchs endothelial corneal dystrophy (FECD; 8, 57.1%), respectively. Staphylococcus spp. were the most commonly identified organisms (15, 50.0%). Bullous keratopathy (18, 36.7%), ocular surface disease (18, 36.7%), and broken/loose sutures (15, 30.6%) were the most common risk factors. Concurrent use of topical steroids was identified in 25 (51.0%) cases. Of 31 functioning grafts at presentation, 12 (38.7%) grafts failed at final follow-up with 15 (48.4%) patients retaining a CDVA of ≥1.0 logMAR. The overall estimated 5-year survival rate post-PKIK was 55.9% (95% CI, 35.9%-75.9%), with DALK having the highest survival rate [63.6% (95% CI, 28.9%-98.3%)], followed by EK [57.1% (95% CI, 20.4%-93.8%)] and PKP [52.7% (95% CI, 25.1%-80.3%)], though no statistical difference was observed (p=0.48).

Conclusions

PKIK represents an important cause of IK and graft failure. Bullous keratopathy, OSD and suture-related complications are the commonest risk factors, highlighting the potential benefit of prophylactic topical antibiotics (for unhealthy ocular surface) and early suture removal (where possible) in reducing the risk of PKIK. Graft survival may be higher in lamellar keratoplasty following PKIK but larger studies are required to elucidate this observation.

Descemet Stripping Without Endothelial Keratoplasty in Early-Stage Central Fuchs Endothelial Dystrophy: Long-term Results

PURPOSE

The purpose of this study was to report long-term results of Descemet stripping without endothelial keratoplasty (DWEK) associated with phacoemulsification in patients with early-stage central Fuchs endothelial corneal dystrophy.

METHODS

This is a retrospective study, including all patients submitted to DWEK associated with cataract surgery with a minimum follow-up of 24 months. Included patients had central confluent guttae confirmed with specular microscopy, a clear peripheral endothelium (with a peripheral endothelial count >1500 cells/mm 2 ), and a central pachymetry <600 μm. The main end points were the presence of a clear cornea and time that was needed to achieve transparency, best-corrected visual acuity in logMAR, endothelial central cell count (ECC), and central pachymetry.

RESULTS

A total of 22 eyes were included with a mean follow-up of 40.8 ± 10.5 months. At baseline, mean central pachymetry was 536 ± 34 mm and 6 eyes had countable ECC (mean 1138 ± 190 cells/mm 2 ). Twenty eyes (90.9%) achieved good corneal transparency 3.2 ± 1.1 months after surgery. There was a significant improvement in logMAR best-corrected visual acuity compared with baseline (0.13 ± 0.10 vs. 0.48 ± 0.24, respectively, P < 0.001). Endothelial central repopulation was observed in all successful cases. Twelve months after DWEK, ECC was 1449 ± 344 cells/mm 2 and 1393 ± 450 cells/mm 2 at the end of follow-up, without a significant decrease between this period ( P = 0.081). Only 2 eyes (9.1%) did not achieve corneal transparency and were submitted to an endothelial keratoplasty.

CONCLUSIONS

According to our results, DWEK is a safe and effective procedure in selected cases of early-stage central Fuchs endothelial corneal dystrophy. This seems to be a promising technique, delaying or avoiding endothelial transplantation.

Twelve-Month Clinical and Histopathological Performance of a Novel Synthetic Cornea Device in Rabbit Model

Purpose

To report the biological stability and postoperative outcomes of a second-generation, single-piece, flexible synthetic cornea in a rabbit model.

Methods

Device materials and design were amended to enhance biointegration. Optic skirt design devices were made from compact perfluoroalkoxy alkane with porous expanded polytetrafluoroethylene ingrowth surface overlying the skirt and optic wall. Sixteen devices were implanted into intrastromal pocket in rabbit eyes. Rabbits were randomly assigned to 6- and 12-month follow-up cohorts (n = 8 in each) postoperatively. Monthly examinations and optical coherence tomography assessed cornea-device integration, iridocorneal angle, optic nerve, and retina.

Results

There were no intraoperative complications. All devices were in situ at exit, with clear optics. No retroprosthetic membrane, glaucoma, cataract formation, or retinal detachment was observed. Two rabbits in the 6-month group had mild, focal anterior lamella thinning without retraction adjacent to the optic near tight sutures. Three postoperative complications occurred in the 12-month group. One rabbit diagnosed with endophthalmitis was euthanized on day 228. Mild sterile focal retraction of anterior lamella occurred in two rabbits, which were terminated on days 225 and 315. Light microscopic examination of enucleated globes demonstrated fibroplasia with new collagen deposition into the porous scaffold without significant inflammation, encapsulation, or granuloma formation.

Conclusions

Clinical evaluations, imaging, and histopathological findings indicate favorable outcomes of this synthetic corneal device in a rabbit model. Early feasibility studies in humans are being planned.

Translational Relevance

Favorable 12-month results of the device in rabbits demonstrate vision-restoring potential in corneally blind individuals at high risk of failure with donor keratoplasty.

[Corneal transplantation at the beginning of the 21th century]

Corneal transplantation (keratoplasty) is necessary when various disorders result in corneal opacities with severe visual loss that cannot be treated conservatively, or the regular structure and curvature of the cornea is distorted, and its function is lost. Among human transplantation, keratoplasty is the most successful surgical procedure. In recent decades, penetrating keratoplasties have been increasingly replaced by lamellar techniques, where only the abnormal layer of the cornea is transplanted. The anterior form is deep anterior lamellar keratoplasty (DALK), recommended mainly for keratoconus. The main forms of posterior lamellar keratoplasty are Descemet's stripping automated endothelial keratoplasty (DSAEK) and Descemet's membrane endothelial keratoplasty (DMEK). The indications are bullous keratopathy after cataract surgery with endothelial destruction and Fuchs endothelial dystrophy. Lamellar keratoplasty has several advantages over penetrating surgery. Postoperative visual acuity is better, wound healing, patient rehabilitation are faster and the course of any immune rejection is milder and can be better managed. Orv Hetil. 2023; 164(28): 1087-1093.

Management of keratoconus: an updated review

Keratoconus is the most common corneal ectatic disorder. It is characterized by progressive corneal thinning with resultant irregular astigmatism and myopia. Its prevalence has been estimated at 1:375 to 1:2,000 people globally, with a considerably higher rate in the younger populations. Over the past two decades, there was a paradigm shift in the management of keratoconus. The treatment has expanded significantly from conservative management (e.g., spectacles and contact lenses wear) and penetrating keratoplasty to many other therapeutic and refractive modalities, including corneal cross-linking (with various protocols/techniques), combined CXL-keratorefractive surgeries, intracorneal ring segments, anterior lamellar keratoplasty, and more recently, Bowman's layer transplantation, stromal keratophakia, and stromal regeneration. Several recent large genome-wide association studies (GWAS) have identified important genetic mutations relevant to keratoconus, facilitating the development of potential gene therapy targeting keratoconus and halting the disease progression. In addition, attempts have been made to leverage the power of artificial intelligence-assisted algorithms in enabling earlier detection and progression prediction in keratoconus. In this review, we provide a comprehensive overview of the current and emerging treatment of keratoconus and propose a treatment algorithm for systematically guiding the management of this common clinical entity.

Ophthalmic surgery in New Zealand: analysis of 410,099 surgical procedures and nationwide surgical intervention rates from 2009 to 2018

BACKGROUND

Surgical intervention rates (SIR) provide a proxy measure of disease burden, surgical capacity, and the relative risk-benefit ratio of surgery. The current study assessed decade trends in ophthalmic surgery and calculated SIRs for all major classes of commonly performed ophthalmic procedures in New Zealand.

METHODS

Retrospective population-based analysis of all ophthalmic surgical procedures performed in New Zealand from 2009 to 2018. National and regional datasets from public and private health sectors and industry were analysed. SIRs were calculated for all major ophthalmic procedures, and subgrouped by patient demographics.

RESULTS

There were 410,099 ophthalmic surgical procedures completed with a 25.3% overall increase over 10 years. Procedures were mostly government-funded (51%, n = 210,830) with 71% of patients aged over 64 years. Cataract surgery (78%, n = 318,564) had the highest mean SIR (703/100,000/year) and increased by 25% during the study period, consistent with population growth in the over 64 years old age group. Vitrectomy surgery had the second highest mean SIR (67/100,000/year) and increased by 50%, well above national population growth during the study period. Other SIRs included conjunctival lesion-biopsy (38/100,000/year), glaucoma (33/100,000/year), strabismus (20/100,000/year), dacryocystorhinostomy (10/100,000/year), and keratoplasty surgery (4/100,000/year).

CONCLUSIONS

This comprehensive review of New Zealand ophthalmic surgery reports increasing SIRs that cannot be explained by population growth alone. Cataract surgery numbers increased year on year consistent with the increase in the over 64 years old population. Vitrectomy surgery growth exceeded that of the national population, including those over 64 years.

Ex vivo demonstration of canine corneal pre-Descemet's anatomy using pneumodissection as for the big bubble technique for deep anterior lamellar keratoplasty

The recent discovery and characterization of pre-Descemet's layer (PDL; also termed the Dua's layer or the Dua-Fine layer) has advanced the understanding of various posterior corneal pathologies and surgeries in human. This study aimed to characterize the ultrastructure of the posterior stroma and interfacial zone of Descemet's membrane (DM) in canine eyes. Eighteen canine corneo-scleral discs were included. Intrastromal air injection resulted in the formation of type 1 big bubble (BB) in 73% (n = 11/15) of corneas, with a mean diameter of 11.0 ± 1.3 mm. No type 2 BB was created. Anterior segment optical coherence tomography, histology and transmission electron microscopy confirmed that the wall of BB was composed of DM, in contact with remaining stroma (canine PDL; cPDL). The cPDL was populated with keratocytes, of varying thickness of 16.2 ± 4.2 µm in close apposition to the DM, and composed of collagen bundles arranged in transverse, longitudinal and oblique directions. The interfacial zone, between DM and cPDL, showed fibril extension in all three directions, predominantly longitudinal. Irregular extensions of DM material into cPDL stroma were observed. No long-spaced collagen was detected. In conclusion, there exists a well-defined cleavage plane between the posterior stroma and cPDL, with similar but not identical characteristics as in humans, that is revealed by pneumodissection. This adds to our understanding of the anatomy of the posterior most canine cornea, which will have significant clinical impact on posterior corneal surgery and understanding of corneal pathology in dogs.

Risk factors for intraocular pressure elevation following Descemet membrane endothelial keratoplasty in Asian patients

PURPOSE

To investigate risk factors for increased intraocular pressure (IOP) after Descemet membrane endothelial keratoplasty (DMEK) in Asian patients.

METHODS

Data from January 2015 to February 2021 were obtained from our prospective database. IOP elevation after DMEK was defined as IOP ≥ 22 mmHg or an increase in IOP of ≥ 10 mmHg from baseline. In addition, we examined maximum IOP. Using iCare, we measured IOP 1, 2, 3, and 6 months after DMEK, and every 6 months thereafter. Logistic regression and linear regression were performed to find factors predictive of IOP elevation and maximum IOP, respectively, based on the results of univariate analysis.

RESULTS

We enrolled 90 eyes (mean patient age, 74.9 ± 7.5 years; mean follow-up duration, 25.6 ± 9.9 months) that underwent DMEK. IOP elevation was present in 19 eyes (21%). IOP increased from 12.6 ± 3.9 mmHg preoperatively to a postoperative maximum of 17.0 ± 5.5 mmHg up to 36 months after DMEK (p < 0.0001). In univariate logistic regression analysis for IOP elevation, only one variable, pseudoexfoliation syndrome (PEX) and preexisting glaucoma, was significant (p < 0.05). Preexisting glaucoma without PEX (OR, 19.33; 95% CI, 4.75-93.46), PEX without glaucoma (OR, 7.25; 95% CI, 1.20-41.63), and PEX glaucoma (OR, 58.00; 95% CI, 6.78-1298.29) were associated with higher risk of IOP elevation.

CONCLUSIONS

In this cohort, the eyes of patients with PEX and preexisting glaucoma were found to be prone to IOP elevation after DMEK.

Spontaneous corneal clearance after graft detachment in DMEK

Descemet Membrane detachment is a potential complication after Descemet Membrane Endothelial Keratoplasty (DMEK). Here, we present a unique case of a DMEK surgery in a complicated eye that suffered a nearly complete DMEK graft detachment and later a graft opacification with a pseudo-anterior chamber. In Mid-November 2020, a planned DMEK was performed in a 64-year-old male patient due to corneal decompensation. Four months after DMEK, a fibrotic DMEK graft was seen across the anterior chamber with a pseudo-anterior chamber; however, the recipient cornea showed complete clearance with an endothelial cell count of about 1204 cells/mm2 and a best-corrected visual acuity of 20/25. Three months later, we observed a significant opacification of the detached graft, and the best-corrected distance visual acuity decreased to 20/63. We proceeded with the graft removal without performing a second DMEK. Ten months after graft removal, the cornea remained clear with an endothelial cell count of about 510 cells/mm², and the best-corrected visual acuity was 20/25.

Clinical Outcomes of the Intraocular Lens Injector and Busin Glide for Descemet Stripping Automated Endothelial Keratoplasty in Patients with Iridocorneal Endothelial Syndrome

Purpose: To report the outcomes of Descemet stripping automated endothelial keratoplasty (DSAEK) performed in iridocorneal endothelial (ICE) syndrome patients using the intraocular lens injector (injector), in comparison with those using the Busin glide. Methods: In this retrospective, interventional comparative study, we evaluated the outcomes of DSAEK performed using the injector (n = 12) or the Busin glide (n = 12) for patients with ICE syndrome. Their graft position and postoperative complications were recorded. Their best-corrected visual acuity (BCVA) and endothelial cell loss (ECL) were monitored over a 12-month follow-up period. Results: DSAEK was conducted successfully in the 24 cases. The BCVA improved from the preoperative 0.99 ± 0.61 to 0.36 ± 0.35 at 12 months after operation (p < 0.001), with no significant difference between the two groups (the injector group and the Busin group) (p = 0.933). ECL at 1 month after DSAEK was 21.80 ± 15.01% in the injector group, which was significantly lower than 33.69 ± 9.75% of the Busin group (p = 0.031). No surgery-related complications were observed in the 24 cases intraoperatively or postoperatively except that one case suffered from postoperative graft dislocation, without statistical difference between the two groups. Conclusions: At 1 month after surgery, the use of graft injector for delivering DSAEK-based endothelial graft may cause significantly less endothelial cell damage than the pull-through technique used in the application of Busin glide. The injector allows safe endothelial graft delivery without the need of anterior chamber irrigation, which increases the ratio of successful graft attachment.

A Novel Murine Model of Endothelial Keratoplasty

PURPOSE

The purpose of this study was to establish a murine model of endothelial keratoplasty.

METHODS

Endothelial keratoplasty (EK) was performed using C57BL/6 donor and BALB/c recipient mice. The central endothelium and Descemet membrane were removed from the recipient cornea, and a 1.5-mm posterior lamellar donor graft was made adherent to the recipient cornea with a small amount of viscoelastic. Mice were followed through slitlamp microscopy postoperatively, and OCT was used to assess the cornea and anterior chamber and measure central corneal thickness. Histology and immunohistochemistry were performed to confirm graft adherence and endothelial cell morphology.

RESULTS

Successfully attached EK grafts were visualized in all transplanted animals. Histology and immunostaining confirmed proper graft orientation and adherence, as well as the presence of donor endothelium on transplanted grafts. We observed maximal corneal edema in all animals at day 1 postoperatively which gradually subsided. EK graft survival was 97% at 8 weeks.

CONCLUSIONS

In this study, we describe a novel murine model for EK which we anticipate will enable detailed investigation into the cellular and molecular mechanisms involved in EK pathobiology.

Big data in corneal diseases and cataract: Current applications and future directions

The accelerated growth in electronic health records (EHR), Internet-of-Things, mHealth, telemedicine, and artificial intelligence (AI) in the recent years have significantly fuelled the interest and development in big data research. Big data refer to complex datasets that are characterized by the attributes of "5 Vs"-variety, volume, velocity, veracity, and value. Big data analytics research has so far benefitted many fields of medicine, including ophthalmology. The availability of these big data not only allow for comprehensive and timely examinations of the epidemiology, trends, characteristics, outcomes, and prognostic factors of many diseases, but also enable the development of highly accurate AI algorithms in diagnosing a wide range of medical diseases as well as discovering new patterns or associations of diseases that are previously unknown to clinicians and researchers. Within the field of ophthalmology, there is a rapidly expanding pool of large clinical registries, epidemiological studies, omics studies, and biobanks through which big data can be accessed. National corneal transplant registries, genome-wide association studies, national cataract databases, and large ophthalmology-related EHR-based registries (e.g., AAO IRIS Registry) are some of the key resources. In this review, we aim to provide a succinct overview of the availability and clinical applicability of big data in ophthalmology, particularly from the perspective of corneal diseases and cataract, the synergistic potential of big data, AI technologies, internet of things, mHealth, and wearable smart devices, and the potential barriers for realizing the clinical and research potential of big data in this field.

Prior Contralateral Penetrating Keratoplasty Is a Risk Factor for Second Eye Graft Rejection

AIMS

To determine whether prior penetrating keratoplasty (PK) in the contralateral eye increases risk of second eye PK graft rejection.

METHODS

Cohort study of 593 consecutive PKs in transplant-naïve eyes (500 unilateral cases, 93 second eyes). Outcomes were compared between PKs performed in eyes with versus without a history of prior contralateral eye PK. Risks of rejection and failure were estimated using Cox proportional hazards models.

RESULTS

Mean age was 53.7 ± 23.3 years; average follow-up was 4.00 ± 2.87 years. Rejection occurred in 211 (35.6%) grafts. The incidence of rejection was 34.0% in unilateral cases and 44.1% in second eyes with PK in the contralateral eye. Prior contralateral PK was a significant risk factor for graft rejection (HR = 1.42, 95% CI 1.01-2.01, p = .045).

CONCLUSION

Contralateral PK is associated with increased risk of second eye graft rejection. Loss of ocular immune privilege is a possible mechanism.

Development of a Nomogram to Predict Graft Survival After Descemet Stripping Endothelial Keratoplasty

BACKGROUND/PURPOSE

The purpose of this study was to analyze Descemet stripping endothelial keratoplasty (DSEK) outcomes and develop a nomogram to compute the probability of 3- and 5-year DSEK graft survival based on risk factors.

STUDY DESIGN/METHODS

The medical records of 794 DSEK procedures between January 1, 2008, and August 1, 2019, were retrospectively reviewed to identify 37 variables. We also evaluated for the presence of corneal graft failure, defined as irreversible and visually significant graft edema, haze, or scarring. Variables were assessed by multivariable Cox models, and a nomogram was created to predict the probability of 3- and 5-year graft survival.

RESULTS

Graft failure occurred in 80 transplants (10.1%). The strongest risk factors for graft failure included graft detachment [hazard ratio (HR) = 4.46; P < 0.001], prior glaucoma surgery (HR = 3.14; P = 0.001), and glaucoma (HR = 2.23; P = 0.018). A preoperative diagnosis of Fuchs dystrophy was associated with a decreased risk of graft failure (HR = 0.47; P = 0.005) compared with secondary corneal edema. Our nomogram has a concordance index of 0.75 (95% confidence interval, 0.69 to 0.81), which indicates that it may predict the probability of graft survival at 3 and 5 years with reasonable accuracy. We also analyzed graft rejection, which occurred in 39 cases (4.9%). The single risk factor found to be significantly associated with graft rejection was prior glaucoma surgery (HR = 2.87; P = 0.008).

CONCLUSIONS

Our nomogram may accurately predict DSEK graft survival after 3 and 5 years based on 4 variables. This nomogram will empower surgeons to share useful data with patients and improve collective clinical decision-making.

Trends in Keratoplasty Procedures During 2 Decades in a Major Tertiary Referral Center in Finland: 1995 to 2015

PURPOSE

The purpose of this study was to analyze trends in number, age-adjusted frequency, and type of keratoplasty in a major tertiary referral center, relative to patient and graft characteristics.

METHODS

A retrospective registry study of 1574 patients who in 1995 to 2015 underwent keratoplasty in the Helsinki University Eye Hospital (HUEH). Graft type and sequence, patient characteristics, and date of surgery were recorded. Main outcome measures were annual number, type, and age-adjusted frequency of keratoplasty; patient and graft characteristics; graft procurement; and national population-adjusted frequency of keratoplasty.

RESULTS

In HUEH, from 1995 to 2015, a total of 2191 keratoplasties were performed with 48% of the grafts procured intramurally; 76% were primary and 24% regrafts. The age-adjusted frequency of primary penetrating keratoplasty decreased by 52% from 0.96 to 0.46 per 100,000. The corresponding frequency of primary Descemet stripping automated endothelial keratoplasty increased by 367% from 0.3 to 1.4 after 2006, finally accounting for 68% of primary grafts. Men underwent primary penetrating keratoplasty (median 48 vs. 67 yrs, P = 0.0001) and anterior lamellar keratoplasty (median 37 vs. 46 yrs, P = 0.0015) at a younger age than women. Interval to the first regraft was comparable between sexes (median 2.2 vs. 1.9 yrs, respectively, P = 0.17). The national median population-adjusted frequency of keratoplasties was 3.2 per 100,000 from 2009 to 2015, and HUEH accounted for a median of 69% of them.

CONCLUSIONS

The increased frequency of keratoplasty in HUEH resulted from rapid adoption of Descemet stripping automated endothelial keratoplasty after 2006 and was facilitated by centralizing graft procurement to HUEH and the National Cell and Tissue Center Regea.

Clinical outcomes of Descemet membrane endothelial keratoplasty performed in eyes with keratoconus and corneal endothelial dysfunction

PURPOSE

To evaluate the clinical outcome of Descemet membrane endothelial keratoplasty (DMEK) performed in eyes with comorbid keratoconus (KCN) and corneal endothelial dysfunction.

METHODS

Twenty-five consecutive eyes of 14 patients with comorbid stable KCN underwent DMEK for corneal endothelial dysfunction; best spectacle corrected visual acuity (BSCVA), maximum corneal curvature (Kmax), maximum corneal power (Pmax), central corneal thickness (CCT), and intra- and postoperative complications were assessed.

RESULTS

Excluding eyes requiring re-transplantation for primary graft failure (n = 3), all eyes showed improvement in BSCVA, reaching ≥ 20/40 (0.5) in 86%, ≥ 20/25 (0.8) in 55%, and ≥ 20/20 (1.0) in 27% by one month postoperatively; 90%, 76%, and 48% by 6 months postoperatively; and 88%, 76%, and 47% by 12 months postoperatively. CCT decreased from 571μm preoperatively to 485μm at 1 month (p < 0.001) and 481μm at 12 months (p < 0.001). Kmax decreased by a median of 1.4 diopters (D) at 1 month (p = 0.003) and 3.1 D at 12 months (p = 0.021), and every eye with a preoperative Kmax ≥ 46 D demonstrated flattening. Pmax decreased by 2.1 D at 1 month (p = 0.001) and 4.0 D at 12 months (p = 0.016).

CONCLUSION

DMEK is technically feasible in eyes with comorbid KCN and may give excellent outcomes visual and refractive outcomes, including significant corneal flattening, which may potentially create a visually significant hyperopic shift in patients with severely ectatic corneas.

Penetrating Keratoplasty: Indications and Graft Survival by Geographic Region

Corneal transplantation, or penetrating keratoplasty (PK), is the most common form of solid-organ transplantation performed worldwide. Here, we evaluated the indications for PK and rates of transplant survival around the world by geographic region. We conducted a literature search of PubMed, MEDLINE, and Google Scholar databases and identified 155 relevant studies from 41 countries published between 1987 and 2021. The most common indications for PK were keratoconus in Europe, Africa, the Middle East, Australia, New Zealand, and Central and South America, bullous keratopathy in North America, and corneal scarring in Asia. The overall global mean graft survival rates at 1-, 2-, 3-, 5-, and 10-years were 88.6%, 81.2%, 78.9%, 72.8%, and 61.2%, respectively. Through this systematic analysis of PK by region, we hope to bring a new perspective to the corneal transplantation literature and to potentially highlight global differences and unmet needs in patient care.