Penetrating keratoplasty: indications over a 10 year period

Herpes simplex virus, varicella-zoster virus and cytomegalovirus keratitis: Facts for the clinician

Keratitis due to Herpes simplex virus (HSK), Varicella-Zoster virus (VZK) and Cytomegalovirus remains a frequent source of concern for many ophthalmologists. They are a frequent cause of emergency consultations at eye care centers and carry the risk of permanent loss of visual acuity or visual quality and/or chronic neurotrophic keratitis, resulting in a significant decrease in the quality of life. HSK and VZK can affect the corneal epithelium, stroma, or endothelium or a combination of layers. In contrast, most cases of CMV keratitis present as isolated endothelitis (CMVE), a clinical entity that has been described within the last 2 decades. These three types of viral keratitis are characterized by a high frequency of recurrences and each new episode increases the risk of sequelae. Hence, ophthalmologists must adapt the treatment to the clinical presentation of each recurrent episode in order to mitigate the immediate consequences of viral replication and the immune response on corneal transparency. In patients with frequent recurrences, preventive long-term antiviral treatment is strongly recommended. However, in some rare cases, continuous exposure to antivirals may promote the emergence of resistant viral strains, which can be difficult to manage. In the future, the introduction of new antiviral drugs, with differing modes of action compared to current medical therapy, could be an alternative until a truly effective preventive solution, such as a vaccine, is available.

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.

Clinical Ocular Exposure Extrapolation for Ophthalmic Solutions Using PBPK Modeling and Simulation

BACKGROUND

The development of generic ophthalmic drug products is challenging due to the complexity of the ocular system, and a lack of sensitive testing to evaluate the interplay of physiology with ophthalmic formulations. While measurements of drug concentration at the site of action in humans are typically sparse, these measurements are more easily obtained in rabbits. The purpose of this study is to demonstrate the utility of an ocular physiologically based pharmacokinetic (PBPK) model for translation of ocular exposure from rabbit to human.

METHOD

The Ocular Compartmental Absorption and Transit (OCAT™) model within GastroPlus® v9.8.2 was used to build PBPK models for levofloxacin (Lev), moxifloxacin (Mox), and gatifloxacin (Gat) ophthalmic solutions. in the rabbit eye. The models were subsequently used to predict Lev, Mox, and Gat exposure after ocular solution administrations in humans. Drug-specific parameters were used as fitted and validated in the rabbit OCAT model. The physiological parameters were scaled to match human ocular physiology.

RESULTS

OCAT model simulations for rabbit well described the observed concentrations in the eye compartments following Lev, Mox, and Gat solution administrations of different doses and various administration schedules. The clinical ocular exposure following ocular administration of Lev, Mox, and Gat solutions at different doses and various administration schedules was well predicted.

CONCLUSION

Even though additional case studies for different types of active pharmaceutical ingredients (APIs) and formulations will be needed, the current study represents an important step in the validation of the extrapolation method to predict human ocular exposure for ophthalmic drug products using PBPK models.

Prevalence of Herpesvirus DNA in Corneal Transplant Recipients

Purpose: Graft failure after penetrating keratoplasty (PK) is a serious complication, especially in eyes with herpetic keratitis (HK). This study evaluated the prevalence and graft survival of herpes simplex virus type 1 (HSV-1) and varicella zoster virus (VZV) DNA in recipient corneas during PK. Methods: The retrospective study was performed at the Department of Ophthalmology at University Hospital in Mainz, Germany. We analyzed data from every patient who underwent PK between January 2020 and June 2021. According to our clinical routine, we performed HSV-1 and VZV polymerase chain reaction (PCR) on all excised corneal buttons regardless of the primary clinical diagnosis. Results: We included 112 eyes of 112 consecutive patients who underwent PK. At the time of PK, 91 (81.25%) patients had no history of HK and 21 (18.75%) patients did. The recipient corneas of 91 patients without a history of HK tested positive for HSV-1 DNA in 12 (13.2%) eyes, for VZV DNA in 3 (3.3%) eyes, and for HSV-1 and VZV DNA simultaneously in 2 (2.2%) eyes. The recipient corneas of 21 patients with a preoperative history of HK tested positive for HSV-1 DNA in 13 (61.9%) eyes and VZV DNA in 1 (4.8%) eye. All patients with positive herpes DNA and no history of HK prior to PK received antiherpetic treatment and had a 100% graft survival rate after 1 year. Conclusions: We found herpesvirus DNA in 18.7% of recipient corneas without clinical suspicion or history of herpes keratitis. This suggests the need of routine HSV-1 and VZV PCR testing in all explanted corneas regardless of clinical suspicion, to detect, treat and prevent possible recurrence of herpes infection in corneal grafts and support graft survival.

Presence of Panel-reactive Antibodies after Penetrating Keratoplasty

PURPOSE

To evaluate the relationship between penetrating keratoplasty (PK) and postoperative PRA level and number of unacceptable antigens.

METHODS

A cross-sectionalstudy was performed on patients with history of PK. Patients with prior solid organ transplantation, pregnancy, or blood transfusion were excluded. These findings were combined with a retrospective review. Patients were grouped by single or multiple PKs. The primary outcome was postoperative PRA level.

RESULTS

Incidence of postoperative PRA elevation and mean peak PRA was higher in the multiple PK group (p = .08 and p = .010, respectively). Mean number of unacceptable antigens was elevated in the multiple PK group (p = .024). There was a moderately positive correlation between number of PK grafts and PRA level (r = 0.629, p = .0002).

CONCLUSIONS

PRA level may be influenced by PKs, with higher PRA associated with increased prior PKs. Further studies are necessary to determine the potential prognostic value.Abbreviations: PK: penetrating keratoplasty; PRA: panel reactive antibodies; OSST: ocular surface stem cell transplantation; LSCD: limbal stem cell deficiency.

Indications and Surgical Techniques for Repeat Corneal Transplantation in Eastern China: A Twelve-Year Study

Purpose

To analyze the indications and surgical procedures for repeat keratoplasty in eastern China from 2008 to 2019.

Methods

This retrospective descriptive study included 418 eyes of 411 patients who underwent no less than 2 keratoplasties at the Eye, Ear, Nose and Throat Hospital of Fudan University from 2008 to 2019. Medical charts were reviewed. The primary indications for repeat keratoplasty, the reasons for regrafting, and the surgical techniques used in the treatment were collected and analyzed.

Results

Among 418 eyes, 337 eyes (80.6%) had one repeat keratoplasty, and 81 eyes (19.4%) had multiple repeat keratoplasties (≥2 repeat keratoplasties). The median interval between the initial keratoplasty and the first repeat keratoplasty was 25 months, and that between two keratoplasties after the first repeat keratoplasty was 27.5 months. Infectious keratitis was the leading primary indication for single repeat keratoplasty (80 cases, 23.7%) and multiple repeat keratoplasties (19 cases, 23.5%). The second most common primary indication was bullous keratopathy for single repeat keratoplasty (49 eyes, 14.5%) and chemical injury for multiple repeat keratoplasties (14 eyes, 17.3%). The main reason for regrafting was allograft rejection (262 cases, 49.3%), followed by endothelial dysfunction (92 cases, 17.3%), and for vision improvement after tectonic keratoplasty (60 cases, 11.3%). Penetrating keratoplasty (PKP) was the major technique used in repeat keratoplasty (447 cases, 84.2%). However, Descemet stripping endothelial keratoplasty was more frequently used than PKP (72.4% vs. 27.6%, P < 0.001) in the treatment of failed endothelial keratoplasty.

Conclusion

Infectious keratitis was still the leading cause of repeat keratoplasty in eastern China. Although PKP remains the major technique of repeat keratoplasty, the application of customized lamellar keratoplasty has greatly expanded in the last decade. Cautious selection of indications, surgical techniques, and timing for surgery is crucial for a good prognosis after repeat keratoplasty.

The Association between Diabetes Mellitus and Keratoplasty in Poland in the Years 2013-2017

BACKGROUND

The aim of this study is to assess the incidence and characteristic of corneal grafts and its association with diabetes mellitus in Poland in the years 2013-2017.

METHODS

The retrospective survey of the National Database of Hospitalizations was performed to identify all the corneal transplantations in Poland between January 2013 and December 2017. The comorbid diseases, in particular diabetes mellitus, were verified in the patients' medical history. The logistic regression was applied to demonstrate the factors related to urgent surgeries.

RESULTS

In total, 5069 corneal grafts in 4710 patients were reported in the years 2013-2017. The number of CTs gradually increased by 37% from 914 (2.37 surgeries per one hundred thousand population) in the year 2013 to 1250 (3.25 surgeries per one hundred thousand population) in 2017, the final year of the study. CT incidence was the highest in subjects aged 70 years or older: 13.18 per one hundred thousand population in the year 2017. On average, about 22.43% of procedures were performed in patients with DM. The chance of urgent surgery was mostly correlated with full thickness CT and patients' age.

CONCLUSIONS

Despite the relatively low value of CT in Poland, there was an increasing number of CTs in the analyzed period.

The intra-operative corneal pachymetry changes during accelerated corneal cross-linking in progressive keratoconus patients with thin corneas

Purpose

To report the intra-operative corneal pachymetry changes during accelerated corneal cross-linking (A-CXL) in progressive keratoconus patients with thin corneas.

Methods

Thirty-six eyes (mean age: 22.26 ± 4.02 years) with progressive keratoconic thin corneas (< 400 µm without epithelium) who underwent A- CXL with ultraviolet A (9 mW/cm2) using isotonic RF-HPMC (riboflavin5-phosphate 0.1% with 1.1% hydroxypropyl methycellulose/Mediocross M®) were included in this retrospective study. Intra-operative corneal pachymetric changes were noted before the procedure, after removal of epithelium, after RF-HPMC instillation, before and after UV irradiation. The mean of corneal pachymetric values were compared statistically.

Results

The mean corneal pachymetry reduced from 415.72±29.66 µm to 369.50±23.45 µm after removal of the epithelium (p<0.05). After the application of RF-HPMC solution the mean TCP increased to 412.89±26.94 µm. Statistically significant increase was observed in TCP after saturation with RF-HPMC (p=0.001). The mean corneal pachymetry was before and after UV-A irradiation respectively 419.86±10.41 µm, 417.47±8.25 µm (p>0.05).

Conclusion

Isotonic RF-HPMC lead to a significant increase in intra-operative mean TCP. RF-HPMC seems to be a favorable riboflavin option in keratoconus patients with thin corneas.

Post-keratoplasty Infectious Keratitis: Epidemiology, Risk Factors, Management, and Outcomes

Post-keratoplasty infectious keratitis (PKIK) represents a unique clinical entity that often poses significant diagnostic and therapeutic challenges. It carries a high risk of serious complications such as graft rejection and failure, and less commonly endophthalmitis. Topical corticosteroids are often required to reduce the risk of graft rejection but their use in PKIK may act as a double-edged sword, particularly in fungal infection. The increased uptake in lamellar keratoplasty in the recent years has also led to complications such as graft-host interface infectious keratitis (IIK), which is particularly difficult to manage. The reported incidence of PKIK differs considerably across different countries, with a higher incidence observed in developing countries (9.2-11.9%) than developed countries (0.02-7.9%). Common risk factors for PKIK include the use of topical corticosteroids, suture-related problems, ocular surface diseases and previous corneal infection. PKIK after penetrating keratoplasty or (deep) anterior lamellar keratoplasty is most commonly caused by ocular surface commensals, particularly Gramme-positive bacteria, whereas PKIK after endothelial keratoplasty is usually caused by Candida spp. Empirical broad-spectrum antimicrobial treatment is the mainstay of treatment for both PKIK, though surgical interventions are required in medically refractory cases (during the acute phase) and those affected by visually significant scarring (during the late phase). In this paper, we aim to provide a comprehensive overview on PKIK, encompassing the epidemiology, risk factors, causes, management and outcomes, and to propose a treatment algorithm for systematically managing this challenging condition.

The impact of biomechanics on corneal endothelium tissue engineering

The integrity of innermost layer of the cornea, the corneal endothelium, is key to sustaining corneal transparency. Therefore, disease or injury causing loss or damage to the corneal endothelial cell population may threaten vision. Transplantation of corneal tissue is the standard treatment used to replace malfunctioning corneal endothelial cells. However, this surgery is dependent upon donor tissue, which is limited in supply. Hence, tissue engineers have attempted to construct alternative transplantable tissues or cell therapies to alleviate this problem. Nevertheless, the intrinsic non-dividing nature of corneal endothelial cells continues to foil scientists in their attempts to yield large numbers of cells in the laboratory for use in such novel therapies. Interestingly, the contribution of the biomechanical properties of the underlying extracellular matrix (ECM) on cell division, tissue development and maintenance has been extensively investigated in other many cell types. However, the impact of biomechanics on corneal endothelial cell behaviour is relatively unexplored. Here, we describe contemporary tissue engineering solutions aimed at circumventing donor tissue scarcity. We review the ECM structure and biomechanical features of corneal endothelial cells. We discuss the alterations of ECM in endothelial disease development and progression and point out the role of ECM in developing a tissue-engineered corneal endothelium. We highlight the main biomechanical cues, including topographical and mechanical features, that impact cellular behaviors. Finally, we discuss the influence of biomechanical cues on cell and tissue development, and how corneal endothelial cells response to individual biomechanical stimuli in tissue engineering, which have implications for designing an engineered endothelium and maintaining cell function.

Survey of Rejection Prophylaxis Following Suture Removal in Penetrating Keratoplasty in Germany

BACKGROUND

Penetrating keratoplasty (PK) gets more and more reserved to cases of increasing complexity. In such cases, ocular comorbidities may limit graft survival following PK. A major cause for graft failure is endothelial graft rejection. Suture removal is a known risk factor for graft rejection. Nevertheless, there is no evidence-based regimen for rejection prophylaxis following suture removal. Therefore, a survey of rejection prophylaxis was conducted at 7 German keratoplasty centres.

OBJECTIVE

The aim of the study was documentation of the variability of medicinal aftercare following suture removal in Germany.

METHODS

Seven German keratoplasty centres with the highest numbers for PK were selected. The centres were sent a survey consisting of half-open questions. The centres performed a mean of 140 PK in 2018. The return rate was 100%. The findings were tabulated.

RESULTS

All centres perform a double-running cross-stitch suture for standard PK, as well as a treatment for rejection prophylaxis with topical steroids after suture removal. There are differences in intensity (1 - 5 times daily) and tapering (2 - 20 weeks) of the topical steroids following suture removal. Two centres additionally use systemic steroids for a few days.

DISCUSSION

Rejection prophylaxis following PK is currently poorly standardised and not evidence-based. All included centres perform medical aftercare following suture removal. It is assumed that different treatment strategies show different cost-benefit ratios. In the face of the diversity, a systematic analysis is required to develop an optimised regimen for all patients.

New perspectives in keratoconus treatment: an update on iontophoresis-assisted corneal collagen crosslinking

Keratoconus is a bilateral, asymmetric and progressive corneal disease. It usually results in apical thinning and steepening with corneal deformation and impaired vision. Since the early 1990 s, corneal collagen crosslinking (CXL) has remained the primary treatment to stabilize the progression of the disease. Iontophoresis-assisted CXL (I-CXL) has been proposed as a non-invasive alternative to standard epithelium-off technique, showing promising results. In this article, we review up to date literature to provide state of art knowledge and future perspectives of I-CXL.

Clinical Characteristics and Outcomes of Short-term Repeat Corneal Transplantation

PURPOSE

To explore the primary indications, direct causes and graft survival of short-term repeat keratoplasty.

METHODS

An analytical cross-sectional study.

RESULTS

The primary indications for keratoplasty were infectious keratitis (67.9%) and immune keratopathy (12.8%). The direct causes of graft failure were infectious ulcer (43.6%) and recurrence (30.8%). Pre-operative hypopyon (P = 0.017, HR = 1.757) and use of decellularized porcine corneas as grafts (P = 0.005, HR = 2.690) were independent risk factors for graft failure. The Kaplan-Meier analysis revealed that the 1-year survival rate of 88 repeat grafts was 85.2%, and the 5-year survival rate was 79.2%. The survival rates of the repeat grafts were significantly higher than those of the first grafts (P < 0.001).

CONCLUSION

Infectious keratitis is the most common indication of short-term graft failure and is often failed by infectious ulcer and keratitis recurrence. While the decellularized porcine cornea is a promising application in developing countries, certain difficulties, such as graft melting, remain unresolved.

Changing trends in penetrating keratoplasty indications at a tertiary eye care center in Budapest, Hungary between 2006 and 2017

AIM

To analyze the changing trends in penetrating keratoplasty (PKP) indications.

METHODS

This retrospective study included all patients with PKP between 2006 and 2017. Patients were classified using histological diagnoses. Our groups were as the following: pseudophakic or aphakic bullous keratopathy, regraft, acute necrotizing and ulcerative keratitis, keratoconus, Fuchs' dystrophy, corneal dystrophy other than Fuchs', corneal scar, other diagnoses and failed endothelial keratoplasty graft. Additionally, two different time-periods (2006-2012 and 2013-2017) were analysed.

RESULTS

Totally 1721 histological analyses of 1214 patients were available for review. The diagnoses were pseudophakic or aphakic bullous keratopathy in 487 (28.3%), regraft in 443 (25.7%), acute necrotizing and ulcerative keratitis in 313 (18.2%), corneal scar in 153 (8.9%), keratoconus in 140 (8.1%). Fuchs' dystrophy in 61 (3.5%), corneal dystrophy other than Fuchs' in 46 (2.7%), other diagnoses in 44 (2.6%) and failed endothelial keratoplasty graft in 34 (2.0%) cases. From the first to the second analysed time-period, incidence of acute necrotizing and ulcerative keratitis, corneal scar, Fuchs' dystrophy increased (P≤0.032 for all) and incidence of keratoconus significantly decreased (P=0.015).

CONCLUSION

Pseudophakic or aphakic bullous keratopathy is the leading indication for PKP, followed by regraft and acute necrotizing and ulcerative keratitis.

Periocular neural crest cell differentiation into corneal endothelium is influenced by signals in the nascent corneal environment

During ocular development, periocular neural crest cells (pNC) migrate into the region between the lens and presumptive corneal epithelium to form the corneal endothelium and stromal keratocytes. Although defects in neural crest cell development are associated with ocular dysgenesis, very little is known about the molecular mechanisms involved in this process. This study focuses on the corneal endothelium, a monolayer of specialized cells that are essential for maintaining normal hydration and transparency of the cornea. In avians, corneal endothelial cells are first to be specified from the pNC during their migration into the presumptive corneal region. To investigate the signals required for formation of the corneal endothelium, we utilized orthotopic and heterotopic injections of dissociated quail pNC into chick ocular regions. We find that pNC are multipotent and that the nascent cornea is competent to induce differentiation of ectopically injected pNC into corneal endothelium. Injected pNC downregulate expression of multipotency transcription factors and upregulate genes that are consistent with ontogenesis of the chick corneal endothelium. Importantly, we showed that TGFβ2 is expressed by the nascent lens and the corneal endothelium, and that TGFβ signaling plays a critical role in changing the molecular signature of pNC in vitro. Collectively, our results demonstrate the significance of the ocular environmental cues towards pNC differentiation, and have potential implications for clinical application of stem cells in the anterior segment.

Repeat keratoplasty in failed Descemet stripping automated endothelial keratoplasty

Purpose:

To evaluate the clinical factors associated with repeat Descemet stripping automated endothelial keratoplasty (DSAEK) or penetrating keratoplasty (PKP) in cases of failed DSAEK.

Methods:

Retrospective observational study of cases with failed DSAEK admitted to our center for a repeat keratoplasty over 5 years (January 2013–Decemeber 2017) was undertaken. Demographic and perioperative details of all cases and type of repeat keratoplasty were recorded. Logistic regression analysis was performed to analyze the factors affecting the type of repeat keratoplasty.

Results:

A total of 94 eyes with failed DSAEK were evaluated. Repeat DSAEK was performed in 66% and PKP in 34% of cases. Significantly increased odds for requiring PKP were observed in association with stromal scarring [odds ratio (OR) = 2.9, P = 0.018)], trainee surgeons (OR = 4.05, P = 0.008), intraoperative complications (OR = 4.58, P = 0.003), scleral fixated intraocular lens or anterior chamber intraocular lens in situ (OR = 33.8, P < 0.001), secondary glaucoma (OR = 3.02, P = 0.015), peripheral anterior synechiae (OR = 8.6, P < 0.001), preoperative corneal thickness (OR = 1.01, P < 0001), time to primary surgery (OR = 1.03, P = 0.03), post-DSAEK host thickness (OR = 1.01, P < 0.001), and time interval from graft failure to regraft (OR = 1.18, P < 0.001). All eyes with congenital hereditary endothelial dystrophy, bee-sting-induced corneal decompensation, Axenfeld-Rieger syndrome, and multiple failed grafts underwent secondary PKP. All cases (nine eyes) that required surgical intervention for secondary glaucoma underwent secondary PKP (P < 0.001).

Conclusion:

Repeat DSAEK is feasible in up to two-third of cases of failed DSAEK. A PKP is required in one-third of cases, and various preoperative, intraoperative and postoperative factors are associated with unsuitability for repeat DSAEK.

A 27-Year Report from the Central Eye Bank of Iran

Purpose

To report the 27-year statistical data from the Central Eye Bank of Iran (CEBI) and its activity.

Methods

All CEBI records regarding procured eyes, tissue utilizations, corneal transplants per capita, and indications for keratoplasty from 1991 to 2017 were analyzed.

Results

In total, 115,743 whole eyes were donated during the 27-year period. Out of the 114,169 eyes donated between 1994 and 2017, 95,314 eyes were distributed for transplantation, and 95,057 corneas were actually transplanted. The mean annual rate of corneal transplants per capita was 55.10 - 6 ± 27.10 - 6 . Although penetrating keratoplasty (PKP, 70%) was the most common technique of corneal transplantation during the study period, it exhibited a decreasing trend between 2006 and 2017 (P = 0.048). It was in contrast to Descemet stripping automated endothelial keratoplasty (DSAEK) that demonstrated an increasing trend during the same period (P < 0.001). Keratoconus (KCN, 39.70%) was the most leading indication for keratoplasty over the last three decades followed by bullous keratopathy (BK, 18.5%), corneal scar and opacities (15.7%), and graft failure (GF, 7.5%), with an increasing trend for BK, GF, and KCN. A majority of scleral tissues (83.7%) were utilized for orbital implant protection.

Conclusion

An increasing trend in the number of procured eyes was observed over the past 27 years in Iran. The most leading indications for corneal transplantation were KCN and BK. While PKP was the most common keratoplasty technique, DSAEK showed an increasing trend over the last 12 years.

Clinical Outcomes of Penetrating Keratoplasty and Descemet Stripping Automated Endothelial Keratoplasty in Asian Population with American Corneas

To determine the comparative efficacy and safety of penetrating keratoplasty (PK) and Descemet stripping automated endothelial keratoplasty (DSAEK) in the Asian population receiving imported donor corneas, our single-center retrospective study provides analysis supporting the transition from PK to DSAEK in the Asian population using imported American donor corneas. We analyzed 259 patients with 241 and 57 cases of PK and DSAEK respectively during 2008 to 2017 using imported corneas at Chang Gung Memorial Hospital, Linkou, Taiwan. In terms of long-term graft survival analysis, there was no difference between PK and DSAEK (log-rank p = 0.386, HR = 0.920, 95% CI: [0.641–1.380]). However, Cox proportional regression analysis revealed that corneal survival rate of DSAEK group in the first 100 days after transplantation was inferior than that of PK group (log-rank p < 0.001, HR = 2.733, 95% CI: [1.501–4.977])]. Despite the inferior survival rate, there were significantly less neovascularization and Descemet membrane folds in the DSAEK group. Importantly, the non-complication rate of DSAEK was much higher than that of PK with significant difference (PK, 25.7% vs. DSAEK 42.0%, p = 0.022). Collectively, DSAEK is suggested as an alternative surgical modality in Asian patients using imported American donor corneas because of less complication, and no difference in long-term corneal graft survival rates between PK and DSAEK.

Investigating the effect of chitosan/ polycaprolactone blends in differentiation of corneal endothelial cells and extracellular matrix compositions

This study aimed to investigate the underlying mechanisms of corneal endothelial cells (CECs) differentiation and identify the extracellular matrix (ECM) compositions using chitosan/polycaprolactone (PCL) blended membrane, hence exploring the potential use of chitosan/PCL blends in tissue engineering of CECs. We utilized the chitosan/PCL blends named as PCL25 consisting of PCL at 25% by weight. The surface characteristics of PCL25 were confirmed by using Fourier Transform Infrared Spectroscopy (FTIR) and Atomic Force Microscope (AFM). Bovine CECs were cultured on the blends, compared with TCPS and pure chitosan membrane. Cell behaviors in terms of cell attachment, proliferation, differentiation phenotype and expression of differentiation proteins were examined. Furthermore, ECM protein productions were also analyzed. From the experiments, we found the topography (roughness) of PCL25 membrane examined by AFM was greater than pure chitosan membrane. FTIR results confirmed the functional groups of C=O bond of PCL. The CECs displayed hexagonal morphology and similar proliferation rate on both PCL25 membrane and TCPS. In addition, the immunofluorescence evidence showed well-localized ZO-1 and Na⁺/K⁺ ATPase expression of membrane proteins. ECM protein productions of CECs on PCL were no inferior to TCPS. Moreover, western blot results verified the higher amount of collagen type IV, and reduced TGF-β2 expression on PCL25 membrane compared to TCPS substrate. In conclusions, chitosan/PCL blends membrane provided a favorable environment for CECs in terms of ECM compositions, therefore enhancing the growth and differentiation. Accordingly, for CEC tissue engineering applications, PCL 25 might be a suitable alternative for cadaveric cornea transplantation in the near future.

Efficacy of Anterior Stromal Puncture Surgery with Corneal Bandage Lens for Bullous Keratopathy

Objective: To investigate the safety and efficacy of the combination therapy of anterior stromal puncture (ASP) with bandage contact lens for bullous keratopathy (BK). Methods: Twelve cases (12 eyes) with vision acuity no better than light perception were treated with ASP surgery and bandage contact lens. 200 points punctures were made through the corneal epithelium and Bowman's layer vertically, using fine needles. A soft bandage contact lens was applied immediately and removed 2 weeks later. The severity of irrigating symptoms including pain, photophobia and tearing was graded and calculated before treatment and 1, 2, 4, 12 weeks after the surgery, slit-lamp microscope examination was used to quantify the time for corneal epithelial blisters disappearing, optical coherence tomography (OCT) was used to monitor the central corneal thickness. Results: No cornea infection was observed during the following up period. The average grade scores of the irrigating symptoms was 8.3 ± 2.1 before surgery, while it was reduced to 4.8 ±1.9 two weeks after the surgery (p=0.0003). Slit-lamp microscope examination showed that corneal edema relieved obviously after the operation, the average time for epithelial blisters disappearing was 15.6 ± 4.0 days. The average central corneal thickness of the eyes was 999.3 ±278.0 μm before the treatment, while it was 805.1 ± 145.0 μm four weeks after the treatment, with a statistically significant difference (p=0.043). Conclusions: ASP with bandage contact lens is an effective and safe treatment for patients with BK and low vision that not suitable for corneal transplantation.

Lymphatic vessels identified in failed corneal transplants with neovascularisation

BACKGROUND

Corneal transplant failure with neovascularisation is a leading indication for full-thickness grafts in patients. Lymphangiogenesis is implicated in the pathology of graft failure, and here we systematically evaluate failed human corneal transplants with neovascularisation for the presence of lymphatic vessels.

METHODS

Nine failed grafts with neovascularisation, based on H&E staining with subsequent immunoperoxidase staining for CD31, a blood vessel marker, were selected. Lymphatics were investigated by immunohistochemical and immunofluorescence approaches using podoplanin as a lymphatic marker. In two of nine cases, fluorescence in situ hybridisation (FISH) was used for detection of lymphatic mRNAs including podoplanin, VEGFR-3 and LYVE-1. All immunofluorescence and FISH samples were compared with positive and negative controls and visualised by confocal microscopy.

RESULTS

Corneal neovascularisation was established in all cases by H&E and further confirmed by CD31 immunoreactive profiles. Immunohistochemistry for the podoplanin antibody was positive in all cases and showed morphologies ranging from distinct luminal structures to elongated profiles. Simultaneous immunofluorescence using CD31 and podoplanin showed lymphatic vessels distinct from blood vessels. Podoplanin immunofluorescence was noted in seven of nine cases and revealed clear lumina of varying sizes, in addition to lumen-like and elongated profiles. The presence of lymphatic mRNA was confirmed by FISH studies using a combination of at least two of podoplanin, VEGFR-3 and LYVE-1 mRNAs.

CONCLUSIONS

The consistent finding of lymphatic vessels in failed grafts with neovascularisation implicates them in the pathogenesis of corneal transplant failure, and points to the lymphatics as a potential new therapeutic target.

Improving precision for detecting change in the shape of the cornea in patients with keratoconus

To investigate a method for precision analysis to discriminate true corneal change from measurement imprecision in keratoconus (KC). Thirty patients with KC and 30 healthy controls were included. Coefficients of repeatability and limits of agreement (LOA) were compared using multiple measurements for inter-observer and inter-device agreement with the Pentacam HR, Orbscan IIz, and Tomey Casia SS-1000. Correlation of repeated measurements was evaluated using a linear mixed effect model (also called random effect model). A formula was derived for the theoretical expected change in precision and compared with measured change. Correlation between measurements from the same eye was small (R = 0.13). The 99.73% LOA (3 SD) of the mean of three measurements, provided better precision than 95% LOA (2 SD) of single cut-off values as expected from statistical theory for uncorrelated measurements for evidence of a significant change in corneal shape in patients with keratoconus. This enabled the determination of cut-off values for the detection of true change in corneal shape. The mean of three repeated measurements will provide better precision when there is minimal correlation. Three (rather than two) standard deviations provides a precise estimate of the LOA within or between observers and can be used as a reliable measure for identifying stage-independent corneal shape changes (progression) in keratoconus.

Changing Indications in Penetrating Keratoplasty: A Systematic Review of 34 Years of Global Reporting

BACKGROUND

Penetrating keratoplasty (PK) ranks among the oldest and most common kinds of human tissue transplantation. Based on the hypothesis that reported indications for PK significantly vary between global regions and over time, the present systematic review aimed to provide a thorough overview of global PK indications as reported in peer-reviewed manuscripts.

METHODS

A literature search of PubMed and MEDLINE was conducted to retrieve articles published from January 1980 to May 2014. Indications for PK within 7 global regions were compared using a modified classification system for PK indications and analyzed via multivariate regression.

RESULTS

A total of 141 publications from 37 countries were included, recording 180 865 PK cases. Postcataract surgery edema was the predominant indication in North America (28.0%) and ranked second in Europe (20.6%), Australia (21.1%), the Middle East (13.6%), Asia (15.5%), and South America (18.6%). Keratoconus was the leading indication in Europe (24.2%), Australia (33.2%), the Middle East (32.8%), Africa (32.4%), and South America (22.8%). It ranked third in North America (14.2%). Keratitis was the primary indication in Asia (32.3%). Fuchs endothelial corneal dystrophy was the fourth most common indication in North America (12.9%) and Europe (10.2%) and fifth in South America (3.8%). Multivariate analysis supported these results and revealed individual regional changes over time.

CONCLUSIONS

Systematic analysis reveals characteristic chronological and regional differences in reported global PK indications. Leading reported indications for PK between 1980 and 2014 were keratoconus (Europe, Australia, the Middle East, Africa, and South America), pseudophakic bullous keratopathy/aphakic bullous keratopathy (North America), and keratitis (Asia).

Cataract Surgery in Patients with Keratoconus: Pearls and Pitfalls

Background:

Keratoconus (KC) is a common ectatic disorder resulting in progressive corneal thinning and irregular astigmatism. It has been observed that patients affected by KC are more likely to develop lens opacities earlier compared to non-keratoconic patients.

Objective:

Intraocular lens (IOL) selection and refractive outcome prediction are among a number of factors that can make cataract surgery in keratoconic patients challenging. Accurate biometry is often difficult to obtain due to unreliable K measurements and lack of dedicated biometric formulae. The use of toric IOLs has also been investigated.

Conclusions:

Determining the stage of KC, pre-operative patient counselling and the preferred method of refractive correction are all crucial to obtain successful postoperative outcomes and good patient satisfaction. The use of toric IOLs can achieve good results only in selected low-grade keratoconic eyes.

Endothelial keratoplasty versus repeat penetrating keratoplasty after failed penetrating keratoplasty: A systematic review and meta-analysis

Objective

This study sought to compare graft survival, graft rejection and the visual acuity outcome of endothelial keratoplasty (EK) with repeat penetrating keratoplasty (PK) after failed PK.

Methods

A systematic literature search with subsequent screening of the identified articles was conducted to obtain potentially eligible randomized clinical trials (RCTs) and comparative cohort studies. To assess the methodological quality of the included studies, the Jadad Scale or Newcastle-Ottawa Scale (NOS) was used based on the study design. To calculate the pooled odds ratios (ORs) for graft survival, graft rejection and the visual acuity outcome with 95% confidential intervals (CIs), a fixed- or random-effects model was applied based on the heterogeneity across studies.

Results

Four comparative cohort studies (n = 649 eyes) comparing the outcome of EK with repeat PK after failed PK were included in this review. These studies were considered high quality, with NOS scores ranging from 6 to 9. The EK group showed a significantly lower risk of graft rejection than the repeat PK group [0.43 (95% CI: 0.23–0.80, P = 0.007)]. In addition, no significant differences were observed in a comparison of graft survival and visual acuity (P values ranged from 0.81 to 0.97 using the Der-Simonian and Laird random-effects model).

Conclusions

As an alternative to repeat PK, EK after failed PK allows for potential reduction of the risk of graft rejection; however, it does not appear to confer a significant advantage in graft survival or visual acuity.

MicroRNA-29b Overexpression Decreases Extracellular Matrix mRNA and Protein Production in Human Corneal Endothelial Cells

PURPOSE

MicroRNAs are small noncoding RNAs that regulate gene expression at the posttranscriptional level. We reported that levels of microRNA (miR)-29 family are decreased in corneas of patients with Fuchs endothelial corneal dystrophy (FECD). The miR-29 family regulates the production of extracellular matrix (ECM) proteins. Accumulation of ECM proteins in Descemet membrane is an important pathologic change in FECD. In this study, we transfected miR-29b into human corneal endothelial cells and tissues and evaluated ECM protein expression levels.

METHODS

An immortalized Fuchs human corneal endothelial cell line (iFECD) was established by infection of corneal endothelial cells from patients with FECD with hTERT lentivirus. MiR-29b was transfected into iFECD, and the expression levels of ECMs collagen type 1 alpha 1 (COL1A1), collagen type 4 alpha 1 (COL4A1), and laminin gamma 1 (LAMC1) were evaluated with quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) and Western blot. Expression level of LAMC1 protein in miR-29b-transfected donor corneal endothelium was also evaluated by Western blot.

RESULTS

Compared with control, miR-29b expression level after transfection of iFECD was increased to 335.6% (±91.0%), and ECM expression levels were significantly decreased. Compared with control, qRT-PCR demonstrated reduction of ECM to the following levels: COL1A1: 1.9% (±0.4%); COL4A1: 7.1% (±1.7%); and LAMC1: 21.5% (±2.7%). Western blot showed reduced protein expression: COL1A1: 4.8% (±3.2%); COL4A1: 42.5% (±25.0%); and LAMC1: 44.8% (±3.1%). In miR-29b-transfected corneal tissue, LAMC1 protein expression level was decreased to 14.4% (±20.5%).

CONCLUSIONS

Overexpression of miR-29b decreased ECM protein production in human corneal endothelial cells. Thus, miR-29 replacement therapy might be a new treatment strategy for FECD aimed at reducing pathologic production of ECM proteins in Descemet membrane.

Comprehensive characterization of DNA methylation changes in Fuchs endothelial corneal dystrophy

Transparency of the human cornea is necessary for vision. Fuchs Endothelial Corneal Dystrophy (FECD) is a bilateral, heritable degeneration of the corneal endothelium, and a leading indication for corneal transplantation in developed countries. While the early onset, and rarer, form of FECD has been linked to COL8A2 mutations, the more common, late onset form of FECD has genetic mutations linked to only a minority of cases. Epigenetic modifications that occur in FECD are unknown. Here, we report on and compare the DNA methylation landscape of normal human corneal endothelial (CE) tissue and CE from FECD patients using the Illumina Infinium HumanMethylation450 (HM450) DNA methylation array. We show that DNA methylation profiles are distinct between control and FECD samples. Differentially methylated probes (10,961) were identified in the FECD samples compared with the control samples, with the majority of probes being hypermethylated in the FECD samples. Genes containing differentially methylated sites were disproportionately annotated to ontological categories involving cytoskeletal organization, ion transport, hematopoetic cell differentiation, and cellular metabolism. Our results suggest that altered DNA methylation patterns may contribute to loss of corneal transparency in FECD through a global accumulation of sporadic DNA methylation changes in genes critical to basic CE biological processes.

Cell viability and shock wave amplitudes in the endothelium of porcine cornea exposed to ultrashort laser pulses

PURPOSE

Some forms of keratoplasty assisted by ultrashort-pulse lasers require performing laser cuts close to the endothelium, which requires the knowledge of "safe" values concerning incision depth and pulse energy preserving endothelial cell viability. Our study aims to determine the thresholds for cell death in porcine corneas exposed to ultrashort laser pulses, in terms of laser pulse energy and nearness of the impacts to the endothelium.

METHODS

Using a laboratory laser set-up, lamellar cuts were induced while varying pulse energies and distances from the endothelium. A fluorescent staining protocol was used to determine the percentage of surviving endothelial cells. Numerical simulations of the Euler equations for compressible fluids provided pressure level and axial and radial pressure gradient estimates at the endothelium.

RESULTS

Ninety percent of the endothelial cells survived when using 16.5 μJ pulses no closer than 200 μm to the endothelium, or pulses not exceeding 2 μJ at a distance of 50 μm. The comparison of the observed percentage of surviving cells with the estimates of the shock wave amplitudes and gradients generated by the laser pulses yielded cell death thresholds at amplitudes in the megapascal range, or gradients of the order of 10⁸ Pa/m.

CONCLUSIONS

Our results provide limits in terms of pulse energy and distance of the incision from the endothelium within which endothelial cell viability is preserved. Current forms of corneal laser surgery are compatible with these limits. However, these limits will need to be considered for the development of future laser routines working in close proximity to the endothelium.

Comparison of Results of Accelerated Corneal Cross-Linking With Hypo-Osmolar Riboflavin Solution Performed on Corneas Thicker and Thinner Than 400 μm

PURPOSE

To evaluate the effect of accelerated corneal cross-linking (CXL) according to corneal thickness in keratoconus.

METHODS

Patients undergoing corneal CXL (9 mW/cm(2)) with hypo-osmolar riboflavin solution were included in this study. The patients were divided into 2 groups. Group 1 included patients with corneal thickness below 400 μm (50 eyes from 45 patients), and group 2 included patients with corneal thickness above 400 μm (50 eyes from 47 patients). Visual acuity (VA), refraction, topographic values, and higher-order aberrations were evaluated in the preoperative term and postoperatively at months 1, 3, and 6.

RESULTS

The improvements in VA were significant and similar in both groups [0.25/0.19 logMAR, P = 0.130]. In group 1, the rate of decrease in spherical refraction [0.85/0.27 diopters (D), P = 0.012] and maximum keratometry (Kmax, 2.49/0.68 D, P < 0.001) was significantly higher than that in group 2. The cylindrical change was similar (0.43/0.29 D P = 0.173). Corneal thinning was higher in group 2 (25/40.4 μm P < 0.001). Anterior elevation values decreased at higher rates in group 1 (3.73/0.24 μm P < 0.001); neither group showed a significant difference in posterior elevation (-0.14/-0.4 μm P > 0.05). In group 1, all aberration values except trefoil significantly decreased, whereas in group 2 none of the aberrations decreased except the total root mean square. All higher-order aberration values decreased at significantly higher rates in group 1 (P < 0.05).

CONCLUSIONS

In thin corneas, accelerated corneal CXL provides better anatomical changes; however, the improvement in VA is similar to that in thick corneas.

[Corneal transplantation: study carried out at the Department of Ophthalmology, University Hospital Center Mohammed VI, Marrakech]

La kératoplastie transfixiante est l'une des plus fréquentes des greffes de tissus et transplantations d'organes. Le but de notre travail est de rapporter notre expérience en matière de greffe de cornée. C'est une étude prospective de 195 patients ayant bénéficié d'une greffe de cornée sur une période allant d'aout 2009 à Août 2015. Le recul moyen est de 21 mois. Les indications de la greffe étaient le kératocône 33.8%, les séquelles de traumatisme 10.7%, la kératopathie bulleuse 19.5%, les dystrophies héréditaires 10.7%, et les kératites herpétiques 9.2%. L'acuité visuelle initiale était inférieure à 1/10 dans 90% des cas. Nous avons observé une réaction de rejet dans 19 yeux dont 14 étaient récupérables, 33 hypertonies oculaires, 20cataracte, et 2 décollements descmetiques. La greffe de cornée apparaît comme une intervention donnant de bons résultats anatomiques et fonctionnels. Les résultats ne doivent pas occulter une surveillance post opératoire étroite et régulière pour dépister à temps d’éventuelles complications, en particulier le rejet de greffe.

Evidence against ZNF469 being causative for keratoconus in Polish patients

PURPOSE

Keratoconus (KTCN) is a degenerative disorder characterized by stromal thinning and protrusion of the cornea, resulting in severe impairment of visual function. A recent study proposed that rare heterozygous mutations in ZNF469 determine KTCN aetiology.

METHODS

To investigate the contribution of ZNF469 to KTCN, we Sanger sequenced ZNF469 in 42 unrelated Polish patients with KTCN and 49 Polish individuals with high myopia (HM) and compared the results with whole-exome sequencing (WES) data performed in 268 Polish individuals without ocular abnormalities.

RESULTS

The average number of ZNF469 non-synonymous variants was 16.31 and 16.0 for individuals with KTCN and HM, respectively (p = 0.3724). All identified variants were previously reported. Alternative allele frequency (AAF) was determined based on the WES results. Among missense variants, only one (rs528085780) has AAF ≤ 0.001 and was identified in one patient with sporadic KTCN. However, the resulting Arg1864Lys substitution was not predicted to be deleterious.

CONCLUSION

In summary, we have not found a significant enrichment of sequence variants in ZNF469 in Polish patients with KTCN. High prevalence of ZNF469 variants identified in our KTCN group is typical for a common genetic variation observed in general population. Our findings indicate that variation in ZNF469 is not responsible for KTCN and other genetic variants are involved in the development and progression of this disease in Polish patients.

Indications for and techniques of keratoplasty at Vietnam National Institute of Ophthalmology

AIM

To report the indications for and techniques of corneal transplantation at Vietnam National Institute of Ophthalmology (VNIO) over a period of 12y (2002-2013).

METHODS

Records of patients who had undergone corneal transplantation at VNIO from January 1, 2002 to January 1, 2014 were reviewed to determine the indication for and type of corneal transplant performed. Patient age, gender, indication for corneal transplantation and surgical technique were recorded and analyzed.

RESULTS

Corneal transplantation were underwent in 1390 eyes of 1278 patients with a mean age of 44.9±18.1y during the period under review. The most common indication was infectious corneal ulcer (n=670; 48.2%), followed by corneal scar (n=333, 24.0%), corneal dystrophy (n=138, 9.9%) and failed graft (n=112, 8.1%). Nearly all procedures performed were penetrating keratoplasty (n=1300, 93.5%), with a few lamellar keratoplasty procedures performed: lamellar keratoplasty (n=52, 3.7%), Descemet's stripping automated endothelial keratoplasty (n=27, 1.9%) and deep anterior lamellar keratoplasty (n=11, 0.8%).

CONCLUSION

While the most common indication for keratoplasty was infectious keratitis, nearly all indications for corneal transplantation were managed with penetrating keratoplasty. However, lamellar keratoplasty techniques, including deep anterior lamellar keratoplasty and Descemet's stripping automated endothelial keratoplasty, are being performed with increasing frequency for isolated stromal and endothelial disorders, respectively.

Evolution of Corneal Graft Survival Over a 30-Year Period and Comparison of Surgical Techniques: A Cohort Study

PURPOSE

To compare graft survival between 3 10-year periods and according to surgical techniques performed in the last years.

DESIGN

Cohort study.

METHODS

setting: Regional center (Besançon University Hospital, France).

PATIENTS

All 1132 patients operated on between 1983 and 2014. Graft and patient baseline characteristics, risk factors for failure, surgical procedures, and postoperative corneal status were collected.

MAIN OUTCOME MEASURES

Five-year survival rate in the whole cohort; 1-year and 3-year survival rates, respectively, among 88 patients with endothelial dystrophy (ED) or postoperative bullous keratopathy (PBK) operated on using endothelial lamellar keratoplasty (ELK) or penetrating keratoplasty (PK), and among 56 patients with keratoconus operated on using anterior lamellar keratoplasty (ALK) or PK.

RESULTS

Between the 1983-1993 and the 2004-2014 periods, overall 5-year graft survival rate increased from 61.4% to 76.5% (P = .0004). The main prognostic factors were preoperative diagnosis, graft endothelial density, and postoperative lens status. After adjusting for these factors, difference in survival rates was no longer significant (hazard ratio 0.90 for the second and 1.17 for the third period, compared to the first, P = .4191). Only 1 graft failure, after PK, occurred among the 56 patients with keratoconus. Among the 88 patients with ED or PBK, the 1-year graft survival was higher with PK (90.6%) than with ELK (60.8%) (P = .0025) but no significance remained after adjustment (hazard ratio 3.22, P = .1304).

CONCLUSIONS

Despite numerous changes in graft procedures and surgical techniques, no noticeable improvement in graft survival was found during the last 30 years while taking into account other prognostic factors.

Comparative Analysis of Refractive and Topographic Changes in Early and Advanced Keratoconic Eyes Undergoing Corneal Collagen Crosslinking

PURPOSE

To compare the refractive and topographic changes at 1 year in eyes with early and advanced keratoconus undergoing corneal collagen crosslinking (CXL). A prospective, nonrandomized comparative clinical intervention study.

METHODS

Thirty eyes of patients with keratoconus underwent CXL. They were divided into 2 groups based on their mean central keratometry: group A [mean central K ≤ 53 diopters (D)] and group B (mean central K > 53 D). Uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), refraction, topography, pachymetry, and endothelial cell counts were evaluated at baseline and at 1, 3, 6, and 12 months of follow-up.

RESULTS

The mean baseline logarithm of the minimum angle of resolution (logMAR) UCVA and logMAR BCVA in group A was 1.007 ± 0.30 and 0.566 ± 0.21, respectively. The values improved to 0.727 ± 0.29 (P = 0.001) and 0.306 ± 0.15 (P = 0.001) at 1-year post CXL. The mean baseline logMAR UCVA and logMAR BCVA in group B were 1.040 ± 0.24 and 0.641 ± 0.25, respectively. It changed to 0.953 ± 0.26 (P = 0.054) and 0.633 ± 0.27 (P = 0.891) at 1 year. The improvement in the UCVA and BCVA was statistically significant in group A as compared with that in group B. The mean baseline flattest, steepest, central, and apical keratometry in group A were 48.7 ± 2.5 D, 54.9 ± 3.3 D, 49.5 ± 1.4 D, and 57.3 ± 2.3 D, respectively. At 12 months, the values changed to 47.8 ± 2.4 D, 54.1 ± 3.0 D, 48.8 ± 1.8 D, and 56.2 ± 2.7 D, the change being statistically significant for mean flat and apical K only (P < 0.05). All the 4 indices did not show any statistically significant difference at 12 months in group B (P > 0.05).

CONCLUSIONS

Corneal CXL is more effective in improving the refractive and topographical parameters at 1 year when it is performed early in the course of the disease.

Prevention and treatment of corneal graft rejection: current practice patterns of the Cornea Society (2011)

PURPOSE

To analyze current practice patterns in the prevention and treatment of corneal graft rejection for both penetrating keratoplasty (PK) and endothelial keratoplasty (EK) and to compare these patterns with previously reported practices.

METHODS

In 2011, an electronic survey was sent to 670 members of the Cornea Society worldwide addressing the routine postoperative management of corneal transplants at different time points, treatment of various manifestations of corneal graft rejection, and preferred surgical techniques.

RESULTS

A total of 204 of 670 surveys (30%) were returned and evaluated. All respondents used topical corticosteroids for routine postoperative management and treatment of endothelial graft rejection. Prednisolone was the topical steroid of choice in all clinical scenarios, similar to previous surveys from 1989 to 2004. Use of subconjunctival and systemic steroids increased for many scenarios of probable and definite graft rejection. Routine use of prednisolone decreased by approximately 10% from previous surveys, whereas difluprednate was used in 13% of high-risk eyes during the first 6 months. Dexamethasone, fluorometholone, and loteprednol use remained stable. Adjunctive topical cyclosporine use increased significantly for PK and EK. EK was the preferred technique for endothelial dysfunction, whereas PK and deep anterior lamellar keratoplasty were both used for keratoconus and anterior scars. Most respondents (75%) felt that graft rejection occurs more frequently after PK than after EK.

CONCLUSIONS

Prednisolone remains the treatment of choice for management and treatment of graft rejection; however, since the introduction of difluprednate, its use has declined slightly since the introduction of difluprednate. Despite perceived differences in rejection rates, there were no differences in prophylactic steroid treatment for PK and EK.

Indications and techniques employed for keratoplasty in the Eastern province of Saudi Arabia: 6 years of experience

BACKGROUND AND OBJECTIVES

Keratoplasty services in Saudi Arabia have progressed steadily in the past few decades. We sought to identify the leading indications and types of keratoplasty performed in the Eastern Province of Saudi Arabia over a six-year period and to compare these indications with published data.

DESIGN AND SETTING

This was a retrospective descriptive analysis of the records of patients who underwent keratoplasty at four ophthalmology centers in the Eastern Province between 2008 and 2013.

PATIENTS AND METHODS

All keratoplasty procedures were included in the analysis. The primary surgical indication and type of surgery were identified for each case.

RESULTS

Keratoplasties included 570 penetrating keratoplasty, 217 deep lamellar keratoplasty, 80 triple procedures, 24 descemet stripping automated endothelial keratoplasty and 12 Boston keratoprosthesis implantations. The mean age of all patients was 28.8 years (range 14-72 years), and 58.9% of the patient were males. The lead.ing indication for keratoplasty was keratoconus 53.10%, bullous keratopathy 13.80%, corneal scarring 10.7%, regrafts 9.1%, and stromal dystrophies 4.9%.

CONCLUSIONS

In this study, the leading indications for keratoplasty were keratoconus, bullous keratopathy, corneal scarring, regrafts and stromal dystrophies. A significant increasing trend for descemet's stripping automated endothelial keratoplasty surgeries was observed in spite of the number of cases.

Progression in keratoconus and the effect of corneal cross-linking on progression

Ultraviolet corneal collagen cross-linking (CXL) has been shown to possibly delay, halt, or even reverse disease progression in keratoconus. Understanding of keratoconic progression in untreated eyes, however, is still incomplete and is hampered by the varying definitions and metrics used to evaluate corneal changes. As a result, the CXL literature varies widely in criteria for progression and parameters for successful outcomes. To date, there have been few long-term, well-controlled clinical trials supporting the efficacy of CXL to prevent progression in keratoconus. Review of our data on keratoconus suggests the course of corneal change is difficult to predict and that many keratoconic eyes appear stable once the eyes begin to exhibit frank changes in corneal curvature typical of keratoconus. Better-defined metrics for progression in keratoconus are needed. Larger, long-term randomized clinical trials may more clearly establish the efficacy and safety of CXL in the management of keratoconus and determine which patients are the best candidates for this procedure.

Deep anterior lamellar keratoplasty in the management of keratoconus

Advanced cases of keratoconus often require surgical intervention to restore corneal anatomy and improve eyesight. Penetrating keratoplasty (PK) although commonly performed has potential risk of immunological rejection and is now no longer automatically the first choice of surgery. DALK procedures have evolved, which allows surgical replacement of recipient's corneal stroma, leaving behind healthy descemet membrane (DM) and endothelium. This reduces the risk of allograft endothelial rejection and late graft failure. In recent times, DALK techniques have led to significant improvements in visual outcome and current results are comparable to PK. Big bubble technique of DALK has become the most popular among the various surgical techniques described. Manual near DM DALK also gives good outcome although the visual recovery is often delayed. Future integration of femtosecond laser technology along with diagnostic imaging technology is likely to further improve outcomes of DALK in keratoconus.

Endothelial keratoplasty versus penetrating keratoplasty for Fuchs endothelial dystrophy

BACKGROUND

Fuchs endothelial dystrophy (FED) is a condition in which there is premature degeneration of corneal endothelial cells. When the number of endothelial cells is reduced to a significant degree, fluid begins to accumulate within the cornea. As a result, the cornea loses its transparency and the individual suffers a reduction in vision. The only successful surgical treatment for this condition is replacement of part or all of the cornea with healthy tissue from a donor. The established procedure, penetrating keratoplasty (PKP), has been used for many years and its safety and efficacy are well known. Endothelial keratoplasty (EK) techniques are relatively new surgical procedures and their safety and efficacy relative to PKP are uncertain.

OBJECTIVES

The objective of this review was to compare the benefits and complications related to two surgical methods (EK and PKP) of replacing the diseased endothelial layer of the cornea with a healthy layer in people with FED.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2014, Issue 1), MEDLINE (January 1950 to January 2014), EMBASE (January 1980 to January 2014), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to January 2014), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com) and ClinicalTrials.gov (www.clinicaltrials.gov). There were no date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 27 January 2014.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) comparing EK versus PKP for people (of any age and gender) who had been clinically diagnosed with FED.

DATA COLLECTION AND ANALYSIS

Two authors independently screened the search results, assessed trial quality and extracted data using the standard methodological procedures expected by The Cochrane Collaboration.

MAIN RESULTS

We included three RCTs that enrolled a total of 139 eyes of 136 participants and analysed 123 (88%) eyes. Two RCTs randomised eyes into either the endothelial keratoplasty (EK) group or penetrating keratoplasty (PKP) group and one RCT randomised eyes into either the femtosecond laser-assisted endothelial keratoplasty (FLEK) group or PKP group. The RCTs comparing EK with PKP did not show any significant differences between procedures with respect to best corrected visual acuity (BCVA) at two years (mean difference (MD) 0.14 logMAR; 95% confidence interval (CI) -0.08 to 0.36; P = 0.23) or at one year (MD 0.09 logMAR; 95% CI -0.05 to 0.23; P = 0.22), whereas the trial comparing FLEK with PKP showed significantly better BCVA after PKP (MD 0.20 logMAR; 95% CI 0.10 to 0.30; P = 0.0001). Only one RCT reported on irregular astigmatism (higher-order aberration), which was less with EK than PKP (MD -1.20 µm; 95% CI -1.53 to -0.87; P < 0.001). Only one RCT reported on endothelial cell counts (lower after FLEK than PKP: MD -969 cells/mm²; 95% CI -1161 to -777; P < 0.001), primary graft failure (higher after FLEK than PKP: RR 7.76; 95% CI 0.41 to 145.22; P = 0.10), and graft rejection (more after FLEK than PKP: RR 1.11; 95% CI 0.07 to 17.12; P = 0.94). Only one RCT reported that 27.8% of participants had graft dislocation, 2.8% had epithelial ingrowth and postoperative pupillary block, and 13.9% had intraocular pressure (IOP)-related problems in the FLEK group compared with the PKP group, in whom 10% had suture-related problems, 5% had wound dehiscence and 10% had suture revision to correct astigmatism. Overall, the adverse events in the FLEK group appeared to be more frequent than in the PKP group. No trials reported information about quality of life or economic data. The overall methodological quality of the three trials was not satisfactory as most did not perform allocation concealment or masking of participants and outcome assessors, and all trials had a small sample size.

AUTHORS' CONCLUSIONS

The rapid growth of endothelial keratoplasty as the treatment of choice for FED is based upon the belief that visual recovery is more rapid, surgically induced astigmatism (regular and irregular) is less and rates of transplant rejection are lower with EK. This change in practice also assumes that the rates of long term transplant survival are equal for the two procedures. The practical differences between the surgical procedures mean that visual recovery is inherently more rapid following EK, but this review found no strong evidence from RCTs of any difference in the final visual outcome between EK and PKP for people with FED. This review also found that higher order aberrations are fewer following EK but endothelial cell loss is greater following EK. The RCTs that we included employed different EK techniques, which may have a bearing on these findings. EK procedures have evolved over the years and can be performed using different techniques, for example deep lamellar endothelial keratoplasty, Descemets stripping endothelial keratoplasty (DSEK), Descemets stripping automated endothelial keratoplasty (DSAEK), femtosecond laser-assisted endothelial keratoplasty and Descemet membrane endothelial keratoplasty (DMEK). More RCTs are needed to compare PKP with commonly performed EK procedures such as DSEK, DSAEK and DMEK in order to determine the answers to two key questions, whether there is any difference in the final visual outcome between these techniques and whether there are differences in the rates of graft survival in the long term?

Endothelial cell microRNA expression in human late-onset Fuchs' dystrophy

PURPOSE

MicroRNAs (miRNAs) are a class of endogenous noncoding RNA and post transcriptionally modulate gene expression during development and disease. Our study investigated the differential miRNA expression in human Fuchs' endothelial corneal dystrophy (FECD) compared with normal endothelium to identify miRNA sequences that are involved in the pathogenesis of FECD.

METHODS

Comparative miRNA expression profiles of endothelial samples obtained from FECD patients during lamellar corneal transplant surgery and from normal donor globes were generated using OpenArray plate technology. Differential expression of individual miRNAs was validated in the original and in independent samples using stem-loop RT qPCR assays. Expression of miRNA target genes was assessed using qPCR and tissue microarray (TMA) immunolabeling.

RESULTS

Our results demonstrate downregulation of 87 miRNAs in FECD compared with normal endothelium (>3-fold change; P < 0.01). Correspondingly, DICER1, (encoding an endoribonuclease critical to miRNA biogenesis) showed a moderate but significant decrease in FECD samples (P < 0.05). Significant repression of three miR-29 family members (miR-29a-3p, miR-29b-2-5p, and miR-29c-5p) was paralleled by upregulation of their extracellular matrix associated mRNA targets collagen I and collagen IV. Tissue microarray immunolabeling showed histologically verifiable subendothelial collagen I and collagen IV deposition and increased endothelial laminin protein expression in FECD samples.

CONCLUSIONS

The present study provides the first miRNA profile in FECD and normal endothelial cells and demonstrates widespread miRNA downregulation in FECD. Decreased endothelial expression of miR-29 family members may be associated with increased subendothelial extracellular matrix accumulation in FECD.

Clinical outcome of repeat penetrating keratoplasty

PURPOSE

To compare the clinical outcome of regrafts with first grafts.

METHODS

Two-year outcome data were obtained from the Swedish Cornea Transplant Register for patients undergoing penetrating keratoplasty between 2001 and 2008. Only data from the 3 centers with follow-up return rates >75% were included. The survival and visual outcome of regrafts with the original diagnoses of keratoconus, Fuchs endothelial dystrophy (FED), or bullous keratopathy (BK) were compared with first grafts for the same diagnoses by univariate and logistic regression methods.

RESULTS

For keratoconus, the failure rate increased 3-fold in regrafts compared with first grafts (ie, 17% vs. 6%; P = 0.002) and doubled in FED regrafts (33% vs. 15%; P = 0.001). In BK, the failure rate was already high in first grafts, and the increase in failure of regrafts was minimal (P = 0.9). Visual acuity was also worse in regrafts compared with first grafts, mainly in the keratoconus and FED patients. In the keratoconus group, visual acuity with preferred correction was ≥0.5 in 69% of first grafts compared with only 55% in regrafts (P = 001). In FED, 52% of first grafts but only 19% of regrafts achieved visual acuity ≥ 0.5 (P = 0.001). The visual outcome of regrafts in BK was poor but little different from first grafts where fewer than 20% achieved visual acuity ≥ 0.5.

CONCLUSIONS

This analysis confirmed the poorer survival of regrafts where the original indication was keratoconus or FED. In addition, visual outcome was also worse than in the first grafts. However, the outcomes of regrafts in BK were similar to first grafts.