Advances in the Medical Management of Neurotrophic Keratitis

Corneal injury repair and the potential involvement of ZEB1

The cornea, consisting of three cellular and two non-cellular layers, is the outermost part of the eyeball and frequently injured by external physical, chemical, and microbial insults. The epithelial-to-mesenchymal transition (EMT) plays a crucial role in the repair of corneal injuries. Zinc finger E-box binding homeobox 1 (ZEB1), an important transcription factor involved in EMT, is expressed in the corneal tissues. It regulates cell activities like migration, transformation, and proliferation, and thereby affects tissue inflammation, fibrosis, tumor metastasis, and necrosis by mediating various major signaling pathways, including transforming growth factor (TGF)-β. Dysfunction of ZEB1 would impair corneal tissue repair leading to epithelial healing delay, interstitial fibrosis, neovascularization, and squamous cell metaplasia. Understanding the mechanism underlying ZEB1 regulation of corneal injury repair will help us to formulate a therapeutic approach to enhance corneal injury repair.

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.

Effect of Topical Recombinant Human Nerve Growth Factor on Corneal Epithelial Regeneration in Refractory Epithelial Keratopathy

PURPOSE

To report the effect of topical application of recombinant human nerve growth factor (rhNGF) eye drops on corneal epithelial regeneration in patients with refractory epitheliopathy.

METHODS

A retrospective chart review was conducted on patients treated with topical rhNGF for refractory epithelial keratopathy due to stage I neurotrophic keratitis (NK). Data regarding demographics and ocular/systemic past medical history was extracted from patient charts. Visual acuity and corneal staining scores were recorded at baseline and subsequent follow-up visits at 8 weeks and 3 months. Measurements from the worse eye were used to compare before and after treatment values.

RESULTS

We identified 14 patients (median age 68 years, 21% male) who received rhNGF treatment for refractory epithelial keratopathy. After an 8-week treatment with topical rhNGF, the median corneal staining score in the worse eye improved from 4 to 1 (p = 0.001). All patients showed at least one-grade improvement in corneal staining at 8 weeks, with sustained effect in seven patients at 3 months. A better response was observed in eyes with post-radiation epithelial keratopathy, LASIK, and Sjogren's disease. Those with chronic use of other topical treatments and uncontrolled diabetes mellitus demonstrated incomplete responses. Eight patients reported mild-to-moderate ocular discomfort from drop application that fully resolved after completion of treatment.

CONCLUSIONS

Topical rhNGF was effective and safe for refractory epithelial keratopathy in our small cohort, but sustained effects were seen only in certain etiologies for up to 3 months. Further studies are needed for optimal dosing and duration based on underlying causes.

Neurotrophic keratopathy: Clinical presentation and outcomes in 354 eyes in a community-based population

PURPOSE

To describe the frequency, clinical presentation, and outcomes of neurotrophic keratopathy (NK).

METHODS

Retrospective cohort study of Kaiser Permanente Northern California patients diagnosed with NK using ICD-10 code H16.23X from October 1, 2016 through May 31, 2021 was conducted. The electronic medical record was used to obtain demographic information, systemic and ocular comorbidities, corrected distance visual acuity (CDVA), Mackie stage, laterality, etiology, complications, interventions, and medications. The data were analyzed using cross-tabulations.

RESULTS

354 eyes in 322 patients presented with an initial or recurrent episode of NK. 9.9% had bilateral NK, 40% were 75 years and older, and 55% were women. Baseline vision was worse than 20/100 in 47.5%. Mackie staging was stage 1 in 37.3%, stage 2 in 32.5%, and stage 3 in 30.2%. Herpetic causes comprised 34.9%, followed by diabetes (12.4%), ocular surgery (10.4%), and central nervous system etiologies (9.0%). Topical antibiotics (74.5%), steroids (54.0%), autologous serum tears (46.0%), and oral antivirals (43.8%) were the most used treatments. There were 8 eyes with perforation, 4 endophthalmitis, and 3 evisceration/enucleations. An increased difference of approximately 0.1 logMAR in CDVA in the affected eye compared with the unaffected eye over one year was not statistically significant. Clinic utilization for stage 2 (average visits per month, 3.2) and stage 3 (5.0) NK gradually decreased over 6 months.

CONCLUSIONS

Summary of the current management, outcomes, and healthcare utilization of NK provides valuable benchmarks in assessing the disease burden in the community and for further development of novel therapies.

Cell Biology of Spontaneous Persistent Epithelial Defects After Photorefractive Keratectomy in Rabbits

Purpose

To evaluate wound healing in rabbit corneas that developed a spontaneous persistent epithelial defect (PED) after photorefractive keratectomy (PRK).

Methods

Forty-eight 10- to 15-week-old female New Zealand White rabbits weighing 2.5 to 3.0 kg underwent either -3 diopter (D) or -9 D PRK to generate a series of corneas to study wound healing after injury. During that series, seven corneas developed a PED detected with 1% fluorescein staining at a slit lamp that either did not have epithelial closure by 1 week after surgery or subsequently had the closed epithelium break down to form a PED 2 to 3 weeks after surgery. The corneas had slit-lamp photography, with and without 1% fluorescein, and were removed from the normal PRK series. Each PED cornea was evaluated using immunohistochemistry for the myofibroblast marker α-smooth muscle actin (α-SMA), keratocyte marker keratocan, and mesenchymal cell marker vimentin, as well as basement membrane components perlecan and collagen type IV.

Results

All seven corneas that had PRK with a PED, even the two evaluated at only 1 week after PRK, had α-SMA-positive myofibroblasts populating the anterior stroma within the PED, along with comingled α-SMA-negative cells that were likely corneal fibroblasts and possibly bone marrow-derived fibrocytes. Both perlecan and collagen type IV accumulated in the anterior stroma of the epithelial defects without an epithelial basement membrane, likely produced by corneal fibroblasts to modulate transforming growth factor-β entering the stroma from the tears and peripheral epithelium.

Conclusions

Corneas with a PED that occurred following PRK (a procedure that produces a transient neurotropic state in the cornea) had myofibroblasts populating the superficial stroma within the epithelial defect as early as 1 week after the surgery.

Translational Relevance

Pharmacologic treatments that trigger myofibroblast apoptosis, including topical losartan, could facilitate decreased scarring fibrosis in corneas with a PED.

Cost and Prescriber and Patient Characteristics of Cenegermin Use in the Medicare Population

PURPOSE

To assess the cost and prescriber and patient characteristics associated with the early use of cenegermin (OXERVATE) after its approval among Medicare beneficiaries to better define resource use and areas for improvement in the treatment of neurotrophic keratopathy.

DESIGN

Retrospective, cross-sectional study.

METHODS

Medicare Part D claims data of all cenegermin prescriptions from January 1, 2019, to December 31, 2020, were identified using its National Drug Code. Patients younger than 65 years and those with missing demographic characteristics were excluded. Information on patient and prescriber demographic characteristics, quantity of cenegermin prescription, gross drug costs, and patient out-of-pocket costs were extracted from each claim.

RESULTS

In 2019-2020, a total of 2410 Medicare beneficiaries aged 65 years or older were prescribed cenegermin. The mean (standard deviation [SD]) age of these patients was 77.3 (7.6) years. Most patients were female (63.6%), White (87.3%), and lived in urban areas (86.9%). The majority (72%) received a standard 8-week course. A total of 1025 clinicians prescribed cenegermin. Most were male (68.2%), in an urban setting (90.8%). The median (interquartile range [IQR]) duration of cenegermin therapy prescribed per patient by each clinician was 8 (7.5-8) weeks. Total gross drug cost of all cenegermin therapy over the study period was $287 million. Median (IQR) out-of-pocket patient cost was $5791 (180-7179).

CONCLUSIONS

Despite the clinical benefits of cenegermin therapy, the associated significant cost warrants further analysis of its cost-effectiveness in patient care, especially in comparison with alternative novel management options.

Ocular pain in ocular graft-versus-host disease patients with neurotrophic keratopathy

PURPOSE

Neurotrophic keratopathy (NK) is a degenerative disorder of the cornea characterized by decreased sensory innervation, epitheliopathy, and impaired epithelial healing. In this study, we assessed ocular pain and quality-of-life-related parameters in ocular graft-versus-host disease (oGVHD) patients with and without NK.

METHODS

We included 213 oGVHD patients in this retrospective study, including 29 patients with NK assessed by the Cochet-Bonnet esthesiometer. We evaluated their records for ocular pain assessment survey (OPAS) scores and clinical parameters, including corneal sensation, corneal fluorescein staining (CFS) score, Schirmer's test, tear break-up time (TBUT), and ocular surface disease index (OSDI) score.

RESULTS

oGVHD patients with NK had lower corneal sensation (3.4 ± 1.4 vs. 5.9 ± 0.3; p < 0.0001), higher CFS scores (6.4 ± 4.2 vs. 4.7 ± 4.0; p = 0.01), and lower TBUT scores (1.2 ± 2.1 vs. 2.2 ± 3.1; p = 0.08) compared to oGVHD patients without NK and additionally had significantly higher ocular pain intensity scores (OPAS 24-h average eye pain intensity: 2.0 ± 2.8 vs. 1.1 ± 1.9; p = 0.03). Patients with NK more commonly reported burning (0.2 ± 0.3 vs. 0.3 ± 0.4; p = 0.021) and sensitivity to light (0.2 ± 0.3 vs. 0.3 ± 0.4; p = 0.049) as compared to patients without NK.

CONCLUSION

Clinical signs of ocular surface disease are worse in oGVHD patients with NK compared to oGVHD patients without NK. These patients additionally experience higher intensity ocular pain and lower quality-of-life-related parameters.

Prevalence of neurotrophic keratopathy in patients with chronic ocular graft-versus-host disease

PURPOSE

To determine the prevalence, clinical characteristics, and risk factors associated with neurotrophic keratopathy (NK) in patients with chronic ocular graft-versus-host disease (oGVHD).

DESIGN

Retrospective cohort study.

METHODS

We performed a chart review of patients diagnosed with chronic oGVHD between January 2015 and December 2018 at a single academic institution and recorded demographic data, systemic and ocular comorbidities, history of hematologic malignancy, transplant characteristics, oGVHD severity scores, and adnexal and ocular examination findings. We determined the prevalence of NK and clinical characteristics associated with NK in these patients. A multivariate logistic regression analysis was performed to determine the risk factors associated with NK in these patients.

MAIN OUTCOME MEASURE

Prevalence of NK in chronic oGVHD.

RESULTS

We identified 213 patients diagnosed with chronic oGVHD following hematopoietic stem cell or bone marrow transplantation from our electronic patient database, and the prevalence of NK was 14%. The mean age of oGVHD patients with NK was 62.6 ± 12.9 years; 48% were women, 19 had unilateral NK, and ten had bilateral NK. In the cohort, 56%, 20%, and 24% eyes of the patients had grades 1, 2, and 3 of NK, respectively. The mean time to diagnose NK after transplantation was 52.9 ± 45.4 months. oGVHD patients diagnosed with NK had a significantly higher NIH oGVHD severity score (p = 0.04) and a lower corneal sensation score (p = 0.0001) than those without NK. Our analyses showed a significantly higher CFS score (p = 0.01) and a trend toward lower Schirmer test scores (p = 0.16) and tear break-up times (p = 0.08) in oGVHD patients with NK. Additionally, we observed a significantly higher prevalence of persistent epithelial defect (p = 0.0001), corneal ulceration (p = 0.0001), and corneal perforation (p = 0.005) in oGVHD patients diagnosed with NK. A logistic regression analysis to determine factors associated with NK showed that a higher NIH oGVHD score (odds ratio [OR] = 2.03, p = 0.026) and history of cataract surgery (odds ratio [OR] = 5.03, p = 0.001) are significant risk factors for NK in oGVHD patients.

CONCLUSIONS

The prevalence of NK in chronic oGVHD patients was 14% during the study period. Our analysis shows that oGVHD patients with a higher NIH oGVHD severity score and previous history of cataract surgery are at a higher risk of developing NK and may develop severe sequelae such as persistent epithelial defect or corneal ulceration.