Risk factors for corneal infiltrative events during continuous wear of silicone hydrogel contact lenses

PURPOSE

This study determined which microbiologic, clinical, demographic, and behavioral factors are associated with corneal infiltrative events (CIEs) during continuous wear of silicone hydrogel (SH) contact lenses.

METHODS

Subjects (n = 205) were fitted with lotrafilcon A lenses for continuous wear and observed for 1 year. The main exposures of interest were corneal staining and bacterial lens contamination. Kaplan-Meier (KM) plots were used to estimate the cumulative unadjusted probability of remaining CIE free, and Cox proportional hazards regression was used to model the hazard of having a CIE, as a function of key predictor variables.

RESULTS

The KM-unadjusted cumulative probability of remaining CIE free was 73.3%. Approximately 53% of subjects had repeated episodes of corneal staining (mild or greater), and 11.3% had repeated episodes of moderate or greater corneal staining. Corneal staining was not associated with the development of a CIE. The frequency of substantial bacterial bioburden on worn lenses at the time of a CIE was 64.7%, compared with only 12.2% during uncomplicated wear. The presence of substantial lens bacterial bioburden was associated with the development of a CIE (adjusted hazards ratio [HR], 8.66; 95% confidence interval [CI], 2.88-26.01). Smoking was also associated with a CIE (adjusted HR, 4.13; 95% CI, 1.27-13.45).

CONCLUSIONS

Corneal staining is common during continuous wear of SH lenses, but it is not associated with the development of a CIE. Smoking and substantial lens bacterial bioburden pose prominent risks of a CIE. In this study, more than 70% of the total risk of CIE in those with substantial lens bioburden is attributable to this exposure. (ClinicalTrials.gov number, NCT00727402).

Effect of incision width on graft survival and endothelial cell loss after Descemet stripping automated endothelial keratoplasty

PURPOSE

To assess the effect of incision width (5.0 and 3.2 mm) on graft survival and endothelial cell loss 6 months and 1 year after Descemet stripping automated endothelial keratoplasty (DSAEK).

METHODS

One hundred sixty-seven subjects with endothelial decompensation from a moderate-risk condition (principally Fuchs dystrophy or pseudophakic corneal edema) underwent DSAEK by 2 experienced surgeons. The donor was folded over and inserted with single-point fixation forceps. This retrospective analysis assessed graft survival, complications, and endothelial cell loss, which was calculated from baseline donor and 6-month and 1-year postoperative central endothelial images evaluated by an independent specular microscopy reading center.

RESULTS

No primary graft failures occurred in either group. One-year graft survival rates were comparable (98% vs 97%) in the 5.0- and 3.2-mm groups, respectively (P = 1.0). Complications included graft dislocation, graft rejection episodes, and elevated intraocular pressure and occurred at similar rates in both groups (P > or = 0.28). Pupillary block glaucoma did not occur in either group. Mean baseline donor endothelial cell density did not differ: 2782 cells per square millimeter in the 5.0-mm (n = 64) and 2784 cells per square millimeter in the 3.2-mm (n = 103) groups. Percent endothelial cell loss was 27% +/- 20% (n = 55) versus 40% +/- 22% (n = 71; 6 months) and 31% +/- 19% (n = 45) versus 44% +/- 22% (n = 62; 12 months) in the 5.0- and 3.2-mm incision groups, respectively (both P < 0.001).

CONCLUSIONS

One year after DSAEK, overall graft success was comparable for the 2 groups; however, the 5.0-mm incision width resulted in substantially lower endothelial cell loss at 6 and 12 months.

Endothelial cell density to predict endothelial graft failure after penetrating keratoplasty

OBJECTIVE

To determine whether preoperative and/or postoperative central endothelial cell density (ECD) and its rate of decline postoperatively are predictive of graft failure caused by endothelial decompensation following penetrating keratoplasty to treat a moderate-risk condition, principally, Fuchs dystrophy or pseudophakic corneal edema.

METHODS

In a subset of Cornea Donor Study participants, a central reading center determined preoperative and postoperative ECD from available specular images for 17 grafts that failed because of endothelial decompensation and 483 grafts that did not fail.

RESULTS

Preoperative ECD was not predictive of graft failure caused by endothelial decompensation (P = .91). However, the 6-month ECD was predictive of subsequent failure (P < .001). Among those that had not failed within the first 6 months, the 5-year cumulative incidence (+/-95% confidence interval) of failure was 13% (+/-12%) for the 33 participants with a 6-month ECD of less than 1700 cells/mm(2) vs 2% (+/-3%) for the 137 participants with a 6-month ECD of 2500 cells/mm(2) or higher. After 5 years' follow-up, 40 of 277 participants (14%) with a clear graft had an ECD below 500 cells/mm(2).

CONCLUSIONS

Preoperative ECD is unrelated to graft failure from endothelial decompensation, whereas there is a strong correlation of ECD at 6 months with graft failure from endothelial decompensation. A graft can remain clear after 5 years even when the ECD is below 500 cells/mm(2).

Descemet's stripping automated endothelial keratoplasty outcomes compared with penetrating keratoplasty from the Cornea Donor Study

PURPOSE

To assess outcomes 1 year after Descemet's stripping automated endothelial keratoplasty (DSAEK) in comparison with penetrating keratoplasty (PKP) from the Specular Microscopy Ancillary Study (SMAS) of the Cornea Donor Study.

DESIGN

Multicenter, prospective, nonrandomized clinical trial.

PARTICIPANTS

A total of 173 subjects undergoing DSAEK for a moderate risk condition (principally Fuchs' dystrophy or pseudophakic/aphakic corneal edema) compared with 410 subjects undergoing PKP from the SMAS who had clear grafts with at least 1 postoperative specular image within a 15-month follow-up period.

METHODS

The DSAEK procedures were performed by 2 experienced surgeons per their individual techniques, using the same donor and similar recipient criteria as for the PKP procedures in the SMAS performed by 68 surgeons at 45 sites, with donors provided from 31 eye banks. Graft success and complications for the DSAEK group were assessed and compared with the SMAS group. Endothelial cell density (ECD) was determined from baseline donor, 6-month (range, 5-7 months), and 12-month (range, 9-15 months) postoperative central endothelial images by the same reading center used in the SMAS.

MAIN OUTCOME MEASURES

Endothelial cell density and graft survival at 1 year.

RESULTS

Although the DSAEK recipient group criteria were similar to the PKP group, Fuchs' dystrophy was more prevalent in the DSAEK group (85% vs. 64%) and pseudophakic corneal edema was less prevalent (13% vs. 32%, P<0.001). The regraft rate within 15 months was 2.3% (DSAEK group) and 1.3% (PKP group) (P = 0.50). Percent endothelial cell loss was 34+/-22% versus 11+/-20% (6 months) and 38+/-22% versus 20+/-23% (12 months) in the DSAEK and PKP groups, respectively (both P<0.001). Preoperative diagnosis affected endothelial cell loss over time; in the PKP group, the subjects with pseudophakic/aphakic corneal edema experienced significantly higher 12-month cell loss than the subjects with Fuchs' dystrophy (28% vs. 16%, P = 0.01), whereas in the DSAEK group, the 12-month cell loss was comparable for the 2 diagnoses (41% vs. 37%, P = 0.59).

CONCLUSIONS

One year post-transplantation, overall graft success was comparable for DSAEK and PKP procedures and endothelial cell loss was higher with DSAEK.

The effect of ABO blood incompatibility on corneal transplant failure in conditions with low-risk of graft rejection

PURPOSE

To determine whether corneal graft survival over a 5-year follow-up period was affected by ABO blood type compatibility in participants in the Cornea Donor Study undergoing corneal transplantation principally for Fuchs dystrophy or pseudophakic corneal edema, conditions at low-risk for graft rejection.

DESIGN

Multi-center prospective, double-masked, clinical trial.

METHODS

ABO blood group compatibility was determined for 1,002 donors and recipients. During a 5-year follow-up period, episodes of graft rejection were documented, and graft failures were classified as to whether or not they were attributable to immunologic rejection. Endothelial cell density was determined by a central reading center for a subset of subjects.

RESULTS

ABO donor-recipient incompatibility was not associated with graft failure attributable to any cause including graft failure because of rejection, or with the occurrence of a rejection episode. The 5-year cumulative incidence of graft failure attributable to rejection was 32 (6%) for recipients with ABO recipient-donor compatibility and 12 (4%) for those with ABO incompatibility (hazard ratio, 0.65; 95% confidence interval, 0.33 to 1.25; P = .20). The 5-year incidence for a definite rejection episode, irrespective of whether graft failure ultimately occurred, was 64 (12%) for ABO compatible compared with 25 (8%) for ABO incompatible cases (P = .09). Among clear grafts at 5 years, percent loss of endothelial cells was similar in ABO compatible and incompatible cases.

CONCLUSIONS

In patients undergoing penetrating keratoplasty for Fuchs dystrophy or pseudophakic corneal edema, ABO matching is not indicated since ABO incompatibility does not increase the risk of transplant failure attributable to graft rejection.

MyD88 regulation of Fusarium keratitis is dependent on TLR4 and IL-1R1 but not TLR2

The fungal pathogens Fusarium solani and Fusarium oxysporum cause severe corneal disease in the United States and worldwide and were the causative organisms in a recent outbreak of contact lens-associated keratitis. To characterize innate immunity in Fusarium keratitis, we developed a murine model in which conidia are injected into the corneal stroma. Immunocompetent C57BL/6 mice rapidly developed severe corneal opacification associated with neutrophil infiltration and clearance of Fusarium hyphae. In contrast, neutrophil infiltration was delayed in MyD88-/- mice, resulting in uncontrolled growth of Fusarium hyphae in the corneal stroma and anterior chamber, and eventually resulting in corneal perforation. Corneal opacification scores in TLR2-/-, TLR4-/-, and TLR2/4-/- mice were similar to those of C57BL/6 mice; however, TLR4-/- and TLR2/4-/- mice had impaired antifungal responses. The phenotype of infected IL-1R1-/- mice was similar to that of MyD88-/- mice, with uncontrolled fungal growth resulting in corneal perforation. IL-1R1-/- mice also produced significantly less CXCL1/KC in the corneal stroma compared with C57BL/6 mice consistent with delayed neutrophil recruitment to the corneal stroma. Together, these findings indicate that IL-1R1 and MyD88 regulate CXC chemokine production and neutrophil recruitment to the cornea, and that TLR4 has an important role in controlling growth and replication of these pathogenic fungi.

Donor age and corneal endothelial cell loss 5 years after successful corneal transplantation. Specular microscopy ancillary study results

OBJECTIVE

To determine whether endothelial cell loss 5 years after successful corneal transplantation is related to the age of the donor.

DESIGN

Multicenter, prospective, double-masked clinical trial.

PARTICIPANTS

Three hundred forty-seven subjects participating in the Cornea Donor Study who had not experienced graft failure 5 years after corneal transplantation for a moderate-risk condition (principally Fuchs' dystrophy or pseudophakic corneal edema).

TESTING

Specular microscopic images of donor corneas obtained before surgery and postoperatively at 6 months, 12 months, and then annually through 5 years were submitted to a central reading center to measure endothelial cell density (ECD).

MAIN OUTCOME MEASURE

Endothelial cell density at 5 years.

RESULTS

At 5 years, there was a substantial decrease in ECD from baseline for all donor ages. Subjects who received a cornea from a donor 12 to 65 years old experienced a median cell loss of 69% in the study eye, resulting in a 5-year median ECD of 824 cells/mm(2) (interquartile range, 613-1342), whereas subjects who received a cornea from a donor 66 to 75 years old experienced a cell loss of 75%, resulting in a median 5-year ECD of 654 cells/mm(2) (interquartile range, 538-986) (P [adjusted for baseline ECD] = 0.04). Statistically, there was a weak negative association between ECD and donor age analyzed as a continuous variable (r [adjusted for baseline ECD] = -0.19; 95% confidence interval, -0.29 to -0.08).

CONCLUSIONS

Endothelial cell loss is substantial in the 5 years after corneal transplantation. There is a slight association between cell loss and donor age. This finding emphasizes the importance of longer-term follow-up of this cohort to determine if this relationship affects graft survival.

The effect of donor age on corneal transplantation outcome results of the cornea donor study

OBJECTIVE

To determine whether graft survival over a 5-year follow-up period using corneal tissue from donors older than 65 is similar to graft survival using corneas from younger donors.

DESIGN

Multicenter prospective, double-masked, controlled clinical trial.

PARTICIPANTS

One thousand ninety subjects undergoing corneal transplantation for a moderate-risk condition (principally Fuchs' dystrophy or pseudophakic corneal edema); 11 subjects with ineligible diagnoses were not included.

METHODS

Forty-three participating eye banks provided corneas from donors in the age range of 12 to 75 with endothelial cell densities of 2300 to 3300 cells/mm(2), using a random approach without respect to recipient factors. The 105 participating surgeons at 80 sites were masked to information about the donor cornea including donor age. Surgery and postoperative care were performed according to the surgeons' usual routines. Subjects were observed for 5 years.

MAIN OUTCOME MEASURES

Graft failure, defined as a regraft or a cloudy cornea that was sufficiently opaque as to compromise vision for a minimum of 3 consecutive months.

RESULTS

The 5-year cumulative probability of graft survival was 86% in both the <66.0 donor age group and the >/=66.0 donor age group (difference = 0%, upper limit of 1-sided 95% confidence interval = 4%). In a statistical model with donor age as a continuous variable, there was no significant relationship between donor age and outcome (P = 0.11). Three graft failures were due to primary donor failure, 8 to uncorrectable refractive error, 48 to graft rejection, 46 to endothelial decompensation (23 of which had a prior, resolved episode of probable or definite graft rejection), and 30 to other causes. Distributions of the causes of graft failure did not differ between donor age groups.

CONCLUSIONS

Five-year graft survivals for cornea transplants at moderate risk for failure are similar using corneas from donors >/= 66.0 years and donors < 66.0. Surgeons and patients now have evidence that corneas comparable in quality to those used in this study from donors through age 75 are suitable for transplantation.

A New Method for Grading the Severity of Keratoconus

PURPOSE

To define a new method for grading severity of keratoconus, the Keratoconus Severity Score (KSS).

METHODS

A rationale for grading keratoconus severity was developed using common clinical markers plus 2 corneal topographic indices, creating a 0 to 5 severity score. An initial test set of 1012 eyes, including normal eyes, eyes with abnormal corneal and topographic findings but not keratoconus, and eyes with keratoconus having a wide range of severity, was used to determine cutpoints for the KSS. Validation set 1, comprising data from 128 eyes, was assigned a KSS and compared with a clinician's ranking of severity termed the "gold standard" to determine if the scale fairly represented how a clinician would grade disease severity. kappa statistics, sensitivity, and specificity were calculated. A program was developed to automate the determination of the score. This was tested against a manual assignment of KSS in 2121 (validation set 2) eyes from the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study, as well as normal eyes and abnormal eyes without keratoconus. Ten percent of eyes underwent repeat manual assignment of KSS to determine the variability of manual assignment of a score.

RESULTS

From initial assessments, the KSS used 2 corneal topography indices: average corneal power and root mean square (RMS) error for higher-order Zernike terms derived from the first corneal surface wavefront. Clinical signs including Vogt striae, Fleischer rings, and corneal scarring were also included. Last, a manual interpretation of the map pattern was included. Validation set 1 yielded a kappa statistic of 0.904, with sensitivities ranging from 0.64 to 1.00 and specificities ranging from 0.93 to 0.98. The sensitivity and specificity for determining nonkeratoconus from keratoconus were both 1.00. Validation set 2 showed kappa statistics of 0.94 and 0.95 for right and left eyes, respectively. Test-retest analysis yielded kappa statistics of 0.84 and 0.83 for right and left eyes, respectively.

CONCLUSION

A simple and reliable grading system for keratoconus was developed that can be largely automated. Such a grading scheme could be useful in genetic studies for a complex trait such as keratoconus requiring a quantitative measure of disease presence and severity.

Specular microscopy ancillary study methods for donor endothelial cell density determination of Cornea Donor Study images

PURPOSE

To describe reliable methods for determining central corneal endothelial cell density (ECD) in a multicenter eye bank study.

METHODS

The Specular Microscopy Reading Center utilized a dual-grading procedure and adjudication process to classify image quality and determine ECD for a subset of donor endothelial images obtained in the Specular Microscopy Ancillary Study, which is part of the Cornea Donor Study. Two certified readers classified images as analyzable (excellent, good, fair) or unanalyzable and determined the ECD using a variable frame technique. An adjudicator also evaluated the images if quality classifications by the two readers differed by one grade, if any reader found the image unanalyzable, and/or if the ECD determination between the two readers was >or= 5%.

RESULTS

Image quality categorization by the two readers was identical for 441 (64%) of 688 donor images. The ECD differed by < 5% for 442 (69%) of the 645 analyzable images. The ECD determined by the adjudicator was < 5% different than the ECD determined by at least one reader for 193 (95%) of the 203 remaining images.

CONCLUSIONS

The dual-grading and adjudication procedures produce reliable, reproducible assessments of image quality and ECD. The importance of two independent readings is evident in that image quality ratings differed between the two readers by one grade in 36% of all images and ECD counts differed by >or=5% for 31% of analyzable images.

Baseline donor characteristics in the Cornea Donor Study

PURPOSE

The Cornea Donor Study (CDS) is an ongoing study that is being conducted to determine whether donor age is related to long-term corneal graft survival. Characteristics of the donor population have been evaluated with respect to donor age, endothelial cell density, and death to preservation interval.

METHODS

Within the context of a prospective, double-masked, controlled trial, 1101 donor corneas were assigned without regard to donor age.

RESULTS

Slit-lamp characteristics of the donor corneas showed little variation with donor age, except for the presence of corneal arcus. As death to preservation time decreased, fewer epithelial abnormalities and a lower frequency of stromal edema and Descemet folds were observed. There was little change in the mean of the endothelial cell density with donor age beyond age 60, despite variation.

CONCLUSION

With respect to donor age, there was little difference in either the slit-lamp characteristics or endothelial cell density of the donor corneas. Fewer epithelial abnormalities were observed with shorter death to preservation time.

An evaluation of image quality and accuracy of eye bank measurement of donor cornea endothelial cell density in the Specular Microscopy Ancillary Study

PURPOSE

The Specular Microscopy Ancillary Study was designed to examine donor corneal endothelial specular image quality, compare the central endothelial cell density determined by eye banks with the endothelial cell density determined by a central specular microscopy reading center, and evaluate donor factors that may have an impact on specular image quality and endothelial cell density accuracy.

DESIGN

Nonrandomized comparative trial.

PARTICIPANTS

Endothelial specular images of donor corneas assigned in the Cornea Donor Study.

METHODS

Certified readers assessed donor image quality (analyzable from fair to excellent vs. unanalyzable) and determined the central endothelial cell density. Independent adjudication was performed if there was a difference in the quality of grading or if the endothelial cell density varied by > or =5.0% between readers. Average reading center-determined endothelial cell density was compared with the endothelial cell density determined by each eye bank.

MAIN OUTCOME MEASURES

Evaluation of image quality and accuracy of endothelial cell density.

RESULTS

Of 688 donor endothelial images submitted by 23 eye banks, 663 (96%) were analyzable (excellent, 40 [6%]; good, 302 [44%]; fair, 321 [47%]), and 25 (4%) were unanalyzable by reading center standards. In situ retrieval and greater epithelial exposure correlated with a higher image quality grading. The eye bank-determined endothelial cell density of 434 of the 663 (65%) analyzable images were within 10% of the endothelial cell density determined by the reading center, whereas 185 (28%) were more than 10% higher and 44 (7%) were more than 10% lower. Greater variation in endothelial cell density between the eye banks and the reading center was observed with shorter time of death to preservation, presence of an epithelial defect, folds in Descemet's membrane, lower image quality, and the use of fixed-frame or center method endothelial cell density analysis.

CONCLUSIONS

Overall, donor endothelial specular image quality and accuracy of endothelial cell density determination were good. However, the data suggest that factors that may affect image quality and contribute to variation in interpretation of the endothelial cell density should be addressed, because the donor endothelial cell density is an important parameter for assessing long-term corneal graft survival.

Activation of toll-like receptor (TLR)2, TLR4, and TLR9 in the mammalian cornea induces MyD88-dependent corneal inflammation

PURPOSE

Toll-like receptors (TLRs), which recognize microbial products, have an important role in the host innate immune response. The purpose of the present study was to determine whether activation of these receptors leads to development of keratitis and to assess the role of the common adaptor molecule myeloid differentiation factor-88 (MyD88).

METHODS

Corneal epithelium of C57BL/6, TLR2(-/-), TLR9(-/-), and MyD88(-/-) mice was abraded and treated with Pam(3)Cys, LPS, or CpG DNA, which bind TLR2, -4, and -9, respectively, and neutrophil recruitment to the corneal stroma, development of corneal haze, and chemokine production were measured.

RESULTS

Activation of TLR2 and -9 stimulated neutrophil recruitment to the corneal stroma of C57BL/6 mice, but not TLR2(-/-) or -9(-/-) mice, respectively. In marked contrast, neutrophil migration to the corneal stroma of MyD88(-/-) mice challenged with Pam(3)Cys, LPS, or CpG DNA was completely ablated. Activation of TLR2, -4, and -9 also caused a significant increase in corneal thickness and haze, indicative of disruption of corneal clarity; however, this response was ablated in MyD88(-/-) mice, which were not significantly different from untreated corneas. Production of CXC chemokines MIP-2 and KC, which mediate neutrophil recruitment to the corneal stroma, was elevated in the corneal epithelium and stroma of control, but not MyD88(-/-) mice.

CONCLUSIONS

Together, these findings demonstrate that the corneal epithelium has functional TLR2 and -9, and that TLR2, -4, and -9 signal through MyD88. This pathway is therefore likely to have an important role in the early events leading to microbial keratitis.

Late-Stage Progressive Corneal Astigmatism After Penetrating Keratoplasty for Keratoconus

PURPOSE

Progressive corneal astigmatism occurring at least 10 years after penetrating keratoplasty for keratoconus is a late-phase complication of surgery. This report characterizes this condition in a series of patients from three corneal referral centers in the United States.

METHODS

Charts were retrospectively reviewed which met the following criteria: penetrating keratoplasty performed for keratoconus at least 10 years ago, keratometry or simulated keratometry from topography as well as manifest refraction recorded at least 6 months after the last suture removal ("baseline"), and an increase in corneal astigmatism of at least three D over baseline recorded at least 5 years later. Patients who had any other corneal or intraocular surgery performed were excluded.

RESULTS

Data from 15 patients (11 males and 4 females) who had penetrating keratoplasties performed by 8 different surgeons are included in this descriptive series. Postoperative follow-up averaged 17.27 years (range 11-24 years). The average donor button size was 7.83 mm (range 7.25-8.5 mm). Baseline corneal astigmatism was obtained an average of 5.2 years after penetrating keratoplasty (range 1.5-16 years) and was on average 3.57 +/- 1.8 D (10 with-the-rule [WTR], 3 against-the-rule [ATR], 2 oblique). Corneal astigmatism significantly increased to an average of 11.23 +/- 3.56 D (range 8.00-19.37 D, P < 0.0001) and most astigmatism was regular and WTR (9 WTR, 3 ATR, 3 oblique) 15.3 years (range 10-22 years) after surgery. Inferior steepening on topography was often noted, even those with oblique and ATR axes.

CONCLUSIONS

High, late-stage, regular astigmatism after penetrating keratoplasty for keratoconus is described in a series of patients occurring at least 10 years after surgery. Possible mechanisms of this progressive astigmatism are recurrence of keratoconus in the graft, progressive corneal thinning of the host cornea, or progressive misalignment of the graft-host interface over time.

Rapid response of cystoid macular edema related to Nd:YAG laser capsulotomy to 0.5% ketorolac

A 68-year-old woman who had had cataract surgery several years previously presented with decreasing visual acuity and posterior capsular opacification. She underwent an Nd:YAG laser capsulotomy, but developed decreased visual acuity secondary to cystoid macular edema 2 months after the procedure. She was immediately administered 0.5% ketorolac drops. Several days after initiating treatment, she noted an improvement in her vision. Eight days later, her vision had improved from 20/400 to 20/60. Three weeks later, her vision returned to her baseline of 20/30 and a fluorescein angiogram showed resolution of the edema. This may indicate that cystoid macular edema related to Nd:YAG laser capsulotomy is caused by prostaglandin release, and that it may be responsive to topical nonsteroidal drops.

IL-4 and IL-13 regulation of ICAM-1 expression and eosinophil recruitment in Onchocerca volvulus keratitis

PURPOSE

The presence of eosinophilic granulocytes in ocular tissue is a hallmark of the host response to environmental and parasite allergens. Using a mouse model of Onchocerca volvulus-mediated keratitis (river blindness), the present study examined the role of the cytokines interleukin (IL)-4 and IL-13 in regulating recruitment of eosinophils to the cornea through expression of intercellular cell adhesion molecule (ICAM)-1.

METHODS

C57BL/6 mice received an intrastromal injection of recombinant IL-4 and IL-13 (rIL-4 and IL-13) or were immunized by subcutaneous injection prior to receiving an intrastromal injection of a soluble O. volvulus extract. Expression of ICAM-1 and recruitment of eosinophils to the cornea were monitored by immunohistochemistry.

RESULTS

Expression of ICAM-1 was elevated after injection of rIL-4 or IL-13 together with recombinant tumor necrosis factor (rTNF)-alpha. Conversely, expression of ICAM-1 in O. volvulus-mediated keratitis was significantly reduced after subconjunctival injection of a monoclonal antibody (mAb) to IL-4 or IL-13. In addition, combined in vivo neutralization of IL-4 and IL-13 inhibited recruitment of eosinophils, but not of neutrophils, to the corneal stroma.

CONCLUSIONS

These findings demonstrate that expression of ICAM-1 and recruitment of eosinophils to the cornea are tightly regulated by IL-4 and IL-13, and indicate that these cytokines are a potential target for immune intervention in ocular allergy and parasitic infections of the eye.

Regulation of endotoxin-induced keratitis by PECAM-1, MIP-2, and toll-like receptor 4

PURPOSE

Bacterial lipopolysaccharide (LPS, endotoxin) is a potent stimulator of inflammatory responses and is likely to contribute to microbial keratitis and to the pathogenesis of sterile corneal ulcers. The purpose of the present study was to identify specific mediators of endotoxin-induced keratitis.

METHODS

The corneal epithelium of BALB/c, C3H/HeJ, and C3H/HeN mice was abraded, and Pseudomonas aeruginosa endotoxin (10 microg in 1 microL) was added. Stromal thickness and haze were measured by in vivo scanning confocal microscopy, and neutrophil recruitment determined by immunohistochemistry.

RESULTS

Pseudomonas endotoxin induced a significant increase in stromal thickness and haze compared with untreated control corneas at each time point examined, and the severity coincided with neutrophil infiltration into the corneal stroma. Furthermore, systemic depletion of neutrophils completely abrogated endotoxin-induced increases in stromal thickness and haze, indicating an essential role for these cells. Expression of platelet endothelial cell adhesion molecule (PECAM)-1 on vascular endothelium and production of macrophage inflammatory protein (MIP)-2 in the corneal stroma were also significantly elevated after exposure to endotoxin, and antibody blockade inhibited neutrophil recruitment to the cornea and abrogated endotoxin-induced increases in stromal thickness and haze. In LPS-hyporesponsive C3H/HeJ mice, PECAM-1 and MIP-2 were not upregulated after exposure to endotoxin, and endotoxin-induced keratitis did not develop in these mice.

CONCLUSIONS

These findings demonstrate that endotoxin-induced keratitis is regulated by toll-like receptor-4 (TLR4)-dependent expression of PECAM-1 and MIP-2, which are essential for recruitment of neutrophils to this site and for development of endotoxin-induced stromal disease.

The role of endosymbiotic Wolbachia bacteria in the pathogenesis of river blindness

Parasitic filarial nematodes infect more than 200 million individuals worldwide, causing debilitating inflammatory diseases such as river blindness and lymphatic filariasis. Using a murine model for river blindness in which soluble extracts of filarial nematodes were injected into the corneal stroma, we demonstrated that the predominant inflammatory response in the cornea was due to species of endosymbiotic Wolbachia bacteria. In addition, the inflammatory response induced by these bacteria was dependent on expression of functional Toll-like receptor 4 (TLR4) on host cells.

Comparison of the corneal effects of latanoprost, fixed combination latanoprost-timolol, and timolol: A double-masked, randomized, one-year study

OBJECTIVE

To compare the long-term effects on corneal endothelial cell density and corneal thickness of latanoprost and the fixed combination latanoprost-timolol to timolol.

DESIGN

Double-masked, randomized, prospective, multicenter clinical trial.

PARTICIPANTS

Three hundred sixty-nine subjects with bilateral ocular hypertension or open-angle glaucoma who had a baseline central corneal endothelial cell density of at least 1500 cells/mm(2), central corneal thickness of less than 0.68 mm, no corneal pathologic condition on slit-lamp examination, and intraocular pressure of less than 22 mmHg after a 3-week run-in on timolol, 0.5%, once daily were included.

INTERVENTION

Subjects were randomly assigned to treatment with latanoprost 0.005% (n = 127), fixed-combination latanoprost 0.005%-timolol 0.5% (FC, n = 116), or timolol 0.5% (n = 126) one drop, once daily in the morning for 1 year. All subjects were treated in both eyes. Specular microscopy and ultrasonic pachymetry were performed before treatment, and after 6 and 12 months of treatment.

MAIN OUTCOME MEASURES

Mean percent change in central endothelial cell density and central corneal thickness after 1 year of treatment.

RESULTS

For both corneal endothelial cell density and corneal thickness, the mean percent changes from baseline were similar in all three treatment groups. Mean percent endothelial cell change at 1 year from baseline for latanoprost, FC, and timolol was 0.3 +/- 2.2%, 0.1 +/- 1.8%, 0.0 +/- 2.5% (mean +/- standard deviation; 95% confidence interval: latanoprost vs timolol -0.2-1.0; FC vs timolol -0.4-0.7) and mean percent change in corneal thickness was -1.1 +/- 2.5%, -1.0 +/- 2.0%, 0.2 +/- 3.1%, respectively.

CONCLUSIONS

Latanoprost and FC are equivalent to timolol regarding long-term corneal effects after 1 year of treatment.

Impaired eosinophil recruitment to the cornea in P-selectin-deficient mice in Onchocerca volvulus keratitis (River blindness)

PURPOSE

A murine model of helminth-induced keratitis (river blindness) that is characterized by a biphasic recruitment of neutrophils (days 1-3) and eosinophils (days 3+) to the cornea has been developed. The purpose of this study was to determine the relative contribution of P- and E-selectin in recruitment of these inflammatory cells from limbal vessels to the corneal stroma.

METHODS

P- and E-selectin gene knockout (-/-) mice were immunized with antigens extracted from the parasitic helminth Onchocerca volvulus. One week after the last immunization, parasite antigens were injected directly into the corneal stroma. Mice were killed on days 1 and 3 postchallenge, and eyes were immunostained with either anti-eosinophil major basic protein (MBP) or with anti-neutrophil Ab. The number of cells in the cornea was determined by direct counting.

RESULTS

Recruitment of eosinophils to the cornea was significantly impaired in P-selectin(-/-) mice (63.9% fewer eosinophils on day 1 [P: = 0.0015], and 61% fewer on day 3 [P: < 0.0001]) compared with control C57BL/6 mice. In contrast, P-selectin deficiency had no effect on neutrophil recruitment to the cornea. There was no inhibition of eosinophil and neutrophil migration to the corneas of E-selectin(-/-) mice, indicating that there is no direct role for this adhesion molecule in helminth-induced keratitis.

CONCLUSIONS

The present study demonstrates that P-selectin is an important mediator of eosinophil recruitment to the cornea. P-selectin interactions may therefore be potential targets for immunotherapy in eosinophil-mediated ocular inflammation.

Corneal opacity in lumican-null mice: defects in collagen fibril structure and packing in the posterior stroma

PURPOSE

Gene targeted lumican-null mutants (lum(tm1sc)/lum(tm1sc)) have cloudy corneas with abnormally thick collagen fibrils. The purpose of the present study was to analyze the loss of transparency quantitatively and to define the associated corneal collagen fibril and stromal defects.

METHODS

Backscattering of light, a function of corneal haze and opacification, was determined regionally using in vivo confocal microscopy in lumican-deficient and wild-type control mice. Fibril organization and structure were analyzed using transmission electron microscopy. Biochemical approaches were used to quantify glycosaminoglycan contents. Lumican distribution in the cornea was elucidated immunohistochemically. RESULTS; Compared with control stromas, lumican-deficient stromas displayed a threefold increase in backscattered light with maximal increase confined to the posterior stroma. Confocal microscopy through-focusing (CMTF) measurement profiles also indicated a 40% reduction in stromal thickness in the lumican-null mice. Transmission electron microscopy indicated significant collagen fibril abnormalities in the posterior stroma, with the anterior stroma remaining relatively unremarkable. The lumican-deficient posterior stroma displayed a pronounced increase in fibril diameter, large fibril aggregates, altered fibril packing, and poor lamellar organization. Immunostaining of wild-type corneas demonstrated high concentrations of lumican in the posterior stroma. Biochemical assessment of keratan sulfate (KS) content of whole eyes revealed a 25% reduction in KS content in the lumican-deficient mice.

CONCLUSIONS

The structural defects and maximum backscattering of light clearly localized to the posterior stroma of lumican-deficient mice. In normal mice, an enrichment of lumican was observed in the posterior stroma compared with that in the anterior stroma. Taken together, these observations indicate a key role for lumican in the posterior stroma in maintaining normal fibril architecture, most likely by regulating fibril assembly and maintaining optimal KS content required for transparency.

An Essential Role for Antibody in Neutrophil and Eosinophil Recruitment to the Cornea: B Cell-Deficient (μMT) Mice Fail to Develop Th2-Dependent, Helminth-Mediated Keratitis

Invasion of the corneal stroma by neutrophils and eosinophils and subsequent degranulation disrupts corneal clarity and can result in permanent loss of vision. In the current study, we used a model of helminth-induced inflammation to demonstrate a novel role for Ab in mediating recruitment of these inflammatory cells to the central cornea. C57BL/6 and B cell-deficient (μMT) mice were immunized s.c. and injected intrastromally with Ags from the parasitic helminth Onchocerca volvulus (which causes river blindness). C57BL/6 mice developed pronounced corneal opacification, which was associated with an Ag-specific IL-5 response and peripheral eosinophilia, temporal recruitment of neutrophils and eosinophils from the limbal vessels to the peripheral cornea and subsequent migration to the central cornea. In contrast, the corneas of μMT mice failed to develop keratitis after intrastromal injection of parasite Ags unless Ags were injected with immune sera. Eosinophils were recruited from the limbal vessels to the peripheral cornea in μMT mice, but failed to migrate to the central cornea, whereas neutrophil recruitment was impaired at both stages. With the exception of IL-5, T cell responses and peripheral eosinophils were not significantly different between C57BL/6 and μMT mice. Taken together, these findings not only demonstrate that Ab is required for the development of keratitis, but also show that recruitment of neutrophils to the cornea is Ab-dependent, whereas eosinophil migration is only partially dependent upon Ab interactions.

An essential role for antibody in neutrophil and eosinophil recruitment to the cornea: B cell-deficient (microMT) mice fail to develop Th2-dependent, helminth-mediated keratitis

Invasion of the corneal stroma by neutrophils and eosinophils and subsequent degranulation disrupts corneal clarity and can result in permanent loss of vision. In the current study, we used a model of helminth-induced inflammation to demonstrate a novel role for Ab in mediating recruitment of these inflammatory cells to the central cornea. C57BL/6 and B cell-deficient (microMT) mice were immunized s. c. and injected intrastromally with Ags from the parasitic helminth Onchocerca volvulus (which causes river blindness). C57BL/6 mice developed pronounced corneal opacification, which was associated with an Ag-specific IL-5 response and peripheral eosinophilia, temporal recruitment of neutrophils and eosinophils from the limbal vessels to the peripheral cornea and subsequent migration to the central cornea. In contrast, the corneas of microMT mice failed to develop keratitis after intrastromal injection of parasite Ags unless Ags were injected with immune sera. Eosinophils were recruited from the limbal vessels to the peripheral cornea in microMT mice, but failed to migrate to the central cornea, whereas neutrophil recruitment was impaired at both stages. With the exception of IL-5, T cell responses and peripheral eosinophils were not significantly different between C57BL/6 and microMT mice. Taken together, these findings not only demonstrate that Ab is required for the development of keratitis, but also show that recruitment of neutrophils to the cornea is Ab-dependent, whereas eosinophil migration is only partially dependent upon Ab interactions.

Pleiotropic skeletal and ocular phenotypes of the mouse mutation congenital hydrocephalus (ch/Mf1) arise from a winged helix/forkhead transcriptionfactor gene

Congenital hydrocephalus is an etiologically diverse, poorly understood, but relatively common birth defect. Most human cases are sporadic with familial forms showing considerable phenotypic and etiologic heterogeneity. We have studied the autosomal recessive mouse mutation congenital hydrocephalus ( ch ) to identify candidate human hydrocephalus genes and their modifiers. ch mice have a congenital, lethal hydrocephalus in association with multiple developmental defects, notably skeletal defects, in tissues derived from the cephalic neural crest. We utilized positional cloning methods to map ch in the vicinity of D13Mit294 and confirm that the ch phenotype is caused by homozygosity for a nonsense mutation in a gene encoding a winged helix/forkhead transcription factor ( Mf1 ). Based on linked genetic markers, we performed detailed phenotypic characterization of mutant homozygotes and heterozygotes to demonstrate the pleiotropic effects of the mutant gene. Surprisingly, ch heterozygotes have the glaucoma-related distinct phenotype of multiple anterior segment defects resembling Axenfeld-Rieger anomaly. We also localized a second member of this gene family ( Hfh1 ), a candidate for other developmental defects, approximately 470 kb proximal to Mf1.

Comparison of corneal endothelial image analysis by Konan SP8000 noncontact and Bio-Optics Bambi systems

PURPOSE

Compare corneal endothelial image analysis by Konan SP8000 and Bio-Optics Bambi image-analysis systems.

METHODS

Corneal endothelial images from 98 individuals (191 eyes), ranging in age from 4 to 87 years, with a normal slit-lamp examination and no history of ocular trauma, intraocular surgery, or intraocular inflammation were obtained by the Konan SP8000 noncontact specular microscope. One observer analyzed these images by using the Konan system and a second observer by using the Bio-Optics Bambi system. Three methods of analyses were used: a fixed-frame method to obtain cell density (for both Konan and Bio-Optics Bambi) and a "dot" (Konan) or "corners" (Bio-Optics Bambi) method to determine morphometric parameters.

RESULTS

The cell density determined by the Konan fixed-frame method was significantly higher (157 cells/mm2) than the Bio-Optics Bambi fixed-frame method determination (p<0.0001). However, the difference in cell density, although still statistically significant, was smaller and reversed comparing the Konan fixed-frame method with both Konan dot and Bio-Optics Bambi comers method (-74 cells/mm2, p<0.0001; -55 cells/mm2, p<0.0001, respectively). Small but statistically significant morphometric analyses differences between Konan and Bio-Optics Bambi were seen: cell density, +19 cells/mm2 (p = 0.03); cell area, -3.0 microm2 (p = 0.008); and coefficient of variation, +1.0 (p = 0.003). There was no statistically significant difference between these two methods in the percentage of six-sided cells detected (p = 0.55).

CONCLUSION

Cell densities measured by the Konan fixed-frame method were comparable with Konan and Bio-Optics Bambi's morphometric analysis, but not with the Bio-Optics Bambi fixed-frame method. The two morphometric analyses were comparable with minimal or no differences for the parameters that were studied. The Konan SP8000 endothelial image-analysis system may be useful for large-scale clinical trials determining cell loss; its noncontact system has many clinical benefits (including patient comfort, safety, ease of use, and short procedure time) and provides reliable cell-density calculations.

A double-masked, randomized, 1-year study comparing the corneal effects of dorzolamide, timolol, and betaxolol. Dorzolamide Corneal Effects Study Group

OBJECTIVE

To compare the long-term effects of dorzolamide hydrochloride (Trusopt, Merck and Co Inc, White-house Station, NJ), timolol maleate, and betaxolol hydrochloride on corneal endothelial cell density and corneal thickness.

METHODS

This 1-year multicenter study was conducted in 298 patients with ocular hypertension or open-angle glaucoma who had a baseline central corneal endothelial cell density greater than 1500 cells/mm2 and central corneal thickness less than 0.68 mm in each eye. Patients were randomized to 0.5% betaxolol twice daily, 0.5% timolol twice daily, or 2.0% dorzolamide 3 times daily. Specular microscopy and ultrasonic pachymetry of the central cornea was performed at baseline and 6 and 12 months following institution of therapy. Endothelial cell densities were determined by a single masked observer.

RESULTS

The mean percent changes from baseline for both outcome measures were similar in all 3 treatment groups at both 6 and 12 months. After 1 year of treatment, the mean percent loss in endothelial cell density from baseline was 3.6%, 4.5%, and 4.2% for the dorzolamide, timolol, and betaxolol groups, respectively. The mean percent change from baseline for corneal thickness was 0.47%, -0.25%, and 0.39% for the dorzolamide, timolol, and betaxolol groups, respectively.

CONCLUSIONS

Dorzolamide is equivalent to timolol and betaxolol in terms of the change in central endothelial cell density and thickness after 1 year of therapy. All 3 treatments exhibit good long-term corneal tolerability in patients with normal corneas at baseline.

The role of eosinophils and neutrophils in helminth-induced keratitis

PURPOSE

Intrastromal injection of mice with antigens from the parasitic helminth that causes river blindness (Onchocerca volvulus) induces eosinophil recruitment to the corneal stroma at the time of maximum corneal opacification and neovascularization. The present study was conducted to examine the role of eosinophils and neutrophils in onchocercal keratitis in control C57Bl/6 mice and in interleukin-5 gene knockout (IL-5(-/-)) mice.

METHODS

C57Bl/6 and IL-5(-/-) mice were immunized subcutaneously and injected intrastromally with soluble O. volvulus antigens. Mice were killed at various times thereafter. Development of keratitis was assessed by slit lamp examination, and inflammatory cells in the cornea were identified by immunohistochemistry.

RESULTS

A biphasic recruitment of inflammatory cells was observed in C57Bl/6 mice; neutrophils predominated during the first 72 hours after intrastromal injection and subsequently declined, whereas eosinophil recruitment increased as time elapsed and comprised the majority (90%) of cells in the cornea by day 7. In contrast, neutrophils were the predominant inflammatory cells in IL-5(-/-) mice at early and late time points and were associated with extensive stromal damage and corneal opacification and neovascularization. Eosinophils were not detected in these mice at any time.

CONCLUSIONS

In the absence of eosinophils, neutrophils can mediate keratitis induced by helminth antigens. Together with the early neutrophilic infiltrate in control animals, these observations indicate that neutrophils have an important role in onchocercal keratitis.

Lumican regulates collagen fibril assembly: skin fragility and corneal opacity in the absence of lumican

Lumican, a prototypic leucine-rich proteoglycan with keratan sulfate side chains, is a major component of the cornea, dermal, and muscle connective tissues. Mice homozygous for a null mutation in lumican display skin laxity and fragility resembling certain types of Ehlers-Danlos syndrome. In addition, the mutant mice develop bilateral corneal opacification. The underlying connective tissue defect in the homozygous mutants is deregulated growth of collagen fibrils with a significant proportion of abnormally thick collagen fibrils in the skin and cornea as indicated by transmission electron microscopy. A highly organized and regularly spaced collagen fibril matrix typical of the normal cornea is also missing in these mutant mice. This study establishes a crucial role for lumican in the regulation of collagen assembly into fibrils in various connective tissues. Most importantly, these results provide a definitive link between a necessity for lumican in the development of a highly organized collagenous matrix and corneal transparency.

Topical diclofenac sodium in the management of anesthetic abuse keratopathy

PURPOSE

To report a case of anesthetic abuse keratopathy and to suggest the use of topical diclofenac sodium in the management of this disorder.

METHOD

Narcotics and topical diclofenac were used to control pain in a patient who developed a corneal ulcer after abusing topical anesthetics.

RESULT

After the institution of topical diclofenac, the patient reported substantial improvement in comfort and less reliance on narcotic agents for analgesia.

CONCLUSION

We found topical diclofenac to be useful in controlling pain in this patient with anesthetic abuse keratopathy.

Ex vivo phosphorus magnetic resonance spectroscopy on eye bank corneas and corneal metabolic health

BACKGROUND

Since a potential exists for untoward effects on the cornea from the high magnetic fields and radio-frequency energies, and the further manipulation required for phosphorus-31 magnetic resonance spectroscopy (31P-MRS), we determined the effects of this technology on tissues using paired human corneas (n = 4) meeting criteria acceptable for transplantation.

METHODS

Slit-lamp biomicroscopy, pachometry, specular microscopy, and redux fluorophotometry were performed on all corneas. One cornea of each pair was examined (< 30 min) by 31P-MRS. Following 31P-MRS, slit-lamp biomicroscopy, pachometry, and redox fluorophotometry were again performed.

RESULTS

Data tabulated included the 31P energy modulus (1.37 +/- 0.28), the ATP/Pi (2.92 +/- 0.59) and SP/Pi (0.76 +/- 0.04) ratios, and the intracorneal pH (7.24 +/- 0.09).

CONCLUSION

Since there were no significant differences in slit-lamp biomicroscopy, endothelial density and morphometry, cell counts, and pachometric and redox fluorophotometric measurements between corneas of each pair before and after 31P-MRS analysis, it was concluded that there was no detectable metabolic damage secondary to such analysis. This study suggests that MRS analysis of human eye-bank tissues does not damage the cornea metabolically and may provide a practical evaluation of the health of the cornea at the biochemical level.

Pleomorphism of stromal eosinophils in murine experimental onchocercal keratitis

Onchocercal keratitis (river blindness) is one of the leading worldwide causes of blindness. Light microscopic analysis of human specimens and corneal tissue from experimental models has implicated the eosinophil as an important cell in the inflammatory response. Our previous studies in experimental murine onchocercal keratitis have demonstrated that the inflammatory infiltrate is composed primarily of eosinophils displaying ring shaped or bilobed nuclei. However, a number of cells were not characterizable by light microscopy, presumably due to mechanical distortion. To more fully characterize the inflammatory cell infiltrate, we examined corneal specimens by transmission electron microscopy. In addition to typical eosinophils with bilobed and ring shaped nuclei, this approach revealed cells with variable nuclear morphology and cell shape which contained the dense cored granules characteristic of eosinophils. Hence, the degree of pleomorphism of eosinophils is broader than appreciated and underscores the importance of this cell in experimental murine onchocercal keratitis.

IL-12 exacerbates helminth-mediated corneal pathology by augmenting inflammatory cell recruitment and chemokine expression

Corneal inflammation (keratitis) is a major cause of visual impairment in Onchocerca volvulus infection. Previous studies showed that onchocercal keratitis can be induced in mice following s.c. immunization and intracorneal injection with soluble O. volvulus Ags (OvAg), and that the inflammatory response is dependent on T cells and IL-4. Since recombinant IL-12 impairs IL-4-dependent, Th2-mediated responses in other parasitic infections and in models of allergic asthma, the present study was undertaken to determine the effect of IL-12 on onchocercal keratitis. Mice were injected i.p. with IL-12 or saline at the time of initial sensitization to OvAg. Surprisingly, IL-12 treatment caused significant exacerbation of corneal pathology, which was associated with increased eosinophil and mononuclear cell infiltration into the corneal stroma. Consistent with the well-documented effect of IL-12 on Th1 cell development, corneas of IL-12-treated animals had elevated expression of the Th1 cytokine IFN-gamma and diminished expression of the Th2 cytokines IL-4, IL-5, IL-10, and IL-13. However, corneas from these animals also had marked elevation of alpha- and beta-chemokines known to be active on eosinophils and mononuclear cells, including IFN-gamma-inducible protein (IP)-10, macrophage inflammatory protein-1alpha, macrophage inflammatory protein-1beta, JE/monocyte chemotactic protein-1, RANTES (regulated upon activation, normal T expressed and secreted), and eotaxin. Together, these data indicate that IL-12 exacerbates OvAg-mediated corneal pathology by enhancing chemokine expression and recruitment of inflammatory cells.

IL-12 exacerbates helminth-mediated corneal pathology by augmenting inflammatory cell recruitment and chemokine expression

Corneal inflammation (keratitis) is a major cause of visual impairment in Onchocerca volvulus infection. Previous studies showed that onchocercal keratitis can be induced in mice following s.c. immunization and intracorneal injection with soluble O. volvulus Ags (OvAg), and that the inflammatory response is dependent on T cells and IL-4. Since recombinant IL-12 impairs IL-4-dependent, Th2-mediated responses in other parasitic infections and in models of allergic asthma, the present study was undertaken to determine the effect of IL-12 on onchocercal keratitis. Mice were injected i.p. with IL-12 or saline at the time of initial sensitization to OvAg. Surprisingly, IL-12 treatment caused significant exacerbation of corneal pathology, which was associated with increased eosinophil and mononuclear cell infiltration into the corneal stroma. Consistent with the well-documented effect of IL-12 on Th1 cell development, corneas of IL-12-treated animals had elevated expression of the Th1 cytokine IFN-gamma and diminished expression of the Th2 cytokines IL-4, IL-5, IL-10, and IL-13. However, corneas from these animals also had marked elevation of alpha- and beta-chemokines known to be active on eosinophils and mononuclear cells, including IFN-gamma-inducible protein (IP)-10, macrophage inflammatory protein-1alpha, macrophage inflammatory protein-1beta, JE/monocyte chemotactic protein-1, RANTES (regulated upon activation, normal T expressed and secreted), and eotaxin. Together, these data indicate that IL-12 exacerbates OvAg-mediated corneal pathology by enhancing chemokine expression and recruitment of inflammatory cells.

Onchocerca volvulus-mediated keratitis: cytokine production by IL-4-deficient mice

Corneal inflammation similar to human onchocercal keratitis can be induced in mice by subcutaneous immunization of a soluble extract of Onchocerca volvulus (OvAg) followed by direct injection of OvAg into the corneal stroma. Previous studies have shown that corneal pathology is associated with increased systemic and corneal Th2 cytokine expression and that IL-4 gene knockout (IL-4-/-) mice develop less severe or no O. volvulus-mediated keratitis. The current study examined the contribution of Th2 cytokines to the diminished OvAg-induced corneal immunopathology observed in IL-4-/- mice. IL-4-/- mice (129Sv x C57B1/6), wild-type F2 littermates (IL-4+/+), and C57B1/6 mice were sensitized by repeated subcutaneous immunization with OvAg. Ten days after the final immunization, mice were sacrificed, spleens were removed, and cells were incubated with OvAg. Cells from immunocompetent C57B1/6 and IL-4+/+ mice produced IL-4 and IL-5, but no IFN-gamma, whereas cells from IL-4-/- mice had elevated IFN-gamma and no IL-4. Interestingly, cells from these animals produced levels of IL-5 protein equivalent to those of C57B1/6 and IL-4+/+ mice. To determine cytokine production in corneas during the onset of onchocercal keratitis, OvAg-immunized mice were injected intracorneally with OvAg, and cytokine gene expression in the cornea was determined by RT-PCR. Temporal analysis of cytokine gene expression in corneas of immunocompetent mice showed that the Th2-associated cytokines IL-4, IL-5, IL-10, and IL-13 were produced within 1 day of intrastromal injection, with sustained elevations for 10 days. Maximal IFN-gamma mRNA levels were not detected until Day 10. This was in contrast to IL-4-/- mice in which IFN-gamma appeared at Day 1 and remained elevated for at least 10 days. Moreover, in corneas from IL-4-/- mice, all Th2 cytokines with the exception of IL-4 were up-regulated and expressed with kinetics similar to that of IL-4+/+ littermates. Histologically, corneas from IL-4-/- mice were less edematous and contained fewer eosinophils and other inflammatory cells than those from immunocompetent controls. As there was no difference in peripheral eosinophil levels, these data indicate that the diminished severity of onchocercal keratitis in IL-4-/- mice is not due to failure to develop systemic or local Th2 cytokine responses or to produce eosinophils, but that IL-4 may be involved in recruitment of eosinophils and other inflammatory cells into the corneal stroma.

Interleukin 4 and T helper type 2 cells are required for development of experimental onchocercal keratitis (river blindness)

Inflammation of the corneal stroma (stromal keratitis) is a serious complication of infection with the nematode parasite Onchocerca volvulus. Because stromal keratitis is believed to be immunologically mediated in humans, we used a murine model to examine the role of T cells and T helper cell cytokines in the immunopathogenesis of these eye lesions. BALB/c mice immunized subcutaneously and injected intrastromally with soluble O. volvulus antigens (OvAg) developed pronounced corneal opacification and neovascularization. The corneal stroma was edematous and contained numerous eosinophils and mononuclear cells. Stromal keratitis in immunized mice was determined to be T cell dependent based on the following observations: (a) T cell-deficient nude mice immunized and injected intrastromally with OvAg fail to develop corneal pathology; and (b) adoptive transfer of spleen cells from OvAg-immunized BALB/c mice to naive nude mice before intrastromal injection of OvAg results in development of keratitis. OvAg-stimulated lymph node and spleen cell cytokine production was dependent on CD4 cells and included interleukin (IL)-4 and IL-5, but not interferon gamma, indicating a predominant T helper type 2 cell-like response. Inflamed corneas from immunized BALB/c mice and from reconstituted nude mice had greatly elevated CD4 and IL-4 gene expression compared with interferon gamma. Mice in which the IL-4 gene was disrupted failed to develop corneal disease, demonstrating that IL-4 is essential in the immunopathogenesis of O. volvulus-mediated stromal keratitis.

Characterization of native pathogenic antigens of Onchocerca volvulus: identification of high molecular mass protein antigens eliciting interstitial keratitis in a guinea pig model

Sclerosing keratitis is the predominant cause of blindness due to onchocerciasis which is a major human parasitic disease caused by the filarial parasite Onchocerca volvulus. In the present investigation, native pathogenic antigens of O. volvulus which are particularly potent in causing interstitial keratitis were characterized utilizing a guinea pig model. Following demonstration of the protein nature of these antigens using pronase digestion, the crude O. volvulus antigen extract was subjected to stepwise procedures of protein purification. At each stage of purification, pooled antigen fractions were injected into one cornea of presensitized guinea pigs followed by clinical evaluation of stromal inflammation and vascularization at different intervals of time after intrastromal challenge. Initial purification of the pathogenic antigens was carried out in the following order: molecular sieve chromatography on Bio-gel A-5m. anion exchange chromatography on Mono Q followed by DEAE-Sepharose CL-6B and cation exchange chromatography on Mono S. Two out of six different pools from the Mono S column (pool a eluted unbound at 10 mM-NaCl and pool e eluted between 130 mM and 475 mM-NaCl) were found to be most pathogenic. Further purification of Mono S pool a and pool e separately by gel filtration chromatography using Superose 12 demonstrated that the fractions which were most potent in inducing interstitial keratitis contained proteins with approximate molecular masses between 100 and 200 kDa. These results show that minor subfractions of total crude antigens of O. volvulus are largely responsible for induction of experimental interstitial keratitis. We have demonstrated the presence of these antigens in O. volvulus microfilariae by their cross-reactivities with anti-microfilarial antibodies, and hence the relevance of the purified antigens to ocular onchocerciasis in man since sclerosing keratitis is associated with invasion of the cornea by O. volvulus microfilariae. Isolation of these two pathogenic antigen pools represents the practical limits of purification and subsequent animal experiments possible with the available amounts of native parasite material obtained from infected human individuals in the absence of a suitable non-human host or of an in vitro culture system for O. volvulus.

The effects of age on phosphatic metabolites of the human cornea

Phosphatic metabolites from human corneas, pooled into 7 decades ranging from ages < 1 year through 79 years, were quantitated using phosphorus-31 magnetic resonance (31P MR) spectroscopy. Relative concentrations of phosphorus-containing compounds measured included the low-energy metabolites [phosphomonoesters (PME), inorganic orthophosphate (Pi), phosphodiesters (glycerol 3-phosphorylethanolamine and glycerol 3-phosphorylcholine)] and the high-energy metabolites [phosphocreatine (PCr), adenosine triphosphate (ATP), adenosine diphosphate (ADP), nucleosidediphosphosugars and the dinucleotides]. Significant linear changes attributable to age occur in the relative mole percentage decrease of phosphate concentrations of human corneal PME, PCr and ATP, and in the increase of Pi. Age-attributable rates of decrease in PME at -0.162 MPP/YR (mole percent phosphorus per year), PCr at -0.015 MPP/YR and ATP at -0.487 MPP/YR combined, approximate the rate of increase in Pi determined to be +0.729 MPP/YR. Of the indices computed from the human corneal spectral data, the ratios of ATP/Pi and PME/Pi and the tissue energy modulus were all found to decrease significantly with age. These changes in corneal phosphatic metabolites are indicative of an overall decline in high-energy metabolism with age.

Infiltration of CD4+ T cells into cornea during development of Onchocerca volvulus-induced experimental sclerosing keratitis in mice

Sclerosing keratitis is the major cause of blindness due to onchocerciasis caused by the parasite Onchocerca volvulus. Although the importance of T cells in the pathogenesis of onchocerciasis has been suggested, their precise role in onchocercal sclerosing keratitis has not yet been defined. Using immunohistological techniques and a murine model of onchocercal sclerosing keratitis, we have performed a temporal analysis of the inflammatory T cells infiltrating into the cornea at Days 4, 7, and 21 following intrastromal challenge with soluble O. volvulus antigens into presensitized mice. The maximum number of CD3+ T cells were observed in the corneal stroma at Day 21 when sclerosing keratitis was most severe. The majority (> 85%) of the CD3+ T cells were CD4+ at all time points. A few infiltrating cells bore IL-2 receptors indicating possible activation of a small fraction of the T cells. These results suggest that CD4+ T cells play an important role in onchocercal sclerosing keratitis.

Localization of the complement membrane attack complex inhibitor (CD59) in human conjunctiva and lacrimal gland

Recent studies have established that complement is present in the eye and participates in ocular defense. The mechanisms by which ocular tissues are protected from bystander injury arising from local activation of the cascade, however, have not been characterized. Decay accelerating factor (DAF or CD55) and the membrane inhibitor of reactive lysis (MIRL or CD59) are cell surface regulatory proteins that protect blood cells from uptake of autologous C3b and polymerization of autologous C9 on their surfaces. In previous studies, we found that DAF is expressed in high levels on corneal, conjunctival, and lacrimal gland acinar surfaces. In this study we assayed ocular and lacrimal gland tissues for CD59. Immunohistochemical analyses demonstrated large amounts of the protein the same locations. The presence of CD59 in these sites is consistent with the proposal that CD59 functions together with DAF in protecting ocular tissues from autologous complement-mediated injury.

Clinical evaluation of a computerized topography software method for fitting rigid gas permeable contact lenses

Computerized videokeratoscope software programs now have the ability to assist in the design of rigid gas permeable (RGP) contact lenses and simulate fluorescein patterns. We evaluated the performance of Computed Anatomy's Topographic Modeling System (TMS-1) and its Contact Lens Fitting Program (version 1.41) in fitting RGP lenses in 31 subjects. Computerized topographic analysis, balanced manifest refraction, slit lamp examination, and keratometry were performed. Initial lens parameters were ordered according to manufacturer's programmed recommendations for base curve, power, lens diameter, optic zone diameter, and edge lift. Final lens parameters were based on clinical performance. Lenses were recorded for base curve changes of 0.1 mm or more, power alterations of +/- 0.50 D or more, or for any alteration in diameter/optic zone. Twenty-seven patients were analyzed for all five recommended parameters. Thirteen of 27 patients (48%) required no parameter changes. Nine of 27 patients (33%) required one parameter change, four of 27 patients (15%) required two parameter changes, and one patient (4%) needed three parameters altered. The most prevalent change was a power alteration, required in nine of 27 patients (33%); however, comparisons of all initial to final parameters showed no statistically significant differences. Comparison of initial base curves to that which would have been chosen via standard keratometry also showed no significant difference. This study found the TMS-1 default lens recommendations to be clinically unacceptable. This system, however, could be an alternative method of initial lens selection if used to titrate a fit or if software enhancements are incorporated to account for lens movement and flexure.

Hypocomplementemic urticarial vasculitis syndrome in identical twins

Hypocomplementemic urticarial vasculitis syndrome (HUVS) is a syndrome of recurrent urticarial vasculitis, arthralgia/arthritis, and hypocomplementemia. Angioedema, ocular inflammation, glomerulonephritis, and obstructive lung disease are other clinical findings. Although the etiology of HUVS is unknown, its resemblance to systemic lupus erythematosus (SLE) suggests a similar pathogenesis. SLE is known to occur in identical twins. This is the first report of a pair of identical twins with HUVS. Concordance for HUVS in identical twins suggests that the pathogenesis of the disease involves abnormal genetic immunoregulation.

The effect of hEGF and insulin on corneal metabolism during Optisol storage

We examined the effect of the growth factors, human epidermal growth factor (hEGF) and insulin, on corneal metabolism during storage in Optisol, a chondroitin-sulfate-(CS)-based storage medium. Paired cat corneas, in either Optisol only or Optisol with growth factor(s), were analyzed using ex vivo 31P nuclear magnetic resonance, after storage for 1 week at 4 degrees C. Lysosomal enzyme release into the media at the end of the storage period also was measured fluorometrically. Both epithelial-intact and epithelial-denuded corneal pairs were examined for all conditions. Considering corneas having either intact epithelia or epithelium-denuded corneas, the addition of either growth factor alone to Optisol did not alter the relative corneal concentrations of five of the six phosphatic metabolite spectral bands measured or two metabolic ratios calculated from these bands. Phosphodiesters, however, were significantly lower in corneas stored in Optisol containing both hEGF and insulin (23%) than in corneas stored in Optisol alone (30%). Intracorneal pH was unaffected by the addition of growth factor(s). A significantly higher release of alpha-glucosidase and alpha-mannosidase was noted in those corneas stored in Optisol containing both hEGF and insulin. Optisol maintains high-energy phosphate corneal metabolism similar to other CS-based media, K-Sol and Chondroitin Sulfate Corneal Storage Medium (CSM). The addition of the growth factors hEGF and insulin to Optisol alters corneal metabolic activity during storage in a manner indicative of conserving corneal phospholipids.

Epidermal growth factor and insulin use in corneal preservation. Results of a multi-center trial. The Corneal Preservation Study Group

PURPOSE

The ability of DexSol medium, supplemented with two growth factors, human epidermal growth factor (hEGF) and human insulin, to improve long-term endothelial survival after penetrating keratoplasty was evaluated in a multi-center, randomized, prospective, double-masked clinical trial.

METHODS

Donor cornea pairs, one stored in DexSol and the other in DexSol with hEGF (10 ng/ml) and human insulin (10 micrograms/ml) (ProCell), were transplanted into 105 pairs of recipients matched by diagnosis and procedure and followed postoperatively for graft and endothelial survival.

RESULTS

No primary donor failures occurred in either group. Graft clarity did not differ between the ProCell and DexSol groups at all postoperative periods: 3 months (98% versus 99%), 6 months (94% versus 98%), and 1 year (95% versus 97%), respectively. Postoperative complications (e.g., glaucoma, rejection) occurred with comparable frequencies in both groups. Mean endothelial cell loss did not significantly differ between the ProCell and DexSol groups at 3 months (5.7% versus 5.1%), 6 months (8.1% versus 10.1%), and 1 year (12.3% versus 15.6%), respectively. Similarly, there were no clinically and statistically significant differences in other endothelial morphometric parameters.

CONCLUSIONS

The use of corneas stored in DexSol medium with added hEGF and insulin in corneal transplantation resulted in a safety and efficacy profile comparable with that observed in patients receiving DexSol-stored corneas; however, there were no clinically and statistically significant differences in postoperative endothelial morphometric parameters.