Keratoplasty Research Articles

Wavefront-guided pupilloplasty in patients following penetrating keratoplasty: Optimizing results

Abstract Purpose: To describe the role of wavefront-guided pupilloplasty in improving visual quality and wavefront parameters in post-keratoplasty patients with pathologically irregular, mydriatic pupils. Methods: A total of 13 eyes of post-penetrating keratoplasty patients with pathologically irregular mydriatic pupil were included in this prospective interventional study. Preoperative wavefront analysis was done with the actual pupil size, and predicted wavefront values were analyzed by setting the postoperative pupil size to 2 mm. Patients showing significant improvement between preoperative and predicted postoperative wavefront values underwent single-pass four-throw pupilloplasty, and all wavefront parameters were again evaluated after 1 week. Preoperative and postoperative best corrected visual acuity (BCVA), pupil size, and wavefront parameters were analyzed. Results: Mean BCVA improved from a preoperative value of 1.03 ± 0.32 log of minimum angle of resolution (logMAR) units to 0.24 ± 0.09 logMAR units. Mean preoperative pupil size was 6.077 ± 0.787 mm, whereas the achieved postoperative pupil size after pupilloplasty was 2.538 ± 0.139 mm. Mean astigmatism root mean square (RMS) value improved from 4.169 ± 3.876 to 0.875 ± 0.926 μm (P < 0.05), and mean coma value changed from 1.525 ± 1.962 to 0.128 ± 0.152 μm (P < 0.05). Mean point spread function Stehl ratio value improved from 0.056 ± 0.032 to 0.223 ± 0.102. Mean RMS (optical path difference) value changed from 6.248 ± 4.721 to 0.943 ± 0.947 μm (P < 0.001), Mean RMS (high orders) value changed from 3.788 ± 3.537 to 0.328 ± 0.256 μm (P value 0.003), and the mean spherical aberration value changed from 0.646 ± 0.873 to 0.223 ± 0.102 μm (P value 0.024). All postoperative wavefront parameters showed statistically significant improvement from the preoperative parameters. Conclusion: Wavefront-guided pupilloplasty can predict and improve wavefront parameters and visual quality in post-keratoplasty patients with pathologically irregular mydriatic pupils.

TCF4 trinucleotide repeat expansions and UV irradiation increase susceptibility to ferroptosis in Fuchs endothelial corneal dystrophy

Fuchs endothelial corneal dystrophy (FECD), the leading indication for corneal transplantation in the U.S., causes loss of corneal endothelial cells (CECs) and corneal edema leading to vision loss. FECD pathogenesis is linked to impaired response to oxidative stress and environmental ultraviolet A (UVA) exposure. Although UVA is known to cause nonapoptotic oxidative cell death resulting from iron-mediated lipid peroxidation, ferroptosis has not been characterized in FECD. We investigated the roles of genetic background and UVA exposure in causing CEC degeneration in FECD. Using ungenotyped FECD patient surgical samples, we found increased levels of cytosolic ferrous iron (Fe2+) and lipid peroxidation in end-stage diseased tissues compared with healthy controls. Using primary and immortalized cell cultures modeling the TCF4 intronic trinucleotide repeat expansion genotype, we found altered gene and protein expression involved in ferroptosis compared to controls including elevated levels of Fe2+, basal lipid peroxidation, and the ferroptosis-specific marker transferrin receptor 1. Increased cytosolic Fe2+ levels were detected after physiologically relevant doses of UVA exposure, indicating a role for ferroptosis in FECD disease progression. Cultured cells were more prone to ferroptosis induced by RSL3 and UVA than controls, indicating ferroptosis susceptibility is increased by both FECD genetic background and UVA. Finally, cell death was preventable after RSL3 induced ferroptosis using solubilized ubiquinol, indicating a role for anti-ferroptosis therapies in FECD. This investigation demonstrates that genetic background and UVA exposure contribute to iron-mediated lipid peroxidation and cell death in FECD, and provides the basis for future investigations of ferroptosis-mediated disease progression in FECD.

Clinical characteristics and viral colonization of corneal donors with coronavirus disease 2019: a comprehensive analysis before and after corneal transplantation

Purpose To evaluate the clinical characteristics and viral Colonization of corneas donated by volunteers with coronavirus disease 2019 (COVID-19) before and after corneal transplantation. Methods We retrospectively compared the characteristics and clinical outcomes of patients who received corneas from donors with and without a history of COVID-19 after corneal transplantation. Reverse transcription-polymerase chain reaction (RT-PCR) was performed to evaluate the expression of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA on ocular surfaces in corneal preservation solutions as well as the recipients’ tears. Immunofluorescence was also performed to evaluate the expression of viral spike proteins in the corneas. Intraocular pressure (IOP) measurement, optical coherence tomography (OCT), and slit-lamp inspection at each follow-up examination were performed to assess the surgical efficacy. Results The RT-PCR results of eye surface swabs before corneal extraction, the corneal preservation solutions before transplantation as well as the recipients’ tears were negative, thereby indicating the suitability for transplantation. No significant differences in IOP measurements, OCT findings, or in the incidence of post transplantation complications were observed between donors with and without COVID-19. Conclusions Corneal transplantation using corneas from COVID-19 infected donors does not alter clinical outcomes when compared to controls receiving corneas from non-infected donors.

Non-Contact-Lens-Related Acanthamoeba Keratitis Caused by Acanthamoeba sp. Group T4D/T4e

Acanthamoeba keratitis (AK) is a rare but serious infection of the cornea, typically associated with contact lens wear. Here, we present a case of AK caused by the Acanthamoeba genotype T4D/T4e in a patient without identifiable risk factors: a 34-year-old woman who initially presented with signs and symptoms suggestive of herpetic keratitis, and who did not respond to conventional treatment. Corneal culture and targeted metagenomic analysis (18S rRNA, 16S-like rRNA) revealed the presence of an Acanthamoeba species closely related to the ‘Nagington’ strain. Despite intensive anti-Acanthamoeba therapy, complications arose necessitating penetrating keratoplasty. In conclusion, this case underscores the importance of considering Acanthamoeba as a causal agent of keratitis in non-contact-lens wearers. The identification of Acanthamoeba genotype T4D/T4e challenges the previous understanding of its pathogenic potential. Furthermore, it emphasizes the need for ongoing research into the pathogenicity of different Acanthamoeba subtypes. Early diagnosis and treatment are essential for preventing vision-threatening complications associated with AK.

A chimeric anti-vascularization immunomodulator prevents high-risk corneal transplantation rejection via ex vivo gene therapy

Corneal blindness affects greater than 5 million individuals, with over 180,000 corneal transplantations (CTs) performed annually. Inhigh-risk CTs, almost all grafts are rejected within 10 years. Herein, adeno-associated virus (AAV) ex vivo gene therapy was investigated to establish immune tolerance in the corneal allograft to prevent high-risk CT rejection. Our previous work has demonstrated that HLA-G contributes to ocular immune privilege by inhibiting both immune cells and neovascularization; however, homodimerization is a rate-limiting step for optimal HLA-G function. Therefore, a chimeric protein termed single chain immunomodulator (sclM), was engineered to mimic the native activity of the secreted HLA-G dimer complex and eliminate the need for homodimerization. In a murine corneal burn model, AAV8-sclM significantly reduced corneal vascularization and fibrosis. Next, ex vivo AAV8-scIM gene delivery to corneal allografts was evaluated in a high-risk CT rejection rabbit model. All sclM treated corneas were well tolerated and transparent after 42 days while 83% of vehicle treated corneas were rejected. Histologically, AAV-scIM treated corneas were devoid of immune cell infiltration, vascularization, with minimal fibrosis at the host-graft interface. The data collectively demonstrate that sclM gene therapy prevents corneal neovascularization, reduces trauma-induced corneal fibrosis, and prevents allogeneic CT rejection in a high-risk large animal model.

Long-Term Evaluation of Patients with Neurotrophic Keratopathy Undergoing Staged Keratoplasty After Corneal Neurotization

Purpose Corneal neurotization (CN) is a novel, potentially curative surgical procedure for the treatment of neurothophic keratopathy (NK). Patients with severe NK can present with corneal opacification requiring optical keratoplasty, which would likely fail without a proper trophic support of corneal nerves in the recipient cornea. Methods This is a pilot study on 4 patients undergoing keratoplasty after CN. Pre- and postoperative data at 12, 24 months and at the last follow-up were collected for the examination of (i) best corrected visual acuity (BCVA), (ii) slit lamp examination and photograph acquisition with and without fluorescein staining, (iii) corneal aesthesiometry, (iv) in vivo confocal microscopy of the central cornea. Neurophysiological study of the corneal reflex before corneal graft and at last follow up was performed. Results Four female patients (47.25 ± 5.06 y.o.) underwent keratoplasty after CN (3 penetrating keratoplasty, 1 deep anterior lamellar keratoplasty). The mean interval between CN and keratoplasty was 22 (± 12) months. The mean graft survival time was 42 (± 25) months. Graft follow-up ranged from 72 to 132 months. At the final follow-up, BCVA was improved in 2 out of 4 patients. The mean corneal sensitivity was 11.9 ± 8.3 mm at last follow-up. In vivo confocal microscopy confirmed the presence of functioning nerves at the last follow-up in all patients. NK-related complications occurred in 3 eyes (2 persistent epithelial defect, 1 corneal melting). The former complication was successfully treated by autologous serum eye drops while the latter required repeated keratoplasty. Conclusions Keratoplasty is a viable strategy to improve visual acuity in patients with corneal opacity who underwent CN for the treatment of NK. Even in the presence of functioning corneal nerves before keratoplasty, surgeons should be aware of the increased rate of NK-related complications that could require the need for repeated procedure.

Cataract surgery with corneal endothelial pathology

Abstract: It is not uncommon for Fuch’s endothelial corneal dystrophy (FECD) patients to present with a co-existent cataract. Surgeons are often faced with a choice between simultaneous and staged corneal and cataract surgery. Descemet’s membrane endothelial keratoplasty (DMEK) has been found to have better visual outcomes as compared to Descemet’s stripping endothelial keratoplasty (DSEK) and penetrating keratoplasty and is currently the preferred surgery for FECD. Endothelial cell count and pachymetry cutoffs were earlier used for decision-making. Various other investigations such as Scheimpflug imaging and confocal microscopy are now used to prognosticate the outcome when performing cataract surgery only. Triple DMEK has the advantage of a definite treatment in a single sitting. Whereas, a staged approach with DMEK followed by cataract surgery has a better visual outcome. This is due to variable refractive changes in the cornea post-DMEK or DSEK that can lead to inaccurate intraocular lens (IOL) power calculation. Even though the graft detachment rates and rebubbling rates have been found to be comparable in triple DMEK versus a staged surgery, in view of increasing patient demands and expectations for a spectacle-independent outcome, a staged surgery is now preferable. Conventionally, surgeons favored the use of only monofocal lenses; however, the use of premium IOLs, especially extended depth of focus lenses, is now increasing. In this review, we will discuss the various advantages and disadvantages of a simultaneous and staged approach and pearls on decision-making in FECD with cataracts.

Clinical Outcomes of Modified Manual Deep Anterior Lamellar Keratoplasty for Eyes with Previous Radial Keratotomy.

Background: The aim of this study was to evaluate the intraoperative complications and visual outcomes of manual deep anterior lamellar keratoplasty (mDALK) in patients who underwent previous radial keratotomy (RK) for myopia. Methods: The notes of patients who underwent mDALK after RK at three different hospitals-San Giovanni Addolorata Hospital (Rome, Italy), Mount Saint Joseph Hospital (Vancouver, Canada), and Tor Vergata University Hospital (Rome, Italy)-were retrospectively reviewed. We analyzed the manual dissection success rate and conversion to penetrating keratoplasty (PK), the residual recipient stromal thickness, the postoperative corrected distance visual acuity (CDVA), postoperative refraction, and topographic astigmatism. Results: Thirteen eyes of eleven patients were included in the analysis (male 7/11, 63.6%). Preoperatively, mean topographic astigmatism was 5.4 ± 3.5 D (range 1.6-14.8 D), and mean CDVA was 0.47 ± 0.2 logMAR (range 0.3-1.0 logMAR) [Snellen equivalent 20/50]. Manual dissection was performed in all cases. None of the examined eyes were converted to PK. An improvement in both topographic astigmatism (2.8 ± 0.9 D, p = 0.0135) and CDVA (0.23 ± 0.2 LogMAR, p = 0.0122) was recorded at 12-month follow-up. Conclusions: mDALK is a safe and effective surgical technique when applied to eyes previously treated with RK, with an observed improvement in CDVA and topographic astigmatism.

Treatment of Corneal Dermoid with Fibrin Glue Boned Multi-Layer Lenticules from Small Incision Lenticules Extraction Surgery: A Preliminary Study of Five Patients

Purpose Dermoid excision combined with lamellar keratoplasty was one of the most common surgical techniques for corneal dermoid. Due to the huge shortage of corneal donors, small incision lenticule extraction (SMILE) derived lenticules might be the novel and feasible corneal grafts instead of traditional corneal donors. Therefore, we tried to use FG boned multi-layer lenticules as grafts in the treatment of corneal dermoid. Methods Five patients (the oldest patient was 54 years old and the youngest case was 5 years old) were diagnosed with corneal dermoid and complaining of blurred vision or unsatisfied cosmetic appearance. All patients underwent corneal dermoid excision combined with FG boned multi-layer corneal lenticules transplantation. Slit-lamp microscopy and anterior-segmental optical coherence tomography(AS-OCT)were used to observe ocular appearance, corneal grafts survival, epithelialization, transparency, interlamellar fluid accumulation and the degradation of FG. The preoperative and postoperative change of best-corrected visual acuity (BCVA) and astigmatism were respectively recorded. Results All patients were satisfied with the postoperative cosmetic results. BCVA had been increased and astigmatism had been decreased in all cases. We observed that the FG boned multi-layer corneal lenticules were covered with smooth corneal epithelium in one week after transplantation and successfully adhered to the corneal beds, without any dislocation or interlayer separation. FG was gradually degraded and absorbed within 1 month after surgery. The lenticule grafts grew well without rejection and kept transparency during the follow-up period. Conclusions FG boned multi-layer lenticules would be the novel and feasible substitute for lamellar keratoplasty in the treatment of corneal dermoid. FG could not be only used as binder adhering multi-layer lenticules, closing the interlayer space of multi-layer lenticules, preventing the formation of interlayer fluid, but also increasing the thickness and toughness of lenticules, and therefore which is more facilitate to intraoperative suture.

Evaluation of Sociomedical Factors on Corneal Donor Recovery Using Machine Learning

ABSTRACT Purpose To evaluate co-morbid sociomedical conditions affecting corneal donor endothelial cell density and transplant suitability. Method(s) Corneal donor transplant information was collected from the CorneaGen eye bank between June 1, 2012 and June 30, 2016. A natural language processing algorithm was applied to generate co-morbid sociomedical conditions for each donor. Variables of importance were identified using four machine learning models (random forest, Glmnet, Earth, nnet), for the outcomes of transplant suitability and endothelial cell density. SHAP (SHapley Additive exPlanations) values were generated, with beeswarm and box plots to visualize the contribution of each feature to the models. Results With a total of 23,522 unique donors, natural language processing generated 30,573 indices, which were reduced to 41 most common co-morbid sociomedical conditions. For transplant suitability, hypertension ranked the top overall variable of importance in two models. Hypertension, chronic obstructive pulmonary disease, history of smoking, and alcohol use appeared consistently in the top variables of importance. By SHAP feature importance, hypertension (0.042), alcohol use (0.017), ventilation of donor (0.011), and history of smoking (0.010) contributed the most to the transplant suitability model. For endothelial cell density, hypertension was the sociomedical condition of highest importance in three models. SHAP scores were highest among the sociomedical conditions of hypertension (0.037), alcohol use (0.013), myocardial infarction (0.012), and history of smoking (0.011). Conclusion In a large cohort of corneal donor eyes, hypertension was identified as the most common contributor to machine learning models examining sociomedical conditions for corneal donor transplant suitability and endothelial cell density.

Construction of tissue engineered cornea with skin-derived corneal endothelial-like cell and mechanism research for the cell differentiation.

Corneal endothelial transplantation accounts for most of corneal transplantation for treating corneal diseases, however severe shortage of corneal donors is the biggest obstacle. In our previous study, we differentiated human skin-derived precursors (SKPs) into corneal endothelial cell (CEC)-like cells with a co-culture system. In this study, we aimed to investigate cell differentiation molecular mechanism and evaluate the function of CEC-like cells by developing tissue-engineered corneas in order to improve cell production efficiency and provide basic research for clinical transformation. We performed transcriptome sequencing of SKPs and CEC-like cells. Further, we focused on the possible enriching pathways, including PI3K/Akt, MAPK/Erk, WNT/β-catenin, and important transcription factors Pitx2 and Foxc1. The PI3K and β-catenin inhibitors were also added to the culture system to observe the differentiation alteration. We developed a graft for a tissue-engineered cornea (TEC) using CEC-like cells and acellular porcine cornea matrix scaffold. The tissue-engineered corneas were transplanted into rabbits via penetrating keratoplasty. The PI3K/Akt, MAPK/Erk, and WNT/β-catenin pathways play important roles during the differentiation of SKPs into CEC-like cells. Crosstalk existed between the PI3K/Akt and MAPK/Erk pathways. The PI3K/Akt and WNT/β-catenin pathways were connected. Pitx2 and Foxc1 were subject to temporal and spatial controls of the WNT/β-catenin pathway. The inhibition of the PI3K/Akt and WNT/β-catenin pathways both prevented cell differentiation. CEC-like cells grew well on the acellular porcine cornea matrix scaffold, and the tissue-engineered corneal graft performed well after transplantation into rabbits. We provide experimental basis for CEC-like cell industrial production and drive the cells to be clinically applied in cellular replacement therapy or alternative graft substitution for treating corneal diseases in the future.

Association between in vitro susceptibility and clinical outcomes in fungal keratitis

PurposeThe purpose of this study was to assess the association between antifungal susceptibility as measured by minimum inhibitory concentration (MIC) and clinical outcomes in fungal keratitis.MethodsThis pre-specified secondary analysis of the Mycotic Ulcer Treatment Trial II (MUTT II) involved patients with filamentous fungal keratitis presenting to Aravind Eye Hospitals in South India. Antifungal susceptibility testing for natamycin and voriconazole was performed on all samples with positive fungal culture results according to Clinical and Laboratory Standards Institute Guidelines. The relationship between MIC and clinical outcomes of best-corrected visual acuity, infiltrate or scar size, corneal perforation, need for therapeutic penetrating keratoplasty, and time to re-epithelialization were assessed.ResultsWe obtained MIC values from 141 patients with fungal keratitis. The most commonly cultured organisms were Aspergillus (46.81%, n = 66) and Fusarium (44.68%, n = 63) species. Overall, there was no association between antifungal MICs and clinical outcomes. Subgroup analysis revealed that among Fusarium-positive cases, higher voriconazole MIC was correlated with worse three-month best-corrected visual acuity (p = 0.03), increased need for therapeutic penetrating keratoplasty (p = 0.04), and time to re-epithelialization (p = 0.03). No significant correlations were found among Aspergillus-positive cases. There were no significant correlations found between natamycin MIC and clinical outcomes among organism subgroups.ConclusionsDecreased susceptibility to voriconazole was associated with increased odds of requiring a therapeutic penetrating keratoplasty in Fusarium-positive cases. Susceptibility to natamycin was not associated with any of the measured outcomes.

A study on knowledge, awareness, and practices about eye donation in medical students

Aim: The aim of the study was to assess knowledge, awareness, and practices about eye donation in medical students of medical colleges. Setting: Tertiary Care Centre. Design: This study involves a cross-sectional study. Materials and Methods: A cross-sectional study at a tertiary care center in Western Vidarbha from August 2023 to October 2023, among medical students. Approval from the institutional ethical committee was taken. A total of 538 students participated in the study. After taking consent, data were collected in self-reported questionnaire consisting of questions about the knowledge and awareness of eye donation, the source of their information, willingness for donation, and respective reasons for willingness and nonwillingness. Data were analyzed. Results: Majority of students belonged to the age group between 21 and 30 years. Most were undergraduates, followed by interns and post-graduates. Five hundred and twenty-nine had heard about eye donation mainly through medical personnel. The majority of students believed that eye donation means giving sight to the blind. Most knew the nearest point of contact for eye donation. The answer given by most to the question “What is removed for transplantation?,” was cornea. The most common response to questions about a site for the removal of eyes was the hospital. The majority knew that no monetary benefits were given for donations. Those willing to pledge their eyes wanted to do so to help the blind, and those not willing said objection by family as the main reason among others. Conclusion: After the study, we concluded that awareness about eye donation was good in the students, while knowledge regarding eye donation varied among the students. Willingness to donate showed mixed responses.

A Case of Fulminant Serratia marcescens Panophthalmitis After Penetrating Keratoplasty

Purpose: To report the first case of fulminant Serratia marcescens panophthalmitis after penetrating keratoplasty (PK). Methods: This is a report of a patient who developed fulminant panophthalmitis shortly after undergoing PK with anterior chamber intraocular lens placement. Slit-lamp examination, B-scan ultrasound (B scan), and orbital computed tomography of the left eye (OS) were performed to further evaluate the patient. Tissue culture and histopathologic examination of the corneal specimen were completed to confirm the diagnosis. Results: A 78-year-old pseudophakic woman presented with 2 days of increasing pain, swelling, and purulent discharge after uneventful PK and secondary anterior chamber intraocular lens placement OS. Examination was notable for light perception without projection, elevated intraocular pressure of 48 mmHg, and a perforated corneal ulcer. B scan demonstrated diffuse vitreous opacities and membranes. Orbital computed tomography demonstrated proptosis and high-attenuation material within the left globe. Canthotomy, vitreous sampling, and antibiotic injections were performed. Corneal tissue cultures grew S. marcescens. Therapeutic PK was performed, but after rapid decompensation, the eye was eviscerated. Conclusions: This is the only reported case of fulminant S. marcescens panophthalmitis after PK. S. marcescens panophthalmitis is an aggressive and rapidly progressive infection with poor visual outcomes despite appropriate intravitreal and systemic antibiotic therapy.

Trends in infectious adverse events after elective optical keratoplasty (PK, EK, and ALK) - Ten years' analysis from an eye bank.

To report the clinical profile and donor characteristics of post-optical keratoplasty adverse events notified at an eye bank. Between January 2013 and December 2022, 37,041 donor corneas were utilized for keratoplasty, of which 16,531 were used for penetrating keratoplasty (PK), 12,171 for endothelial keratoplasty (EK), and 1356 for anterior lamellar keratoplasty (ALK). EK included 10,956 Descemet stripping automated endothelial keratoplasty (DSAEK) and 1215 Descemet membrane endothelial keratoplasty (DMEK). The adverse events reported within the first 6 weeks of optical keratoplasty were analyzed for donor-related parameters. A total of 41 (0.11%) recipients had post-keratoplasty infections. Of these, 33 occurred after EK (29 after DSAEK, and four after DMEK), two after ALK, and six after PK. The clinical presentation was keratitis alone in 16 eyes and associated with endophthalmitis in 25 eyes. The organisms isolated were gram-negative bacteria in 26 eyes, fungus in eight eyes, gram-positive bacteria in four eyes, mixed infection in five eyes, and microbiology inconclusive in seven eyes. The majority (78%) of the gram-negative infections were due to multidrug-resistant organisms. Most (88%) donor corneas were harvested from hospital premises. The most common cause of donor mortality was trauma. The median duration of presentation from surgery was 4.46 (range: 1-30) days. The death to preservation time was 4.18 (1.5-7.65) hours. The death to utilization time was 3 (2-4.7) days. The overall risk of infectious adverse events after keratoplasty was 0.11%, ranging from 0.08% to 0.36%. Most (80.4%) of the adverse events occurred after EK. The majority (78.9%) of the adverse events were of bacterial etiology, of which gram-negative infections (68.4%) were the most common. The trends and microbiological spectrum of organisms associated with infections should be thoroughly documented in eye banks to gain insights and formulate guidelines on the management of adverse events.

Perceptions on Corneal and Eye Donation: Implications for Corneal Donor Programs

Perceptions on Corneal and Eye Donation: Implications for Corneal Donor Programs

Microsporidial stromal keratitis: treatment outcomes, clinical manifestations, confocal microscopy and histopathology findings: a retrospective observational study

ObjectiveMicrosporidial stromal keratitis (MSK) is an uncommon disease. Only several case series have been reported. We aimed to describe the clinical manifestations, histopathology and treatment outcomes of MSK.Methods and analysisRetrospective...

P.101: Tissue bank of the state of Mexico and its impact on the National Cornea Transplant Program.

P.101: Tissue bank of the state of Mexico and its impact on the National Cornea Transplant Program.

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.

A review of Bowman's layer structure, function, and transplantation.

Bowman's layer is an acellular corneal structure, which is considered to be a specially modified anterior stroma. It is presumed, that it forms as a result of ongoing epithelial-stromal interactions and no clear physiological purpose has been proven. Despite this fact, Bowman's layer has found its place in corneal transplantation. It has been performed for over adecade, mainly in treatment of advanced keratoconus with multiple modifications. Transplantation of Bowman's layer can be expected to become a widely used surgical procedure in the treatment of many corneal pathologies involving fragmentation and destruction of Bowman's layer. This article aims to summarize information available on its structure, possible function, and transplantation. A thorough literature search was performed in the PubMed database and Google Scholar using keywords: Bowman's layer, structure, function, preparation and corneal transplantation. All the relevant sources were used, which represent 77 peer-reviewed articles with information corcerning the topic of this article.