Matrix Regeneration Therapy: A Case Series of Corneal Neurotrophic Ulcers

Neurotrophic keratopathy: General features and new therapies

Neurotrophic keratopathy is an uncommon degenerative corneal disorder characterized by compromised corneal sensory innervation resulting in the formation of epithelial defects and nonhealing corneal ulcers. Various treatment modalities are available to stabilize disease progression, improve patient well-being, and prevent vision loss. For eligible patients, medical and surgical reinnervation have emerged as pioneering therapies, holding promise for better management. We present a comprehensive review of the disorder, providing an update relevant to ophthalmologists on pathogenesis, diagnosis, treatment options, and novel therapies targeting pathophysiological pathways.

Evaluation of the Use of Highly Concentrated Autologous Platelet-Rich Plasma and Platelet-Rich Fibrin Membrane to Improve the Outcome in the Management of Severe Dry Eye Disease, Corneal Neurotrophic Ulcer and Corneal Burn

INTRODUCTION

The aim of this study was to evaluate the use of highly concentrated platelet-rich plasma (PRP) subconjunctival injections, in combination with eye drops (eye PRP, or E-PRP), in treating dry eye disease (DED) and the use of platelet-rich fibrin (PRF) membrane in treating corneal burns and neurotrophic ulcers for the restoration of the homeostasis of the tear film and the morphology and function of the cornea.

METHODS

We studied 16 patients (n=32 eyes) with severe DED. The disease was graded as severe according to the Oxford Grading Scale. There were 12 males (75%) and four females (25%) with a mean age of 56 years; these patients were treated with monotherapy, which involved a single subconjunctival injection of 0.2-0.3 mL of PRP prepared from autologous blood, followed by application of autologous PRP eye drops four times a day for 15 days between September 2019 and December 2020 in the same geographic area. All patients gave written informed consent before undergoing the outlined treatment protocol. We evaluated best corrected visual acuity (BCVA), Schirmer test score, tear film breakup time (TBUT) and corneal staining with fluorescein (Oxford Grading Scale) before and after six to eight weeks of treatment. Subjective normalization was defined by a decrease in the Ocular Surface Disease Index (OSDI) score to 10 or less, an objective normalization of the TBUT to five to six seconds, improvement in the Schirmer test score and Oxford grading and the BCVA gain of at least one line in the vision chart (Snellen chart). Furthermore, we report on the results from different variants of platelet concentrate-based treatments in five cases of corneal diseases: neurotrophic ulcers and corneal burns due to different causes (e.g., chemical burns) using E-PRP and PRF membrane with regard to normalization of morphology and function.

RESULTS

The OSDI score decreased to normalization in 75% of the patients (p=6.545 × 10-15). TBUT was restored significantly in 20 of 32 eyes from 2.78±0.55 to 5.43±0.71 (p=1.612 × 10-24). The Schirmer test score showed an improvement from 4.46±0.67 to 10.28±1.18 (p=3.411 × 10-29), and BCVA improved by 43.75%, from 0.15±0.19 to 0.09±0.16 (logMAR, p=0.2331). Oxford grading changed to Scale I in 75% and Scale 0 in 25% of the patients. No complications or adverse reactions occurred in the five cases of corneal injuries. We observed a restoration of the morphology and function of the cornea with PRP injections or PRF+PRP application in 7-12 days, depending on the severity of the initial finding.

CONCLUSION

 PRP treatment is a new approach in ophthalmology with impressive results. Although patients show good compliance and acceptance of the treatment protocol, studies with larger sample sizes are needed to confirm and optimize its use.

Neurotrophic keratitis: inflammatory pathogenesis and novel therapies

PURPOSE OF REVIEW

Neurotrophic keratitis is a rare degenerative disease characterized by decrease or absence of corneal sensation. Neurotrophic keratitis varies from mild forms with mild epitheliopathy to severe manifestations such as corneal ulceration, melting and perforation that can lead to irreversible visual loss. The cause of neurotrophic keratitis comprises a long list of diseases, medications, congenital or genetic conditions as well as trauma. The mechanism of neurotrophic keratitis is complex and multifactorial and its understanding is crucial to better address the treatment strategies. We aimed to review neurotrophic keratitis pathology, mechanisms and management.

RECENT FINDINGS

Corneal nerves are critical for the homeostasis of a healthy ocular surface. The lack of nerve-derived neuromediators and corneal-released neuropeptides, neuro-trophins and neurotrophic factors in neurotrophic keratitis leads to a decrease in trophic supply to corneal cells in addition to a decrease in afferent signaling to the brain. This results in pathological tear secretion, decreased blinking rate, corneal healing along with ocular surface and corneal inflammation. Lately, nerve growth factor in special gained emphasis as a treatment strategy targeting the disease mechanism rather than its manifestations. Other therapies, including surgical interventions, are in the pipeline of neurotrophic keratitis management. However, there are still no proper therapeutic guidelines and neurotrophic keratitis treatment remains challenging.

SUMMARY

Neurotrophic keratitis may have a devastating outcome and treatment is still challenging. Understanding the disease pathology may assist in the development of new treatment strategies. Prompt disease recognition and immediate intervention are key factors to promote corneal healing and avoid further deterioration.

Neurotrophic keratopathy: An updated understanding

PURPOSE

To propose an updated definition and staging system for neurotrophic keratopathy (NK) and provide consensus on diagnosis and treatment.

METHODS

A study group was convened to review the data pertinent to NK using a modified nominal group process. They proposed an updated definition for NK and a new 6-step staging system (Neurotrophic Keratopathy Study Group [NKSG] Classification) that can be used in conjunction with the different treatment options available currently or in the future.

RESULTS

NK is defined as the dysfunction of corneal innervation that results in dysregulation of corneal and/or cellular function. It is characterized by loss of corneal sensation and neuronal homeostasis, leading to eventual corneal epithelial breakdown and ultimately keratolysis if untreated. The NKSG classification emphasizes verifying corneal sensation early and distinguishes different epithelial and stromal aspects of NK with the following stages: stage 1 (altered sensation without keratopathy), stage 2 (epitheliopathy/punctate epithelial keratopathy [PEK] without stromal haze), stage 3 (persistent/recurrent epithelial defects without stromal haze), stage 4 (epitheliopathy/PEK or persistent/recurrent epithelial defects with stromal haze), stage 5 (persistent/recurrent epithelial defect with corneal ulceration), and stage 6 (corneal perforation). Treatment consists of a variety of modalities (both indirect and direct).

CONCLUSIONS

This updated definition and staging system will provide clinicians with the necessary information to diagnose and treat NK at an early stage before it becomes a sight-threatening disorder. It also provides a framework for evaluating current and future treatment options at distinct stages of the disease.

Neurotrophic keratopathy: current challenges and future prospects

Neurotrophic keratopathy (NK), or neurotrophic keratitis, is a degenerative condition that results from decreased innervation to the cornea. The cornea is innervated by the ophthalmic branch of the trigeminal nerve. Neurotrophic keratopathy is most commonly caused by herpes keratitis however, any condition that disrupts the normal corneal innervation can cause NK. Neurotrophic keratopathy is a clinical diagnosis and is classified into three stages based on the disease severity. Stage 1 has mild epithelial defects, such as punctate keratopathy, stage 2 disease has persistent epithelial defects, and stage 3 is defined by the presence of ulcers. Current treatment modalities consist of medical and surgical options. Stage 1 is treated with lubrication through artificial tears, eyelid taping, and punctal plug/cautery. Stage 2 treatment can involve therapeutic contact lenses, topical autologous or allogenic serum, tarsorrhaphy, botulinum toxin injections, and possibly anti-inflammatory medications. Stage 3 disease may require human nerve growth factor, amniotic membrane transplantation, conjunctival flap, or corneal neurotization. New therapies, such as matrix regenerating therapy, plasma rich in growth factors, Thymosin β4, Substance P/Insulin like growth factor-1, and nicergoline represent exciting future options.KEY MESSAGESNeurotrophic keratopathy is a rare degenerative disease defined by decreased innervation to the cornea that is associated with significant morbidity.Treatment options range from lubrication alone to various medical and surgical treatments.Matrix regenerating therapy, plasma rich in growth factors, Thymosin β4, Substance P/Insulin like growth factor-1, and nicergoline are exciting novel therapies that will influence how neurotrophic keratopathy is treated in the future.

Neurotization of the human cornea - A comprehensive review and an interim report

We present a comprehensive review of existing literature on surgical corneal neurotization (SCN) as a treatment modality for neurotrophic keratopathy (NK) with an interim report of seven cases where SCN was performed using the indirect approach and followed up till 18 months postoperatively to look for improvement in ocular surface, corneal sensations, and nerve regeneration by using in vivo confocal microscopy (IVCM). A literature search was performed for publications with keywords “corneal nerves,” “neurotization,” “esthesiometry,” “corneal anesthesia,” and “neurotrophic keratopathy.” All literature available till December 31, 2020 was reviewed and included to describe NK and its management options, particularly SCN. NK is associated with absent or reduced corneal sensations and is managed using a step-ladder algorithm ranging from medical management for symptomatic relief to surgical corneal neurotization. Both direct and indirect approaches of SCN have a favorable outcome with reduced surgical morbidity in the indirect approach using sural nerve graft. Post neurotization, corneal sensation recovery may take up to 3–6 months, while nerve regeneration on confocal microscopy can take as long as 6 months–1 year.

New Pharmacological Approaches for the Treatment of Neurotrophic Keratitis

Neurotrophic keratitis (NK) is a rare degenerative condition that is caused by damage to the trigeminal nerve, with partial or complete loss of corneal sensory innervation. The loss of innervation leads to impaired healing of corneal epithelium, which subsequently results in punctate epithelial erosions, persistent epithelial defects, corneal ulcers and corneal perforation. Management of NK is often supportive and aims to promote epithelial healing and prevent progression of disease. Multiple novel pharmacological approaches have been proposed to address the underlying pathophysiology of NK, which are discussed in this paper.

Treatment of Non-Infectious Corneal Injury: Review of Diagnostic Agents, Therapeutic Medications, and Future Targets

Corneal injuries can occur secondary to traumatic, chemical, inflammatory, metabolic, autoimmune, and iatrogenic causes. Ocular infection may frequently occur concurrent to corneal injury; however, antimicrobial agents are excluded from this present review. While practitioners may primarily rely on clinical examination techniques to assess these injuries, several pharmacological agents, such as fluorescein, lissamine green, and rose bengal, can be used to formulate a diagnosis and develop effective treatment strategies. Practitioners may choose from several analgesic medications to help with patient comfort without risking further injury or delaying ocular healing. Atropine, cyclopentolate, scopolamine, and homatropine are among the most frequently used medications for this purpose. Additional topical analgesic agents may be used judiciously to augment patient comfort to facilitate diagnosis. Steroidal anti-inflammatory agents are frequently used as part of the therapeutic regimen. A variety of commonly used agents, including prednisolone acetate, loteprednol, difluprednate, dexamethasone, fluorometholone, and methylprednisolone are discussed. While these medications are effective for controlling ocular inflammation, side effects, such as elevated intraocular pressure and cataract formation, must be monitored by clinicians. Non-steroidal medications, such as ketorolac, bromfenac, nepafenac, and diclofenac, are additionally used for their efficacy in controlling ocular inflammation without incurring side effects seen with steroids. However, these agents have their own respective side effects, warranting close monitoring by clinicians. Additionally, ophthalmologists routinely employ several agents in an off-label manner for supplementary control of inflammation and treatment of corneal injuries. Patients with corneal injuries not infrequently have significant ocular surface disease, either as a concurrent pathology or as an exacerbation of previously existing disease. Several agents used in the management of ocular surface disease have also been found to be useful as part of the therapeutic armamentarium for treatment of corneal injuries. For example, several antibiotics, such as doxycycline and macrolides, have been used for their anti-inflammatory effects on specific cytokines that are upregulated during acute injuries. There has been a recent wave of interest in amniotic membrane therapies (AMTs), including topical, cryopreserved and dehydrated variants. AMT is particularly effective in ocular injuries with violation of corneal surface integrity due to its ability to promote re-epithelialization of the corneal epithelium. Blood-based therapies, including autologous serum tears, plasma-enriched growth factor eyedrops and autologous blood drops, have additionally been explored in small case series for effectiveness in challenging and recalcitrant cases. Protection of the ocular surface is also a vital component in the treatment of corneal injuries. Temporary protective methods, such as bandage contact lenses and mechanical closure of the eyelids (tarsorrhaphy) can be particularly helpful in selective cases. Glue therapies, including biologic and non-biologic variants, can also be used in cases of severe injury and risk of corneal perforation. Finally, there are a variety of recently introduced and in-development agents that may be used as adjuvant therapies in challenging patient populations. Neurotrophic corneal disease may occur as a result of severe or chronic injury. In such cases, recombinant human nerve growth factor (cenegermin), topical insulin, and several other novel agents may be an alternate and effective option for clinicians to consider.

Comparative Analysis of Matrix-Regenerating Agent and Corneal Cross-Linking in an Experimental Alkali Burn Rabbit Model

PURPOSE

This study aimed to investigate the clinical and histopathological effects of corneal cross-linking (CXL) and matrix-regenerating agent (RGTA) treatments after corneal alkali burn.

MATERIALS AND METHODS

Twenty-four alkali-burned corneas from 24 rabbits were divided into three groups: control, CXL, and RGTA. All animals were investigated for epithelial healing, opacification, ulceration, and neovascularization at days 1, 7, 14, and 21 after the alkali burn. Corneas were excised and sent for histological examination on day 21.

RESULTS

One animal each from the CXL and control groups exhibited moderate ulceration, while no ulceration was observed in the RGTA group. No significant difference was observed among the groups in corneal thickness or corneal opacity measurements at the final visit (p = .058 and p = .544, respectively). Both RGTA and CXL treatments were effective in terms of epithelial healing and neovascularization (p = .023 and p = .03, respectively). On histological examination, the CXL and RGTA groups were more effective in treating epithelial loss, stromal edema, corneal vascularization, and leukocytic infiltration than the control group (p < .05). The immunohistochemical staining scores of the CXL and RGTA groups for caspase-3, vascular endothelial growth factor, and matrix metalloproteinase-9 in the epithelium and stroma were significantly lower than those in the control group (p < .05). In the immunohistochemical examination for inducible nitric oxide synthase, epithelial staining scores were similar among the groups (p > .05). In contrast, the stromal staining scores of the CXL and RGTA groups were lower than those of the control group (p < .05).

CONCLUSION

Both CXL and RGTA therapies were effective in reducing anatomical and histopathological complications after corneal alkali burn. Further investigation is needed to determine the optimal timing, duration, and dosage of these treatments.

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.

Management of corneal neurotrophic ulcers with Cacicol®-RGTA (ReGeneraTing Agent): a case series

PURPOSE

Neurotrophic corneal ulcers are difficult to treat, and the conventional treatment often results in failure. A new matrix regenerating agent ("ReGeneraTing Agents"), Cacicol® (Laboratoires Théa), has demonstrated good results over the last few years. Therefore, the aim of this study was to evaluate the response to Cacicol® in a series of cases with neurotrophic corneal ulcers.

METHODS

Retrospective case series looking at 11 patients with corneal ulcers unresponsive to conventional therapy that underwent treatment with Cacicol®. One cycle included 1 drop every two days for 5 days.

RESULTS

The range of conventional therapy prior to Cacicol® was 0-91 days. On introducing Cacicol® 82% (9/11) of the cases were cured, and 18% (2/11) failed, requiring an amniotic membrane transplant or penetrating keratoplasty. The healing only required one cycle of Cacicol® in 67% (6/9) of the patients. More than one cycle of Cacicol® was needed in 45% (5/11) patients. One corneal bacterial ulcer responded favourably and one case related to Acanthamoeba did not respond. Most of the patients improved or maintained their visual acuity.

CONCLUSION

Cacicol® was a useful therapy in a high number of difficult neurotrophic corneal ulcers, including corneal infections. Some cases may require more than one cycle of Cacicol® or used as first-line treatment in order to achieve the desired result.

Fast and sustained healing of resistant corneal ulcers using corneal scrubbing and matrix regenerating therapy

AIM

The aim of this study was to assess the efficacy and safety of corneal scrubbing associated with matrix regenerating agent on corneal wound healing in patients with persistent corneal ulcers.

METHODS

This was a retrospective case study in patients with difficult-to-treat corneal ulcer. Corneal scrubbing was performed with a sterile dry cotton bud to eliminate damaged epithelial cells and corneal deposits, promoting epithelial renewal. Regenerating agent was then administered as one eye drop every 2 days in addition to preservative-free ocular lubricants. A bandage contact lens was applied in case of moderate-to-severe corneal pain. Corneal ulcers were regularly assessed until healing.

RESULTS

In total, 17 patients with a chronic corneal ulcer of various etiologies for several months on average were enrolled. Corneal scrubbing combined with regenerating agent administration led to a rapid corneal ulcer size reduction from 26.4 ± 20.6 mm² after scrubbing (before regenerating agent) to 7.2 ± 7.1 mm² at day 5, 3.3 ± 6.0 mm² at day 10, and 0.9 ± 2.3 mm² at day 18. Complete corneal ulcer healing was observed in 35.2% of patients within 10 days, in 70.4% within 18 days, and in all patients within 25 days. Corneal ulcer relapse was observed in two (11.8%) patients after 6 weeks and 5 months, respectively; both were successfully treated using the same procedure. The regenerating agent was well tolerated in all patients.

CONCLUSION

In this study, combined corneal scrubbing and matrix regenerating therapy (with or without bandage contact lens) led to a rapid healing and successful resolution of persisting corneal ulcers, including large and deep corneal ulcers.

Equine non-healing corneal ulcers: a retrospective evaluation of 57 cases (2001-2017)

BACKGROUND AND OBJECTIVES

Non-healing corneal ulcers (NHCU) are a common problem in equine practice and several treatment options are available with different success and healing times. The aim of this retrospective study was to evaluate and to compare treatment protocols, clinical courses, corneal healing time and outcomes of NHCU.

METHODS

From December 2001 to December 2017, a total of 57 horses with NHCU were presented at the Vetmeduni Vienna. Recorded data included affected eye, signalment, clinical symptoms, season of diagnosis, treatment protocols, complications and corneal healing rate.

RESULTS

Sixty-three eyes were diagnosed with a NHCU. Follow-up information was available for 48/63 eyes. For those treated medically mean corneal healing time was 15.7 days (± SD 12.0). Medical treatment included topical antibiotics, antimycotics, cycloplegics, and systemic anti-inflammatory drugs. Twelve eyes received treatment with a poly-carboxymethylglucose-sulfate regenerating agent (Cacicol^®; Thea Pharma GmbH, Wien, Austria). Other common additional treatments included debridement with an iodine drenched cotton tip (48 eyes; 76.2 %) and diamond burr debridement (30 eyes; 47.6 %). A bandage contact lens (BCL) was used for 10 eyes. Each eye received at least one additional treatment, although none of them led to a statistically significant alteration in healing time. Only usage of a BCL significantly increased healing time when compared to not using a BCL (p = 0.035). When all treatments failed, superficial keratectomy with placement of a conjunctival flap was performed. Secondary complications included stromal cellular infiltration, keratomycosis, keratomalacia, and corneal abscess formation.

CONCLUSIONS

Results correlated with those previously described and thus demonstrated the difficulty and complexity of this disease. Further research is needed to determine an optimal treatment protocol for non-healing ulcers in horses.

CLINICAL RELEVANCE

Since NHCUs are a commonly encountered problem in equine practice a reliable treatment protocol is required. This study reflects the problems with those ulcers and provides several protocols for possible treatments.

Topical Pergolide Enhance Corneal Nerve Regrowth Following Induced Corneal Abrasion

Purpose

Neurotrophic keratopathy is a degenerative disease that may be improved by nerve growth factor (NGF). Our aim was to investigate the use of pergolide, a dopamine (D1 and D2) receptor agonist known to increase the synthesis and release of NGF for regeneration of damaged corneal nerve fibers.

Methods

Pergolide function was evaluated by measuring axon length and NGF levels by enzyme-linked immunosorbent assay in cultured chicken dorsal root ganglion (DRG) cells with serial doses of pergolide (10, 25, 50, 150, and 300 µg/ml) and with different concentrations of a D1 antagonist. Pergolide function was further evaluated by cornea nerve fiber density and wound healing in a cornea scratch mouse model.

Results

Pergolide increased DRG axon length significantly at a dose between 50 and 300 µg/ml. Different concentrations of D1 antagonist (12, 24, 48, and 96 µg/ml) inhibited DRG axon length growth with pergolide (300 µg/ml). Pergolide (50 µg/ml) upregulated NGF expression in DRG cells at both 24 hours and 48 hours. Pergolide improved cornea nerve fiber density at both 1 week and 2 weeks. Pergolide also improved cornea wound healing.

Conclusions

We demonstrated that pergolide can act to promote an increase in NGF which promotes corneal nerve regeneration and would therefore improve corneal sensation and visual acuity in eyes with peripheral neurotrophic keratopathy.

Corneal Repair and Regeneration: Current Concepts and Future Directions

The cornea is a unique tissue and the most powerful focusing element of the eye, known as a window to the eye. Infectious or non-infectious diseases might cause severe visual impairments that need medical intervention to restore patients' vision. The most prominent characteristics of the cornea are its mechanical strength and transparency, which are indeed the most important criteria considerations when reconstructing the injured cornea. Corneal strength comes from about 200 collagen lamellae which criss-cross the cornea in different directions and comprise nearly 90% of the thickness of the cornea. Regarding corneal transparency, the specific characteristics of the cornea include its immune and angiogenic privilege besides its limbus zone. On the other hand, angiogenic privilege involves several active cascades in which anti-angiogenic factors are produced to compensate for the enhanced production of proangiogenic factors after wound healing. Limbus of the cornea forms a border between the corneal and conjunctival epithelium, and its limbal stem cells (LSCs) are essential in maintenance and repair of the adult cornea through its support of corneal epithelial tissue repair and regeneration. As a result, the main factors which threaten the corneal clarity are inflammatory reactions, neovascularization, and limbal deficiency. In fact, the influx of inflammatory cells causes scar formation and destruction of the limbus zone. Current studies about wound healing treatment focus on corneal characteristics such as the immune response, angiogenesis, and cell signaling. In this review, studied topics related to wound healing and new approaches in cornea regeneration, which are mostly related to the criteria mentioned above, will be discussed.

Post-herpes neurotrophic keratopathy: Aetiopathogenesis, clinical signs and current therapies

Neurotrophic keratopathy (NK) is a degenerative corneal disease caused by damage of trigeminal innervation. This leads to epithelial defects, ulceration and, eventually, perforation. Both herpes simplex and varicella zoster keratitis are reported to be the main causes of NK. Furthermore, prognosis in this type of NK is poor. Classic clinical findings in post-herpes NK are spontaneous epithelial breakdown, round and central epithelial defects with smooth edges, stromal melting and thinning, scarring, and neovascularisation. Although several medical and surgical treatments have been reported, no therapies are currently available to definitely restore corneal sensitivity. Therefore, NK remains a challenging disease to treat. In this review a summary is presented of the pathogenesis, manifestations, and current management of post-herpes NK. The role of antiviral treatment and varicella-zoster vaccination is also discussed. A description is also presented on both medical and surgical novel therapies, such as regenerative drugs and corneal neurotization.

Neurotrophic keratitis: current challenges and future prospects

Neurotrophic keratitis (NK) is a degenerative corneal disease caused by damage of trigeminal corneal innervation, which leads to spontaneous epithelial breakdown and corneal ulceration. The impairment of corneal sensory innervation causes the reduction of both protective reflexes and trophic neuromodulators that are essential for the vitality, metabolism, and wound healing of ocular surface tissues. A wide range of ocular and systemic conditions, including herpetic keratitis, ocular chemical burns, corneal surgery, diabetes, multiple sclerosis, and neurosurgical procedures, can cause NK by damaging trigeminal innervation. Diagnosis of NK requires careful investigation of any ocular and systemic condition associated with the disease, complete ocular surface examination, and quantitative measurement of corneal sensitivity. The clinical stages of NK range from corneal epithelial alterations (stage 1) to persistent epithelial defect (stage 2) and ulcer (stage 3), which may progress to corneal perforation. Management of NK is based on clinical severity, and the aim of the therapy is to halt the progression of corneal damage and promote epithelial healing. Although several medical and surgical treatments have been proposed, no therapies are currently available to restore corneal sensitivity, and thus, NK remains difficult and challenging to treat. The purpose of this review is to summarize available evidence on the pathogenesis, diagnosis, and treatment of NK. Novel medical and surgical therapies including the topical administration of nerve growth factor and corneal neurotization are also described.

Clinical Efficacy of Platelet-Rich Plasma in the Treatment of Neurotrophic Corneal Ulcer

Purpose

Platelet-rich plasma (PRP) is an autologous blood product without preservatives and rich in proteins and growth factors which make it possible for cells to differentiate, proliferate, and migrate, thus stimulating healing and regeneration of tissues. The aim of this study was to evaluate the efficiency of autologous platelet-rich plasma in the treatment of neurotrophic keratopathy.

Methods

The study group consists of 25 patients with nonhealing corneal ulcers due to herpes simplex or herpes zoster infection and facial nerve or trigeminal nerve paralysis as a result of a neurosurgical operation caused by a tumour or stroke. The patients were given autologous platelet-rich plasma drops five times a day and additionally preservative-free artificial tears and a vitamin A ointment at night for maximum 3 months. The following were evaluated: best corrected visual acuity (BCVA), healing of corneal surface, subjective symptoms, and changes in corneal thickness with the use of anterior segment optical coherent tomography (AS-OCT).

Results

BCVA before the treatment was 0.10 ± 0.14, and after the treatment it was –0.3 ± 0.27 (p=0.001). Improved visual acuity and less subjective symptoms were observed in all patients. Complete healing of the ulceration was observed in 20 patients (80%). Four patients (16%) experienced considerable improvement of their clinical condition (reduced size and depth of the ulceration and inflammatory state: smaller conjunctival injection and swelling, improved visual acuity, and less subjective symptoms). In one of the patients, an amniotic membrane was transplanted due to the lack of improvement of his local condition. In all patients, the progression of corneal thinning was stopped. An average corneal thickness in its thinnest point was 322.3 ± 125.8 µm before the treatment, and 404.5 ± 118.7 µm (p < 0.05) after the treatment. None of the patients reported general or local side effects of the treatment.

Conclusions

Autologous platelet-rich plasma is a blood-based product which seems efficient in the treatment of neurotrophic keratopathy.

Application of Novel Drugs for Corneal Cell Regeneration

Corneal transplantation has been the only treatment method for corneal blindness, which is the major cause of reversible blindness. However, despite the advancement of surgical techniques for corneal transplantation, demand for the surgery can never be met due to a global shortage of donor cornea. The development of bioengineering and pharmaceutical technology provided us with novel drugs and biomaterials that can be used for innovative treatment methods for corneal diseases. In this review, the authors will discuss the efficacy and safety of pharmacologic therapies, such as Rho-kinase (ROCK) inhibitors, blood-derived products, growth factors, and regenerating agent on corneal cell regeneration. The promising results of these agents suggest that these can be viable options for corneal reconstruction and visual rehabilitation.

Lack of effect of a topical regenerative agent on re-epithelialization rate of canine spontaneous chronic corneal epithelial defects: A randomized, double-masked, placebo-controlled study

Spontaneous chronic corneal epithelial defects (SCCEDs) are characteristic ulcers in dogs that are refractory to healing. The aim of the study was to evaluate the use of a topical regenerative agent to promote healing of SCCEDs. Nineteen dogs (20 eyes) were randomized to receive either regenerative agent (10 eyes) or placebo (10 eyes) every 48h following corneal debridement, which was repeated 1 week later if the SCCED had not yet healed. The mean±standard deviation time to re-epithelialization was 17.3±12.8 days for the group treated with a topical regenerative agent and 19.3±11.7 days for the group treated with a placebo; the cumulative healing rates were not statistically different (P>0.650). A positive association was found between the initial size of the ulcer and the time to re-epithelialization (r=0.555, P=0.011). Although well tolerated by dogs, there was no therapeutic advantage in using a topical regenerative agent for re-epithelialization of SCCEDs.

New Therapeutic Perceptions in a Patient with Complicated Herpes Simplex Virus 1 Keratitis: A Case Report and Review of the Literature

Patient: Male, 80

Final Diagnosis: Unilateral complicated Herpetic Simplex Virus 1 Keratitis

Symptoms: Visual impairment

Medication: Anti-herpetic treatment • Anti-VEGF • Cyclosporine A • Matrix regeneration therapy

Clinical Procedure: Amniotic membrane and limbal stem cell transplantation

Specialty: Ophthalmology

Matrix regeneration agents improve wound healing in non-stressed human corneal epithelial cells

PurposeMatrix regenerating agents (RGTAs) emerged as promising in vivo wound-healing agents. These agents could prove beneficial for the treatment of dry eye disease-associated corneal micro-erosions; therefore, we aimed to evaluate the wound healing efficacy of regenerative agents (RGTAs or serum) in an in vitro model of hyperosmolarity (HO) stressed and non-stressed human corneal epithelial cells.Patients and methodsThe migration and proliferation induced by the regenerative agents was evaluated using an in vitro scratch wound assay and brome-deoxy-uridine incorporation. The inflammatory profile and effects of osmoregulators were also investigated. The two-tailed paired t-test calculated the statistical significance, with P-value<0.05 considered significant.ResultsThe most efficient inducer of re-epithelization was 2% serum, followed closely by 2% RGTA with an average improvement in cell migration of 1.8- and 1.4-fold, respectively, when compared with the non-treated control. Hyperosmolar stress significantly reduced the restorative effects of both serum and RGTAs; these effects were, however, neutralized by the osmoregulator betaine.ConclusionThese findings suggest that RGTAs could provide efficient treatment for dry-eye associated corneal micro-lesions if ocular surface HO is neutralized.

Ocular surface chemical injury treated by regenerating agent (RGTA, Cacicol20)

Objective: To present the successful outcome of regenerating agent (RGTA) treatment in a patient with severe ocular surface chemical injury. Methods: Case report Results: A 14-year-old female patient was admitted to our clinic following chemical burn in the left eye. Her best corrected visual acuity (BCVA) was 20/40; and she had total corneal and 75% conjunctival epithelial loss, corneal haze, and limbal ischemia for nine clock hours in the left eye. The patient had already received standard therapy consisting of patching, preservative-free artificial tears, topical netilmicin, topical dexamethasone, oral doxycycline, and vitamin C for two weeks. We initially cleaned the conjunctival necrotic tissues, applied the silicon hydrogel bandage contact lens, exchanged the topical netilmicin with preservative-free moxifloxacin and supplemented this therapy with RGTA (Cacicol20, Paris, France) once in two days. The BCVA of the patient improved to 20/20 and the ocular surface re-epithelization was completed on day 20. Conclusion: RGTAs are effective biological agents for the treatment of corneal epithelial defects following severe ocular surface chemical injuries.

Plasma rich in growth factors for the treatment of rapidly progressing refractory corneal melting due to erlotinib in nonsmall cell lung cancer

RATIONALE

Erlotinib, an antineoplastic agent, is indicated for the treatment of patients with advanced nonsmall cell lung cancer. Most common adverse events are manageable, although more severe ones require dose reduction or discontinuation of erlotinib treatment.

PATIENT CONCERNS

We present a case of severe corneal ulcer treated with autologous plasma rich in growth factors.

DIAGNOSES

A 76-year-old woman with stage IVB (cT2a N0 M1c) lung cancer under erlotinib treatment presented with rapidly progressing corneal ulcer. Evolution was torpid and refractory to conventional treatment.

INTERVENTIONS

Surgical options were dismissed because of the poor performance status of the patient. Despite temporary discontinuation of erlotinib treatment, the corneal ulcer continued to worsen with peripheral corneal neovascularization, stromal thinning, corneal edema, and profuse inflammation of the ocular surface.

OUTCOMES

Treatment with autologous plasma rich in growth factors prevented an imminent corneal perforation and improved the corneal ulcer for over a year of follow-up.

LESSONS

Considering the poor results of conventional treatment, both medical and surgical, management of the inflammation of the ocular surface together with the stimulation of the healing processes through regenerative therapy such as PRGF, can be an option worth considering in these cases.

Neurotrophic factors and corneal nerve regeneration

The cornea has unique features that make it a useful model for regenerative medicine studies. It is an avascular, transparent, densely innervated tissue and any pathological changes can be easily detected by slit lamp examination. Corneal sensitivity is provided by the ophthalmic branch of the trigeminal nerve that elicits protective reflexes such as blinking and tearing and exerts trophic support by releasing neuromediators and growth factors. Corneal nerves are easily evaluated for both function and morphology using standard instruments such as corneal esthesiometer and in vivo confocal microscope. All local and systemic conditions that are associated with damage of the trigeminal nerve cause the development of neurotrophic keratitis, a rare degenerative disease. Neurotrophic keratitis is characterized by impairment of corneal sensitivity associated with development of persistent epithelial defects that may progress to corneal ulcer, melting and perforation. Current neurotrophic keratitis treatments aim at supporting corneal healing and preventing progression of corneal damage. Novel compounds able to stimulate corneal nerve recovery are in advanced development stage. Among them, nerve growth factor eye drops showed to be safe and effective in stimulating corneal healing and improving corneal sensitivity in patients with neurotrophic keratitis. Neurotrophic keratitis represents an useful model to evaluate in clinical practice novel neuro-regenerative drugs.

Understanding the Pathogenesis of Neurotrophic Keratitis: The Role of Corneal Nerves

Neurotrophic keratitis (NK) is a rare degenerative disease of the cornea caused by trigeminal nerve damage, which leads to loss of corneal sensitivity, corneal epithelium breakdown, and poor healing. Though extremely uncommon, NK is increasingly recognized for its characteristics as a distinct and well-defined clinical entity rather than a rare complication of various diseases that can disrupt trigeminal innervation. Indeed, the defining feature of NK is loss of corneal sensitivity, and its clinical findings do not correlate with the wide range of systemic or ocular conditions that underlie trigeminal nerve damage. Despite increasing awareness of NK as a distinct condition, its management continues to be challenged by the lack of treatments that target nerve regeneration. This review focuses on the role of corneal nerves in maintaining ocular surface homeostasis, the consequences (such as alterations in neuromediators and corneal cell morphology/function) of impaired innervation, and advances in NK diagnosis and management. Novel therapeutic strategies should aim to improve corneal innervation in order support corneal renewal and healing. J. Cell. Physiol. 232: 717-724, 2017. © 2016 Wiley Periodicals, Inc.