Moein H-R, Saeed HN, Jacobs DS, Rapoport Y, Yoon MK, Shah AS, Khan H, Raoof D, Jurkunas UV. Exposure, entropion, and bilateral corneal ulceration in a newborn as a manifestation of chromosome 22 q11.2 duplication syndrome. Am J Ophthalmol Case Rep 2019;13:16-19.Abstract
Purpose: Chromosome 22q11.2 micro-duplication syndrome (MDS), is a rare autosomal dominant condition, with a highly variable phenotype that ranges from unremarkable and asymptomatic, to fatal due to cardiovascular defects. Hypertelorism, downslanting palpebral fissures, superior displacement of the eyebrows, and ptosis are the most commonly reported ocular manifestations. Here, we report a newborn with bilateral exposure, entropion, and corneal ulceration related to 22q11.2 MDS. Observation: A newborn girl presented with bilateral upper eyelid entropion, bilateral lower eyelid ectropion, and lagophthalmos. She subsequently developed bilateral corneal ulcers. Topical antibacterial drops, bandage contact lenses, medroxyprogesterone 1%, and fluorometholone 0.1%, together with partial tarsorrhaphy and correction of eyelid malposition, were used to treat the ulcers and address the underlying issues of exposure and entropion. Genetic testing revealed chromosome 22q11.2.MDS; further evaluation revealed systemic manifestations of this syndrome. The ocular surface healed well with gradual improvement of corneal opacification as well as bilateral partial tarsorrhaphy. Conclusion and importance: This report is the first that describes a newborn with 22q11.2 MDS presenting with sight-threatening corneal ulceration. Entropion, ectropion, and lagophthalmos were identified and treated, allowing for healing of the corneal surface. Genetic testing revealed a syndrome not known to be associated with eyelid abnormalities and corneal ulceration, but with other important systemic and ocular implications. Bilateral partial tarsorrhaphy should not be excluded as a treatment option for infants who fail more conservative measures for the treatment of exposure.
Shirzaei Sani E, Kheirkhah A, Rana D, Sun Z, Foulsham W, Sheikhi A, Khademhosseini A, Dana R, Annabi N. Sutureless repair of corneal injuries using naturally derived bioadhesive hydrogels. Sci Adv 2019;5(3):eaav1281.Abstract
Corneal injuries are common causes of visual impairment worldwide. Accordingly, there is an unmet need for transparent biomaterials that have high adhesion, cohesion, and regenerative properties. Herein, we engineer a highly biocompatible and transparent bioadhesive for corneal reconstruction using a visible light cross-linkable, naturally derived polymer, GelCORE (gel for corneal regeneration). The physical properties of GelCORE could be finely tuned by changing prepolymer concentration and photocrosslinking time. GelCORE revealed higher tissue adhesion compared to commercial adhesives. Furthermore, in situ photopolymerization of GelCORE facilitated easy delivery to the cornea, allowing for bioadhesive curing precisely according to the required geometry of the defect. In vivo experiments, using a rabbit stromal defect model, showed that bioadhesive could effectively seal corneal defects and induce stromal regeneration and re-epithelialization. Overall, GelCORE has many advantages including low cost and ease of production and use. This makes GelCORE a promising bioadhesive for corneal repair.
Wu W, Hutcheon AEK, Sriram S, Tran JA, Zieske JD. Initiation of fibrosis in the integrin Αvβ6 knockout mice. Exp Eye Res 2019;180:23-28.Abstract
We previously demonstrated that β6 knockout mice showed impaired wound repair in corneal debridement and keratectomy wounds. In the current investigation, we continued our examination of integrin αvβ6 in order to determine if it was required for the initiation of wound healing in a corneal wound model that normally heals in a fibrotic manner. A full-thickness corneal incision was made in C57BL/6 J wild type (WT) and C57BL/6-Itgb6 KO (β6) mice. The mice were observed at 3, 7, 14, and 28 days post-incision. The morphology of corneal restoration was observed in tissue sections stained with hemotoxilin and eosin (H&E). In addition, indirect-immunofluorescence (IF) was performed on sections and/or whole mounts to evaluate the immunolocalization of α-smooth muscle actin (SMA) and thrombospondin-1 (TSP-1). H&E staining revealed that the corneas in β6 mice healed slower than those in WT mice, with an obvious delay in the restoration of the stromal matrix and epithelium. In sections at 3 and 7 days, SMA and TSP-1 were greatly reduced in the β6 mice as compared to WT, but peaked at 28 days after incision. Whole mount SMA IF results were consistent with those from sections. Therefore, the initiation of fibrosis was inhibited by the lack of αvβ6; however, there appeared to be an alternate mechanism that initiated fibrosis 7-14 days later. Localization of TSP-1 correlated with expression of SMA whether wound healing was delayed or initiated immediately after wounding.
Deng SX, Borderie V, Chan CC, Dana R, Figueiredo FC, Gomes JAP, Pellegrini G, Shimmura S, Kruse FE, and Group TILSCDW. Global Consensus on Definition, Classification, Diagnosis, and Staging of Limbal Stem Cell Deficiency. Cornea 2019;38(3):364-375.Abstract
PURPOSE: Despite extensive knowledge gained over the last 3 decades regarding limbal stem cell deficiency (LSCD), the disease is not clearly defined, and there is lack of agreement on the diagnostic criteria, staging, and classification system among treating physicians and research scientists working on this field. There is therefore an unmet need to obtain global consensus on the definition, classification, diagnosis, and staging of LSCD. METHODS: A Limbal Stem Cell Working Group was first established by The Cornea Society in 2012. The Working Group was divided into subcommittees. Four face-to-face meetings, frequent email discussions, and teleconferences were conducted since then to obtain agreement on a strategic plan and methodology from all participants after a comprehensive literature search, and final agreement was reached on the definition, classification, diagnosis, and staging of LSCD. A writing group was formed to draft the current manuscript, which has been extensively revised to reflect the consensus of the Working Group. RESULTS: A consensus was reached on the definition, classification, diagnosis, and staging of LSCD. The clinical presentation and diagnostic criteria of LSCD were clarified, and a staging system of LSCD based on clinical presentation was established. CONCLUSIONS: This global consensus provides a comprehensive framework for the definition, classification, diagnosis, and staging of LSCD. The newly established criteria will aid in the correct diagnosis and formulation of an appropriate treatment for different stages of LSCD, which will facilitate a better understanding of the condition and help with clinical management, research, and clinical trials in this area.
Dana R, Bradley JL, Guerin A, Pivneva I, Stillman IÖ, Evans AM, Schaumberg DA. Estimated Prevalence and Incidence of Dry Eye Disease Based on Coding Analysis of a Large, All-age United States Health Care System. Am J Ophthalmol 2019;202:47-54.Abstract
PURPOSE: To assess overall prevalence, annual prevalence, and incidence of dry eye disease (DED) in a large, representative population in the United States. DESIGN: Prevalence and incidence study. METHODS: Retrospective analysis using the Department of Defense (DOD) Military Health System (MHS) data on beneficiary medical claims from United States DOD military and civilian facilities, January 1, 2003 through March 31, 2015. PATIENT POPULATION: Using an algorithm, medical diagnostic codes indicative of DED and prescriptions for cyclosporine ophthalmic emulsion identified a DED population from 9.7 million MHS beneficiaries (DOD service members, retirees, and dependents, aged 2-80+ years). MAIN OUTCOME MEASURES: DED overall prevalence (2003-2015), annual prevalence (2005-2012), and annual incidence (2008-2012) stratified by sex, age group, and International Statistical Classification of Diseases and Related Health Problems, Ninth Revision diagnosis code grouping. RESULTS: DED prevalence was 5.28% overall, 7.78% among female beneficiaries, 2.96% among male beneficiaries and increased with age from 0.20% for ages 2-17 years, to 11.66% for individuals aged 50+ years. Annual prevalence increased from 0.8% to 3.0% overall, from 1.4% to 4.5% in female beneficiaries, and from 0.3% to 1.6% in male beneficiaries. Annual prevalence increased across age groups starting at age 18-39, 0.1%-0.6%, to age 50+, 1.8%-6.0%. Annual incidence increased from 0.6% to 0.9% overall, from 0.8% to 1.2% in female beneficiaries, and from 0.3% to 0.6% in male beneficiaries. Across age groups, annual incidence increased starting at age 18-39 (0.2%-0.3%), to age 50+ (1.0%-1.6%). CONCLUSIONS: DED overall prevalence, annual prevalence, and incidence were found to increase over time for all demographics. These findings highlight the continued importance of research and therapeutic development for this common condition.
Sharifi R, Yang Y, Adibnia Y, Dohlman CH, Chodosh J, Gonzalez-Andrades M. Finding an Optimal Corneal Xenograft Using Comparative Analysis of Corneal Matrix Proteins Across Species. Sci Rep 2019;9(1):1876.Abstract
Numerous animal species have been proposed as sources of corneal tissue for obtaining decellularized xenografts. The selection of an appropriate animal model must take into consideration the differences in the composition and structure of corneal proteins between humans and other animal species in order to minimize immune response and improve outcome of the xenotransplant. Here, we compared the amino-acid sequences of 16 proteins present in the corneal stromal matrix of 14 different animal species using Basic Local Alignment Search Tool, and calculated a similarity score compared to the respective human sequence. Primary amino acid structures, isoelectric point and grand average of hydropathy (GRAVY) values of the 7 most abundant proteins (i.e. collagen α-1 (I), α-1 (VI), α-2 (I) and α-3 (VI), as well as decorin, lumican, and keratocan) were also extracted and compared to those of human. The pig had the highest similarity score (91.8%). All species showed a lower proline content compared to human. Isoelectric point of pig (7.1) was the closest to the human. Most species have higher GRAVY values compared to human except horse. Our results suggest that porcine cornea has a higher relative suitability for corneal transplantation into humans compared to other studied species.
Chirapapaisan C, Abbouda A, Jamali A, Müller RT, Cavalcanti BM, Colon C, Witkin D, Sahin A, Dana R, Cruzat A, Hamrah P. In Vivo Confocal Microscopy Demonstrates Increased Immune Cell Densities in Corneal Graft Rejection Correlating With Signs and Symptoms. Am J Ophthalmol 2019;203:26-36.Abstract
PURPOSE: Diagnosis of graft rejection is based on patient symptoms and on clinical signs detected by slit-lamp biomicroscopy. This study investigated whether laser in vivo confocal microscopy (IVCM) can aid in the diagnosis of corneal graft rejection by detecting cellular corneal changes that take place after transplantation. DESIGN: Prospective case-control study. SUBJECTS: Thirty-eight eyes of 38 patients with penetrating keratoplasty (15 eyes with corneal graft rejection, 23 eyes without rejection) and 9 age-matched normal controls. METHODS: Laser IVCM was performed in the corneal grafts centrally. The density of immune cells (IC) was assessed for epithelial, sub-epithelial, stromal, and endothelial layers by 2 masked observers. IC density was compared among different groups and correlated to clinical signs and symptoms of corneal graft rejection. MAIN OUTCOME MEASUREMENTS: Outcome measurement was the IC density in the corneal layers and its associations with the presence of clinical signs and symptoms of corneal graft rejection. RESULTS: The IC density was significantly different between rejected and non-rejected grafts (P = 0.004) and different from that of normal controls (P = 0.001). Among corneal layers, IC density was significantly higher in rejected grafts than in non-rejected grafts in only the sub-basal (611.54 ± 573.74 vs. 340.61 ± 268.60 cells/mm, respectively; P = 0.049) and endothelial layers (250.62 ± 267.13 vs. 103.47 ± 81.91 cells/mm, respectively; P = 0.001). Patients with decreased best corrected visual acuity, Khodadoust line, and anterior chamber cells demonstrated a significant increase in total IC density (P < 0.05), whereas patients with symptoms of irritation, light sensitivity, and pain revealed a specific increase in IC density in the sub-basal layer (P < 0.05). Patients with ocular pain had higher IC density in the epithelial layer than those without pain (P = 0.03). CONCLUSIONS: Patients with corneal graft rejection demonstrate a significant increase in corneal immune cells, particularly, in the sub-basal and endothelial layers compared to patients with non-rejected grafts and controls. Although symptoms associated with endothelial rejection demonstrate a general increase in IC, pain, irritation, and light sensitivity are associated with increased IC in the sub-basal layer. Assessment of patients with corneal graft rejection by IVCM may serve as an adjunctive tool in the diagnosis and management of corneal graft rejection.
Lin SR, Aldave AJ, Chodosh J. Recurrent corneal erosion syndrome. Br J Ophthalmol 2019;103(9):1204-1208.Abstract
Recurrent corneal erosion syndrome (RCES) is a disorder characterised by a dysfunctional epithelial ecosystem. It often begins after trauma, or in the setting of epithelial basement membrane degeneration or dystrophy. Historically, RCES has been understood as a structural derangement of the anterior corneal architecture. More recently, studies have demonstrated the important role of neuropeptides in corneal homoeostasis. Thus, RCES may also be understood as a disorder of corneal epithelial cell biology. Management of RCES can be challenging, but newer therapies have demonstrated improved efficacy for this condition. This review examines the aetiology and pathogenesis of RCES, and provides an update on current and emerging treatment modalities for the management of this disorder.
Bradley JL, Stillman IÖ, Pivneva I, Guerin A, Evans AM, Dana R. Dry eye disease ranking among common reasons for seeking eye care in a large US claims database. Clin Ophthalmol 2019;13:225-232.Abstract
Objectives: Dry eye disease (DED) is a complex multifactorial condition of the ocular surface characterized by symptoms of ocular discomfort, irritation, and visual disturbance. Data previously reported from this study showed an increase in prevalence and incidence of DED with age and over time. The objective of this study was to compare the ranking of DED prevalence among other ocular conditions that led patients to seek eye care. Methods: In this population-based study using the US Department of Defense Military Health System claims database of >9.7 million beneficiaries, indicators of DED and other ocular conditions were analyzed over time. The overall prevalence (2003-2015) and annual incidence (2008-2012) of DED and other ocular conditions were estimated using an algorithm based on two independent indicators derived from selected diagnostic and procedure codes and prescriptions for cyclosporine ophthalmic emulsion for DED and diagnostic codes for the indicators of other common ocular conditions. Results: In 2003-2015, the most common ocular conditions were disorders of refraction and accommodation (25.84%), cataracts (17.14%), glaucoma (7.27%), disorders of the conjunctiva (6.76%), other retinal disorders (5.94%), and DED (5.28%). DED was the fifth most prevalent ocular condition in women (7.78%) and ninth most prevalent in men (2.96%). In 2012, DED had the third highest annual incidence (0.87%), behind disorders of refraction/accommodation (1.87%) and cataracts (1.50%). Conclusion: This study provided further epidemiologic evidence for DED as a commonly occurring condition that drives patients to seek treatment.
Paschalis EI, Taniguchi EV, Chodosh J, Pasquale LR, Colby K, Dohlman CH, Shen LQ. Blood Levels of Tumor Necrosis Factor Alpha and Its Type 2 Receptor Are Elevated in Patients with Boston Type I Keratoprosthesis. Curr Eye Res 2019;44(6):599-606.Abstract
: Boston keratoprosthesis (KPro) patients are prone to glaucoma even with well-controlled intraocular pressure (IOP). Recent experimental data have shown that soluble tumor necrosis factor alpha (TNF-) after ocular injury may contribute to progressive retinal damage and subsequent glaucoma. This study evaluates the blood plasma levels of soluble TNF-, TNF receptors 1 (TNFR1) and 2 (TNFR2), and leptin in patients with Boston type I KPro. : Venous blood samples were collected from KPro patients with glaucoma (KPro G, = 19), KPro patients without glaucoma (KPro NoG, = 12), primary angle closure glaucoma without KPro (PACG, = 13), and narrow angles without glaucoma or KPro (NA, = 21). TNF-, TNFR1, TNFR2, and leptin levels were quantified using the enzyme-linked immunosorbent assay. Erythrocyte sedimentation rate (ESR) was assessed using the Westergren test. Patients with underlying autoimmune conditions or diabetes were excluded from the study. : All groups had similar age, body mass index (BMI), IOP, and ESR ( ≥ 0.11). The mean time from KPro surgery to blood draw was 5.3 ± 3.7 years. Compared to NA patients (0.72 ± 0.3 pg/ml), KPro G and KPro NoG patients had higher blood plasma levels of TNF- (1.18 ± 0.58 pg/ml, = 0.006; 1.16 ± 0.50 pg/ml, = 0.04, respectively). Similarly, KPro G patients had higher blood plasma levels of TNFR2 (2768 ± 1368 pg/ml) than NA patients (2020 ± 435 pg/ml, = 0.048). In multivariate analysis, KPro status remained positively associated with TNF- levels ( = 0.36; 95% confidence intervals [CI]: 0.14-0.58; = 0.002) and TNFR2 levels ( = 458.3; 95% CI: 32.8-883.7; = 0.035) after adjusting for age, gender, BMI, glaucoma status, and ESR. TNFR1 and leptin levels were not significantly different in the study groups. : We detected elevated serum levels of TNF- and TNFR2 in KPro patients. Longitudinal studies are needed to establish TNF- and TNFR2 as serum biomarkers related to KPro surgery. : BCVA: best corrected visual acuity; BMI: body mass index; CDR: cup-to-disc ratio; EDTA: ethylenediaminetetraacetic acid; ELISA: enzyme-linked immunosorbent assay; ESR: erythrocyte sedimentation rate; HVF: Humphrey visual field; IOP: intraocular pressure; KPro G: keratoprosthesis with glaucoma; KPro NoG: keratoprosthesis without glaucoma; KPro: keratoprosthesis; MD: mean deviation; NA: narrow angle; non-KPro: without keratoprosthesis; PACG: primary angle closure glaucoma; RNFL: retinal nerve fiber layer; TNF-α: tumor necrosis factor alpha; TNFR1: tumor necrosis factor receptor 1; TNFR2: tumor necrosis factor receptor 2.
Wang Y, Rao R, Jacobs DS, Saeed HN. Prosthetic Replacement of the Ocular Surface Ecosystem Treatment for Ocular Surface Disease in Pediatric Patients With Stevens-Johnson Syndrome. Am J Ophthalmol 2019;201:1-8.Abstract
PURPOSE: To report the outcomes of prosthetic replacement of the ocular surface ecosystem (PROSE) treatment in pediatric patients with chronic ocular surface disease associated with Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN). DESIGN: Retrospective, interventional case series. METHODS: Patients aged 18 years or younger seen in consultation for PROSE treatment at a single center between January 1992 and December 2016 with a history of SJS/TEN were reviewed. Demographics, etiology of SJS/TEN, age at treatment milestones, best-corrected visual acuity (BCVA) at treatment milestones, and treatment failures were recorded. BCVA at the initial presentation visit was compared to BCVA at the time of PROSE device dispense and at the last recorded visit. RESULTS: Twenty-seven female and 22 male patients were reviewed. Reported etiology was antibiotic (n = 19), antiepileptic (n = 9), antipyretic (n = 9), other (n = 3), and unknown (n = 9). The mean age was 6.4 years at disease onset and 9.3 years at time of initial presentation. The mean duration of follow-up was 5.45 years. The median BCVA at the initial presentation was 0.6 logMAR (20/80 Snellen), and was significantly improved to 0.18 logMAR (20/30 Snellen) at the time a PROSE device was dispensed (P < .0001). The median BCVA at the last recorded visit was significantly improved to 0.18 logMAR (20/30 Snellen, P = .0004). There were 15 patients who failed PROSE treatment (30.6%). CONCLUSIONS: PROSE treatment is feasible in over two thirds of pediatric patients with chronic ocular surface disease related to SJS/TEN and results in significant improvement in vision that is durable over a period of many years.
Bakshi SK, Paschalis EI, Graney J, Chodosh J. Lucia and Beyond: Development of an Affordable Keratoprosthesis. Cornea 2019;38(4):492-497.Abstract
PURPOSE: Severe corneal disease contributes significantly to the global burden of blindness. Corneal allograft surgery remains the most commonly used treatment, but does not succeed long term in every patient, and the odds of success fall with each repeated graft. The Boston keratoprosthesis type I has emerged as an alternative to repeat corneal allograft. However, cost limits its use in resource-poor settings, where most corneal blind individuals reside. METHODS: All aspects of the Boston keratoprosthesis design process were examined to determine areas of potential modification and simplification, with dual goals to reduce cost and improve the cosmetic appearance of the device in situ. RESULTS: Minor modifications in component design simplified keratoprosthesis manufacturing. Proportional machinist time could be further reduced by adopting a single axial length for aphakic eyes, and a single back plate diameter. The cosmetic appearance was improved by changing the shape of the back plate holes from round to radial, with a petaloid appearance, and by anodization of back plate titanium to impute a more natural color. CONCLUSIONS: We have developed a modified Boston keratoprosthesis type I, which we call the "Lucia." The Lucia retains the 2 piece design and ease of assembly of the predicate device, but would allow for manufacturing at a reduced cost. Its appearance should prove more acceptable to implanted patients. Successful keratoprosthesis outcomes require daily medications for the life of the patient and rigorous, frequent, postoperative care. Effective implementation of the device in resource-poor settings will require further innovations in eye care delivery.
Martínez-Carrasco R, Sánchez-Abarca LI, Nieto-Gómez C, García EM, Sánchez-Guijo F, Argüeso P, Aijón J, Hernández-Galilea E, Velasco A. Subconjunctival injection of mesenchymal stromal cells protects the cornea in an experimental model of GVHD. Ocul Surf 2019;Abstract
PURPOSE: To evaluate the therapeutic effect of subconjunctival injection of human mesenchymal stromal cells (hMSCs) in the cornea of mice with graft versus host disease (GVHD). METHODS: GVHD was induced in mice after hematopoietic stem cell transplantation (HSCT) between MHC-mismatched mouse strains. Subconjunctival injection of hMSCs was applied at day 10 post-HSCT. Infiltration of CD3 cells in the cornea and epithelial alterations were analyzed by immunofluorescence. Tear was assessed using the PRT test and TearLab Osmolarity System. qPCR was used to evaluate changes in cytokines, Pax6 and Sprr1b expression. To evaluate the effect of irradiation, we analyzed the expression of these genes in TBI mice. RESULTS: Immune cell invasion occurs in mice with GVHD, as shown by the presence of CD3 cells in the cornea. Interestingly, eyes treated with hMSC did not present CD3 cells. Tear osmolarity was increased in GVHD eyes, but not in treated eyes. TNFa expression was highly increased in all corneas except in Control and treated eyes. Pax6 in corneal epithelium showed a similar pattern in GVHD and Control mice, and its gene expression was enhanced in GVHD corneas. In contrast, Pax6 was reduced in GVHD + MSC corneas. We also found an increase in SPRR1B staining in GVHD eyes that was lower in GVHD + MSC mice, demonstrating that corneal keratinization is less frequent after treatment with hMSC. CONCLUSIONS: The treatment with hMSCs by subconjunctival injection is effective in reducing corneal inflammation and squamous metaplasia in ocular GVHD (oGVHD). Local treatment with hMSCs is a promising strategy for oGVHD.
Trujillo-de Santiago G, Sharifi R, Yue K, Sani ES, Kashaf SS, Alvarez MM, Leijten J, Khademhosseini A, Dana R, Annabi N. Ocular adhesives: Design, chemistry, crosslinking mechanisms, and applications. Biomaterials 2019;197:345-367.Abstract
Closure of ocular wounds after an accident or surgery is typically performed by suturing, which is associated with numerous potential complications, including suture breakage, inflammation, secondary neovascularization, erosion to the surface and secondary infection, and astigmatism; for example, more than half of post-corneal transplant infections are due to suture related complications. Tissue adhesives provide promising substitutes for sutures in ophthalmic surgery. Ocular adhesives are not only intended to address the shortcomings of sutures, but also designed to be easy to use, and can potentially minimize post-operative complications. Herein, recent progress in the design, synthesis, and application of ocular adhesives, along with their advantages, limitations, and potential are discussed. This review covers two main classes of ocular adhesives: (1) synthetic adhesives based on cyanoacrylates, polyethylene glycol (PEG), and other synthetic polymers, and (2) adhesives based on naturally derived polymers, such as proteins and polysaccharides. In addition, different technologies to cover and protect ocular wounds such as contact bandage lenses, contact lenses coupled with novel technologies, and decellularized corneas are discussed. Continued advances in this area can help improve both patient satisfaction and clinical outcomes.
Aggarwal S, Colon C, Kheirkhah A, Hamrah P. Efficacy of autologous serum tears for treatment of neuropathic corneal pain. Ocul Surf 2019;Abstract
OBJECTIVE: Corneal nerve damage may result in neuropathic corneal pain (NCP). Autologous serum tears (AST) have been shown to results in nerve regeneration and may help alleviate corneal pain. This study aimed to evaluate the efficacy of AST in the treatment of NCP. METHODS: This was a retrospective case-control study. Sixteen patients suffering from severe NCP and no current ocular surface disease were compared to 12 controls. In vivo confocal microscopy (IVCM) (HRT3/RCM; Heidelberg, Germany) of the central corneas was performed bilaterally. Change in pain severity (scale of 0-10), corneal nerve density, tortuosity, reflectivity and presence of beading and microneuromas before and after treatment were recorded. RESULTS: All patients had severe pain of 9.1 ± 0.2 (range 8-10). Before treatment, subbasal nerves were significantly decreased compared to controls, including total nerve length (10,935.5 ± 1264.3 vs. 24,714.4 ± 1056.2 μm/mm; p < 0.0001) and total number of nerves (10.5 ± 1.4 vs. 28.6 ± 2.0; p < 0.0001), respectively. Morphologically, significantly increased reflectivity (2.9 ± 0.2 vs. 1.2 ± 0.1; p = 0.00008) and tortuosity (2.4 ± 0.2 vs. 1.7 ± 0.1; p = 0.001), both graded on a scale of 0-4, were noted. After 3.8 ± 0.5 months (range 1-8 months) of AST treatment, pain severity decreased to 3.1 ± 0.3 (range 0-4), (p < 0.0001). Further, IVCM demonstrated a significant improvement (p < 0.005) in total nerve length (17,351.3 ± 1395.6 μm/mm) and number (15.1 ± 1.6) as well as significant decrease in reflectivity (2.4 ± 0.2; p = 0.001) and tortuosity (2.2 ± 0.2; p = 0.001). CONCLUSION: IVCM demonstrates underlying alterations of the subbasal corneal nerve plexus in patients suffering from debilitating NCP. AST-induced nerve regeneration is seen following treatment with AST, which correlates with improvement in patient symptoms of NCP.