In vivo microscopic and optical coherence tomography classification of neurotrophic keratopathy

The use of rh-NGF in the management of neurotrophic keratopathy

Neurotrophic keratitis or keratopathy (NK) is a degenerative corneal disease induced by impairment of the trigeminal nerve function. This condition may lead to persistent epithelial defects, corneal ulceration, and perforation. The diagnosis of NK requires a careful investigation of any ocular and systemic condition associated with the disease and ocular surface and corneal sensitivity examinations. In the past, several medical and surgical procedures were used to treat this condition with different clinical effectiveness. Cenegermin is a recombinant human nerve growth factor (rh-NGF) that supports corneal reinnervation. Different clinical trials have demonstrated the safety and efficacy of topical cenegermin in patients with moderate to severe neurotrophic keratitis. In this review, we report the literature on clinical results regarding the treatment of NK with cenegermin since its approval by the European Medicines Agency (EMA) and the Food and Drug Administration (FDA) in 2017 and 2018, respectively.

Immune-Mediated Ocular Surface Disease in Diabetes Mellitus-Clinical Perspectives and Treatment: A Narrative Review

Diabetes mellitus (DM) is a chronic metabolic disorder marked by hyperglycemia due to defects in insulin secretion, action, or both, with a global prevalence that has tripled in recent decades. This condition poses significant public health challenges, affecting individuals, healthcare systems, and economies worldwide. Among its numerous complications, ocular surface disease (OSD) is a significant concern, yet understanding its pathophysiology, diagnosis, and management remains challenging. This review aims to explore the epidemiology, pathophysiology, clinical manifestations, diagnostic approaches, and management strategies of diabetes-related OSD. The ocular surface, including the cornea, conjunctiva, and associated structures, is vital for maintaining eye health, with the lacrimal functional unit (LFU) playing a crucial role in tear film regulation. In DM, changes in glycosaminoglycan metabolism, collagen synthesis, oxygen consumption, and LFU dysfunction contribute to ocular complications. Persistent hyperglycemia leads to the expression of cytokines, chemokines, and cell adhesion molecules, resulting in neuropathy, tear film abnormalities, and epithelial lesions. Recent advances in molecular research and therapeutic modalities, such as gene and stem cell therapies, show promise for managing diabetic ocular complications. Future research should focus on pathogenetically oriented therapies for diabetic neuropathy and keratopathy, transitioning from animal models to clinical trials to improve patient outcomes.

Corneal Nerve Assessment by Aesthesiometry: History, Advancements, and Future Directions

The measurement of corneal sensation allows clinicians to assess the status of corneal innervation and serves as a crucial indicator of corneal disease and eye health. Many devices are available to assess corneal sensation, including the Cochet-Bonnet aesthesiometer, the Belmonte Aesthesiometer, the Swiss Liquid Jet Aesthesiometer, and the newly introduced Corneal Esthesiometer Brill. Increasing the clinical use of in vivo confocal microscopy and optical coherence tomography will allow for greater insight into the diagnosis, classification, and monitoring of ocular surface diseases such as neurotrophic keratopathy; however, formal esthesiometric measurement remains necessary to assess the functional status of corneal nerves. These aesthesiometers vary widely in their mode of corneal stimulus generation and their relative accessibility, precision, and ease of clinical use. The development of future devices to optimize these characteristics, as well as further comparative studies between device types should enable more accurate and precise diagnosis and treatment of corneal innervation deficits. The purpose of this narrative review is to describe the advancements in the use of aesthesiometers since their introduction to clinical practice, compare currently available devices for assessing corneal innervation and their relative limitations, and discuss how the assessment of corneal innervation is crucial to understanding and treating pathologies of the ocular surface.

A New Treatment for Recalcitrant Neurotrophic Keratopathy of Ocular Graft-Versus-Host Disease with Virus Infection

INTRODUCTION

Neurotrophic keratopathy (NK) is a rare degenerative ocular disease that can be difficult to treat. There were no effective resolutive treatments for severe NK caused by ocular graft-versus-host disease (oGVHD) along with virus infection. To address this question, we designed a prospective cohort study to evaluate the efficacy and safety of topical recombinant human nerve growth factor (rhNGF) in patients with recalcitrant NK of oGVHD and viral infection.

METHODS

This prospective cohort study enrolled patients with recalcitrant NK diagnosed with oGVHD and treated with rhNGF. Clinical evaluations included the range of epithelial defects, best corrected visual acuity, intraocular pressure, slit-lamp examination, and corneal fluorescein staining. Examinations of the central corneal thickness, corneal sensitivity, and nerve fiber regeneration were performed at each visit at 4, 8, 12, 20 weeks and 6 months, respectively, after initiating rhNGF treatment.

RESULTS

All enrolled patients were diagnosed with NK at stage 2 (7 eyes, 63.6%) or stage 3 (4 eyes, 36.4%) and responded to rhNGF treatment. Five of 11 (45.5%) and 9 of 11 eyes (81.8%) achieved complete corneal epithelial healing after 4 and 8 weeks, respectively. All 11 eyes (100%) achieved complete corneal healing after 12 weeks. There was also a significant reduction in the corneal ulcer area during each visit (P < 0.001), as well as in the corneal fluorescein staining score (P < 0.010). There was a significant improvement in corneal sensation when compared to the baseline (P < 0.050).

CONCLUSION

Topical treatment with rhNGF effectively promoted the complete corneal healing of persistent epithelial defects and corneal ulcers in patients with recalcitrant NK in oGVHD and viral infection.

Human Stem Cells for Ophthalmology: Recent Advances in Diagnostic Image Analysis and Computational Modelling

Purpose of Review

To explore the advances and future research directions in image analysis and computational modelling of human stem cells (hSCs) for ophthalmological applications.

Recent Findings

hSCs hold great potential in ocular regenerative medicine due to their application in cell-based therapies and in disease modelling and drug discovery using state-of-the-art 2D and 3D organoid models. However, a deeper characterisation of their complex, multi-scale properties is required to optimise their translation to clinical practice. Image analysis combined with computational modelling is a powerful tool to explore mechanisms of hSC behaviour and aid clinical diagnosis and therapy.

Summary

Many computational models draw on a variety of techniques, often blending continuum and discrete approaches, and have been used to describe cell differentiation and self-organisation. Machine learning tools are having a significant impact in model development and improving image classification processes for clinical diagnosis and treatment and will be the focus of much future research.

TFOS Lifestyle: Impact of elective medications and procedures on the ocular surface

The word "elective" refers to medications and procedures undertaken by choice or with a lower grade of prioritization. Patients usually use elective medications or undergo elective procedures to treat pathologic conditions or for cosmetic enhancement, impacting their lifestyle positively and, thus, improving their quality of life. However, those interventions can affect the homeostasis of the tear film and ocular surface. Consequently, they generate signs and symptoms that could impair the patient's quality of life. This report describes the impact of elective topical and systemic medications and procedures on the ocular surface and the underlying mechanisms. Moreover, elective procedures performed for ocular diseases, cosmetic enhancement, and non-ophthalmic interventions, such as radiotherapy and bariatric surgery, are discussed. The report also evaluates significant anatomical and biological consequences of non-urgent interventions to the ocular surface, such as neuropathic and neurotrophic keratopathies. Besides that, it provides an overview of the prophylaxis and management of pathological conditions resulting from the studied interventions and suggests areas for future research. The report also contains a systematic review investigating the quality of life among people who have undergone small incision lenticule extraction (SMILE). Overall, SMILE refractive surgery seems to cause more vision disturbances than LASIK in the first month post-surgery, but less dry eye symptoms in long-term follow up.

Efficacy of Plasma Rich in Growth Factors (PRGF) in Stage 1 Neurotrophic Keratitis

Background/Aims

Neurotrophic keratitis (NK) is a neurodegenerative disease that can lead to corneal hypoesthesia, decreased tear production, and epitheliopathy. Based on the severity of ocular surface damage, NK is classified into 3 stages. Stage 1 NK is characterized by superficial punctate keratopathy, tear film instability, and reduced corneal sensation. The therapeutic efficacy of PRGF eye drops for NK stages 2 and 3 has been previously reported. In this study, we evaluated the efficacy and safety of autologous PRGF eye drops in improving corneal sensitivity and other ocular surface clinical signs in patients with stage 1 NK.

Methods

Retrospective chart review.

Results

26 eyes of 15 stage 1 NK patients (seven males, eight females), aged 76.3 ± 12.1 years, were included in the study. The mean treatment duration was 2 ± 1.8 months. With PRGF treatment, corneal sensitivity increased from 2.8 to 4.5 cm in 53.8% (14/26) (p < 0.01), TBUT increased from 3.6 to 5.0 s in 69.2% (18/26) (p < 0.01), and Schirmer score increased from 13.7 to 16.8 mm in 80.7% (21/26) of treated eyes (p < 0.01). Similarly, an improvement in corneal staining (punctate epithelial erosions) and MMP-9 levels was seen in 80.7% (n = 21) and 65.4% (n = 17) of treated eyes, respectively. BCVA improvement was seen in 26.9% of treated eyes (n = 7).

Conclusions

This study demonstrates the effective role of PRGF therapy in recovering corneal sensation and tear film function and in the healing of corneal erosions in stage 1 NK patients.

Corneal Neurotization—Indications, Surgical Techniques and Outcomes

Corneal neurotization is a promising surgical approach for the treatment of moderate to severe neurotrophic keratopathy. This technique aims to restore corneal sensation by transferring healthy nerves, either directly or via a conduit, to the anesthetic cornea. This review provides a report on the current state of development, evidence, and experience in the field. We summarize the data available from clinical reports and case series, placing an emphasis on the diversity of the surgical techniques reported. While these data are encouraging, they also highlight the need for a consensus in reporting outcomes and highlight how the next step will involve validating putative outcome parameters when researching and reporting corneal neurotization surgery.

Clinical and instrumental assessment of the corneal healing in moderate and severe neurotrophic keratopathy treated with rh-NGF (Cenegermin)

PURPOSE

To evaluate corneal healing in patients with moderate and severe neurotrophic keratitis (NK) treated with topical rh-NFG (Cenegermin).

METHODS

Twenty-one patients (12F and 9M) aged from 21 to 93 years (62.5 ± 19.4) with moderate and severe NK were enrolled in the study. The patients were divided into 2 groups accordingly to the severity of the disease. The underlying causes of NK were determined. The VAS questionnaire was dispensed. The ocular examination comprised slit lamp evaluation, ocular surface assessment with Keratograph 5M (Oculus, Germany), corneal sensitivity with Cochet-Bonnet esthesiometer (Lunneaux, France) and corneal thickness measurement with AC-OCT (DRI, Triton, Topcon, Japan). The drops of Cenegermin 0.002% were administrated 6 times daily for 8 weeks. All participants were evaluated at baseline, after 4 and 8 weeks of the treatment. The area of corneal defect with maximum diameter less than 0.5 mm was considered as healed. The main outcome measures were corneal healing, corneal sensitivity recovery and corneal thickness in the ulcer group.

RESULTS

The herpetic keratitis was the most common cause of NK. Thirteen eyes were affected by severe grade of NK with corneal ulcer and 8 eyes presented a moderate grade. After 8 weeks a complete healing of the corneal defects was registered both in moderate and severe NK. Significant increase of the corneal sensitivity and thickness were registered.

CONCLUSIONS

The rh-NGF (Cenegermin) resulted effective in the treatment of the severe and moderate NK with significant recovery of the corneal sensitivity and healing of the corneal defects in both groups.

The Role of Hi-Tech Devices in Assessment of Corneal Healing in Patients with Neurotrophic Keratopathy

To prove the role of high-tech investigation in monitoring corneal morphological changes in patients with neurotrophic keratopathy (NK) using Keratograph 5M (K5M) and anterior segment OCT (AS-OCT), corneal healing was monitored with Keratograph 5M (Oculus, Wetzlar, Germany) and AS-OCT (DRI, Triton, Topcon, Tokyo, Japan) in 13 patients (8F and 5M), aged from 24 to 93 years (67.8 ± 19) with severe NK, who were treated with Cenegermin 0.002% (20 μg/mL) (Oxervate^®, Dompè, Farmaceutici Spa, Milan, Italy). The surface defects were evaluated on Keratograph 5M with ImageJ software and the corneal thickness variations were measured using DRI-Triton OCT software. Instrumental procedures were performed at baseline, and after 4 and 8 weeks of the treatment, respectively. The main outcome measures were reduction of the ulcers’ area and corneal thickness recovery. The mean area of the corneal ulcers was reduced between baseline and 4 weeks examination in all patients, and at 8 weeks all ulcers were completely healed. An increase of the corneal thickness was evidenced between the baseline visit and after the 4- and 8-week follow-up, respectively. Additionally, only in collaborating subjects the In Vivo Confocal Microscopy (IVCM) was performed with HRT Rostock Cornea Module (Heidelberg Eng GmbH) to study the corneal nerves fibres. High-tech diagnostics with K5M, AS-OCT and IVCM proved useful in the assessment of corneal morphology and the healing process in patients with NK and could be extended to assess other corneal pathologies.

Recombinant Human Nerve Growth Factor (Cenegermin)–Driven Corneal Wound Healing Process: An Evidence-Based Analysis

Purpose: To evaluate anterior segment optical coherence tomography (AS-OCT) to detect the wound healing process as per monitoring the effectiveness of cenegermin to treat moderate to severe neurotrophic keratoplasty.

Methods: A retrospective chart review was realized to identify patients treated with cenegermin at the Clinica Oculistica, University of Genoa, Italy. All patients underwent careful examinations at baseline and follow-up visits. AS-OCT scans centered on the minimum corneal thickness (CT) area were always performed. We compared findings of AS-OCT with the findings from the slit-lamp examination. A linear regression analysis was used to evaluate factors associated with corneal healing. A further analysis, including a control group treated with 50% autologous serum (AS), was done to investigate and compare the efficacy of cenegermin.

Results: Data from 16 eyes were studied. The average patients' age was 60.9 ± 21.1 years; five (31.2%) eyes experienced persistent epithelial defect and 11 (68.8%) eyes had neurotrophic corneal ulcer. The average reepithelialization time was 3.9 ± 0.5 weeks in the cenegermin group versus 5.9 ± 1.9 weeks in the AS group (p < 0.01). The AS‐OCT scans revealed an average CT at the thinnest point of 276.3 ± 74.1 μm before treatment with an average increase of 176.5 ± 60.3 μm at the end of the cenegermin treatment (B = −0.15; p = 0.035). The AS-OCT percentage increase in corneal thickness between the two groups was statistically significant (p < 0.02).

Conclusion: Understanding the cascade of events involved in the nerve growth factor–driven corneal wound healing process is clinically meaningful for the clinician. AS-OCT is an effective tool for systematic anterior segment imaging, allowing the detailed detection of the front-to-back layered corneal structure for quantitative analysis and monitoring of the healing process.

Tear proteomics reveals the molecular basis of the efficacy of human recombinant nerve growth factor treatment for Neurotrophic Keratopathy

Neurotrophic Keratopathy (NK), classified as an orphan disease (ORPHA137596), is a rare degenerative corneal disease characterized by epithelial instability and decreased corneal sensitivity caused by the damage to the corneal nerves. The administration of human recombinant nerve growth factor (rhNGF) eye drops, as a licensed-in-Europe specific medication for treatment of moderate and severe NK, has added promising perspectives to the management of this disorder by providing a valid alternative to the neurotization surgery. However, few studies have been conducted to the molecular mechanism underlying the response to the treatment. Here, we carried out tears proteomics to highlight the protein expression during pharmacological treatment of NK (Data are available via ProteomeXchange with identifier PXD025408).Our data emphasized a proteome modulation during rhNGF treatment related to an increase in DNA synthesis, an activation of both BDNF signal and IL6 receptor. Furthermore, the amount of neuronal Extracellular Vesicles EVs (CD171+) correlated with the EVs carrying IL6R (CD126+) together associated to the inflammatory EVs (CD45+) in tears. Such scenario determined drug response, confirmed by an in vivo confocal microscopy analysis, showing an increase in length, density and number of nerve fiber branches during treatment. In summary, rhNGF treatment seems to determine an inflammatory micro-environment, mediated by functionalized EVs, defining the drug response by stimulating protein synthesis and fiber regeneration.

Observational study of cenegermin for the treatment of limbal stem cell deficiency associated with neurotrophic keratopathy

Background:

Neurotrophic keratopathy (NK) and limbal stem cell deficiency (LSCD) have high morbidity and require aggressive management to prevent permanent vision loss. Cenegermin, a recombinant human nerve growth factor, was approved by the Federal Drug Administration in 2018 for the treatment of NK.

Objectives:

To determine the efficacy and safety of cenegermin in the treatment of LSCD associated with NK.

Design:

Prospective cohort study

Methods:

Patients diagnosed with LSCD and NK who had failed conventional treatment were enrolled in this prospective open-label study. Patients were treated with cenegermin for 8 weeks. The primary objective was to determine whether the area of abnormal epithelium decreased following treatment. Corneal sensation, visual acuity (VA), and LSCD severity were also evaluated.

Results:

Six eyes of 5 patients were included in the study. Cenegermin significantly improved the area of abnormal corneal epithelium in 5 of 6 eyes, measuring 73% of total corneal area at the initial visit and 48% at the final visit ( P = .036). Corneal sensation improved in all patients, Cochet–Bonnet aesthesiometry measured 14.7 and 26.7 mm at the initial and final visit, respectively ( P = .009). VA improved in 4 out of 6 eyes, with mean initial logMAR VA of 1.67 and final logMAR VA of 1.19 ( P = .045). Finally, LSCD grading improved using the Aravena scoring system; however, this difference was not statistically significant ( P = .14). One patient presented with an epithelial defect at baseline, which resolved following treatment. No patient withdrew from the study due to adverse effects.

Conclusions:

Cenegermin effectively improved the cornea epithelium, VA, and corneal sensation in patients with LSCD and NK who had failed prior treatment. Further studies are necessary to better understand the anatomical changes and to confirm our results with a larger randomized control trial.

Registration:

The study was registered at ClinicalTrials.gov with identifier NCT04552730 ( https://clinicaltrials.gov/ct2/show/NCT04552730 ).

Associated Neurotrophic Keratopathy in Complex Regional Pain Syndrome

PURPOSE

To report a case of neurotrophic keratopathy (NK) in a patient with complex regional pain syndrome (CRPS) with ipsilateral facial involvement.

METHODS

Case report.

RESULTS

An 18-year old woman with a 5-year history of CRPS type I, a systemic disorder with a neuropathic component with associated limb and right facial involvement, presented with an insidious onset of blurred vision and pain in the right eye. Ocular examination revealed decreased corneal sensation, as measured by Cochet-Bonnet testing, associated with recurrent epithelial defects and whorl-like superficial corneal epitheliopathy. NK was suspected and confirmed by in vivo confocal microscopy (IVCM), which revealed rarefaction of the subbasal nerve plexus in the affected eye. To enhance corneal nerve health, plasma rich in growth factors drops were used. Persistence of NK prompted a superficial keratectomy with placement of an amniotic membrane graft and a course of cenegermin 0.002% (Oxervate; Dompé Farmaceutici SpA, Italy) in the postoperative period. This combination therapy resulted in successful epithelial closure and vision improvement after 8 weeks of therapy with no recurrence of disease for 11 months. Importantly, at that final visit, IVCM demonstrated growth of corneal nerves for the first time in this patient.

CONCLUSIONS

This is the first case report of NK occurring in the context of CRPS, a neuropathy with ipsilateral facial pain involvement. IVCM was important in the diagnosis of NK, which responded successfully to ocular surface treatments focused on nerve health stimulation that ultimately resulted in corneal nerve growth.

Neurotrophic keratopathy and Wallenberg – Zakharchenko syndrome: a clinical case

BACKGROUND: Degenerative changes of cornea after transection of the trigeminal nerve were first described by F. Magendie in 1824. Neurotrophic keratopathy is considered to be an orphan disease which lately has been recognized more and more often. According to literature data, neurotropchic keratopathy affects 5 individuals in 10,000. The diagnosis is difficult due to the lack of information about this condition, the rare occurrence and the presence of a large number of etiological factors. AIM: To determine the causes of the neurotrophic keratopathy development and the treatment tactics in a patient with a neurological disease. The article presents a case of neurotrophic keratopathy in a patient with Wallenberg Zakharchenko syndrome. Because of the fact that neurotrophic keratopathy was diagnosed late and the correct treatment did not start in time, further progression of the pathological process in the cornea could not be avoided. Periodic recurrence of neurotrophic keratopathy is associated with an underlying chronic neurological disease. CONCLUSIONS: Neurotrophic keratopathy requires early diagnosis. In certain clinical cases, for the successful treatment of this pathology, it is necessary to prescribe systemic therapy.

Expert consensus on the identification, diagnosis, and treatment of neurotrophic keratopathy

Background

Neurotrophic keratopathy (NK) is a relatively uncommon, underdiagnosed degenerative corneal disease that is caused by damage to the ophthalmic branch of the trigeminal nerve by conditions such as herpes simplex or zoster keratitis, intracranial space-occupying lesions, diabetes, or neurosurgical procedures. Over time, epithelial breakdown, corneal ulceration, corneal melting (thinning), perforation, and loss of vision may occur. The best opportunity to reverse ocular surface damage is in the earliest stage of NK. However, patients typically experience few symptoms and diagnosis is often delayed. Increased awareness of the causes of NK, consensus on when and how to screen for NK, and recommendations for how to treat NK are needed.

Methods

An 11-member expert panel used a validated methodology (a RAND/UCLA modified Delphi panel) to develop consensus on when to screen for and how best to diagnose and treat NK. Clinicians reviewed literature on the diagnosis and management of NK then rated a detailed set of 735 scenarios. In 646 scenarios, panelists rated whether a test of corneal sensitivity was warranted; in 20 scenarios, they considered the adequacy of specific tests and examinations to diagnose and stage NK; and in 69 scenarios, they rated the appropriateness of treatments for NK. Panelist ratings were used to develop clinical recommendations.

Results

There was agreement on 94% of scenarios. Based on this consensus, we present distinct circumstances when we strongly recommend or may consider a test for corneal sensitivity. We also present recommendations on the diagnostic tests to be performed in patients in whom NK is suspected and treatment options for NK.

Conclusions

These expert recommendations should be validated with clinical data. The recommendations represent the consensus of experts, are informed by published literature and experience, and may improve outcomes by helping improve diagnosis and treatment of patients with NK.

Aftermarket effects of cenegermin for neurotrophic keratopathy in pediatric patients

PURPOSE

Neurotrophic keratopathy (NK) is a rare condition characterized by poor corneal sensation and healing. Cenegermin (topical recombinant nerve growth factor) has gained traction as a medical therapy for NK in recent years, and is FDA-approved for patients over two years old. However, no major trials have demonstrated the drug's efficacy in children. This study reviews the outcomes of cenegermin therapy in a pediatric patient population.

METHODS

Retrospective case series of patients from three tertiary referral institutions who 1) initiated an 8-week course of cenegermin therapy, and 2) were 18 years or less at time of treatment initiation.

RESULTS

Eight pediatric patients, with a total of nine affected eyes, underwent cenegermin therapy. All eight patients had previously trialed other NK-specific treatments, none of which had been entirely successful. Five patients (63%) completed the full eight-week therapy course. Five patients (63%) experienced clinical improvement not attributed to another treatment, through improved corneal ulcer stage (n = 5) and best-corrected visual acuity (n = 2). Clinical improvements persisted through a mean recurrence-free period of 10 months. Adverse effects reported during therapy included ocular pain, difficulty sleeping, and continued corneal thinning.

CONCLUSION

The results provide modest support for the use of cenegermin in pediatric patients with neurotrophic keratopathy. The primary benefit was an improvement in corneal epithelial stability. Clinicians should be aware that pre-existing corneal scarring in NK may significantly limit the ability of cenegermin alone to improve visual acuity, and should closely monitor the corneal epithelial status during therapy in pediatric patients.

Neurotrophic Keratopathy in Pediatric Patients

Purpose: This review provides an overview of the causes and treatment of neurotrophic keratopathy in the pediatric population.Methods: A thorough review of the current literature discussing neurotrophic keratopathy was conducted then summarized.Results:Fourty-nine papers were reviewed. Congenital and acquired causes of neurotrophic keratopathy exist in the pediatric population. Both medical and surgical approaches to treatment have been trialed, albeit to a limited extent, in pediatric patients. Conservative treatment includes topical lubrication and antibiotics to prevent concurrent infectious ulcer formation. Various neurotrophic factors have been trialed in the form of serum drops to restore corneal sensation when conservative measures fail. Surgically, different corneal neurotization techniques have been developed whereby a donor nerve is routed to the anesthetized cornea to restore innervation and sensation. Conclusions: Advances in the treatment of neurotrophic keratopathy have made corneal reinnervation and restoration of vision more easily attainable in pediatric patients.

Dorsolateral medullary infarction registry: a study protocol for a prospective, multicentric registry

Background

Dorsolateral medullary infarction is a typical cerebral infarction which is characterized by Wallenberg’s syndrome. Neurotrophic keratopathy is an uncommon consequence of dorsolateral medullary infarction. At present, the protocol is aimed to study the dynamic changes in corneal innervation and the ocular surface environment after dorsolateral medullary infarction.

Methods

This study will involve consecutive data from all medical records of patients within 7 days of acute dorsolateral medullary infarction onset at the Departments of Neurology from 10 collaborating stroke centers. Eligible patients will mainly be characterized based on detailed physical examinations, multimodal imaging, and corneal related examinations and patients will be followed-up for 2 years. Neurotrophic keratopathy after dorsolateral medullary infarction is the primary endpoint. The dynamic histological corneal innervation and ocular surface environment after dorsolateral medullary infarction will be observed during the follow-up period.

Discussion

This multicentric, prospective registry is the first to identify and characterize the dynamic changes of corneal innervation and the ocular surface environment after acute dorsolateral medullary infarction. The significance of the study is to emphasize that the curative effect is based on the doctors’ identification of the disease in the earliest stage before irreversible damage occurs to the cornea.

Trial registration

The registry was registered (ChiCTR-OPC-17,011,625) on June 11, 2017.

Role of the Neurokinin-1 Receptor in the Promotion of Corneal Epithelial Wound Healing by the Peptides FGLM-NH2 and SSSR in Neurotrophic Keratopathy

Purpose

Neurotrophic keratopathy is a corneal epitheliopathy induced by trigeminal denervation that can be treated with eyedrops containing the neuropeptide substance P (or the peptide FGLM-NH₂ derived therefrom) and insulin-like growth factor 1 (or the peptide SSSR derived therefrom). Here, we examine the mechanism by which substance P (or FGLM-NH₂) promotes corneal epithelial wound healing in a mouse model of neurotrophic keratopathy.

Methods

The left eye of mice subjected to trigeminal nerve axotomy in the right eye served as a model of neurotrophic keratopathy. Corneal epithelial wound healing was monitored by fluorescein staining and slit-lamp examination. The distribution of substance P, neurokinin-1 receptor (NK-1R), and phosphorylated Akt was examined by immunohistofluorescence analysis. Cytokine and chemokine concentrations in intraocular fluid were measured with a multiplex assay.

Results

Topical administration of FGLM-NH₂ and SSSR promoted corneal epithelial wound healing in the neurotrophic keratopathy model in a manner sensitive to the NK-1R antagonist L-733,060. Expression of substance P and NK-1R in the superficial layer of the corneal epithelium decreased and increased, respectively, in model mice compared with healthy mice. FGLM-NH₂ and SSSR treatment suppressed the production of interleukin-1α, macrophage inflammatory protein 1α (MIP-1α) and MIP-1β induced by corneal epithelial injury in the model mice. It also increased the amount of phosphorylated Akt in the corneal epithelium during wound healing in a manner sensitive to prior L-733,060 administration.

Conclusions

The substance P–NK-1R axis promotes corneal epithelial wound healing in a neurotrophic keratopathy model in association with upregulation of Akt signaling and attenuation of changes in the cytokine-chemokine network.

Corneal Neurotization for Postherpetic Neurotrophic Keratopathy: Initial Experience and Clinical Outcomes

PURPOSE

To assess early outcomes of corneal neurotization for postherpetic neurotrophic keratopathy (NK).

METHODS

Retrospective analysis of patients who underwent corneal neurotization for postherpetic NK by a single experienced oculoplastic surgeon was performed. Collected data included stage and etiology of NK as well as comorbidities, prior treatment history, neurotization technique, donor nerve site, preoperative and postoperative examination findings (i.e., ocular surface quality, corneal clarity, corneal sensation by Cochet-Bonnet esthesiometry, and visual acuity [VA]), and follow-up duration. Differences between preoperative and postoperative values were analyzed by Wilcoxon signed-rank test.

RESULTS

Of 23 adult patients who underwent corneal neurotization, 3 (13%) had history of herpes simplex keratitis and/or endotheliitis, and 4 (17%) had history of herpes zoster ophthalmicus. One patient with herpes zoster ophthalmicus was excluded due to inadequate follow-up duration. Of the 6 patients included in the study, 3 (50%) had Mackie stage 1 disease, 1 (17%) had stage 2, and 2 (33%) had stage 3 with impending perforation, but all had markedly diminished corneal sensation, with a median denervation time of 11.8 months (interquartile range [IQR] 9.4-29.2 months). Following neurotization, median corneal sensation improved significantly from 1.6 cm (interquartile range 0.0-1.9 cm) to 3.6 cm (IQR 3.0-5.6 cm, p = 0.028), with 1 patient achieving full sensation by postoperative month 5. All patients with a persistent epithelial defect preoperatively showed complete corneal healing by their last follow-up visit. VA also improved postoperatively in all patients (p = 0.028). Median follow-up duration was 11.3 months (interquartile range 9.6-17.9 months).

CONCLUSIONS

Corneal neurotization can successfully reinnervate corneas previously devitalized by herpetic disease and halt the progressive nature of postherpetic NK. If utilized appropriately and early in the disease process, neurotization may reduce morbidity and maximize visual potential in postherpetic NK.

Genetically Encoded Calcium Indicators for In Situ Functional Studies of Corneal Nerves

Purpose

Millions of people suffer from diseases that involve corneal nerve dysfunction, caused by various conditions, including dry eye syndrome, neurotrophic keratopathy, diabetes, herpes simplex, glaucoma, and Alzheimer's disease. The morphology of corneal nerves has been studied extensively. However, corneal nerve function has only been studied in a limited fashion owing to a lack of tools. Here, we present a new system for studying corneal nerve function.

Methods

Optical imaging was performed on the cornea of excised murine globes taken from a model animal expressing a genetically encoded calcium indicator, GCaMP6f, to record calcium transients. A custom perfusion and imaging chamber for ex vivo murine globes was designed to maintain and stabilize the cornea, while allowing the introduction of chemical stimulation during imaging.

Results

Imaging of calcium signals in the ex vivo murine cornea was demonstrated. Strong calcium signals with minimal photobleaching were observed in experiments lasting up to 10 minutes. Concentrated potassium and lidocaine solutions both modulated corneal nerve activity. Similar responses were observed in the same neurons across multiple chemical stimulations, suggesting the feasibility of using chemical stimulations to test the response of the corneal nerves.

Conclusions

Our studies suggest that this tool will be of great use for studying functional changes to corneal nerves in response to disease and ocular procedures. This process will enable preclinical testing of new ocular procedures to minimize damage to corneal innervation and therapies for diminished neural function.

Corneal Nerve Abnormalities in Ocular and Systemic Diseases

The trigeminal nerve gives rise to the corneal subbasal nerve system, which plays a crucial role in sensations of touch, pain, and temperature and in ocular healing processes. Technological advancements in instruments, in particular in vivo confocal microscopy and aethesiometry, have allowed for the structural and functional evaluation of corneal nerves in health and disease. Through application of these technologies in humans and animal models, structural and functional abnormalities have been detected in several ocular and systemic disorders, including dry eye disease (DED), glaucoma, migraine, and fibromyalgia. However, studies across a number of conditions have found that structural abnormalities do not always relate to functional abnormalities. This review will discuss instruments used to evaluate corneal nerves and summarize data on nerve abnormalities in a number of ocular and systemic conditions. Furthermore, it will discuss potential treatments that can alleviate the main manifestations of nerve dysfunction, namely ocular surface pain and persistent epithelial defects.

Corneal Neurotization and Novel Medical Therapies for Neurotrophic Keratopathy

Purpose of Review

Neurotrophic keratopathy (NK) is a degenerative corneal disease characterized by decreased corneal sensibility and impaired corneal healing. In this article, we review surgical techniques for corneal neurotization (CN) and novel medical therapies for the treatment of NK.

Recent Findings

In recent decades, there has been a paradigm shift in the treatment strategies for NK. New minimally invasive direct and indirect CN approaches have demonstrated efficacy at improving best-corrected visual acuity and central corneal sensation while decreasing surgical morbidity. In addition, several targeted medical therapies, such as recombinant human nerve growth factor (rhNGF), regenerating agents (RGTA), and nicergoline, have shown promise in improving corneal epithelial healing. Of these options, cenegermin (Oxervate®, Dompé), a topical biologic medication, has emerged as an approved medical treatment for moderate to severe NK.

Summary

NK is a challenging condition caused by alterations in corneal nerves, leading to impairment in sensory and trophic function with subsequent breakdown of the cornea. Conventional therapy for NK depends on the severity of disease and focuses primarily on protecting the ocular surface. In recent years, numerous CN techniques and novel medical treatments have been developed that aim to restore proper corneal innervation and promote ocular surface healing. Further studies are needed to better understand the long-term efficacy of these treatment options, their target populations, and the potential synergistic efficacy of combined medical and surgical treatments.

In Vivo Evaluation of Corneal Nerves and Epithelial Healing After Treatment With Recombinant Nerve Growth Factor for Neurotrophic Keratopathy

PURPOSE

To evaluate the renewal of corneal nerve structure and function in patients with neurotrophic keratopathy (NK) treated with recombinant human nerve growth factor (rhNGF) eye drops.

DESIGN

Prospective, interventional, before-and-after case series.

METHODS

This study included 18 patients with NK with a persistent epithelial defect or corneal ulcer, treated with topical rhNGF, and age-matched healthy controls. Patients underwent clinical examination with corneal fluorescein staining, Schirmer 1 tear test, assessment of corneal sensitivity with the Cochet-Bonnet esthesiometer, and morphologic examination of the nerves by in vivo confocal microscopy (IVCM) at baseline and at 4 and 8 weeks of treatment. IVCM analysis was used to assess corneal sub-basal nerve density, number of nerve branches, and the diameter of nerve fibers.

RESULTS

A complete resolution of the epithelial defect was observed in all patients within 8 weeks. Schirmer 1 test showed a significant improvement of tear film secretion. Change from baseline in corneal sensation was significant (P < .001) but did not approach that of healthy controls. After 8 weeks of treatment, there was a significant increase in the mean nerve density in affected eyes as compared to baseline (P = .007) as well as in the number of nerve branches (P = .008) and nerve fiber diameter (P = .007).

CONCLUSIONS

Topical treatment with rhNGF was effective in promoting complete corneal healing of persistent epithelial defects and corneal ulcers in patients with NK. This was associated with an improvement of corneal sensitivity and an increase of sub-basal nerve density, diameter, and number of nerve branches, indicating improvement in structure and function of corneal nerves.

Long-term restoration of corneal sensitivity in neurotrophic keratopathy after rhNGF treatment

BACKGROUND

To report the long-term effects of the new rhNGF treatment on corneal sensitivity in patients with.

CASES PRESENTATION

We present three cases of corneal ulcers due to NK that were treated with rhNGF. In each patient wound healing evolution was documented by clinical pictures and corneal sensitivity measured by Cochet-Bonnet aesthesiometry. Best corrected visual acuity and Type I Schirmer test were also assessed neurotrophic keratopathy.All patients healed within 8 weeks and NK showed no recurrences in the mean follow-up period of 35 weeks. Each subject showed a significant increase of corneal sensitivity and tear secretion, with concomitant improvement in visual acuity.

CONCLUSION

Corneal sensitivity, measured by Cochet-Bonnet aesthesiometer, markedly increased in all eyes. Further studies are warranted to demonstrate a possible mechanism of nerve restoration with rhNGF treatment.

Novel Approaches for Imaging-Based Diagnosis of Ocular Surface Disease

Imaging has become indispensable in the diagnosis and management of diseases in the posterior part of the eye. In recent years, imaging techniques for the anterior segment are also gaining importance and are nowadays routinely used in clinical practice. Ocular surface disease is often synonymous with dry eye disease, but also refers to other conditions of the ocular surface, such as Meibomian gland dysfunction or keratitis and conjunctivitis with different underlying causes, i.e., allergies or infections. Therefore, correct differential diagnosis and treatment of ocular surface diseases is crucial, for which imaging can be a helpful tool. A variety of imaging techniques have been introduced to study the ocular surface, such as anterior segment optical coherence tomography, in vivo confocal microscopy, or non-contact meibography. The present review provides an overview on how these techniques can be used in the diagnosis and management of ocular surface disease and compares them to clinical standard methods such as slit lamp examination or staining of the cornea or conjunctiva. Although being more cost-intensive in the short term, in the long term, the use of ocular imaging can lead to more individualized diagnoses and treatment decisions, which in turn are beneficial for affected patients as well as for the healthcare system. In addition, imaging is more objective and provides good documentation, leading to an improvement in patient follow-up and education.

Long-term evaluation of corneal sub-basal nerve recovery after photorefractive keratectomy and influence of pars plana vitrectomy

The corneal sub-basal nerve (SBN) plexus is destroyed during photorefractive keratectomy (PRK) and its recovery is still a matter of debate. In vivo confocal microscopy (IVCM) was used to evaluate SBN plexus in 23 patients at a distance of 10-25 years (mean 15.6 years) from myopic PRK. Because 8 out of the 23 PRK patients underwent pars plana vitrectomy (PPV) for rhegmatogenous retinal detachment, IVCM was also performed on those patients 6 months after PPV. Thirteen patients matched for age and myopia served as controls (non-PRK). SBN plexus was markedly reduced after PRK compared with non-PRK eyes and showed a slow, continuous but incomplete recovery up to the end of our follow-up (range 10-25 years). PRK and non-PRK eyes showed a marked reduction in SBN density 6 months after PPV, thus demonstrating a detrimental effect exerted by PPV on SBN plexus.