Zhu H, Alt C, Webb RH, Melki S, Kochevar IE. Corneal Crosslinking With Rose Bengal and Green Light: Efficacy and Safety Evaluation. Cornea 2016;35(9):1234-41.Abstract

PURPOSE: To evaluate crosslinking of cornea in vivo using green light activation of Rose Bengal (RGX) and assess potential damaging effects of the green light on retina and iris. METHODS: Corneas of Dutch belted rabbits were de-epithelialized, then stained with Rose Bengal and exposed to green light, or not further treated. Corneal stiffness was measured by uniaxial tensiometry. Re-epithelialization was assessed by fluorescein fluorescence. Keratocytes were counted on hematoxylin and eosin (H&E)-stained sections, and iris cell damage was assessed by lactate dehydrogenase staining. Thermal effects on the blood-retinal barrier (BRB) were assessed by fluorescein angiography and those on photoreceptors, retinal pigment epithelium (RPE), and choriocapillaris by light microscopy and transmission electron microscopy. RESULTS: RGX (10-min irradiation; 150 J/cm) increased corneal stiffness 1.9-fold on day 1 (1.25 ± 0.21 vs. 2.38 ± 0.59 N/mm; P = 0.036) and 2.8-fold compared with controls on day 28 (1.70 ± 0.74 vs. 4.95 ± 1.86 N/mm; P = 0.003). Keratocytes decreased only in the anterior stroma on day 1 (24.0 ± 3.0 vs. 3.67 ± 4.73, P = 0.003) and recovered by day 28 (37.7 ± 8.9 vs. 34.5 ± 2.4, P = 0.51). Iris cells were not thermally damaged. No evidence of BRB breakdown was detected on days 1 or 28. Retina from RGX-treated eyes seemed normal with RPE cells showing intact nuclei shielded apically by melanosomes, morphologically intact photoreceptor outer segments, normal outer nuclear layer thickness, and choriocapillaris containing intact erythrocytes. CONCLUSIONS: The substantial corneal stiffening produced by RGX together with the lack of significant effects on keratocytes and no evidence for retina or iris damage suggest that RGX-initiated corneal crosslinking may be a safe, rapid, and effective treatment.

Ramke M, Zhou X, Materne EC, Rajaiya J, Chodosh J. Resident corneal c-fms(+) macrophages and dendritic cells mediate early cellular infiltration in adenovirus keratitis. Exp Eye Res 2016;147:144-7.Abstract

The cornea contains a heterogeneous population of antigen-presenting cells with the capacity to contribute to immune responses. Adenovirus keratitis is a severe corneal infection with acute and chronic phases. The role of resident corneal antigen-presenting cells in adenovirus keratitis has not been studied. We utilized transgenic MaFIA mice in which c-fms expressing macrophages and dendritic cells can be induced to undergo apoptosis, in a mouse model of adenovirus keratitis. Clinical keratitis and recruitment of myeloperoxidase and CD45(+) cells were diminished in c-fms depleted, adenovirus infected mice, as compared to controls, consistent with a role for myeloid-lineage cells in adenovirus keratitis.

Uchino Y, Uchino M, Yokoi N, Dogru M, Kawashima M, Komuro A, Sonomura Y, Kato H, Argüeso P, Kinoshita S, Tsubota K. Impact of Cigarette Smoking on Tear Function and Correlation between Conjunctival Goblet Cells and Tear MUC5AC Concentration in Office Workers. Sci Rep 2016;6:27699.Abstract

The first aim of this study was to clarify whether cigarette smoking affects tear secretion, goblet cell density, and tear MUC5AC concentration. The second purpose was to evaluate the correlations of conjunctival goblet cell density with tear MUC5AC concentration and other ocular surface evaluation factors. This cross-sectional study included 88 office workers. All subjects were required to fill in dry eye and smoking questionnaires, in addition to ocular surface evaluation. Tear wash fluid was collected from inferior fornix, and conjunctival epithelium was obtained by impression cytology. Tear MUC5AC concentration was quantified using enzyme-linked immunoassay, and conjunctival goblet cell density was counted after Periodic-acid Schiff staining. Tear MUC5AC concentration had significant positive correlation with conjunctival goblet cell density (r = 0.181, P = 0.03). In current smokers, Schirmer I test value, goblet cell density and tear MUC5AC concentration were significantly lower than non-smokers. Pack-years of smoking have significant negative correlation with goblet cell density (r = -0.174, P = 0.036) and tear MUC5AC concentration (r = -0.183, P = 0.028). We concluded that smoking might decrease tear secretion, goblet cell density and tear MUC5AC concentration. In addition, MUC5AC concentration in tears depends on goblet cell density in the conjunctiva among office workers.

Borkar DS, Veldman P, Colby KA. Treatment of Fuchs Endothelial Dystrophy by Descemet Stripping Without Endothelial Keratoplasty. Cornea 2016;35(10):1267-73.Abstract

PURPOSE: To evaluate the effect of deliberate removal of the central Descemet membrane on endothelial function and morphology in patients with Fuchs endothelial dystrophy (FED) and cataract undergoing phacoemulsification. METHODS: In this retrospective case series, patients with FED and visually significant cataract underwent phacoemulsification in an academic cornea practice in Boston, MA. Four millimeters of the central Descemet membrane was stripped and removed after intraocular lens insertion. Vision, corneal pachymetry, and confocal imaging of the endothelial anatomy were performed before surgery and at 1, 3, 6, and 12 months after surgery. Patients were classified as fast responders, responders, slow responders, and nonresponders on the basis of postoperative time to resolution of corneal edema with visible central endothelial mosaic. RESULTS: Eleven patients (13 eyes) aged 51 to 91 years were included in the study. No eyes had countable central endothelial cells by confocal imaging before surgery. Preoperative visual acuity ranged from 20/25 to 20/400. All corneas showed stromal and microcystic edema in the area of Descemet stripping at days 1 and 7 after surgery. Four eyes demonstrated resolution of corneal edema with visible central endothelial cell mosaic (range: 410-864 cells/mm) by postoperative month 1 with visual acuity ranging between 20/25 and 20/40. Four additional eyes demonstrated a similar response by postoperative month 3 and an additional 2 eyes had resolution of corneal edema with an intact central endothelial mosaic at postoperative month 6 or later. Cell counts (range: 428-864 cells/mm) were maintained in all 10 responders at the last follow-up visit (range: postoperative months 6-24). Final vision ranged from 20/15 to 20/20 in these 10 eyes with the exception of 2 eyes with retinal pathology. Three eyes required endothelial keratoplasty. CONCLUSIONS: Repopulation of the central corneal endothelium with corneal deturgescence can occur after deliberate central Descemet stripping in patients with FED who underwent cataract removal. This may offer a novel treatment for patients with FED that could reduce the need for endothelial transplantation. Further studies are needed to delineate the optimal patient population for Descemet stripping because not all patients will respond to this intervention.

Rodriguez JD, Lane KJ, Ousler GW, Angjeli E, Smith LM, Bateman KM, Abelson MB. Diurnal Tracking of Blink and Relationship to Signs and Symptoms of Dry Eye. Cornea 2016;35(8):1104-11.Abstract

PURPOSE: To assess diurnal changes in the signs and symptoms of dry eyes and their relationship to diurnal interblink interval (IBI) in normal subjects and in subjects with dry eye. METHODS: Blink data were collected from 9:00 AM to 8:00 PM during 2 days of normal activity using an electrocardiogram monitoring device. All subjects recorded ocular discomfort (0-5 scale) and primary activity hourly each day in a diary. Inferior and central fluorescein staining was graded by slit lamp (0-4) at the start and end of each day. Blink activity was detected using an algorithm based on recognition of the waveform corresponding to the kinematic properties of the blink signal. RESULTS: Normal subjects (N = 12) reported negligible symptoms, and results did not show a diurnal change in group hourly IBI. Mean daily IBI for the group with dry eye (N = 15) (4.63 ± 1.63 s) was shorter than that for the normal group (5.28 ± 1.48 s) (P = 0.0483). Correlation of diurnal symptoms and mean hourly IBI was relatively weak (r = -0.248). A repeated-measures model found IBI to be significantly associated with the time of day (P = 0.0028). Inferior corneal staining showed a small but significant diurnal increase for both normal group and group with dry eyes. CONCLUSIONS: Diurnal blink tracking reveals significant trending with symptoms. Diurnal change in IBI may be an appropriate surrogate for symptoms in the study of dry eye.

Liu C, Vojnovic D, Kochevar IE, Jurkunas UV. UV-A Irradiation Activates Nrf2-Regulated Antioxidant Defense and Induces p53/Caspase3-Dependent Apoptosis in Corneal Endothelial Cells. Invest Ophthalmol Vis Sci 2016;57(4):2319-27.Abstract

PURPOSE: To examine whether Nrf2-regulated antioxidant defense and p53 are activated in human corneal endothelial cells (CEnCs) by environmental levels of ultraviolet A (UV-A), a known stimulator of oxidative stress. METHODS: Immortalized human CEnCs (HCEnCi) were exposed to UV-A fluences of 2.5, 5, 10, or 25 J/cm2, then allowed to recover for 3 to 24 hours. Control HCEnCi did not receive UV-A. Reactive oxygen species (ROS) were measured using H2DCFDA. Cell cytotoxicity was evaluated by lactate dehydrogenase (LDH) release. Levels of Nrf2, HO-1, NQO-1, p53, and caspase3 were detected by immunnoblotting or real-time PCR. Activated caspase3 was measured by immunoblotting and a fluorescence assay. RESULTS: Exposure of HCEnCi to 5, 10, and 25 J/cm2 UV-A increased ROS levels compared with controls. Nrf2, HO-1, and NQO-1 mRNA increased 1.7- to 3.2-fold at 3 and 6 hours after irradiation with 2.5 and 5 J/cm2 UV-A. At 6 hours post irradiation, UV-A (5 J/cm2) enhanced nuclear Nrf2 translocation. At 24 hours post treatment, UV-A (5, 10, and 25 J/cm2) produced a 1.8- to 2.8-fold increase in phospho-p53 and a 2.6- to 6.0-fold increase in activated caspase3 compared with controls, resulting in 20% to 42% cell death. CONCLUSIONS: Lower fluences of UV-A induce Nrf2-regulated antioxidant defense and higher fluences activate p53 and caspase3, indicating that even near-environmental levels of UV-A may affect normal CEnCs. This data suggest that UV-A may especially damage cells deficient in antioxidant defense, and thus may be involved in the etiology of Fuchs' endothelial corneal dystrophy (FECD).

Salvador-Culla B, Kolovou PE. Keratoprosthesis: A Review of Recent Advances in the Field. J Funct Biomater 2016;7(2)Abstract

Since its discovery in the years of the French Revolution, the field of keratoprostheses has evolved significantly. However, the path towards its present state has not always been an easy one. Initially discarded for its devastating complications, the introduction of new materials and the discovery of antibiotics in the last century gave new life to the field. Since then, the use of keratoprostheses for severe ocular surface disorders and corneal opacities has increased significantly, to the point that it has become a standard procedure for corneal specialists worldwide. Although the rate of complications has significantly been reduced, these can impede the long-term success, since some of them can be visually devastating. In an attempt to overcome these complications, researchers in the field have been recently working on improving the design of the currently available devices, by introducing the use of new materials that are more biocompatible with the eye. Here we present an update on the most recent research in the field.

Fostad IG, Eidet JR, Utheim TP, Ræder S, Lagali NS, Messelt EB, Dartt DA. Dry Eye Disease Patients with Xerostomia Report Higher Symptom Load and Have Poorer Meibum Expressibility. PLoS One 2016;11(5):e0155214.Abstract

The purpose of the study was to investigate if xerostomia (dry mouth) is associated with symptoms and signs of dry eye disease (DED). At the Norwegian Dry Eye Clinic, patients with symptomatic DED with different etiologies were consecutively included in the study. The patients underwent a comprehensive ophthalmological work-up and completed self-questionnaires on symptoms of ocular dryness (Ocular Surface Disease Index [OSDI] and McMonnies Dry Eye Questionnaire) and the Sjögren's syndrome (SS) questionnaire (SSQ). Three hundred and eighteen patients (52% women and 48% men) with DED were included. Patient demographics were: 0 to 19 years (1%), 20 to 39 (25%), 40 to 59 (34%), 60 to 79 (35%) and 80 to 99 (5%). Xerostomia, defined as "daily symptoms of dry mouth the last three months" (as presented in SSQ) was reported by 23% of the patients. Female sex was more common among patients with xerostomia (81%) than among non-xerostomia patients (44%; P<0.001). Patients with xerostomia (60 ± 15 years) were older than those without xerostomia (51 ± 17; P<0.001). The use of prescription drugs was more prevalent among xerostomia patients (65%) than among non-xerostomia patients (35%; P<0.021; adjusted for age and sex). Patients with xerostomia had a higher OSDI score (19.0 ± 10.0) than those without xerostomia (12.9 ± 8.0; P<0.001). Moreover, xerostomia patients had more pathological meibum expressibility (0.9 ± 0.7) than those without xerostomia (0.7 ± 0.8; P = 0.046). Comparisons of OSDI and ocular signs were performed after controlling for the effects of sex, age and the number of systemic prescription drugs used. In conclusion, xerostomia patients demonstrated a higher DED symptom load and had poorer meibum expressibility than non-xerostomia patients.

Cruzat A, Hamrah P, Cavalcanti BM, Zheng L, Colby K, Pavan-Langston D. Corneal Reinnervation and Sensation Recovery in Patients With Herpes Zoster Ophthalmicus: An In Vivo and Ex Vivo Study of Corneal Nerves. Cornea 2016;35(5):619-25.Abstract

PURPOSE: To study corneal reinnervation and sensation recovery in Herpes zoster ophthalmicus (HZO). METHODS: Two patients with HZO were studied over time with serial corneal esthesiometry and laser in vivo confocal microscopy (IVCM). A Boston keratoprosthesis type 1 was implanted, and the explanted corneal tissues were examined by immunofluorescence histochemistry for βIII-tubulin to stain for corneal nerves. RESULTS: The initial central corneal IVCM performed in each patient showed a complete lack of the subbasal nerve plexus, which was in accordance with severe loss of sensation (0 of 6 cm) measured by esthesiometry. When IVCM was repeated 2 years later before undergoing surgery, case 1 showed a persistent lack of central subbasal nerves and sensation (0 of 6). In contrast, case 2 showed regeneration of the central subbasal nerves (4786 μm/mm) with partial recovery of corneal sensation (2.5 of 6 cm). Immunostaining of the explanted corneal button in case 1 showed no corneal nerves, whereas case 2 showed central and peripheral corneal nerves. Eight months after surgery, IVCM was again repeated in the donor tissue around the Boston keratoprosthesis in both patients to study innervation of the corneal transplant. Case 1 showed no nerves, whereas case 2 showed new nerves growing from the periphery into the corneal graft. CONCLUSIONS: We demonstrate that regaining corneal innervation and corneal function are possible in patients with HZO as shown by corneal sensation, IVCM, and ex vivo immunostaining, indicating zoster neural damage is not always permanent and it may recover over an extended period of time.

Rapoport Y, Singer JM, Ling JD, Gregory A, Kohanim S. A Comprehensive Review of Sex Disparities in Symptoms, Pathophysiology, and Epidemiology of Dry Eye Syndrome. Semin Ophthalmol 2016;Abstract

INTRODUCTION: The etiology, frequency, manifestation, and treatment of dry eye syndrome are commonly influenced by sex and gender. MATERIALS AND METHODS: This study aims to review the differences in epidemiology, pathophysiology, and associated diseases between the sexes. The terms men and male and women and female are used interchangeably throughout the review to refer to biological sex. RESULTS: There are numerous objective and subjective markers of dry eye syndrome but not one diagnostic criterion. There are numerous associated conditions with dry eye syndrome varying from autoimmune to allergic. Large epidemiologic studies reviewed suggest that there does indeed exist a difference between dry eye symptoms between men and women, with women having dry eye signs and reporting dry eye symptoms more often than men. The increased prevalence in women could be correlated to an increased association with certain systemic diseases, specifically autoimmune diseases, and to hormonal variations. Several studies found equivocal data about prevalence of dry eye symptoms between men and women. DISCUSSION: Interpreting studies that investigate epidemiology, pathogenesis, and treatment of dry-eye conditions is complicated by the lack of universally adapted diagnostic criteria and standardized, specific diagnostic tests, and inter-study variability in the definition of dry eye syndrome.

Abud TB, Amparo F, Saboo US, Di Zazzo A, Dohlman TH, Ciolino JB, Hamrah P, Dana R. A Clinical Trial Comparing the Safety and Efficacy of Topical Tacrolimus versus Methylprednisolone in Ocular Graft-versus-Host Disease. Ophthalmology 2016;123(7):1449-57.Abstract

PURPOSE: To evaluate the safety and efficacy of topical tacrolimus 0.05% versus topical methylprednisolone 0.5% in patients with ocular graft-versus-host disease (GVHD). DESIGN: Phase 1/2 prospective, randomized, double-masked clinical trial. PARTICIPANTS: Eighty eyes of 40 patients diagnosed with chronic ocular GVHD were enrolled. METHODS: Forty patients with ocular GVHD were randomized; 24 patients were treated with topical tacrolimus 0.05% and 16 patients were treated with topical methylprednisolone 0.5% twice daily for 10 weeks, in addition to continuing their baseline treatment regimen. MAIN OUTCOME MEASURES: Safety was evaluated based on occurrence of adverse events. Tolerability was assessed based on subject reports of discomfort after drop instillation. Intraocular pressure (IOP) was monitored. The main efficacy end points were corneal fluorescein staining (CFS), tear film break-up time (TBUT), Schirmer test results, and expression of the ocular surface inflammatory markers human leukocyte antigen-DR (HLA-DR) and intercellular adhesion molecule-1 (ICAM-1). Symptoms were evaluated using the Ocular Surface Disease Index (OSDI). RESULTS: After 10 weeks of treatment, no major adverse events occurred in either treatment group, and there was no significant difference in the composite tolerability scores between the 2 groups (P = 0.06). However, burning sensation was more pronounced with tacrolimus (P = 0.002). Topical tacrolimus was more effective than methylprednisolone in reducing the CFS score at week 10 (55% vs. 23% reduction, respectively; P = 0.01) and achieved significant improvement in TBUT when compared with baseline (P < 0.001). Reduction in OSDI score achieved statistical significance with tacrolimus (27% reduction; P = 0.02), but was marginal with methylprednisolone (32% reduction; P = 0.06). Expression of ICAM-1 by ocular surface epithelium decreased significantly in both groups (tacrolimus, P = 0.003; methylprednisolone, P = 0.008), whereas HLA-DR expression decreased significantly only in the tacrolimus group (P = 0.03). Schirmer test scores did not change significantly in either group during the study; IOP increased significantly with methylprednisolone at week 10 (P = 0.04). CONCLUSIONS: Topical tacrolimus 0.05% is safe, generally well tolerated, and effective for the treatment of ocular GVHD without the hypertensive effects of topical corticosteroids.

Crnej A, Omoto M, Dohlman TH, Gonzalez-Andrades M, Paschalis EI, Cruzat A, Vu KTH, Doorenbos M, Chen DF, Dohlman CH, Dana R. Effect of Penetrating Keratoplasty and Keratoprosthesis Implantation on the Posterior Segment of the Eye. Invest Ophthalmol Vis Sci 2016;57(4):1643-8.Abstract

PURPOSE: To compare the effects of post-penetrating keratoplasty (PK) and post-keratoprosthesis (KPro) surgery-related inflammation on the posterior segment of the eye and to assess inhibition of tumor necrosis factor alpha (TNFα) and interleukin-1 beta (IL-1β) on these effects. METHODS: BALB/C (syngeneic) or C57BL/6 (allogeneic) corneas were transplanted onto BALB/C host beds as part of PK or miniature KPro (m-KPro) implantation. Intraocular pressure (IOP) was measured via an intracameral pressure sensor; tissues were harvested and analyzed 8 weeks after surgery. Expression of TNFα and IL-1β in the retina was analyzed using real-time quantitative (q)PCR. Optic nerve degeneration (axon count, circularity, and area) was assessed quantitatively using ImageJ software. After m-KPro implantation, mice were treated with saline, anti-TNFα, or anti-IL-1β antibody, and axonal loss was assessed after 10 weeks. RESULTS: Mean IOP was within normal limits in the operated and fellow eyes in all groups. The mRNA expression of TNFα and IL-1β was highest in m-KPro groups with either syngeneic or an allogeneic carrier. We observed optic nerve degeneration in both allogeneic PK and m-KPro implanted eyes with an allogeneic carrier. However, TNFα blockade significantly reduced axonal loss by 35%. CONCLUSIONS: Allogeneic PK and m-KPro implants with an allogeneic carrier lead to chronic inflammation in the posterior segment of the eye, resulting in optic nerve degeneration. In addition, blockade of TNFα prevents axonal degeneration in this preclinical model of allogeneic m-KPro (alloKPro) implantation.

Salvador-Culla B, Kolovou PE, Arzeno L, Martínez S, López MA. Boston Keratoprosthesis Type 1 in Chemical Burns. Cornea 2016;35(6):911-6.Abstract

PURPOSE: To describe and further analyze the long-term results in visual acuity (VA), anatomical retention, and rate of complications from patients who underwent Boston keratoprosthesis (B-Kpro) type 1 after ocular chemical burns in the Dominican Republic. METHODS: A retrospective review of 42 eyes (22 OD:20 OS) of 36 patients who underwent B-Kpro type 1 implantation after severe ocular burn at Hospital Elías Santana in Santo Domingo, Dominican Republic, between April 2006 and October 2014, were included. RESULTS: Demographics, VA, anatomical retention, and the rates of postoperative complications and concurrent surgeries were evaluated. CONCLUSIONS: The excellent anatomical retention rates and visual outcomes presented in this study support the remarkable capability of B-Kpro type 1 to restore functional VA in eyes with severe chemical injuries. However, strict control of the postoperative complications is necessary for long-term success. In conclusion, the use of a B-Kpro type 1 after severe chemical burn is a viable option in patients otherwise condemned to the high risk of failure associated with conventional corneal grafts.

Robert M-C, Črnej A, Shen LQ, Papaliodis GN, Dana R, Foster SC, Chodosh J, Dohlman CH. Infliximab after Boston Keratoprosthesis in Stevens-Johnson Syndrome: An Update. Ocul Immunol Inflamm 2016;:1-5.Abstract

PURPOSE: To report our experience using intravenous infliximab for the treatment of tissue melt after Boston keratoprosthesis (B-KPro) types I and II in patients with autoimmune disease. METHODS: Case series. RESULTS: We identified four patients who were treated with intravenous infliximab in the context of tissue melt after B-KPro. Stevens-Johnson syndrome-associated corneal blindness was the primary surgical indication for B-KPro implantation in all patients. Two patients received a B-KPro type I and two patients received a B-KPro type II. The patients received intravenous infliximab for skin retraction around B-KPro type II, melting of the carrier graft or leak. Treatment resulted in a dramatic decrease in inflammation and, in some cases, arrest of the melting process. Cost and patient adherence were limiting factors to pursuing infliximab therapy. In addition, one patient developed infusion reactions. CONCLUSIONS: Intravenous infliximab may be considered as globe- and sight-saving therapy for tissue melt after B-KPro.

Tahvildari M, Omoto M, Chen Y, Emami-Naeini P, Inomata T, Dohlman TH, Kaye AE, Chauhan SK, Dana R. In Vivo Expansion of Regulatory T Cells by Low-Dose Interleukin-2 Treatment Increases Allograft Survival in Corneal Transplantation. Transplantation 2016;100(3):525-32.Abstract

BACKGROUND: Corneal allograft survival dramatically decreases in hosts with inflamed or vascularized recipient beds. We have previously shown that in rejected corneal allografts regulatory T cells (Treg) demonstrate diminished Foxp3 expression and immunoregulatory function. Treatment with low doses of IL-2 selectively expands Treg and has been proposed for the treatment of autoimmune diseases. In this study, we investigated the effect of low-dose IL-2 administration on Treg function and corneal allograft survival. METHODS: Allogeneic corneal transplantation was performed on inflamed host beds. Low-dose systemic IL-2 was administered starting 3 days before grafting until 6 weeks after transplantation. Frequencies of Treg and their immunosuppressive function and antigen specificity were assessed using flow cytometry, in vitro proliferation assays, and adoptive transfer experiments. Frequencies of effector T cells (Teff) and graft infiltrating immune cells were measured at 2 weeks posttransplantation. Long-term allograft survival was evaluated for up to 9 weeks using Kaplan-Meier survival analysis. RESULTS: Treatment with low-dose IL-2 significantly increased frequencies of CD4CD25Foxp3 Treg and their immunosuppressive function. It also suppressed alloimmune response as shown by the decreased CD4 IFNγ T cell frequencies and graft infiltration of CD45 and CD4 cells. Clinical evaluation of the grafts showed significant improvement in long-term corneal allograft survival in the IL-2 treated group compared with controls. CONCLUSIONS: Our study is the first to report that treatment with low-dose IL-2 increases survival of corneal allografts. We propose that IL-2-mediated Treg expansion can be an effective tool to prevent alloimmunity and to improve long-term allograft survival in transplantation.