Limbal Area Research Articles

Immunofluorescence of Rabbit Corneas After Collagen Cross-Linking Treatment With Riboflavin and Ultraviolet A

To assess ultrastructural modifications in keratocytes and inflammatory cell response in rabbit corneas after riboflavin and ultraviolet A exposure using immunofluorescence microscopy. Twenty adult New Zealand albino rabbits weighing 2.0–3.0 kg were used in this study. Two rabbits served as controls.The animals had their epithelia removed and were cross-linked with riboflavin 0.1% solution (10 mg riboflavin-5-phosphate in 10 mL of 20% dextran-T-500) applied every 3 minutes for 30 minutes, and exposed to ultraviolet A (360 nm, 3 mW/cm2) for 30 minutes. Four rabbits were humanely euthanized at each time point of 1, 3, and 11 days and at 3 and 5 weeks after the procedure. Immunohistochemistry studies of thin sections of each cornea were performed using terminal deoxynucleotyl transferase–mediated uridine triphosphate biotin nick-end labeling staining, alpha smooth muscle actin (a-SMA),CD-3, myeloperoxidase antibodies, and 4',6-diamidino-2-phenylindole(DAPI) counterstaining. In another experiment, 6 additional rabbits were treated as above, and after 10 days of cross-linking, 5 mL of lipopolysaccharide endotoxin (1 mg/mL) was injected in the midstroma. Cross-linked corneas showed early stromal edema. By 5 weeks, complete resolution of the edema and a pronounced highly-organized anterior 200-mm fluorescent zone was observed. Terminal deoxynucleotyl transferase mediated uridine triphosphate biotin nick-end labeling staining showed keratocyte death by both necrosis and apoptosis between days 1 and 3 after cross-linking. At day 1,the limbal area close to the cross-linking zone showed some inflammatory cells and a-SMA–positive cells, indicative of the presence of myofibroblasts. By day 3, some myofibroblasts had migrated to the area beneath the cross-linked stroma. Between days 3 and 5 weeks, there was an increase in a-SMA staining in the area surrounding the cross-linked stroma. The area of cross-linking remained acellular up to 5 weeks. Collagen cross-linking results in early edema,keratocyte apoptosis, and necrosis, appearance of inflammatory cells in the surrounding area of treatment and transformation of surrounding keratocytes into myofibroblasts. Compaction of anterior stroma fibers, keratocyte loss, and displacement of cell nuclei including inflammatory cells may have clinical implications in the long-term risk of further corneal thinning in keratoconus and in the cross-linked corneal immune response.

Cauterization of Central Cornea Induces Recruitment of Major Histocompatibility Complex Class II+ Langerhans Cells From Limbal Basal Epithelium

The purpose of this study was to investigate the distribution and characterization of Langerhans cells (LCs) in the rat corneal epithelium and to compare the findings with those obtained earlier in the mouse corneal epithelium. Normal and cauterized corneal tissues were excised from Wistar rats, and immunofluorescence staining for major histocompatibility complex (MHC) class II, CD3, CD11c, CD11b, CD45, CD80(B-1), and CD86(B-2) was performed by confocal microscopy. The density of intraepithelial MHC class II+ LCs was quantified. In the normal corneal epithelium, CD11c+ cells were exclusively distributed in the limbal and peripheral areas. Double staining showed that these cells were CD45 and MHC class II positive and B7 (CD80 or CD86) costimulatory molecules, CD11b, and CD3 negative, exhibiting a dendritic cell phenotype. In cauterized cornea, the expression of MHC class II was significantly enhanced in the limbal basal epithelium. The expression of the activation markers, CD80 and CD86, by MHC class II+ LCs was first present in the limbal basal epithelium as early as 4 hours after corneal inflammation and later throughout the entire corneal epithelium. The present study demonstrates for the first time the distribution and characterization of LCs in the rat corneal epithelium, which largely resembles most of those observed in the mouse cornea. In the cauterized cornea, B7+ LCs were first present in the limbal basal epithelium, suggesting that these cells play an important role in corneal inflammatory reaction.

Differential Distribution of Blood and Lymphatic Vessels in the Murine Cornea

Because of its unique characteristics, the cornea has been widely used for blood and lymphatic vessel research. However, whether limbal or corneal vessels are evenly distributed under normal or inflamed conditions has never been studied. The purpose of this study was to investigate this question and to examine whether and how the distribution patterns change during corneal inflammatory lymphangiogenesis (LG) and hemangiogenesis (HG). Corneal inflammatory LG and HG were induced in two most commonly used mouse strains, BALB/c and C57BL/6 (6-8 weeks of age), by a standardized two-suture placement model. Oriented flat-mount corneas together with the limbal tissues were used for immunofluorescence microscope studies. Blood and lymphatic vessels under normal and inflamed conditions were analyzed and quantified to compare their distributions. The data demonstrate, for the first time, greater distribution of both blood and lymphatic vessels in the nasal side in normal murine limbal areas. This nasal-dominant pattern was maintained during corneal inflammatory LG, whereas it was lost for HG. Blood and lymphatic vessels are not evenly distributed in normal limbal areas. Furthermore, corneal LG and HG respond differently to inflammatory stimuli. These new findings will shed some light on corneal physiology and pathogenesis and on the development of experimental models and therapeutic strategies for corneal diseases.

Lymphangiogenesis and angiogenesis: concurrence and/or dependence? Studies in inbred mouse strains

Genetic background significantly affects angiogenesis in mice. However, lymphangiogenic response to growth factors (GFs) in different strains has not been studied. We report constitutive expression of corneal lymphatics that extends beyond the limits of normal limbal vessels. In untreated corneas, the total number (P=0.006), the number above blood vessels (P=10(-8)), and the area of preexisting lymphatics (P=0.007) were significantly higher in C57BL/6 than in BALB/c mice. Normal corneas of three other strains, the nu/nu, 129E, and Black Swiss mice, showed in most parameters intermediate phenotypes. FGF-2(-/-) mice showed significantly less preexisting lymphatics than control (P=0.009), which suggests a role for this GF in lymphatic development. VEGF-A-induced corneal lymphangiogenic response was significantly higher in BALB/c mice (P=0.03), but it did not differ significantly in C57BL/6 mice, when compared to PBS-implanted control. FGFR-3 expression was higher in C57BL/6 than BALB/c mice, which suggests GF-receptor heterogeneity as a possible explanation for strain-dependent differences. The heterogeneity of preexisting lymphatic vessels in the limbal area significantly correlated with the extent of corneal lymphangiogenesis (VEGF-A: r=0.7, P=0.01; FGF-2: r=0.96, P=10(-5)) in BALB/c but not in C57BL/6 mice. Removal of conjunctival lymphatics did not affect GF-induced lymphangiogenesis. This work introduces physiological expression of lymphatics without blood vessels, which indicates that angiogenesis and lymphangiogenesis, even though intricately related, may occur independently. Furthermore, we show strain-dependence of normal and GF-induced lymphangiogenesis. These differences may affect disease development in various strains.

Early Diagnosis of Ocular Hypertension Using a Low-Intensity Laser Irradiation Test

We investigated the potential use of low-intensity laser irradiation (LILI) as a diagnostic tool for identifying hypertensive eyes at risk of glaucoma. The diagnosis of early-stage ocular hypertension is particularly difficult to establish. This study of a case series included 123 healthy subjects with normal vision. The intraocular pressure (IOP) was determined before (baseline) and 30 min after a 30-sec irradiation of the limbus area with laser light (780 nm; 7.5 mW; 292 Hz modulation). Baseline IOP was >21 mm Hg in 44 of 211 eyes (20.9%), consistent with ocular hypertension. LILI decreased the mean IOP by 6.2 mm Hg (-25.7%; p < 0.001; paired t test) in these eyes. The remaining 167 eyes (79.1%) exhibited a normotensive IOP <or=21 mm Hg. LILI reduced the mean IOP by 2.9 mm Hg (-17.1%; p < 0.001) in these eyes, but there were different response patterns: 1) the IOP did not change (27.0%); 2) the IOP was reduced by the same extent in both eyes (32.3%); 3) initial IOP differences between left and right eyes became level and the absolute IOP was reduced to a lower level that was identical in both eyes (18.0%); and 4) the initial difference in IOP between the left and right eye persisted despite LILI (22.7%). LILI lowers IOP, even in normotensive eyes. This effect may be useful to determine the individual physiological IOP and to diagnose latent ocular hypertension in eyes with presumably normotensive IOP.

Structures of the corneal limbus detected by laser-scanning confocal biomicroscopy as related to the palisades of Vogt detected by slit-lamp microscopy

To examine the relations between specific structures detected at the corneal limbus by confocal biomicroscopy with palisades of Vogt detected by slit-lamp microscopy Twenty-five eyes of 25 normal participants were examined. The presence or absence of the palisades of Vogt and limbal pigmentation were assessed by slit-lamp microscopy. The presence or absence of four structures in the corneal limbal area--hyperreflective parallel trabecular extensions, borders of bright-cell groups and dark-cell groups, hyperreflective cells and bright corpuscular particles with dendritic cell-like morphology--were assessed by confocal biomicroscopy. The relations between the presence of these four structures and the presence of either the palisades of Vogt or limbal pigmentation of the palisade ridges were evaluated by the chi-squared test. Only the presence of hyperreflective parallel trabecular extensions was significantly related to the presence of the palisades of Vogt (P < 0.01). The presence of hyperreflective cells was not significantly related to the presence of limbal pigmentation. The hyperreflective parallel trabecular extensions observed by confocal biomicroscopy may correspond to the palisades of Vogt detected by slit-lamp microscopy. Further studies are needed to determine whether confocal biomicroscopy can be used to diagnose and monitor the clinical course of limbal stem cell deficiency.

Melanoqueratosis estriada postraumática en mujer de raza blanca

A fair-skinned woman presented marked striate melanokeratosis in her left eye related to recurrent corneal erosion. The source of pigmentation was a conjunctival melanosis. The conjunctival melanosis responded to treatment with topical mitomycin, while the corneal pigmentation persisted. Striate melanokeratosis is a condition described in dark-skinned patients who show a well-defined pigmentation of the limbal area, with only one case of striate melanokeratosis reported previously in a Caucasian person. The stimuli for this proliferation are corneal lesions or melanosis close to the limbus. Avoiding both stimuli are the main steps in its management.

Isoliertes Carcinoma in situ der Kornea

We present the case of an 83-year-old patient with an isolated epithelial dysplasia of the cornea. After corneal abrasion the lesion reoccurred 14 days later. The abrasion was then increased to cover the whole corneal epithelium and adjacent limbal and conjunctival areas were also biopsied. Histology revealed a corneal epithelial dysplasia stage 3, whereas the limbal and conjunctival biopsies showed normal epithelium. After resection two cycles of local mitomycin C application (2 cycles of 14 days each) were administered and 9 months after the second intervention the cornea remained clear with good vision. The investigation for human papillomavirus showed a type 6, which is not associated with an increased risk of malignancy.

Expression Pattern of Connexins in the Corneal and Limbal Epithelium of a Primate

To detect the expression pattern of connexins in epithelial cells of the central cornea and limbus of the macaque. Total RNA was extracted from the central corneal and limbal epithelia of Macaca fascicularis and processed by reverse transcriptase-polymerase chain reaction with isoform primers to detect the expression of 16 connexin (Cx). Immunofluorescent staining of frozen sections of corneal tissue confirmed and localized connexin proteins expression. Transcripts encoding 10 Cx isoforms (Cx26, Cx30, Cx30.3, Cx31, Cx31.1, Cx32, Cx43, Cx45, Cx50, and Cx58) were detected by reverse transcriptase-polymerase chain reaction in both central and peripheral corneal epithelium. Six (Cx26, Cx31, Cx32, Cx43, Cx45, and Cx58) were confirmed by laser scanning confocal microscopy. Cx26 was detected throughout the central corneal epithelium and in the mid and superficial layers of the limbal epithelium. Cx43 and Cx45 were localized to the basal and suprabasal epithelial cells. Cx58 was expressed in the superficial epithelium throughout the cornea, whereas Cx31 and Cx32 were mainly expressed in the central corneal epithelium and weakly in the limbal area. The complex distribution pattern of the connexins suggests that selected isoforms play important roles in maintaining corneal homeostasis.

New Surgical Strategy for Corneal Tattooing Using a Femtosecond Laser

The purpose of this study was to describe a new method of femtosecond (FS) laser-assisted corneal tattooing and to report the results of this method in a case series. The study involved 6 eyes of 6 patients with total or partial corneal opacity. An FS laser was used for lamellar dissection and to make a side cut with a hinge, creating a corneal flap. Laser parameters were adjusted depending on ocular condition and the location of the corneal opacity. After lifting the corneal flap, further lamellar dissection with a diamond blade was performed up to the periphery of the limbal area. Using a cannula, dye was injected into the lamellar stromal bed and the space of the lamellar dissected pocket in the limbus, after which the flap was repositioned. The design and application of the FS laser for dissection and flap creation were successful in all cases. There were no significant complications other than an incomplete cut under band keratopathy in 1 eye. The cosmetic effects were satisfactory in all cases. No patient complained of pain for more than 1 day after surgery. The advantages of the FS laser-assisted corneal tattooing include a customized design, speed, decreased pain, reduced risk of perforation, and good wound healing. This procedure provides improvements over current corneal tattooing techniques, although it is relatively expensive.

Secondary Glaucoma and Sclerokeratitis After Cosmetic Eye Whitening by Regional Conjunctivectomy with Mitomycin C Application

Purpose: To report a case of secondary glaucoma and sclerokeratitis after cosmetic eye whitening by regional conjunctivectomy with Mitomycin C application. Case summary: A 69 year-old man was referred to our clinic for a left ocular pain and ocular hypertension sustained for 3 months after cosmetic eye whitening by regional conjunctivectomy with Mitomycin C application for chronic conjunctival hyperemia. On first examination, the scleromalacia and large conjunctival epithelium defect in the nasal quadrant of the limbus area and diffuse sclerokeratitis were observed. Conjunctival and episcleral vessel deficit were seen except superior 30% portion in the left eye. The anterior chamber depth in the left eye was very shallow compared to the right eye and cell reaction in the left anterior chamber was detected. Intraocular pressure (IOP) in the left eye was 28 mmHg after Cosopt and 15% mannitol 500 ml use. Glaucomatous cupping was detected. During follow-up, left IOP increased over 40 mmHg despite the maximal medical treatment and the progression of visual field defects was detected, so then left phacoemulsification, Ahmed valve implantation and amnion membrane transplantation were done. After surgery, the conjunctival epithelial defect and sclerokeratitis were improved much and IOP was regulated 2030 mmHg without medication. Digital massage was done 2 times per day for decreasing IOP and wound remodeling after 1 month. At 3 month after surgery, the conjunctival epithelial defect recurred and scleromalacia was also progressed, so then we performed autoconjunctival flap and amnion membrane transplantation in left eye. The conjunctival epithelial defect were recovered completely, IOP was regulated 2436 mmHg without medication, and 2024 mmHg with Cosopt. The compliance of patient is very poor, further management may be needed for IOP control. Conclusions: Cosmetic eye whitening by regional conjunctivectomy with Mitomycin C application can cause serious complications such as scleromalcia and secondary glaucoma. This case shows that particular care should be taken in order to minimize these complications.

Visante® anterior segment OCT in a patient with gas bubbles in the anterior chamber after femtosecond laser corneal flap formation

A patient with anterior chamber gas bubbles after LASIK flap formation with femtosecond laser is presented. A 33-year-old male patient had LASIK for myopia with corneal flap formation with IntraLase FS30 femtosecond laser. In the right eye, air bubbles were observed in anterior chamber after successful flap formation. Laser correction was completed successfully, by Wavelight Allegretto Wave Eye-Q excimer laser, without eye-tracker. Visante anterior segment optical coherence tomography imaging displayed that the pocket extended to limbal area, with stromal bed thickness of >600 microm at that area. We propose as possible causes of the air bubbles scattering of femtosecond laser beam producing direct photodissociation of aqueous humor, or direct cavitation effect in aqueous humor due to rapid pressure changes in corneal lamellar interface during the femtosecond laser procedure. Other causes such as migration of intrastromal bubbles through peripheral corneal stroma and trabecular meshwork, or through posterior stroma and endothelium, seem to be unlikely.

Analysis of clear corneal incision integrity in an ex vivo model

To determine the most favorable sutureless incision configuration to minimize extraocular fluid inflow after cataract surgery. The Wilmer Eye Institute, Baltimore, Maryland, USA. Five fresh human eyes were used in the study. Two 27-gauge needles connected to a saline solution bag and a digital manometer were inserted through the limbus 180 degrees from each other. Intraocular pressure (IOP) was maintained at 15 to 20 mm Hg. Three incisions were performed in different quadrants of each cornea: uniplanar 1.0 mm and 3.0 mm tunnel lengths and 2-step 3.0 mm tunnel length. India ink was applied to the incision site, and IOP fluctuation was induced by applying pressure to the limbal area of the opposite quadrant using an ophthalmodynamometer. Imaging was performed before and after pressure application. The linear distance of India ink inflow after pressure application was higher than the prepressure measurements in the 1.0 mm and 3.0 mm incision groups (P = .039 and P = .023, respectively). The maximum mean of inflow after pressure application was not higher than the prepressure measurement in the 2-step incision group (P = .105). The total ink area measured before and after pressure applications in the incisions of the 3 groups was not significantly different (P = .285). Intraocular pressure fluctuations may promote entry of bacteria-size particles into the eye when 1.0 mm and 3.0 mm single-plane incisions are performed. Stepped incisions seem to be more resistant to inflow in the presence of IOP fluctuation.

Transplantation of fresh amniotic membrane with limbal stem cells autografts for recurrent pterygium

目的 探讨新鲜羊膜移植联合自体角膜缘干细胞移植术在复发性翼状胬肉治疗中的作用.方法 以新鲜羊膜移植联合自体角膜缘移植手术治疗复发性翼状胬肉30例35眼,术后随访12月.结果 植片全部存活,无排斥反应发生,有2眼复发(5.71%).供体眼角膜缘区无并发症发生.结论 新鲜羊膜移植联合自体角膜缘干细胞移植是一种治疗复发性翼状胬肉的简单,高治愈率和低复发率的手术方法。

Virologic and Immunologic Events in Hilar Lymph Nodes During Simian Immunodeficiency Virus Infection

To report the results of one 60 degrees conjunctival limbal autograft (CLAU) combined with amniotic membrane (AM) transplantation for an eye with total limbal stem cell deficiency (LSCD).One eye of a patient with chronic total LSCD and symblepharon caused by chemical burn was subjected to symblepharon lysis, removal of pannus from corneal surface, AM transplantation to cover the conjunctival and corneal surfaces as a permanent graft, one 60 degrees CLAU to the superior limbal area, and insertion of ProKera as a temporary AM patch to cover the CLAU.After surgery, corneal epithelialization over the AM was evident adjacent to the CLAU on day 6, progressed to pass the horizontal midline by day 11, and was completed by day 18. During a follow-up of 1 year, the corneal surface remained stable and smooth, and the stroma considerably regained clarity with regression of midstromal vascularization. The best-corrected visual acuity improved from 20/400 to 20/50. The conjunctival inflammation completely resolved, and the fornices were deep.One 60 degrees CLAU combined with AM transplantation as both a permanent graft and a temporary patch can restore the entire corneal surface in an eye with total LSCD caused by chemical burn.

Pigmented squamous cell carcinoma of the limbus area: A rare case

Pigmented squamous cell carcinoma of the limbus area: A rare case

Histopathologic Limbus Evolution After Alkaline Burns

To study the histopathologic evolution of the corneal limbus after alkaline burns according to the clinical severity and therapy used. A prospective study of 15 eyes from 12 patients (9 men and 3 women) with moderate and severe alkaline burns was performed. All patients were divided into 2 groups in accordance with the clinical ocular severity and the therapy that was used: medical therapy, amniotic membrane transplantation (AMT), autologous limbal transplantation (ALT), and ALT combined with AMT (ALT + AMT). Biopsies were obtained from affected limbal areas immediately after the ocular burn and 9 months later. Limbal regeneration was limited to small areas in patients with moderate burns treated with medical therapy; in contrast, the limbal structure showed significant stromal and epithelial regeneration in patients with moderate burns treated with AMT. There was an important stromal regeneration with an incomplete reepithelialization in patients with severe burns treated with AMT. Patients treated with ALT showed a good reepithelialization with a defective stromal regeneration. Epithelial and stromal regeneration was notable in patients with severe burns treated with ALT + AMT. In patients with moderate alkaline burns, AMT improved both limbal stromal and epithelial regeneration more effectively than medical therapy. In patients with severe burns, the best reepithelialization and stromal regeneration were obtained with ALT + AMT.

Characterization of extracellular matrix components in the limbal epithelial stem cell compartment

A specialized microenvironment or niche, which regulates maintenance, self-renewal, activation, and proliferation of stem cells by external signals, is one of the key prerequisites for stem cell function. However, the parameters determining the limbal stem cell niche are not yet defined. In order to characterize the role of basement membrane (BM) and extracellular matrix components in the generation of a microenvironmental niche for limbal stem and progenitor cells, we extensively analyzed the topographical variations of the BM zone of human ocular surface epithelia using immunohistochemistry and a large panel of antibodies to most of the presently described intrinsic and associated BM components. Apart from BM components uniformly expressed throughout all ocular surface epithelia (e.g. type IV collagen α5 and α6 chains, collagen types VII, XV, XVII, and XVIII, laminin-111, laminin-332, laminin chains α3, β3,and γ2, fibronectin, matrilin-2 and -4, and perlecan), the BM of the limbal epithelium shared many similarities with that of the conjunctival epithelium, including positive labelling for type IV collagen α1 and α2 chains, laminin α5, β2, and γ1 chains, nidogen-1 and -2, and thrombospondin-4, whereas type IV collagen α3, type V collagen, fibrillin-1 and -2, thrombospondin-1, and endostatin were present in the corneal BM, but lacking or more weakly expressed in the limbal and conjunctival BMs. As compared to both the corneal and conjunctival BMs, the limbal BM showed a markedly increased immunoreactivity for laminin α1, α2, β1 chains, and agrin, and a specific but patchy immunoreactivity for laminin γ3 chain, BM40/SPARC, and tenascin-C, which co-localized with ABCG2/p63/K19-positive and K3/Cx43/desmoglein/integrin-α2-negative cell clusters comprising putative stem and early progenitor cells in the basal epithelium of the limbal palisades. Components that were particularly expressed in the corneal–limbal transition zone included type XVI collagen, fibulin-2, tenascin-C/R, vitronectin, bamacan, chondroitin sulfate, and versican, all of which co-localized with vimentin-positive cell clusters comprising putative late progenitor cells in the basal epithelium. This pronounced heterogeneity of the BM in the limbal area, both in the region of limbal palisades and the corneal–limbal transition zone, appears to be involved in providing unique microenvironments for corneal epithelial stem and late progenitor cells. Identification of specific niche parameters might not only help to understand limbal stem cell regulation, but also to improve their selective enrichment and in vitro expansion for therapeutic strategies.

Caractéristiques cliniques et angiographiques de la dystrophie cristalline de Bietti: À propos d’une patiente âgée de 8 ans

Bietti's crystalline corneoretinal dystrophy is a tapetoretinal degeneration, characterized by the presence of refringent crystals in the corneal limbus and the retina with sclerosis of choroidal vessels. We report the clinical and angiographic features of an 8-year-old girl affected with Bietti's crystalline dystrophy.This 8-year-old girl was a sporadic case, born of consanguineous parents. She was referred to our hospital for intermittent strabismus. Her visual acuity was 4/10 at the right eye and 3/10 at the left eye. Biomicroscopy revealed very fine crystals in the limbal area bilaterally. Mydriatic funduscopic examination showed bilateral macular pigment mottling and depigmentation, numerous tiny refractile yellow dots scattered throughout the posterior pole and the mid-periphery associated with diffuse retinal pigment epithelial atrophy and pigment accumulation. Fluorescein angiography revealed retinal pigmentary epithelium alterations. Indocyanine green (Infracyanin) angiography showed areas of choroidal atrophy. The electroretinogram noted a reduction in the number of both types of photoreceptors.Ophthalmological lesions normally occur between 20 and 30 years of age. The particularity of our case report is the manifestation of the disease at an earlier age (8 years). The progression is characterized by a centrifuge expansion of lesions.

The role of CXC chemokine receptor 2 inPseudomonas aeruginosacorneal infection

Pseudomonas is one of the leading causes of contact lens-related microbial keratitis. Despite the use of antibiotics, the host inflammatory response continues to cause damage to the cornea, which may lead to blindness. CXCR2-binding chemokines have been implicated in the pathogenesis of Pseudomonas keratitis, and the exact role of this receptor remains to be elucidated. Corneas of CXCR2 knockout and wild-type mice (Cmkar 2-/- and Cmkar 2+/+) were scratched, and 2x10(6) CFU/mL Pseudomonas 6294 or 6206 was added to corneas. Twenty-four hours postinfection, mice were killed, and eyes were harvested for enumeration of bacteria, myeloperoxidase (MPO) levels, and inflammatory mediators. Cmkar 2-/- had 20- to 100-fold more bacteria than Cmkar 2+/+ mice. There were no differences in MPO levels between gene knockout and Cmkar 2+/+ mice. Histology revealed PMN were restricted to the limbal area. Levels of CXCR2 chemokines (keratinocyte-derived chemokine and MIP-2) were elevated significantly in gene knockout mice. A lack of CXCR2 leads to an inability to control bacterial numbers as a result of the inability of PMN to reach the site of infection in the avascular cornea. These results imply that CXCR2 is critical to the extravasation of neutrophils into the avascular cornea.