Pathological Corneas Research Articles

Rapport de cas d’un ulcère de Mooren sévère

Mooren's ulcer is a painless and idiopathic ulcer of the peripheral cornea related to autoimmunity provided by a corneal stromal antigen that is calgranulin C. Corneal involvement is isolated. There are no specific histological features to differentiate Mooren's ulcer from pseudo-Mooren's, the latter being part of a systemic disease. Mooren ulcer is a diagnosis of elimination based on a complete etiological check-up. However, histological examination, when performed, could provide additional data to support the diagnosis.We report the case of a 78-year-old female patient who presented with Mooren's ulcer. The patient had complained of red eye and photophobia for two weeks. Initial visual acuity was "counting fingers". Clinical examination revealed a perforated perilimbic ulcer with an iris prolapse. Due to the peripheral ulcerative keratitis, with a negative etiological work-up and anatomopathological analysis of the pathological cornea, the diagnosis of Mooren's ulcer was proposed.This rare case illustrates the need for a multidisciplinary approach involving ophthalmologists, pathologists, and internists, to obtain an etiological diagnosis and optimize the functional prognosis.

Cellular structural and functional imaging of donor and pathological corneas with label-free dual-mode full-field optical coherence tomography.

In this study, a dual-mode full-field optical coherence tomography (FFOCT) was customized for label-free static and dynamic imaging of corneal tissues, including donor grafts and pathological specimens. Static images effectively depict relatively stable structures such as stroma, scar, and nerve fibers, while dynamic images highlight cells with active intracellular metabolism, specifically for corneal epithelial cells. The dual-mode images complementarily demonstrate the 3D microstructural features of the cornea and limbus. Dual-modal imaging reveals morphological and functional changes in corneal epithelial cells without labeling, indicating cellular apoptosis, swelling, deformation, dynamic signal alterations, and distinctive features of inflammatory cells in keratoconus and corneal leukoplakia. These findings propose dual-mode FFOCT as a promising technique for cellular-level cornea and limbus imaging.

Synthetic solutions for re‐growing human corneas

Cornea blindness is still treated mainly by corneal transplantation, using donated allograft human corneas. However, a severe global shortfall leaves an estimated 12.7 million patients on waiting lists despite methods of using one cornea for two different partial‐thickness grafts. Even more individuals are not on waiting lists because they have no access to transplantation in their countries or regions. However, even if donor tissues were readily available, patients with inflamed, severely damaged corneas are at high risk of rejecting conventional transplantation. Various solutions have been proposed as alternatives to corneal allografting, including the development of keratoprostheses and stem cell grafting. We posited using cell‐free implants that mimic the extracellular matrix of the human cornea to recapitulate the environment during corneal development and stimulate the endogenous cells within the patient's eyes to affect regeneration. We used cell‐free corneal implants made from chemically crosslinked recombinant human collagen to promote in situ tissue regeneration in pathologic corneas, including high‐risk ones. We successfully developed and tested recombinant human solid collagen‐based implants that promoted stable regeneration in inflamed human patient corneas based on phosphorylcholine (MPC). However, solid corneas require a full operating theatre and staffing, which is costly and not accessible to more remote regions in Canada and globally. Burns and severe infections that can lead to perforations are medical emergencies that require immediate methods to seal the eye. In many centres, cyanoacrylate glue is used as a sealant, but this is toxic and kills surrounding cells, often necessitating follow‐on transplantation. We developed a synthetic, biocompatible, and adhesive liquid hydrogel (LiQD Cornea), which would replace these toxic cyanoacrylate glues. LiQD cornea is applied as a liquid but quickly adheres and gels within corneal tissue defects like a dental filling. It can be used to fill ulcers and other damaged areas. Then its similarity at a molecular level to a natural tissue framework promotes tissue regeneration, treating corneal perforations effectively without transplantation. Further, due to the synthetic nature of the material, risks associated with disease transmission are reduced compared to natural products. We see LiQD Cornea potentially used in outpatient clinics instead of operating theatres, maximizing practicality and minimizing health care costs.

Automated cornea diagnosis using deep convolutional neural networks based on cornea topography maps

Cornea topography maps allow ophthalmologists to screen and diagnose cornea pathologies. We aim to automatically identify any cornea abnormalities based on such cornea topography maps, with focus on diagnosing keratoconus. To do so, we represent the OCT scans as images and apply Convolutional Neural Networks (CNNs) for the automatic analysis. The model is based on a state-of-the-art ConvNeXt CNN architecture with weights fine-tuned for the given specific application using the cornea scans dataset. A set of 1940 consecutive screening scans from the Saarland University Hospital Clinic for Ophthalmology was annotated and used for model training and validation. All scans were recorded with a CASIA2 anterior segment Optical Coherence Tomography (OCT) scanner. The proposed model achieves a sensitivity of 98.46% and a specificity of 91.96% when distinguishing between healthy and pathological corneas. Our approach enables the screening of cornea pathologies and the classification of common pathologies like keratoconus. Furthermore, the approach is independent of the topography scanner and enables the visualization of those scan regions which drive the model’s decisions.

Retrospective Analysis of the Results and Causes of Penetrating Keratoplasty with Native Donor Material in a Multidisciplinary Hospital (Along the Example of MCOC Botkin Hospital)

Penetrating keratoplasty (PC) is an operation of choice for urgent and planned conditions of the pathologic cornea. Moscow City Ophthalmological Center “Botkin Hospital” together with the Moscow Coordination Center for Organ Donation) over the past five years, has been performing corneal transplants using native donor material. In the available literature sources, we could not find publications devoted to conducting PC with native donor material in a multidisciplinary hospital. This publication analyzes our own experience of end-to-end corneal transplantation with native donor material for the period from 2018 to 2022.

A study on the safety and therapeutic effect of Xiaoyaosan on depressive disorder related dry eye disease in a murine animal model

ABSTRACT This study was done to observe the safety and effect of Xiaoyaosan (XYS) on the stimulated depressive disorder (DD) related dry eye disease (DED) in mice. Normal control (NC) group, Vehicle group, and drug treatment groups, including Sertraline Hydrochloride (SH), XYS low-dose (XYS-LD), medium-dose (XYS-MD), and high-dose (XYS-HD), were established. The drug quality of XYS was assessed by high-performance liquid chromatography (HPLC). XYS toxicity in kidney and liver was assessed with Hematoxylin & Eosin (H&E) staining. Serum enzyme-linked immunosorbent assay (ELISA) and body weights were used to evaluate the depression status of mice. Tear production, corneal sensitivity, Oregon Green Dye (OGD) staining, and corneal confocal microscopy were used to assess ocular surface changes. H&E staining was also used to assess pathological cornea and lacrimal gland changes. HPLC results showed that XYS complied with Chinese drug quality standards. The drug treatment groups observed no drug toxicity reactions in the liver and kidney. SH and XYS groups improved DD-related serological indices as compared with Vehicle. Body weight was enhanced in mice with XYS groups compared to Vehicle and SH. Mice with XYS treatments showed increased tear production and corneal sensitivity, decreased corneal OGD staining scores, improved morphology, and decreased inflammatory cell infiltration in the cornea and lacrimal gland. In conclusion, XYS had no drug toxicity, improved serological indices, and ocular surface pathological changes in DD-related DED mice. XYS is safe and may have a therapeutic effect on DD-related DED.

Evaluation of optimal Zernike radial degree for representing corneal surfaces.

Tomography data of the cornea usually contain useful information for ophthalmologists. Zernike polynomials are often used to characterize and interpret these data. One of the major challenges facing researchers is finding the appropriate number of Zernike polynomials to model measured data from corneas. It is undeniable that a higher number of coefficients reduces the fit error. However, utilizing too many coefficients consumes computational power and time and bears the risk of overfitting as a result of including unnecessary components. The main objective of the current study is to analyse the accuracy of corneal surface data modelled with Zernike polynomials of various degrees in order to estimate a reasonable number of coefficients. The process of fitting the Zernike polynomials to height data for corneal anterior and posterior surfaces is presented and results are shown for normal and pathological corneas. These results indicate that polynomials of a higher degree are required for fitting corneas of patients with corneal ectasia than for normal corneas.

Presence of Protease Inhibitor 9 and Granzyme B in Healthy and Pathological Human Corneas.

Simple SummaryDetailed knowledge of the structure and properties of the human cornea is a prerequisite not only for the treatment of various corneal diseases but also for successful corneal transplantation and its long-term survival after grafting. Using various cell and molecular biology approaches, we found in cornea the protease inhibitor 9. This protein, known to be present in other human tissues but not yet reported in cornea, is directly involved in the immune response after transplantation. Together with its inhibitor (granzyme B), we localized this protein, especially in the superficial and inner cornea layers. This localization indicates that protease inhibitor 9 protein may be involved in protecting the cornea from external damage, but also in protection against immune cells inducing corneal graft rejection. Furthermore, we have shown on pathological corneal samples from corneal melting and herpes virus keratitis that the increased expression of both proteins is linked to these diseases. These experiments and their results represent an important contribution to the basic research of cornea biological properties with direct overlap into clinical practice.The aim of this study was to find out whether protease inhibitor 9 (PI-9) and granzyme B (GrB) molecules that contribute to immune response and the immunological privilege of various tissues are expressed in healthy and pathological human corneas. Using cryosections, cell imprints of control corneoscleral discs, we showed that PI-9 was expressed particularly in the endothelium, the superficial and suprabasal epithelium of healthy corneas, limbus, and conjunctiva. GrB was localized in healthy corneal and conjunctival epithelium, while the endothelium showed weak immunostaining. The expression of PI-6 and GrB was confirmed by qRT-PCR. Increased expression levels of the PI-9 and GrB genes were determined when the corneas were cultured with proinflammatory cytokines. Fluorescent and enzymatic immunohistochemistry of pathological corneal explants (corneal melting and herpes virus keratitis) showed pronounced PI-9, GrB, human leucocyte antigen (HLA)-DR, and leukocyte-common antigen (CD45) signals localized in multicellular stromal infiltrates and inflammatory cells scattered in the corneal stroma. We conclude that increased expression of the PI-9 and GrB proteins under pathological conditions and their upregulation in an inflammatory environment indicate their participation in immune response of the cornea during the inflammatory process.

A mathematical model for the corneal transparency problem

AbstractUnderstanding the physical basis of corneal transparency has been a subject of interest amongst physicists, basic scientists and ophthalmologists. Impairment of corneal clarity is a significant cause of visual morbidity worldwide. Thus, it is essential to understand the mechanisms behind corneal transparency and how the alterations due to corneal pathologies affect vision. We use Maxwell’s equations to model light propagation in ocular tissues and a nodal discontinuous Galerkin method combined with an explicit Runge-Kutta method to simulate light propagation in normal and pathological corneas. Our simulation results illustrate that an increase in the diameter of some fibres causes an increase in backscattering. Thus, these may represent some of the physical changes in the cornea that might result in loss of transparency and visual morbidity.

Multiscale mechanical model based on patient-specific geometry: Application to early keratoconus development

Keratoconus is a pathology of the cornea associated with a tissue thinning and a weakening of its mechanical properties. However, it remains elusive which aspect is the leading cause of the disease. To investigate this question, we combined a multiscale model with a patient-geometry in order to simulate the mechanical response of healthy and pathological corneas under intraocular pressure. The constitutive behavior of the cornea is described through an energy function which takes into account the isotropic matrix of the cornea, the geometric structure of collagen lamellae and the quasi-incompressibility of the tissue. A micro-sphere description is implemented to take into account the typical features of the collagen lamellae as obtained experimentally, namely their orientation, their stiffness and their dispersion, as well as the their unfolding stretch, at which they start to provide a significant force. A set of reference parameters is obtained to fit experimental inflation data of the literature. We show that the most sensitive parameter is the unfolding stretch, as a small variation of this parameter induces a major change in the corneal apex displacement. The keratoconus case is then studied by separating the impact of the geometry and the one of the mechanics. We computed the evolution of the SimK (a clinical indicator of cornea curvature) and elevation maps: we were able to reproduce the reported changes of SimK with pressure only by a mechanical weakening, and not by a change in geometry. More specifically, the weakening has to target the lamellae and not the matrix. The mechanical weakening leads to elevations close to early stage keratoconus, but our model lacks the remodeling component to couple the change in mechanics with changes in geometry. Still, these findings indicate that new methods for early diagnosis of keratoconus should focus on the detection of a mechanical weakening, and that stiffening treatments should be appropriate.

Digital Image Processing and Development of Machine Learning Models for the Discrimination of Corneal Pathology: An Experimental Model

Machine learning (ML) has an impressive capacity to learn and analyze a large volume of data. This study aimed to train different algorithms to discriminate between healthy and pathologic corneal images by evaluating digitally processed spectral-domain optical coherence tomography (SD-OCT) corneal images. A set of 22 SD-OCT images belonging to a random set of corneal pathologies was compared to 71 healthy corneas (control group). A binary classification method was applied where three approaches of ML were explored. Once all images were analyzed, representative areas from every digital image were also extracted, processed and analyzed for a statistical feature comparison between healthy and pathologic corneas. The best performance was obtained from transfer learning—support vector machine (TL-SVM) (AUC = 0.94, SPE 88%, SEN 100%) and transfer learning—random forest (TL- RF) method (AUC = 0.92, SPE 84%, SEN 100%), followed by convolutional neural network (CNN) (AUC = 0.84, SPE 77%, SEN 91%) and random forest (AUC = 0.77, SPE 60%, SEN 95%). The highest diagnostic accuracy in classifying corneal images was achieved with the TL-SVM and the TL-RF models. In image classification, CNN was a strong predictor. This pilot experimental study developed a systematic mechanized system to discern pathologic from healthy corneas using a small sample.

Diffusion-based degeneration of the collagen reinforcement in the pathologic human cornea

We describe a multiphysics model of the collagen structure of the cornea undergoing a progressive localized reduction of the stiffness, preluding to the development of ectasia and keratoconus. The architecture of the stromal collagen is assumed to follow the simplified two-family model proposed in Pandolfi et al. (A microstructural model of cross-link interaction between collagen fibrils in the human cornea. Philos Trans R Soc A 377:20180079, 2019), where the mechanical stiffness of the structure is supplied by transversal bonds within the fibrils of the same family (inter-crosslink bonds) and across the fibrils of the two families (intra-crosslink bonds). In Pandolfi et al. (A microstructural model of cross-link interaction between collagen fibrils in the human cornea. Philos Trans R Soc A 377:20180079, 2019), it was shown that the loss of the spherical shape due to the protrusion of a cone can be ascribed to the mechanical weakening of the intra-crosslink bonds in the central region of the collagen structure. In the present study, the reduction of bond stiffness is coupled to an evolutive pathologic phenomenon, modeled as a reaction–diffusion process of a normalized scalar field. We assume that the scalar field is a concentration-like measure of the degeneration of the chemical bonds stabilizing the structural collagen. We follow the evolution of the mechanical response of the system in terms of shape change, according to the propagation of the degeneration field, and identify the critical loss of mechanical stability resulting in the typical bulging of keratoconus corneas.

Cobalt blue light unit filter - A smartphone attachment for blue light photography.

Purpose:The aim of this study was to carry out blue light photography of fluorescein-stained corneas using a novel smartphone attachment.Methods:A smartphone attachment known as the cobalt blue light unit (C-BLU) was developed. It can filter out all wavelengths of light except the blue light emerging from the flashlight of a smartphone. A pilot study was carried out wherein the images captured with the C-BLU system were compared with slit-lamp photographs of the same patients. This setup was then used to photo document fluorescein-stained corneas in various clinical settings assembled at point-of-care.Results:Many pathologies of the fluorescein-stained cornea were captured using the C-BLU filter. It was used effectively in various settings (remote eye camps, intensive care units (ICU), pediatric group, corneal trauma triaging, etc.). C-BLU was assembled and used by optometrists and ophthalmology residents. The images captured were used for documenting, assisting in the treatment, and also for telecommunication of the patients’ findings.Conclusion:C-BLU is a low-cost pocket-size filter which is easy to use with a modern smartphone without any technical expertise needed to obtain a clear image of fluorescein-stained pathological corneas.

Corneal Biomechanics After Intrastromal Ring Surgery: Optomechanical In Silico Assessment.

PurposeTo provide a biomechanical framework to better understand the postsurgical optomechanical behavior of the cornea after ring implantation.MethodsCalibrated in silico models were used to determine the corneal shape and stresses after ring implantation. After mechanical simulations, geometric ray-tracing was used to determine the change in spherical equivalent. The effect of the surgical procedure, circadian variation of intraocular pressure, or the biomechanical weakening introduced by keratoconus (KC) were evaluated for each intrastromal ring.ResultsModels predicted the postsurgical optomechanical response of the cornea at a population level. The localized mechanical effect of the additional intrastromal volume introduced by the implants (size and diameter) drives the postsurgical corneal response. However, central corneal stresses did not increase more than 50%, and thus implants did not strengthen the cornea globally. Because of the biomechanical weakening introduced by laser pocketing, continuous implants in a pocket resulted in higher refractive corrections and in the relaxation of the anterior stroma, which could slow down KC progression. Implants can move within the stroma, acting as a dynamic pivot point that modifies corneal kinematics and flattens the corneal center. Changes in stromal mechanical properties did not impact on refraction for normal or pathological corneas.ConclusionsImplants do not stiffen the cornea but create a local bulkening effect that regularizes the corneal shape by modifying corneal kinematics without canceling corneal motion.Translational RelevanceIn silico models can help to understand corneal biomechanics, to plan patient-specific interventions, or to create biomechanically driven nomograms.

Pathological-Corneas Layer Segmentation and Thickness Measurement in OCT Images.

PurposeThe purpose of this study was to propose a new algorithm for the segmentation and thickness measurement of pathological corneas with irregular layers using a two-stage graph search and ray tracing.MethodsIn the first stage, a graph, with only gradient edge-cost, is used to segment the air-epithelium and endothelium-aqueous boundaries. In the second stage, a graph, with gradient, directional, and multiplier edge-cost, is used to correct segmentation. The optical coherence tomography (OCT) image is flattened using the air-epithelium boundary and a graph search is used to segment the epithelium-Bowman's and Bowman's-stroma boundaries. Then, the OCT image is flattened using the endothelium-aqueous boundary and a graph search is used to segment the Descemet's membrane. Ray tracing is used to correct the inter-boundary distances, then the thickness is measured using the shortest distance. The proposed algorithm was trained and evaluated using 190 OCT images manually segmented by trained operators.ResultsThe mean and standard deviation of the unsigned errors of the algorithm-operator and inter-operator were 0.89 ± 1.03 and 0.77 ± 0.68 pixels in segmentation and 3.62 ± 3.98 and 2.95 ± 2.52 µm in thickness measurement.ConclusionsOur proposed algorithm can produce accurate segmentation and thickness measurements compared with the manual operators.Translational RelevanceOur algorithm could be potentially useful in the clinical practice.

Deep Learning for Assessing the Corneal Endothelium from Specular Microscopy Images up to 1 Year after Ultrathin-DSAEK Surgery.

PurposeTo present a fully automatic method to estimate the corneal endothelium parameters from specular microscopy images and to use it to study a one-year follow-up after ultrathin Descemet stripping automated endothelial keratoplasty.MethodsWe analyzed 383 post ultrathin Descemet stripping automated endothelial keratoplasty images from 41 eyes acquired with a Topcon SP-1P specular microscope at 1, 3, 6, and 12 months after surgery. The estimated parameters were endothelial cell density (ECD), coefficient of variation (CV), and hexagonality (HEX). Manual segmentation was performed in all images.ResultsOur method provided an estimate for ECD, CV, and HEX in 98.4% of the images, whereas Topcon's software had a success rate of 71.5% for ECD/CV and 30.5% for HEX. For the images with estimates, the percentage error in our method was 2.5% for ECD, 5.7% for CV, and 5.7% for HEX, whereas Topcon's software provided an error of 7.5% for ECD, 17.5% for CV, and 18.3% for HEX. Our method was significantly better than Topcon's (P < 0.0001) and was not statistically significantly different from the manual assessments (P > 0.05). At month 12, the subjects presented an average ECD = 1377 ± 483 [cells/mm2], CV = 26.1 ± 5.7 [%], and HEX = 58.1 ± 7.1 [%].ConclusionsThe proposed method obtains reliable and accurate estimations even in challenging specular images of pathologic corneas.Translational RelevanceCV and HEX, not currently used in the clinic owing to a lack of reliability in automatic methods, are useful biomarkers to analyze the postoperative healing process. Our accurate estimations allow now for their clinical use.

Isolation and Characterization of a New Human Corneal Epithelial Cell Line: HCE-F

To isolate and characterize an epithelial cell (EC) line from a human donor cornea, which may serve as a reliable test cell line to address biomolecular issues and study the response of corneal epithelium to stressing events and therapeutic treatments. A corneal button from a donor patient was treated with enzymes to separate the epithelial sheet and to free EC, which were put in tissue culture. ECs were characterized by optic and electronic microscopies, cytokeratins and PAX6 were detected by SDS-PAGE and western immunoblotting, the barrier function was evaluated by transepithelial electric resistance and by the immune detection of membrane junction proteins, and the karyotype was characterized according to the classical methods. Morphological analyses returned the picture of classical homogeneous polygonal morphology as expecetd by EC that was maintained over time and several in vitro passages. Transepithelial electric resistance values were characteristic of a typical barrier-forming cell line. The cytokeratin expression pattern was the one expected for corneal EC with a predominance of CK3 and CK5 and different from a human keratocyte cell line. The male karyotype showed 2 trisomies, of chromosomes 8 and 11. All the data so far obtained with the HCE-F cells concur to certify this cell line as a stable, true primary human corneal EC line, which could then be used as a test cell line to study and address the questions concerning the biological response of human corneal epithelium to stressing and/or therapeutic treatments and as a term of comparison for EC derived from pathological corneas.

Generating density maps for convolutional neural network-based cell counting in specular microscopy images

Accurate endothelial cell density with specular microscopy is essential for correct clinical assessment of the cornea. Commercial specular microscopes incorporate automated cell segmentation methods to estimate cell density. However, these methods are prone to false cell detections in pathological corneas. This project aims to obtain a reliable automated cell density from specular microscopy images of both healthy and pathological corneas with convolutional neural networks. Convolutional neural networks require labeled datasets. Thus, we developed custom software for producing a curated dataset of labeled ground-truth images and cell density maps. In this paper, we implemented a fully convolutional regression network to predict the cell density map from the input microscopy image. Encouraging preliminary results show the potential of the method. This approach may pave the way for dealing with the variability of corneal endothelial cell images.

Nerve regeneration in liquid cornea patches

AbstractIn current clinical practice, corneas with perforations that are repaired by cyanoacrylate gluing and those with recurrent ulcerations are often treated by corneal grafting as the treatment to restore vision. However, there is a severe shortage of donor corneas worldwide. More importantly, when someone has a toothache and visits the dentist, the dentist removed the pathologic portions and fills the tooth. Corneal transplantation for a perforation or ulcer would be similar to extracting the tooth and replacing with an implant. Our objective was to develop a method for restoring pathologic corneas such as those with ulcers or perforations that avoids corneal transplantation. We have developed a Liquid Cornea Patch (LCP) that is based on a collagen‐like peptide conjugated to a polyethylene glycol backbone. The LCP is applied as a viscous liquid that polymerises in situ to form a hydrogel. We previously reported its efficacy in sealing large perforation in vitro (Samarawickrama et al. 2018). We also showed that the crosslinking agent used was non‐toxic to corneal epithelial and endothelial cells at doses used for hydrogel formation. Here, we report on a second‐generation patch which we successfully tested in vivo in rabbit and mini‐pig corneas. The LCP withstands bursting pressures up to 170 mm Hg. Although not as strong as cyanoacrylate glue, the bursting pressure is much higher than would be encountered in the human eye (where normal intraocular pressure is between 12 and 22 mm Hg). Over 12 months in mini‐pig corneas, the LCPs promoted regeneration of cornea tissue and nerves. We show that nerve in‐growth proceeded as per solid versions of collagen and collagen‐like peptide‐based implants.

Stepwise Decreasing of Vitreous Pressure by Anterior Vitrectomy: A Novel Method for Preventing Positive Vitreous Pressure During Penetrating Keratoplasty.

This study evaluates the clinical effects of the stepwise anterior vitrectomy on the prevention of positive vitreous pressure (PVP) during penetrating keratoplasty (PKP). PKP in conjunction with stepwise anterior vitrectomy was performed on 15 eyes of 15 patients under retrobulbar anesthesia. A preset vitrectomy trocar-cannula was inserted into the vitreous cavity before PKP. During the opening of the anterior chamber, intermittent vitrectomy and corneal incision expansion were performed alternately to keep the lens or artificial intraocular lens (IOL) and iris flat until the entirety of the pathological cornea had been dissected. The main outcome measures include visual acuity, crystalline lens rise (CLR), corneal curvature and diopter, and corneal endothelial cell loss. All surgical procedures were performed successfully without any PVP-related intraoperative complications. The mean time of the stepwise vitrectomies was 3.1 ± 0.7s, the duration of each vitrectomy was 8.1 ± 5.3s, and the duration of the total surgery was 60.5 ± 5.3min. The anterior segment reaction was mild and the shape of the pupil remained normal 1day after surgery. The mean preoperative and mean 3-month postoperative CLR values were 0.48 ± 0.09mm and - 0.16 ± 0.04mm, respectively (p < 0.0001). The mean preoperative endothelial cell density in donor buttons was 2570 ± 171cells/mm2, and the mean 6- and 12-month postoperative endothelial cell density in donor buttons was 2207 ± 127cells/mm2 and 2000 ± 198cells/mm2, respectively. The novel and stabilized PKP procedure, performed in conjunction with the stepwise anterior vitrectomy, effectively avoided the PVP during open-sky surgery. Chinese Clinical Trial Registry, ChiCTR1900021227.