The molecular basis of neurotrophic keratopathy: Diagnostic and therapeutic implications. A review

Deep-learning based analysis of in-vivo confocal microscopy images of the subbasal corneal nerve plexus' inferior whorl in patients with neuropathic corneal pain and dry eye disease

PURPOSE

To evaluate and compare subbasal corneal nerve parameters of the inferior whorl in patients with dry eye disease (DED), neuropathic corneal pain (NCP), and controls using a novel deep-learning-based algorithm to analyze in-vivo confocal microscopy (IVCM) images.

METHODS

Subbasal nerve plexus (SNP) images of the inferior whorl of patients with DED (n = 49, 77 eyes), NCP (n = 14, 24 eyes), and controls (n = 41, 59 eyes) were taken with IVCM and further analyzed using an open-source artificial intelligence (AI)-based algorithm previously developed by our group. This algorithm automatically segments nerves, immune cells, and neuromas in the SNP. The following parameters were compared between groups: nerve area density, average nerve thickness, average nerve segment tortuosity, junction point density, neuroma density, and immune cell density.

RESULTS

160 eyes of 104 patients (63 % females), aged 56.8 ± 15.4 years, were included. The mean nerve area density was significantly lower in the DED (P = 0.012) and NCP (P < 0.001) groups compared to the control group. The junction point density was lower in the NCP group compared with control (P = 0.001) and DED (P = 0.004) groups. The immune cell density was higher in the DED group compared with controls (P < 0.001).

CONCLUSIONS

Deep-learning-based analysis of IVCM images of the corneal SNP inferior whorl distinguished a decreased mean nerve area density in patients with DED and NCP compared with controls and an increased immune cell density in patients with oGVHD- and SS-associated DED. These findings suggest that the inferior whorl could be used as landmark to distinguish between patients with DED and NCP.

The Utilization of Topical Insulin for Ocular Surface Diseases: A Narrative Review

Various etiologies, including diabetic keratopathy (DK), dry eye disease (DED), and neurotrophic keratopathy (NK), can disrupt corneal homeostasis, exacerbating corneal epithelial defects. Topical insulin has emerged as a promising therapy for promoting corneal wound healing and addressing underlying pathologies. This review systematically evaluates the efficacy of topical insulin across different corneal disorders. A literature review was conducted across the PubMed, Google Scholar, and Scopus research databases. The search resulted in a total of 19 articles, consisting of clinical trials, retrospective studies, and case reports. In DK, topical insulin accelerates corneal wound healing post-vitreoretinal surgery with lower concentrations showing higher outcomes when compared to conventional therapy, possibly due to improved epithelial stem cell migration. In comparison, the dry-eye disease results are inconclusive regarding patient-reported outcomes and corneal staining. For NK, topical insulin accelerates corneal wound healing and restores corneal nerve sensation. Other persistent epithelial defect (PED) etiologies that have been treated with topical insulin are infection, immune-mediated, mechanical and chemical trauma, and chronic ocular surface alterations. Although individual mechanisms for the benefits of topical insulin for each of these etiologies have not been studied, the literature demonstrates that topical insulin is efficacious for PEDs regardless of etiology. Future clinical trials need to be conducted to further evaluate optimal dosing, duration, and use of topical insulin for the restoration of the corneal surface.

Topical insulin in neurotrophic keratopathy after diabetic vitrectomy

To assess the efficacy and safety of topical insulin (TI) for treating neurotrophic keratopathy (NK) within one-month post-diabetic vitrectomy (DV) compared to conventional non-invasive measures, we conducted this retrospective case-control study including all eyes that developed acute NK (stages 2 and 3) following DV between October 2020 and June 2023. The control group included NK cases managed with preservative-free lubricant eye drops and prophylactic topical antibiotics. In contrast, the study group included NK cases treated with TI [1 unit per drop] four times daily, in addition to the previously mentioned treatment. The primary outcome measure was time to epithelial healing. Secondary outcome measures included any adverse effect of TI or the need for amniotic membrane transplantation (AMT). During the study period, 19 patients with a mean age of 49.3 ± 8.6 years received TI versus 18 controls with a mean age of 52.5 ± 10.7 years. Corneal epithelial healing was significantly faster in the TI-treated group compared to controls, with a mean difference of 12.16 days (95% CI 6.1-18.3, P = 0.001). Survival analysis indicated that the insulin-treated group had 0% and 20% of NK stages 2 and 3, respectively, that failed to achieve corneal epithelial healing, compared to 20% and 66.7% for the control group (P < 0.001). In the control group, two eyes required AMT due to progressive thinning. Additionally, three patients in the control group, progressing to stage 3 NK, were switched to TI, achieving healing after a mean of 14 days. No adverse effects were reported in the TI-treated group. Our study suggests that TI can effectively and safely promote the healing of NK after DV.

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.

Lessons Learned From Ocular Graft versus Host Disease: An Ocular Surface Inflammatory Disease of Known Time of Onset

ABSTRACT

The ocular surface inflammatory disorders (OSIDs) comprise a group of conditions characterized by persistent inflammation of the ocular surface and adnexal tissues. Systemic autoimmune diseases and hypersensitivity reactions cause them, and, if left untreated, can result in severe inflammatory dry eye, corneal damage, and vision loss. Ocular graft-versus-host disease (oGVHD) forms part of the ocular surface inflammatory disease umbrella. It is a condition occurring after allogeneic hematopoietic stem cell or bone marrow transplantation, usually in chronic graft-versus-host disease. oGVHD can virtually affect any ocular adnexal tissue, especially the meibomian glands, and cause persistent inflammation, tissue fibrosis, and subsequent chronic, severe dry eye disease. Among the OSIDs, oGVHD has the particularity that it has a "time zero," meaning we know when the disease started. As such, preclinical models have leveraged this to investigate the molecular mechanisms involved in the damage oGVHD causes to the ocular surface. In oGVHD, establishing a "time zero" allows for predicting the clinical course and establishing adequate treatment. This is also possible because the inflammatory infiltration occurs in ocular surface tissues, which are readily accessible. Using oGVHD, we might be able to understand the immune response mechanisms in other OSIDs better (i.e., Sjögren syndrome, Stevens-Johnson syndrome, among others). This review presents an up-to-date overview of the pathogenesis, clinical presentation, and treatment of oGVHD. In addition, we will discuss the value of the "time zero" concept in the study of oGVHD.

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.

Insights on the Choice and Preparation of the Donor Nerve in Corneal Neurotization for Neurotrophic Keratopathy: A Narrative Review

The article introduces neurotrophic keratopathy (NK), a condition resulting from corneal denervation due to various causes of trigeminal nerve dysfunctions. Surgical techniques for corneal neurotization (CN) have evolved, aiming to restore corneal sensitivity. Initially proposed in 1972, modern approaches offer less invasive options. CN can be performed through a direct approach (DCN) directly suturing a sensitive nerve to the affected cornea or indirectly (ICN) through a nerve auto/allograft. Surgical success relies on meticulous donor nerve selection and preparation, often involving multidisciplinary teams. A PubMed research and review of the relevant literature was conducted regarding the surgical approach, emphasizing surgical techniques and the choice of the donor nerve. The latter considers factors like sensory integrity and proximity to the cornea. The most used are the contralateral or ipsilateral supratrochlear (STN), and the supraorbital (SON) and great auricular (GAN) nerves. Regarding the choice of grafts, the most used in the literature are the sural (SN), the lateral antebrachial cutaneous nerve (LABCN), and the GAN nerves. Another promising option is represented by allografts (acellularized nerves from cadavers). The significance of sensory recovery and factors influencing surgical outcomes, including nerve caliber matching and axonal regeneration, are discussed. Future directions emphasize less invasive techniques and the potential of acellular nerve allografts. In conclusion, CN represents a promising avenue in the treatment of NK, offering tailored approaches based on patient history and surgical expertise, with new emerging techniques warranting further exploration through basic science refinements and clinical trials.

New disposable esthesiometer (KeraSenseⓇ) to improve diagnosis and management of neurotrophic keratitis

PURPOSE

To validate the use, repeatability, and reproducibility of a new, cost-effective, disposable, sterile device (KeraSenseⓇ, Dompè farmaceutici SpA, Milan Italy) compared to Cochet-Bonnet (CB) esthesiometer. Secondly, to identify a simple, safe, rapid, and low-cost test to diagnose neurotrophic keratitis (NK).

METHODS

16 patients with diagnosis of NK stage I, 25 patients with diabetes mellitus (DM), and 26 healthy subjects were included in the study. Corneal sensitivity (CS) was assessed by CB and KeraSenseⓇ. Repeatability, accuracy, and reproducibility of the novel disposable aesthesiometer were assessed. Specificity, sensitivity, and cut-off value for NK diagnosis were calculated by ROC curve analysis.

RESULTS

All NK patients showed a CS ≤ 40 mm, while none of the healthy patients showed a CS value < 50 mm. Significant agreement was found between CB measurements and the single use esthesiometer evaluations of CS (p < 0.001). Repeatability evaluations of the single use esthesiometer showed 100% agreement between different measurements (p < 0.001). Reproducibility evaluations showed 99.6% concordance between different operators (p < 0.001). A 55 mm value of the single use esthesiometer was adequate to exclude an NK diagnosis, while all NK patients showed a value ≤ 35 mm.

CONCLUSIONS

Corneal hypo/anaesthesia is considered the hallmark of NK. The use of the novel single-use esthesiometer will allow for a diagnostic improvement in NK, sparing time and guaranteeing patients' safety. Diabetic patients despite normal corneal findings may show impairment of CS, suggesting a preclinical stage of NK, requiring a close follow-up.

Establishment of mouse model of neurotrophic keratopathy through TRPV1 neuronal ablation

Neurotrophic keratopathy (NK) is a challenging disease with the reduced innervation to the cornea. To establish a genetic and stable mouse model of NK, we utilized the TRPV1-DTR mice with intraperitoneal injection of diphtheria toxin (DT) to selectively eliminate TRPV1 neurons. After DT administration, the mice exhibited robust ablation of TRPV1 neurons in the trigeminal ganglion, accompanied with reduced corneal sensation and nerve density, as well as the decreased calcitonin-gene-related peptide (CGRP) and substance P levels. According to disease progression of TRPV1 neuronal ablation, tear secretion was reduced from day 3, which followed by corneal epithelial punctate lesions from day 7. From day 11 to day 16, the mice exhibited persistent corneal epithelial defects and stromal edema. By day 21, corneal ulceration and stromal melting were observed with the abundant inflammatory cell infiltration, corneal neovascularization, and enhanced cell apoptosis. Moreover, subconjunctival injection of CGRP delayed the NK progression with the characteristics of reduced severe corneal epithelial lesions and corneal inflammation. In addition, the impairments of conjunctival goblet cells, lacrimal gland, and meibomian gland were identified by the diminished expression of MUC5AC, AQP5, and PPARγ, respectively. Therefore, these results suggest that the TRPV1-DTR mice may serve as a reliable animal model for the research of NK pathogenesis.

Phase IV Multicenter, Prospective, Open-Label Clinical Trial of Cenegermin (rhNGF) for Stage 1 Neurotrophic Keratopathy (DEFENDO)

INTRODUCTION

Cenegermin is approved for treatment of neurotrophic keratopathy (NK) and has been studied in patients with stage 2 or 3 NK. This study evaluated the efficacy and safety of cenegermin in adults with stage 1 NK.

METHODS

This was a phase IV, multicenter, prospective, open-label, uncontrolled trial. Adults with stage 1 NK (Mackie criteria) and decreased corneal sensitivity (≤ 4 cm) received 1 drop of cenegermin 20 mcg/ml in the affected eye(s) 6 times/day for 8 weeks with a 24-week follow-up.

RESULTS

Of 37 patients, corneal epithelial healing was observed in 84.8% (95% confidence interval [CI] 68.1-94.9%; P < 0.001) at week 8; 95.2% (95% CI 76.2-99.9%; P < 0.001) of those patients remained healed at the end of the 24-week follow-up (week 32). At week 8, 91.2% (95% CI 76.3-98.1%; P < 0.001) of patients experienced improved corneal sensitivity; this improvement was observed in 82.1% (95% CI 63.1-93.9%; P < 0.001) of patients at week 32. Mean best-corrected distance visual acuity change from baseline at week 8 was - 0.10 logMAR (standard deviation [SD], 0.15; 95% CI - 0.16 to - 0.05; P < 0.001) and at week 32 was - 0.05 logMAR (SD, 0.16; 95% CI - 0.11 to 0.01; P = 0.122). At weeks 8 and 32, 15.2% (95% CI 5.1-31.9%; P < 0.001) and 10.7% (95% CI 2.3-28.2%; P < 0.001) of patients, respectively, had a 15-letter gain from baseline. At least one adverse event (AE) was reported by 73.0% and 45.7% of patients during the treatment and follow-up periods, respectively. The most common treatment-related, treatment-emergent AEs were eye pain (37.8%), blurred vision (10.8%), and eyelid pain (8.1%); these were mostly mild or moderate and were only reported during the treatment period.

CONCLUSIONS

These results support the potential use of cenegermin for treating patients with stage 1 NK, and future confirmatory studies would be beneficial to elaborate on these findings.

TRIAL REGISTRATION

DEFENDO; NCT04485546.

Topical Insulin in Neurotrophic Keratopathy: A Review of Current Understanding of the Mechanism of Action and Therapeutic Approach

Neurotrophic keratopathy is a corneal disease characterized by impaired corneal innervation. It can lead to corneal epithelial defects, ulcerations, and perforations. Topical insulin has been shown to be effective in treating this disorder. Insulin is a growth factor that can promote corneal epithelial cell proliferation and migration. In addition, it can also inhibit corneal epithelial cell apoptosis. Topical insulin has previously been found to enhance corneal wound healing. This article reviews the current understanding of the mechanism of action of topical insulin in the treatment of neurotrophic keratopathy.

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.

Establishing a Mouse Model of Chlorpromazine-Induced Corneal Trigeminal Denervation

Purpose

This study aimed to establish a mouse model of chlorpromazine-induced corneal trigeminal denervation (CCTD).

Methods

Retrobulbar chlorpromazine injections were administered to 6- to 8-week-old C57BL/6j mice to induce corneal denervation. Additionally, apoptosis was assessed in isolated primary trigeminal ganglion cells after culturing in a conditioned medium containing chlorpromazine. Finally, the success rate of model generation, mortality and complication rates, and model-preparation learning curves were compared between the CCTD model and the electrocoagulation and axotomy models.

Results

Chlorpromazine retrobulbar injections resulted in trigeminal denervation, leading to a reduced blink reflex, corneal nerve density, and corneal epithelium thickness. Furthermore, 90% (9/10) of the mice developed epithelial defects, accompanied by increased apoptosis and inhibited proliferation of corneal epithelial cells. In vitro, trigeminal ganglion cell apoptosis increased after culturing in a conditioned medium containing chlorpromazine. Moreover, the CCTD model exhibited a higher success rate, longer survival rate, and lower complication rate compared to the electrocoagulation and axotomy models. Crucially, the learning curve demonstrated that the method used to generate the CCTD model was easy to learn.

Conclusions

The CCTD model is a user-friendly mouse model for studying corneal trigeminal denervation that offers a less invasive alternative to existing models.

Translational Relevance

The CCTD model serves as a valuable tool for investigating the functional mechanisms of corneal trigeminal nerves and their interactions with corneal cells.

Evaluation of Corneal Nerve Regeneration After Minimally Invasive Corneal Neurotization

PURPOSE

To evaluate the corneal nerve regeneration after minimally invasive corneal neurotization (MICN) and to further clarify the recovery patterns of sensory and trophic functions of the corneal nerves.

DESIGN

A retrospective cohort study based in the Shanghai Ninth People's Hospital.

METHODS

Eighteen patients (18 eyes) who underwent MICN for neurotrophic keratopathy due to intracranial surgery was conducted to analyze their follow-up data at 6, 12, 18, and 24 months after surgery.

RESULTS

At 12 months postoperatively, the growth of the central and peripheral corneal nerve fiber density (CNFD) was 11.47±8.56 and 14.73±8.08 n/mm 2 with subsequent improvement slowing down, and the patient's corneal epithelium defect was healed ahead of the accomplishment of corneal nerve regeneration. The number of dendritic cells also reached its peak. At 18 months postoperatively, the recovery of central and peripheral corneal sensation was 37.22±23.06 mm and 39.38±18.08 mm with no subsequent improvement, and the growth of the central and peripheral corneal nerve branch density (CNBD) was 29.69±11.05 and 43.75±1.41 n/mm 2 , with a positive and significant correlation between corneal sensation and CNBD (at central r =0.632, P <0.005; at peripheral r =0.645, P <0.005). At 24 months postoperatively, mean CNFD, CNBD, and corneal sensation recovered significantly compared with preoperative, but a few patients' corneal sensation recovered insignificantly with good CNFD recovery and poor CNBD recovery.

CONCLUSIONS

After MICN, the trophic function of the corneal nerve recovers before the sensory function, and in particular, the recovery of sensation is based on the coexistence of the corneal nerve trunk and branches.

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.

Wessely corneal ring phenomenon: An unsolved pathophysiological dilemma

The cornea is a densely innervated, avascular tissue showing exceptional inflammatory and immune responses. The cornea is a site of lymphangiogenic and angiogenic privilege devoid of blood and lymphatic vessels that limits the entry of inflammatory cells from the adjacent and highly immunoreactive conjunctiva. Immunological and anatomical differences between the central and peripheral cornea are also necessary to sustain passive immune privilege. The lower density of antigen-presenting cells in the central cornea and the 5:1 peripheral-to-central corneal ratio of C1 are 2 main features conferring passive immune privilege. C1 activates the complement system by antigen-antibody complexes more effectively in the peripheral cornea and, thus, protects the central corneas' transparency from immune-driven and inflammatory reactions. Wessely rings, also known as corneal immune rings, are non-infectious ring-shaped stromal infiltrates usually formed in the peripheral cornea. They result from a hypersensitivity reaction to foreign antigens, including those of microorganism origin. Thus, they are thought to be composed of inflammatory cells and antigen-antibody complexes. Corneal immune rings have been associated with various infectious and non-infectious causes, including foreign bodies, contact lens wear, refractive procedures, and drugs. We describe the anatomical and immunologic basis underlying Wessely ring formation, its causes, clinical presentation, and management.

Noxious effects of riot control agents on the ocular surface: Pathogenic mechanisms and management

Riot Control Agents (RCAs) are chemical compounds used by law enforcement agencies to quell violent demonstrations as an alternative to lethal force and as part of police/military training. They are also known as tear gases because of the hallmark ocular irritation and lacrimation they cause. The most common RCAs include oleoresin capsicum (contained in Mace and pepper spray), chlorobenzylidene malononitrile, dibenzoxazepine, and chloroacetophenone (previously the main content of Mace); some of which have been in use for decades. Their immediate incapacitating effects are mediated through polymodal afferent fibers innervating the corneal surface, inducing the release of peptides that cause neurogenic inflammation. Although previously thought to have only transient effects on exposed patients more severe complications such as corneal stromal opacities, corneal neovascularization, neurotrophic keratopathy, conjunctival necrosis, and pseudopterygium can occur. Concerningly, the lack of research and specific therapies restrict the current management to decontamination and symptom-tailored support. This manuscript will provide an overview of the toxic mechanisms of RCAs, their clinical manifestations, and current therapy after exposure to tear gases.

0.1% RGN-259 (Thymosin ß4) Ophthalmic Solution Promotes Healing and Improves Comfort in Neurotrophic Keratopathy Patients in a Randomized, Placebo-Controlled, Double-Masked Phase III Clinical Trial

We determined the efficacy and safety of 0.1% RGN-259 ophthalmic solution (containing the regenerative protein thymosin ß4) in promoting the healing of persistent epithelial defects in patients with Stages 2 and 3 neurotrophic keratopathy. Complete healing occurred after 4 weeks in 6 of the 10 RGN-259-treated subjects and in 1 of the 8 placebo-treated subjects (p = 0.0656), indicating a strong efficacy trend. Additional efficacy was seen in the significant healing (p = 0.0359) with no recurrent defects observed at day 43, two weeks after cessation of treatment, while the one healed placebo-treated subject at day 28 suffered a recurrence at day 43. The Mackie classification disease stage improved in the RGN-259-treated group at Days 29, 36, and 43 (p = 0.0818, 0.0625, and 0.0467, respectively). Time to complete healing also showed a trend towards efficacy (p = 0.0829, Kaplan-Meier) with 0.1% RGN-259. RGN-259-treated subjects had significant improvements at multiple time points in ocular discomfort, foreign body sensation, and dryness which were not seen in the placebo group. No significant adverse effects were observed. In summary, the use of 0.1% RGN-259 promotes rapid healing of epithelial defects in neurotrophic keratopathy, improves ocular comfort, and is safe for treating this challenging population of patients.

Characteristics of the ocular surface in neurotrophic keratitis induced by trigeminal nerve injury following neurosurgery

Purpose

To analyse and quantify ocular surface parameters in patients with unilateral neurotrophic keratitis (NK) induced by trigeminal nerve injury post-neurosurgery.

Methods

The study included 26 unilateral NK patients who had undergone neurosurgery, and 20 matched normal controls. Demographic and clinical characteristics of all participants were collected and analysed. Slit-lamp examination, Cochet–Bonnet aesthesiometry, Keratograph 5 M, and LipiView interferometer were performed on both eyes of 17 mild NK patients. For nine moderate/severe NK patients, sub-basal nerve density was measured by in vivo confocal microscopy.

Results

Of the 26 patients, nine had acoustic neuroma, nine had trigeminal neuralgia, and eight had neoplasms. Facial nerve paralysis was observed in one of the 17 mild NK eyes (5.9%) and seven of the nine moderate/severe NK eyes (77.8%). Compared to contralateral and normal control eyes, 26 NK eyes showed significantly reduced sensitivity in five corneal regions (P < 0.05). Corneal sensitivity in moderate/severe NK eyes was significantly lower than in mild NK eyes (P < 0.05). Moderate/severe NK eyes had poor visual acuity, and their sub-basal nerve density was lower than that of the controls. The onset of the moderate/severe NK was from 0.5 to 24 months (median [Q1, Q3], 1 [0.5, 2.5] months) after neurosurgery. For the mild NK eyes, the number of total blinks, the first non-invasive tear breakup time (NITBUT) and average NITBUT were significantly lower than contralateral and normal control eyes (P < 0.05), and the number of partial blinks and partial blinking rate were significantly higher than the other two control groups (P < 0.05).

Conclusions

Patients with NK induced by trigeminal nerve injury following neurosurgery had decreased corneal sensitivity to various degrees accompanied by increased partial blinks and shortened NITBUT. The severity of NK is related to the severity of the corneal sensory impairment. Facial nerve paralysis can worsen the clinical progression of NK.

Trial registration Chinese Clinical Trial Registry (ChiCTR2100044068, Date of Registration: March 9, 2021).

Minimally Invasive Corneal Neurotization Provides Sensory Function, Protects Against Recurrent Ulceration, and Improves Visual Acuity

PURPOSE

To measure sensory recovery after minimally invasive corneal neurotization, and to identify and quantify the extent to which patient and technical factors influence sensory recovery, ulceration rate, and visual outcomes.

DESIGN

Retrospective case series.

METHODS

This study included 23 patients with neurotrophic keratopathy who underwent indirect corneal neurotization. The primary outcome measure was corneal sensitivity with Cochet-Bonnet aesthesiometry (CBA), and the secondary outcome measure was epithelial breakdown.

RESULTS

Over a 7-year period, 28 eyes of 23 patients (mean age, 15.6 ± 13.6 years) were included in the study. The CBA measurements improved from 3.5 ± 9.1 mm at baseline to 44.1 ± 18.2 mm at 24 months after surgery (P < .001). Maximum CBA was reached after 11.1 ± 6.2 months (median, 9 months). Compared to eyes neurotized with a contralateral donor nerve, eyes with an ipsilateral donor nerve achieved a higher mean CBA (36.0 ± 10.9 vs 10.4 ± 14.0 mm, P = .001) at 3 months. Both the number of fascicles (Spearman correlation coefficient, r_s -0.474, P = .11) and insertions (r_s -0.458, P = .014) negatively correlated with the final CBA. Nine eyes (32.1%) experienced at least 1 episode of epithelial breakdown after surgery. Visual acuity improved in the neurotized corneas from logMAR 0.57 ± 0.79 at baseline to 0.39 ± 0.66 at 12 months (P = .043).

CONCLUSIONS

Corneal sensation improves over time after corneal neurotization. There is resultant improvement in visual acuity and protection against epithelial breakdown. It is important to maximize sensory recovery to protect against recurrent ulceration.

A Practical Approach to Severity Classification and Treatment of Dry Eye Disease: A Proposal from the Mexican Dry Eye Disease Expert Panel

Dry eye disease (DED) has a higher prevalence than many important systemic disorders like cardiovascular disease and diabetes mellitus, representing a significant quality of life burden for the affected patients. It is a common reason for consultation in general eye clinics worldwide. Nowadays, the diagnostic and therapeutic approach at the high corneal and ocular surface specialty level should be reserved for cases of severe and chronic dry eye disease associated with systemic autoimmune diseases or complicated corneal and ocular surface pathologies. In such cases, the diagnostic and therapeutic approach is often complex, elaborate, time-consuming, and costly due to the use of extensive dry eye questionnaires, noninvasive electronic diagnostic equipment, and clinical laboratory and ancillary tests. However, other eye care specialists attend a fair amount of DED cases; therefore, its diagnosis, classification, and management should be simple, practical, achievable, and effective. Considering that many patients attending non-specialized dry eye clinics would benefit from better ophthalmological attention, we decided to elaborate a practical DED classification system based on disease severity to help clinicians discriminate cases needing referral to subspecialty clinics from those they could attend. Additionally, we propose a systematic management approach and general management considerations to improve patients' therapeutic outcomes according to disease severity.

A multicenter report of the use of plasma rich in growth factors (PRGF) for the treatment of patients with ocular surface diseases in North America

PURPOSE

To investigate the efficacy and safety of plasma rich in growth factors (PRGF) eyedrops in the management of patients with ocular surface diseases in North America.

METHODS

Multicenter interventional case series of patients using PRGF eyedrops for the first time. A cohort of patients was analyzed for corneal staining score at initial visit and at 3 months of therapy with PRGF. Another cohort responded to a 10-item questionnaire that evaluated patients' satisfaction and safety, which included the symptom assessment questionnaire in dry eye (SANDE) score, after 6 months of PRGF treatment.

RESULTS

A total of 153 patients were analyzed. Of these, 102 were reviewed for corneal epitheliopathy and 99 patients responded to the questionnaire. The mean (±SD) age of the population was 63.7 ± 17 years and 72.5% were female. The clinical indications for PRGF usage were dry eye (60%), neurotrophic keratopathy (15%), dormant corneal ulcers (12%), limbal stem cell deficiency (10%), and cicatrizing conjunctivitis (4%). At the final visit, 74.3% of patients showed an improvement of their corneal staining. Those who had punctate epithelial erosions or epithelial defects were reduced from 76.5% to 47% and 23.5%-7.8% respectively (p < 0.0001). Symptoms, measured via SANDE score, significantly decreased from a median of 90 to 34.6 out of 100 points on follow-up (p < 0.0001). Only one patient (0.98%) complained of ocular burning sensation as a side effect.

CONCLUSIONS

This multicentric study demonstrates the safety and efficacy of the use of PRGF for treating signs and symptoms in patients with significant ocular surface diseases.

Dry eye disease, a prominent manifestation of systemic autoimmune disorders

OBJECTIVES

Dry eye disease (DED) is arguably the most frequent ocular disease encountered in ophthalmic clinical practice. DED is frequently an underestimated condition causing a significant impact on visual function and quality of life. Many systemic autoimmune diseases (SAIDs) are related to moderate to severe DED. The main objective of this review is to enhance the awareness among ophthalmologists of the potential association of an underlying SAID in a high-risk patient with DED.

METHODS

An exhaustive literature search was performed in the National Library of Medicine's Pubmed, Scopus, Web of Science, and Google Scholar databases for all English language articles published until November 2021. The main keywords included "dry eye disease" associated with autoimmune, connective tissue, endocrine, gastrointestinal, hematopoietic, vascular, and pulmonary diseases. Case reports, series, letters to the editor, reviews, and original articles were included.

RESULTS

Although DED is frequently associated with SAIDs, its diagnosis is commonly delayed or missed, producing significant complications, including corneal ulceration, melting, scleritis, uveitis, and optic neuritis resulting in severe complications detrimental to visual function and quality of life. SAID should be suspected in a woman, 30 to 60 years old with a family history of autoimmunity, presenting with DED symptoms and extraocular manifestations including arthralgias, dry mouth, unexplained weight and hair loss, chronic fatigue, heat or cold intolerance, insomnia, and mood disorders.

CONCLUSIONS

Establishing the correct diagnosis and treatment of DED associated with SAIDs is crucial to avoid its significant burden and severe ocular complications.

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.

Polymyositis and dermatomyositis: ocular manifestations and potential sight-threatening complications

Dermatomyositis (DM) and polymyositis (PM) are idiopathic inflammatory myopathies characterized by progressive, symmetric, mainly proximal muscle weakness. DM is also characterized by cutaneous involvement. However, other clinical features, systemic involvement, histopathological findings, response to treatment, and prognosis, differ significantly. Although uncommon, ocular manifestations in DM and PM may potentially affect any structure within the eye. Notwithstanding being generally mild, ocular involvement in DM and PM may result in significant morbidity. Left untreated, significant retinal inflammation associated with hemorrhage and detachment may occur, leading to significant vision loss. This review aims to present an up-to-date overview for rheumatologists about the ocular involvement and potential complications of DM and PM and when to refer to the ophthalmologist to avoid sight-threatening complications.

Long-term clinical outcome and satisfaction survey in patients with neurotrophic keratopathy after treatment with cenegermin eye drops or amniotic membrane transplantation

Purpose

Neurotrophic keratopathy (NK) is a degenerative corneal disease caused by damage of trigeminal innervation. The purpose of this study is to evaluate the clinical outcomes and patient-reported satisfaction of treatment with amniotic membrane transplantation (AMT) or cenegermin eye drops in patients with NK.

Methods

Clinical charts of patients with NK treated with AMT (group A) or cenegermin eye drops (group B), with at least 12 months of follow-up, were reviewed for demographics, medical history, corneal healing, and disease recurrence. Patient satisfaction was evaluated by a newly developed questionnaire investigating patient’s appreciation of treatment of NK (2 items) and satisfaction with NK treatment outcomes (5 items).

Results

At the end of treatment, complete corneal healing was observed in 13/15 (86%) patients in group A and in 23/24 (96%) in group B. At 12 months follow-up, 6/13 patients (46%) in group A and 3/23 patients (13%) in group B showed recurrence of NK (p = 0.037).

Survival analysis showed that group B remained recurrence free for a significantly longer period of time than the group A (p = 0.028). Patients in group B showed a significantly higher satisfaction when compared with patients in group A (total score: 65.7 ± 15.7 vs 47.4 ± 12.8, p = 0.003), both in terms of patients’ appreciation of treatment (78.3 ± 15.9 vs 52.2 ± 30, p = 0.020) and satisfaction with treatment outcomes (60.7 ± 21 vs 45.4 ± 13.3, p = 0.037).

Conclusions

Treatment of NK with cenegermin was associated with long-term maintenance of corneal integrity and a higher degree of patient satisfaction.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00417-021-05431-6.

Neurotrophic keratopathy and refractive surgery

PURPOSE OF REVIEW

Corneal nerve function is an important consideration for the refractive surgeon. In patients without a history of neuropathy, refractive surgery can lead to destruction of corneal nerves and may predispose to keratopathy. The purpose of this review is to provide an update on the effect of refractive surgery on corneal nerve function and the potential for an increased risk of neurotrophic keratopathy development.

RECENT FINDINGS

Recent studies have reinforced that refractive surgery can cause anatomical and functional changes in corneal nerve function. Among the most commonly performed refractive surgery procedures are Laser Assisted In-situ Keratomileusis, Photorefractive Keratectomy, and Small Incision Lenticule Extraction. Due to differences in technique, these procedures can have varying effects on corneal nerve structure. Using in vivo confocal microscopy, postrefractive patients were found to have decreased total nerve density when compared with controls in the immediate postoperative period. In some studies, patients have been shown to undergo re-innervation and regain significant amounts of nerve function. The majority of studies have found that despite decreased nerve cell density, long-term outcomes of refractive surgery patients are generally favorable. However, loss of corneal nerve function can lead to a variety of serious effects ranging from dry eye disease, corneal hypoesthesia/anesthesia, neuropathic pain, to neurotrophic keratopathy and ulceration in the rare cases.

SUMMARY

Neurotrophic keratopathy is a rare occurrence after keratorefractive surgery and is largely due to damage to corneal nerves. Proper patient selection and counseling are essential to decrease the risk of development of this devastating complication.

Corneal neurotization for neurotrophic keratopathy: Review of surgical techniques and outcomes

Neurotrophic keratopathy is a degenerative disease in which damage to the corneal nerves leads to corneal hypoesthesia. Injuries to neurotrophic corneas are notoriously difficult to treat and have traditionally been approached with supportive management. However, recent progress in the field of corneal neurotization has given new direction for addressing nerve loss directly by stimulating new nerve growth onto the cornea from nearby sensory nerves transferred to the perilimbal region. Herein, we review the surgical techniques utilized in corneal neurotization, including direct transfers and the use of nerve grafts. Considerations in surgical approach, as well as factors that influence prognosis and outcomes of the surgical intervention are also discussed.